# Patent

## Title
Synthesis of terminal alkenes from internal alkenes and ethylene via olefin metathesis

## Abstract

This invention relates generally to olefin metathesis, and more particularly relates to the synthesis of terminal alkenes from internal alkenes using a cross-metathesis reaction catalyzed by a selected olefin metathesis catalyst. In one embodiment of the invention, for example, a method is provided for synthesizing a terminal olefin, the method comprising contacting an olefinic substrate comprised of at least one internal olefin with ethylene, in the presence of a metathesis catalyst, wherein the catalyst is present in an amount that is less than about 1000 ppm relative to the olefinic substrate, and wherein the metathesis catalyst has the structure of formula (II)




wherein the various substituents are as defined herein. The invention has utility, for example, in the fields of catalysis, organic synthesis, and industrial chemistry.

## Background
RELATED APPLICATIONS
This application is a divisional of U.S. Patent application Ser. No. 11/879,029, filed Jul. 13, 2007, and issued as U.S. Pat. Ser. No. 8,067,610 on Nov. 29, 2011, which claims priority to U.S. Provisional Application Ser. No. 60/830,944, filed Jul. 13, 2006, the disclosures of which are incorporated herein by Reference.


GOVERNMENT RIGHTS
This invention was made with Government support under grant no. DE-FG36-04GO14016 awarded by the Department of Energy. The U.S. Government has certain rights in this invention.


TECHNICAL FIELD
This invention relates generally to olefin metathesis, and more particularly relates to the synthesis of terminal alkenes from internal alkenes using a cross-metathesis reaction catalyzed by a selected olefin metathesis catalyst. The invention has utility in the fields of catalysis, organic synthesis, and industrial chemistry.
BACKGROUND
Ethenolysis is a specific cross metathesis reaction between an internal olefin and ethylene to produce terminal olefins. Scheme 1 demonstrates the ethenolysis reaction:




Examples of ethenolysis include the conversion of a mixture of ethylene and 2-butene into propene (as in the Phillips triolefin process and the Meta-4 process developed by the Institut Francais du Pétrole), and the conversion of a mixture of ethylene and 2,4,4-trimethyl-2-pentene into neohexene. These processes typically use heterogeneous ill-defined olefin metathesis catalysts based on tungsten and rhenium oxides and which are not compatible with air, water, oxygenates, and many functional groups. The ethenolysis reaction has also been implemented in the conversion of seed oil-derived substrates such as fatty acid methyl esters (FAME) into terminally unsaturated carboxylic acids (e.g., 9-decenoic acid) and terminal olefins (e.g., 1-decene). The ethenolysis of FAME was originally performed with a heterogeneous, ill-defined rhenium catalyst to give turnover numbers (TON) of about 100. The so-called “first generation” Grubbs catalysts such as Cl2(PCy3)2Ru═CH—CH═CPh2, Cl2(PCy3)2Ru═CHPh (“C823”), and complexes that contain bicyclic phosphines, as well as first generation Grubbs-Hoveyda catalyst (“C601”), have been used in the ethenolysis of vegetable oil-derived materials. The production of 1-octene from linoleic acid using an enzyme-mediated isomerization reaction, followed by a metathesis reaction using ethylene and various metathesis catalysts, has also been described. However, the conjugation present in these reactants necessitated a high catalyst loading and often resulted in a relatively low yield of terminal olefin products.

It is therefore desirable to provide a convenient and effective route for the production of terminal olefins. Compared with known metathesis methods, an ideal process would: substantially reduce the amount of catalyst that is needed for the cross-metathesis reaction; provide a high degree of selectivity for the preparation of terminal olefins from internal olefins; and allow the use of a mixture of internal olefins from a variety of sources. An ideal process would also not require isomerization of the olefinic substrate prior to the metathesis reaction, and an ideal process would allow for the preparation of terminal olefins directly from seed oils and from the component materials of seed oils, or from non-isomerized derivatives of seed oils.
SUMMARY OF THE DISCLOSURE
Accordingly, the disclosure is directed to addressing one or more of the aforementioned issues, and, in one embodiment, provides a method for synthesizing a terminal olefin. The method comprises contacting an olefinic substrate comprised of at least one internal olefin with ethylene in the presence of a metathesis catalyst. The catalyst is present in an amount that is less than about 1000 ppm relative to the olefinic substrate. The metathesis catalyst has the structure of formula (II)




wherein:

m is zero, 1, or 2;
M is Ru or Os;
n1 and n2 are independently selected from zero and 1;
X1 and X2 are anionic ligands, and may be the same or different;
R1 and R2 are independently selected from H, hydrocarbyl, substituted hydrocarbyl, heteroatom-containing hydrocarbyl, and substituted heteroatom-containing hydrocarbyl;
L2 and L3 are neutral electron donating ligands, and may be the same or different; and
L1 is a carbene ligand with the structure of formula (IIIa)




wherein:

Z1 is —N(Ar1)(R9) and Z2 is —N(Ar2)(R9A) or —C(R10)(R11)(R12);

    
    
        Ar1 and Ar2 are independently aryl substituted with at least one group selected from C2-C12 alkyl, C2-C12 alkenyl, C2-C12 alkynyl, C5-C12 aryl, C6-C12 aralkyl, and C6-C12 alkaryl; and
    
    


R9, R9A, R10, R11, and R12 are independently selected from hydrogen, hydrocarbyl, substituted hydrocarbyl, heteroatom-containing hydrocarbyl, and substituted heteroatom-containing hydrocarbyl, provided that any two of X1, X2, L1, L2, L3, R1, R2, R9, R9A, R10, R11, and R12 may be taken together to form a cycle.
In another embodiment, the invention provides a method for synthesizing a terminal olefin. The method comprises contacting, under reaction conditions effective to prepare a terminal olefin, an olefinic substrate comprising a mixture of mono-, di-, and tri-glycerides with ethylene in the presence of a ruthenium alkylidene metathesis catalyst. The catalyst comprises an N-heterocyclic carbene ligand, and the olefinic substrate comprises at least one internal olefin.
In yet another embodiment, the invention provides a method for synthesizing a terminal olefin. The method comprises contacting, under reaction conditions effective to prepare a terminal olefin, an olefinic substrate with ethylene in the presence of a ruthenium alkylidene metathesis catalyst. The olefinic substrate comprises at least one internal olefin, and further comprises a seed oil or a composition derived from a seed oil. The catalyst comprises an N-heterocyclic carbene ligand. At least about 50% of the metathesis reaction products comprise a terminal olefin and at least about 50% of the internal olefins initially present in the reaction mixture are converted into terminal olefins.
In a still further embodiment, the invention provides a method for synthesizing a terminal olefin. The method comprises contacting, in the presence of a metathesis catalyst, an olefinic substrate comprising at least one internal olefin with ethylene. The metathesis catalyst has the structure of formula (IIA)




wherein:

m is 0, 1, or 2;
M is Ru or Os;
n1 and n2 are independently selected from zero and 1;
X1A and X2A are CF3CO2;
R1 and R2 are independently selected from H, hydrocarbyl, substituted hydrocarbyl, heteroatom-containing hydrocarbyl, and substituted heteroatom-containing hydrocarbyl;
L2 and L3 are neutral electron donating ligands; and
L1A is an N-heterocyclic carbene ligand.
In a still further embodiment, the invention provides a method for synthesizing a terminal olefin. The method comprises contacting, under reaction conditions effective to prepare a terminal olefin, an olefinic substrate with ethylene, in the presence of a metathesis catalyst. The olefinic substrate comprises at least one internal olefin, and comprises a seed oil or a composition derived from a seed oil. The metathesis catalyst comprises an N-heterocyclic carbene ligand and is present in an amount that is less than about 50 ppm.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a graph showing the results from an etheneolysis reaction of methyl oleate and ethylene.



DETAILED DESCRIPTION OF THE INVENTION
Terminology and Definitions:
Unless otherwise indicated, the invention is not limited to specific reactants, substituents, catalysts, reaction conditions, or the like, as such may vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting.
As used in the specification and the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “an α-olefin” includes a single α-olefin as well as a combination or mixture of two or more α-olefin, reference to “a substituent” encompasses a single substituent as well as two or more substituents, and the like.
As used in the specification and the appended claims, the terms “for example,” “for instance,” “such as,” or “including” are meant to introduce examples that further clarify more general subject matter. Unless otherwise specified, these examples are provided only as an aid for understanding the invention, and are not meant to be limiting in any fashion.
In this specification and in the claims that follow, reference will be made to a number of terms, which shall be defined to have the following meanings:
The term “alkyl” as used herein refers to a linear, branched, or cyclic saturated hydrocarbon group typically although not necessarily containing 1 to about 24 carbon atoms, preferably 1 to about 12 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, octyl, decyl, and the like, as well as cycloalkyl groups such as cyclopentyl, cyclohexyl and the like. Generally, although again not necessarily, alkyl groups herein contain 1 to about 12 carbon atoms. The term “lower alkyl” intends an alkyl group of 1 to 6 carbon atoms, and the specific term “cycloalkyl” intends a cyclic alkyl group, typically having 4 to 8, preferably 5 to 7, carbon atoms. The term “substituted alkyl” refers to alkyl substituted with one or more substituent groups, and the terms “heteroatom-containing alkyl” and “heteroalkyl” refer to alkyl in which at least one carbon atom is replaced with a heteroatom. If not otherwise indicated, the terms “alkyl” and “lower alkyl” include linear, branched, cyclic, unsubstituted, substituted, and/or heteroatom-containing alkyl and lower alkyl, respectively. If not otherwise indicated, the terms “alkyl” and “lower alkyl” include primary, secondary, and tertiary alkyl and lower alkyl.
The term “alkylene” as used herein refers to a difunctional linear, branched, or cyclic alkyl group, where “alkyl” is as defined above.
The term “alkenyl” as used herein refers to a linear, branched, or cyclic hydrocarbon group of 2 to about 24 carbon atoms containing at least one double bond, such as ethenyl, n-propenyl, isopropenyl, n-butenyl, isobutenyl, octenyl, decenyl, tetradecenyl, hexadecenyl, eicosenyl, tetracosenyl, and the like. Preferred alkenyl groups herein contain 2 to about 12 carbon atoms. The term “lower alkenyl” intends an alkenyl group of 2 to 6 carbon atoms, and the specific term “cycloalkenyl” intends a cyclic alkenyl group, preferably having 5 to 8 carbon atoms. The term “substituted alkenyl” refers to alkenyl substituted with one or more substituent groups, and the terms “heteroatom-containing alkenyl” and “heteroalkenyl” refer to alkenyl in which at least one carbon atom is replaced with a heteroatom. If not otherwise indicated, the terms “alkenyl” and “lower alkenyl” include linear, branched, cyclic, unsubstituted, substituted, and/or heteroatom-containing alkenyl and lower alkenyl, respectively.
The term “alkenylene” as used herein refers to a difunctional linear, branched, or cyclic alkenyl group, where “alkenyl” is as defined above.
The term “alkynyl” as used herein refers to a linear or branched hydrocarbon group of 2 to about 24 carbon atoms containing at least one triple bond, such as ethynyl, n-propynyl, and the like. Preferred alkynyl groups herein contain 2 to about 12 carbon atoms. The term “lower alkynyl” intends an alkynyl group of 2 to 6 carbon atoms. The term “substituted alkynyl” refers to alkynyl substituted with one or more substituent groups, and the terms “heteroatom-containing alkynyl” and “heteroalkynyl” refer to alkynyl in which at least one carbon atom is replaced with a heteroatom. If not otherwise indicated, the terms “alkynyl” and “lower alkynyl” include linear, branched, unsubstituted, substituted, and/or heteroatom-containing alkynyl and lower alkynyl, respectively.
The term “aryl” as used herein, and unless otherwise specified, refers to an aromatic substituent containing a single aromatic ring or multiple aromatic rings that are fused together, directly linked, or indirectly linked (such that the different aromatic rings are bound to a common group such as a methylene or ethylene moiety). Preferred aryl groups contain 5 to 24 carbon atoms, and particularly preferred aryl groups contain 5 to 14 carbon atoms. Exemplary aryl groups contain one aromatic ring or two fused or linked aromatic rings, e.g., phenyl, naphthyl, biphenyl, diphenylether, diphenylamine, benzophenone, and the like. “Substituted aryl” refers to an aryl moiety substituted with one or more substituent groups, and the terms “heteroatom-containing aryl” and “heteroaryl” refer to aryl substituents in which at least one carbon atom is replaced with a heteroatom, as will be described in further detail infra.
The term “alkaryl” refers to an aryl group with an alkyl substituent, and the term “aralkyl” refers to an alkyl group with an aryl substituent, wherein “aryl” and “alkyl” are as defined above. Preferred alkaryl and aralkyl groups contain 6 to 24 carbon atoms, and particularly preferred alkaryl and aralkyl groups contain 6 to 16 carbon atoms. Alkaryl groups include, for example, p-methylphenyl, 2,4-dimethylphenyl, p-cyclohexylphenyl, 2,7-dimethylnaphthyl, 7-cyclooctylnaphthyl, 3-ethyl-cyclopenta-1,4-diene, and the like. Examples of aralkyl groups include, without limitation, benzyl, 2-phenyl-ethyl, 3-phenyl-propyl, 4-phenyl-butyl, 5-phenyl-pentyl, 4-phenylcyclohexyl, 4-benzylcyclohexyl, 4-phenylcyclohexylmethyl, 4-benzylcyclohexylmethyl, and the like. The terms “alkaryloxy” and “aralkyloxy” refer to substituents of the formula —OR wherein R is alkaryl or aralkyl, respectively, as just defined.
The term “acyl” refers to substituents having the formula —(CO)-alkyl, —(CO)-aryl, or —(CO)-aralkyl, and the term “acyloxy” refers to substituents having the formula —O(CO)-alkyl, —O(CO)-aryl, or —O(CO)-aralkyl, wherein “alkyl,” “aryl, and “aralkyl” are as defined above.
The terms “cyclic” and “ring” refer to alicyclic or aromatic groups that may or may not be substituted and/or heteroatom containing, and that may be monocyclic, bicyclic, or polycyclic. The term “alicyclic” is used in the conventional sense to refer to an aliphatic cyclic moiety, as opposed to an aromatic cyclic moiety, and may be monocyclic, bicyclic or polycyclic.
The terms “halo” and “halogen” are used in the conventional sense to refer to a chloro, bromo, fluoro or iodo substituent.
“Hydrocarbyl” refers to univalent hydrocarbyl radicals containing 1 to about 30 carbon atoms, preferably 1 to about 24 carbon atoms, most preferably 1 to about 12 carbon atoms, including linear, branched, cyclic, saturated and unsaturated species, such as alkyl groups, alkenyl groups, aryl groups, and the like. The term “lower hydrocarbyl” intends a hydrocarbyl group of 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms, and the term “hydrocarbylene” intends a divalent hydrocarbyl moiety containing 1 to about 30 carbon atoms, preferably 1 to about 24 carbon atoms, most preferably 1 to about 12 carbon atoms, including linear, branched, cyclic, saturated and unsaturated species. The term “lower hydrocarbylene” intends a hydrocarbylene group of 1 to 6 carbon atoms. “Substituted hydrocarbyl” refers to hydrocarbyl substituted with one or more substituent groups, and the terms “heteroatom-containing hydrocarbyl” and “heterohydrocarbyl” refer to hydrocarbyl in which at least one carbon atom is replaced with a heteroatom. Similarly, “substituted hydrocarbylene” refers to hydrocarbylene substituted with one or more substituent groups, and the terms “heteroatom-containing hydrocarbylene” and heterohydrocarbylene” refer to hydrocarbylene in which at least one carbon atom is replaced with a heteroatom. Unless otherwise indicated, the term “hydrocarbyl” and “hydrocarbylene” are to be interpreted as including substituted and/or heteroatom-containing hydrocarbyl and hydrocarbylene moieties, respectively.
The term “heteroatom-containing” as in a “heteroatom-containing hydrocarbyl group” refers to a hydrocarbon molecule or a hydrocarbyl molecular fragment in which one or more carbon atoms is replaced with an atom other than carbon, e.g., nitrogen, oxygen, sulfur, phosphorus or silicon, typically nitrogen, oxygen or sulfur. Similarly, the term “heteroalkyl” refers to an alkyl substituent that is heteroatom-containing, the term “heterocyclic” refers to a cyclic substituent that is heteroatom-containing, the terms “heteroaryl” and “heteroaromatic” respectively refer to “aryl” and “aromatic” substituents that are heteroatom-containing, and the like. It should be noted that a “heterocyclic” group or compound may or may not be aromatic, and further that “heterocycles” may be monocyclic, bicyclic, or polycyclic as described above with respect to the term “aryl.” Examples of heteroalkyl groups include alkoxyaryl, alkylsulfanyl-substituted alkyl, N-alkylated amino alkyl, and the like. Examples of heteroaryl substituents include pyrrolyl, pyrrolidinyl, pyridinyl, quinolinyl, indolyl, pyrimidinyl, imidazolyl, 1,2,4-triazolyl, tetrazolyl, etc., and examples of heteroatom-containing alicyclic groups are pyrrolidino, morpholino, piperazino, piperidino, etc.
By “substituted” as in “substituted hydrocarbyl,” “substituted alkyl,” “substituted aryl,” and the like, as alluded to in some of the aforementioned definitions, is meant that in the hydrocarbyl, alkyl, aryl, or other moiety, at least one hydrogen atom bound to a carbon (or other) atom is replaced with one or more non-hydrogen substituents. Examples of such substituents include, without limitation: functional groups referred to herein as “Fn,” such as halo, hydroxyl, sulfhydryl, C1-C24 alkoxy, C2-C24 alkenyloxy, C2-C24 alkynyloxy, C5-C24 aryloxy, C6-C24 aralkyloxy, C6-C24 alkaryloxy, acyl (including C2-C24 alkylcarbonyl (—CO-alkyl) and C6-C24 arylcarbonyl (—CO-aryl)), acyloxy (—O-acyl, including C2-C24 alkylcarbonyloxy (—O—CO-alkyl) and C6-C24 arylcarbonyloxy (—O—CO-aryl)), C2-C24 alkoxycarbonyl (—(CO)—O-alkyl), C6-C24 aryloxycarbonyl (—(CO)—O-aryl), halocarbonyl (—CO)—X where X is halo), C2-C24 alkylcarbonato (—O—(CO)—O-alkyl), C6-C24 arylcarbonato (—O—(CO)—O-aryl), carboxy (—COOH), carboxylato (—COO−), carbamoyl (—(CO)—NH2), mono-(C1-C24 alkyl)-substituted carbamoyl (—(CO)—NH(C1-C24 alkyl)), di-(C1-C24 alkyl)-substituted carbamoyl (—(CO)—N(C1-C24 alkyl)2), mono-(C5-C24 aryl)-substituted carbamoyl (—(CO)—NH-aryl), di-(C5-C24 aryl)-substituted carbamoyl (—(CO)—N(C5-C24 aryl)2), di-N—(C1-C24 alkyl), N—(C5-C24 aryl)-substituted carbamoyl, thiocarbamoyl (—(CS)—NH2), mono-(C1-C24 alkyl)-substituted thiocarbamoyl (—(CO)—NH(C1-C24 alkyl)), di-(C1-C24 alkyl)-substituted thiocarbamoyl (—(CO)—N(C1-C24 alkyl)2), mono-(C5-C24 aryl)-substituted thiocarbamoyl (—(CO)—NH-aryl), di-(C5-C24 aryl)-substituted thiocarbamoyl (—(CO)—N(C5-C24 aryl)2), di-N—(C1-C24 alkyl), N—(C5-C24 aryl)-substituted thiocarbamoyl, carbamido (—NH—(CO)—NH2), cyano(—C≡N), cyanato (—O—C≡N), thiocyanato (—S—C≡N), formyl (—(CO)—H), thioformyl (—(CS)—H), amino (—NH2), mono-(C1-C24 alkyl)-substituted amino, di-(C1-C24 alkyl)-substituted amino, mono-(C5-C24 aryl)-substituted amino, di-(C5-C24 aryl)-substituted amino, C2-C24 alkylamido (—NH—(CO)-alkyl), C6-C24 arylamido (—NH—(CO)-aryl), imino (—CR═NH where R=hydrogen, C1-C24 alkyl, C5-C24 aryl, C6-C24 alkaryl, C6-C24 aralkyl, etc.), C2-C20 alkylimino (—CR═N(alkyl), where R=hydrogen, C1-C24 alkyl, C5-C24 aryl, C6-C24 alkaryl, C6-C24 aralkyl, etc.), arylimino (—CR═N(aryl), where R=hydrogen, C1-C20 alkyl, C5-C24 aryl, C6-C24 alkaryl, C6-C24 aralkyl, etc.), nitro (—NO2), nitroso (—NO), sulfo (—SO2—OH), sulfonato (—SO2—O−), C1-C24 alkylsulfanyl (—S-alkyl; also termed “alkylthio”), C5-C24 arylsulfanyl (—S-aryl; also termed “arylthio”), C1-C24 alkylsulfinyl (—(SO)-alkyl), C5-C24 arylsulfinyl (—(SO)-aryl), alkylsulfonyl (—SO2-alkyl), C5-C24 arylsulfonyl (—SO2-aryl), boryl (—BH2), borono (—B(OH)2), boronato (—B(OR)2 where R is alkyl or other hydrocarbyl), phosphono (—P(O)(OH)2), phosphonato (—P(O)(O−)2), phosphinato (—P(O)(O−)), phospho (—PO2), phosphino (—PH2), silyl (—SiR3 wherein R is hydrogen or hydrocarbyl), and silyloxy (—O-silyl); and the hydrocarbyl moieties C1-C24 alkyl (preferably C1-C12 alkyl, more preferably C1-C6 alkyl), C2-C24 alkenyl (preferably C2-C12 alkenyl, more preferably C2-C6 alkenyl), C2-C24 alkynyl (preferably C2-C12 alkynyl, more preferably C2-C6 alkynyl), C5-C24 aryl (preferably C5-C14 aryl), C6-C24 alkaryl (preferably C6-C16 alkaryl), and C6-C24 aralkyl (preferably C6-C16 aralkyl).
In addition, the aforementioned functional groups may, if a particular group permits, be further substituted with one or more additional functional groups or with one or more hydrocarbyl moieties such as those specifically enumerated above. Analogously, the above-mentioned hydrocarbyl moieties may be further substituted with one or more functional groups or additional hydrocarbyl moieties such as those specifically enumerated.
“Optional” or “optionally” means that the subsequently described circumstance may or may not occur, so that the description includes instances where the circumstance occurs and instances where it does not. For example, the phrase “optionally substituted” means that a non-hydrogen substituent may or may not be present on a given atom, and, thus, the description includes structures wherein a non-hydrogen substituent is present and structures wherein a non-hydrogen substituent is not present.
Methods and Compositions:
Accordingly, the invention provides an olefin cross-metathesis method for synthesizing a terminal olefin from ethylene and an olefinic substrate comprised of at least one internal olefin. The reactions are carried out catalytically, in the presence of a ruthenium alkylidene metathesis catalyst.
In a first embodiment of the invention, then, the olefin metathesis reaction is carried out by contacting the at least one internal olefin with ethylene in the presence of the metathesis catalyst under reaction conditions effective to allow cross-metathesis to occur.
The olefin metathesis catalyst for carrying out the cross-metathesis reactions of the invention is preferably a Group 8 transition metal complex having the structure of formula (II)




wherein:

m is zero, 1, or 2;
M is Ru or Os;
n1 and n2 are independently selected from zero and 1;
X1 and X2 are anionic ligands and may be the same or different;
R1 and R2 are independently selected from H, hydrocarbyl, substituted hydrocarbyl, heteroatom-containing hydrocarbyl, and substituted heteroatom-containing hydrocarbyl;
L2 and L3 are neutral electron donating ligands and may be the same or different; and
L1 is a carbene ligand with the structure of formula (IIIa)




wherein:

Z1 is —N(Ar1)(R9) and Z2 is —N(Ar2)(R9A) or —C(R10)(R11)(R12);
Ar1 and Ar2 are independently aryl substituted with at least one group selected from C2-C12 alkyl, C2-C12 alkenyl, C2-C12 alkynyl, C5-C12 aryl, C6-C12 aralkyl, and C6-C12 alkaryl; and
R9, R9A, R10, R11, and R12 are independently selected from hydrogen, hydrocarbyl, substituted hydrocarbyl, heteroatom-containing hydrocarbyl, and substituted heteroatom-containing hydrocarbyl,
wherein any two of X1, X2, L1, L2, L3, R1, R2, R9, R9A, R10, R11, and R12 may be taken together to form a cycle.
Preferred catalysts contain Ru or Os as the Group 8 transition metal, with Ru particularly preferred.
Numerous embodiments of the catalysts useful in the reactions of the invention are described in more detail infra. For the sake of convenience, the catalysts are described in groups, but it should be emphasized that these groups are not meant to be limiting in any way. That is, any of the catalysts useful in the invention may fit the description of more than one of the groups described herein.
A first group of catalysts having the structure of formula (II) is commonly referred to as Second Generation Grubbs-type catalysts. For catalysts of the first group, M, n1, n2, and m are as described above, and X1, X2, L1, L2, L3, R1, and R2 are further described as follows.
L2 is selected from phosphine, sulfonated phosphine, phosphite, phosphinite, phosphonite, arsine, stibine, ether, amine, amide, imine, sulfoxide, carboxyl, nitrosyl, pyridine, substituted pyridine, imidazole, substituted imidazole, pyrazine, and thioether. Exemplary ligands are trisubstituted phosphines.
X1 and X2 are anionic ligands, and may be the same or different, or are linked together to form a cyclic group, typically although not necessarily a five- to eight-membered ring. In preferred embodiments, X1 and X2 are each independently hydrogen, halide, or one of the following groups: C1-C20 alkyl, C5-C24 aryl, C1-C20 alkoxy, C5-C24 aryloxy, C2-C20 alkoxycarbonyl, C6-C24 aryloxycarbonyl, C2-C24 acyl, C2-C24 acyloxy, C1-C20 alkylsulfonato, C5-C24 arylsulfonato, C1-C20 alkylsulfanyl, C5-C24 arylsulfanyl, C1-C20 alkylsulfinyl, or C5-C24 arylsulfinyl. Optionally, X1 and X2 may be substituted with one or more moieties selected from C1-C12 alkyl, C1-C12 alkoxy, C5-C24 aryl, and halide, which may, in turn, with the exception of halide, be further substituted with one or more groups selected from halide, C1-C6 alkyl, C1-C6 alkoxy, and phenyl. In more preferred embodiments, X1 and X2 are halide, benzoate, C2-C6 acyl, C2-C6 alkoxycarbonyl, C1-C6 alkyl, phenoxy, C1-C6 alkoxy, C1-C6 alkylsulfanyl, aryl, or C1-C6 alkylsulfonyl. In even more preferred embodiments, X1 and X2 are each halide, CF3CO2, CH3CO2, CFH2CO2, (CH3)3CO, (CF3)2(CH3)CO, (CF3)(CH3)2CO, PhO, MeO, EtO, tosylate, mesylate, or trifluoromethane-sulfonate.
R1 and R2 are independently selected from hydrogen, hydrocarbyl (e.g., C1-C20 alkyl, C2-C20 alkenyl, C2-C20 alkynyl, C5-C24 aryl, C6-C24 alkaryl, C6-C24 aralkyl, etc.), substituted hydrocarbyl (e.g., substituted C1-C20 alkyl, C2-C20 alkenyl, C2-C20 alkynyl, C5-C24 aryl, C6-C24 alkaryl, C6-C24 aralkyl, etc.), heteroatom-containing hydrocarbyl (e.g., heteroatom-containing C1-C20 alkyl, C2-C20 alkenyl, C2-C20 alkynyl, C5-C24 aryl, C6-C24 alkaryl, C6-C24 aralkyl, etc.), and substituted heteroatom-containing hydrocarbyl (e.g., substituted heteroatom-containing C1-C20 alkyl, C2-C20 alkenyl, C2-C20 alkynyl, C5-C24 aryl, C6-C24 alkaryl, C6-C24 aralkyl, etc.), and functional groups. R1 and R2 may also be linked to form a cyclic group, which may be aliphatic or aromatic, and may contain substituents and/or heteroatoms. Generally, such a cyclic group will contain 4 to 12, preferably 5, 6, 7, or 8 ring atoms.
In preferred catalysts, R1 is hydrogen and R2 is selected from C1-C20 alkyl, C2-C20 alkenyl, and C5-C24 aryl, more preferably C1-C6 alkyl, C2-C6 alkenyl, and C5-C14 aryl. Still more preferably, R2 is phenyl, vinyl, methyl, isopropyl, or t-butyl, optionally substituted with one or more moieties selected from C1-C6 alkyl, C1-C6 alkoxy, phenyl, and a functional group Fn as defined earlier herein. Most preferably, R2 is phenyl or vinyl substituted with one or more moieties selected from methyl, ethyl, chloro, bromo, iodo, fluoro, nitro, dimethylamino, methyl, methoxy, and phenyl. Optimally, R2 is phenyl or —C═C(CH3)2.
Any two or more (typically two, three, or four) of X1, X2, L1, L2, L3, R1, and R2 can be taken together to form a cyclic group. When any of X1, X2, L1, L2, L3, R1, and R2 are linked to form cyclic groups, those cyclic groups may contain 4 to 12, preferably 4, 5, 6, 7 or 8 atoms, or may comprise two or three of such rings, which may be either fused or linked. The cyclic groups may be aliphatic or aromatic, and may be heteroatom-containing and/or substituted. The cyclic group may, in some cases, form a bidentate ligand or a tridentate ligand. Examples of bidentate ligands include, but are not limited to, bisphosphines, dialkoxides, alkyldiketonates, and aryldiketonates.
L1 is a carbene ligand with the structure of formula (IIIa)




wherein Z1 is —N(Ar1)(R9) and Z2 is —N(Ar2)(R9A) or —C(R10)(R11)(R12). Ar1 and Ar2 are aryl substituted with at least one group selected from C2-C12 alkyl, C2-C12 alkenyl, C2-C12 alkynyl, C5-C12 aryl, C6-C12 aralkyl, and C6-C12 alkaryl, and Ar1 and Ar2 may be the same or different. R9, R9A, R10, R11, and R12 are independently selected from hydrogen, hydrocarbyl, substituted hydrocarbyl, heteroatom-containing hydrocarbyl, and substituted heteroatom-containing hydrocarbyl. Furthermore, any two of X1, X2, L1, L2, L3, R1, R2, R9, R9A, R10, R11, and R12 may be taken together to form a cycle.

For example, Z1 is —N(Ar1)(R9), Z2 is —C(R10)(R11)(R12), and R9 and R12 are linked. The linkage formed by R9 and R12 has the structure




such that L1 has the structure of formula (IIIb)





wherein α is an optional double bond, and R13, R14, R15, and R16 are independently selected from hydrogen, hydrocarbyl, substituted hydrocarbyl, heteroatom-containing hydrocarbyl, and substituted heteroatom-containing hydrocarbyl, provided that R14 and R16 are not present if α is present, and provided that any two or more of Ar1, R10, R11, R13, R14, R15, and R16 may be taken together to form a cyclic group. For example, R10 and R11 are taken together to form a cyclic group, such as a six-membered cyclic group.

In a preferred embodiment, Ar1 has the structure of formula (VIIa)




wherein  represents the attachment point to N in formula (IIIb), R17 and R18 are independently selected from C2-C12 alkyl, C2-C12 alkenyl, C2-C12 alkynyl, C5-C12 aryl, C6-C12 aralkyl, and C6-C12 alkaryl, and R19, R20, and R21 are independently selected from H, C1-C12 alkyl, C2-C12 alkenyl, C2-C12 alkynyl, C5-C12 aryl, C6-C12 aralkyl, and C6-C12 alkaryl. For example, R19, R20, and R21 are H such that Ar1 has the structure of formula (VIIb)





wherein the wavy line represents the attachment point to N in formula (IIIb) and R17 and R18 are independently selected from C2-C12 alkyl, C2-C12 alkenyl, C2-C12 alkynyl, C5-C12 aryl, C6-C12 aralkyl, and C6-C12 alkaryl. In a more preferred embodiment, R17 and R18 are independently C2-C12 alkyl; for example, R17 and R18 are both ethyl.

As another example, Z1 is —N(Ar1)(R9) and Z2 is —N(Ar2)(R9A). In a preferred embodiment, R9 and R9A are linked such that L1 has the structure of formula (IIIc)




wherein α is an optional double bond, Ar2 is aryl substituted with at least one group selected from C2-C12 alkyl, C2-C12 alkenyl, C2-C12 alkynyl, C5-C12 aryl, C6-C12 aralkyl, and C6-C12 alkaryl, and R13, R14, R15, and R16 are as described previously. In a preferred embodiment, L1 has the formula of (IIId)





wherein R22, R23, R27 and R28 are independently selected from C2-C12 alkyl, C2-C12 alkenyl, C2-C12 alkynyl, C5-C12 aryl, C6-C12 aralkyl, and C6-C12 alkaryl, and R24, R25, R26, R29, R30, and R31 are independently selected from H, C1-C12 alkyl, C2-C12 alkenyl, C2-C12 alkynyl, C5-C12 aryl, C6-C12 aralkyl, and C6-C12 alkaryl. For example, α is not present, and L1 has the structure of formula (IIId-1)





As a further example, α is not present, and R13, R14, R15, R16, R24, R25, R26, R29, R30, and R31 are each H such that L1 has the structure of formula (IIIe)





wherein R22, R23, R27, and R28 are independently selected from C2-C12 alkyl, C2-C12 alkenyl, C2-C12 alkynyl, C5-C12 aryl, C6-C12 aralkyl, and C6-C12 alkaryl. As a further example, R22, R23, R27, and R28 are each independently C3-C12 secondary alky or C4-C12 tertiary alkyl, and as a still further example, R22, R23, R27, and R28 are isopropyl.

Examples of N-heterocyclic carbene ligands suitable as L1 also include the following:




In a second group of catalysts having the structure of formula (II), M, m, n, X1, X2, L1, R2, and R2 are as defined for the first group of catalysts having the structure of formula (II), and L2 and L3 are weakly coordinating neutral electron donor ligands in the form of optionally substituted heterocyclic groups. Again, n is zero or 1, such that L3 may or may not be present. Generally, in the second group of catalysts, L2 and L3 are optionally substituted five- or six-membered monocyclic groups containing 1 to 4, preferably 1 to 3, most preferably 1 to 2 heteroatoms, or are optionally substituted bicyclic or polycyclic structures composed of 2 to 5 such five- or six-membered monocyclic groups. If the heterocyclic group is substituted, it should not be substituted on a coordinating heteroatom, and any one cyclic moiety within a heterocyclic group will generally not be substituted with more than 3 substituents.
Examples of L2 and L3 include, without limitation, heterocycles containing nitrogen, sulfur, oxygen, or a mixture thereof.
Examples of nitrogen-containing heterocycles appropriate for L2 and L3 include pyridine, bipyridine, pyridazine, pyrimidine, bipyridamine, pyrazine, 1,3,5-triazine, 1,2,4-triazine, 1,2,3-triazine, pyrrole, 2H-pyrrole, 3H-pyrrole, pyrazole, 2H-imidazole, 1,2,3-triazole, 1,2,4-triazole, indole, 3H-indole, 1H-isoindole, cyclopenta(b)pyridine, indazole, quinoline, bisquinoline, isoquinoline, bisisoquinoline, cinnoline, quinazoline, naphthyridine, piperidine, piperazine, pyrrolidine, pyrazolidine, quinuclidine, imidazolidine, picolylimine, purine, benzimidazole, bisimidazole, phenazine, acridine, and carbazole.
Examples of sulfur-containing heterocycles appropriate for L2 and L3 include thiophene, 1,2-dithiole, 1,3-dithiole, thiepin, benzo(b)thiophene, benzo(c)thiophene, thionaphthene, dibenzothiophene, 2H-thiopyran, 4H-thiopyran, and thioanthrene.
Examples of oxygen-containing heterocycles appropriate for L2 and L3 include 2H-pyran, 4H-pyran, 2-pyrone, 4-pyrone, 1,2-dioxin, 1,3-dioxin, oxepin, furan, 2H-1-benzopyran, coumarin, coumarone, chromene, chroman-4-one, isochromen-1-one, isochromen-3-one, xanthene, tetrahydrofuran, 1,4-dioxan, and dibenzofuran.
Examples of mixed heterocycles appropriate for L2 and L3 include isoxazole, oxazole, thiazole, isothiazole, 1,2,3-oxadiazole, 1,2,4-oxadiazole, 1,3,4-oxadiazole, 1,2,3,4-oxatriazole, 1,2,3,5-oxatriazole, 3H-1,2,3-dioxazole, 3H-1,2-oxathiole, 1,3-oxathiole, 4H-1,2-oxazine, 2H-1,3-oxazine, 1,4-oxazine, 1,2,5-oxathiazine, o-isooxazine, phenoxazine, phenothiazine, pyrano[3,4-b]pyrrole, indoxazine, benzoxazole, anthranil, and morpholine.
Preferred L2 and L3 ligands are aromatic nitrogen-containing and oxygen-containing heterocycles, and particularly preferred L2 and L3 ligands are monocyclic N-heteroaryl ligands that are optionally substituted with 1 to 3, preferably 1 or 2, substituents. Specific examples of particularly preferred L2 and L3 ligands are pyridine and substituted pyridines, such as 3-bromopyridine, 4-bromopyridine, 3,5-dibromopyridine, 2,4,6-tribromopyridine, 2,6-dibromopyridine, 3-chloropyridine, 4-chloropyridine, 3,5-dichloropyridine, 2,4,6-trichloropyridine, 2,6-dichloropyridine, 4-iodopyridine, 3,5-diiodopyridine, 3,5-dibromo-4-methylpyridine, 3,5-dichloro-4-methylpyridine, 3,5-dimethyl-4-bromopyridine, 3,5-dimethylpyridine, 4-methylpyridine, 3,5-diisopropylpyridine, 2,4,6-trimethylpyridine, 2,4,6-triisopropylpyridine, 4-(tert-butyl)pyridine, 4-phenylpyridine, 3,5-diphenylpyridine, 3,5-dichloro-4-phenylpyridine, and the like.
In general, any substituents present on L2 and/or L3 are selected from halo, C1-C20 alkyl, substituted C1-C20 alkyl, C1-C20 heteroalkyl, substituted C1-C20 heteroalkyl, C5-C24 aryl, substituted C5-C24 aryl, C5-C24 heteroaryl, substituted C5-C24 heteroaryl, C6-C24 alkaryl, substituted C6-C24 alkaryl, C6-C24 heteroalkaryl, substituted C6-C24 heteroalkaryl, C6-C24 aralkyl, substituted C6-C24 aralkyl, C6-C24 heteroaralkyl, substituted C6-C24 heteroaralkyl, and functional groups, with suitable functional groups including, without limitation, C1-C20 alkoxy, C5-C24 aryloxy, C2-C20 alkylcarbonyl, C6-C24 arylcarbonyl, C2-C20 alkylcarbonyloxy, C6-C24 arylcarbonyloxy, C2-C20 alkoxycarbonyl, C6-C24 aryloxycarbonyl, halocarbonyl, C2-C20 alkylcarbonato, C6-C24 arylcarbonato, carboxy, carboxylato, carbamoyl, mono-(C1-C20 alkyl)-substituted carbamoyl, di-(C1-C20 alkyl)-substituted carbamoyl, di-N—(C1-C20 alkyl), N—(C5-C24 aryl)-substituted carbamoyl, mono-(C5-C24 aryl)-substituted carbamoyl, di-(C6-C24 aryl)-substituted carbamoyl, thiocarbamoyl, mono-(C1-C20 alkyl)-substituted thiocarbamoyl, di-(C1-C20 alkyl)-substituted thiocarbamoyl, di-N—(C1-C20 alkyl)-N—(C6-C24 aryl)-substituted thiocarbamoyl, mono-(C6-C24 aryl)-substituted thiocarbamoyl, di-(C6-C24 aryl)-substituted thiocarbamoyl, carbamido, formyl, thioformyl, amino, mono-(C1-C20 alkyl)-substituted amino, di-(C1-C20 alkyl)-substituted amino, mono-(C5-C24 aryl)-substituted amino, di-(C5-C24 aryl)-substituted amino, di-N—(C1-C20 alkyl) N—(C5-C24 aryl)-substituted amino, C2-C20 alkylamido, C6-C24 arylamido, imino, C1-C20 alkylimino, C5-C24 arylimino, nitro, and nitroso. In addition, two adjacent substituents may be taken together to form a ring, generally a five- or six-membered alicyclic or aryl ring, optionally containing 1 to 3 heteroatoms and 1 to 3 substituents as above.
Preferred substituents on L2 and L3 include, without limitation, halo, C1-C12 alkyl, substituted C1-C12 alkyl, C1-C12 heteroalkyl, substituted C1-C12 heteroalkyl, C5-C14 aryl, substituted C5-C14 aryl, C5-C14 heteroaryl, substituted C5-C14 heteroaryl, C6-C16 alkaryl, substituted C6-C16 alkaryl, C6-C16 heteroalkaryl, substituted C6-C16 heteroalkaryl, C6-C16 aralkyl, substituted C6-C16 aralkyl, C6-C16 heteroaralkyl, substituted C6-C16 heteroaralkyl, C1-C12 alkoxy, C5-C14 aryloxy, C2-C12 alkylcarbonyl, C6-C14 arylcarbonyl, C2-C12 alkylcarbonyloxy, C6-C14 arylcarbonyloxy, C2-C12 alkoxycarbonyl, C6-C14 aryloxycarbonyl, halocarbonyl, formyl, amino, mono-(C1-C12 alkyl)-substituted amino, di-(C1-C12 alkyl)-substituted amino, mono-(C5-C14 aryl)-substituted amino, di-(C5-C14 aryl)-substituted amino, and nitro.
Of the foregoing, the most preferred substituents are halo, C1-C6 alkyl, C1-C6 haloalkyl, C1-C6 alkoxy, phenyl, substituted phenyl, formyl, N,N-diC1-C6 alkyl)amino, nitro, and nitrogen heterocycles as described above (including, for example, pyrrolidine, piperidine, piperazine, pyrazine, pyrimidine, pyridine, pyridazine, etc.).
L2 and L3 may also be taken together to form a bidentate or multidentate ligand containing two or more, generally two, coordinating heteroatoms such as N, O, S, or P, with preferred such ligands being diimine ligands of the Brookhart type. One representative bidentate ligand has the structure of formula (VIII)




wherein R32, R33, R34, and R35 are independently hydrocarbyl (e.g., C1-C20 alkyl, C2-C20 alkenyl, C2-C20 alkynyl, C5-C24 aryl, C6-C24 alkaryl, or C6-C24 aralkyl), substituted hydrocarbyl (e.g., substituted C1-C20 alkyl, C2-C20 alkenyl, C2-C20 alkynyl, C5-C24 aryl, C6-C24 alkaryl, or C6-C24 aralkyl), heteroatom-containing hydrocarbyl (e.g., C1-C20 heteroalkyl, C5-C24 heteroaryl, heteroatom-containing C6-C24 aralkyl, or heteroatom-containing C6-C24 alkaryl), or substituted heteroatom-containing hydrocarbyl (e.g., substituted C1-C20 heteroalkyl, C5-C24 heteroaryl, heteroatom-containing C6-C24 aralkyl, or heteroatom-containing C6-C24 alkaryl), or (1) R32 and R33, (2) R34 and R35, (3) R33 and R34, or (4) both R32 and R33, and R34 and R35, may be taken together to form a ring, i.e., an N-heterocycle. Preferred cyclic groups in such a case are five- and six-membered rings, typically aromatic rings.

A third group of catalysts having the structure of formula (II), includes catalysts wherein M, n1, n2, m, X1, X2, R1, R2, L1, L2, and L3 are as defined for any of the previously defined catalysts, and two of the substituents are taken together to form a bidentate ligand or a tridentate ligand.
Examples of bidentate ligands include, but are not limited to, bisphosphines, dialkoxides, alkyldiketonates, and aryldiketonates. Specific examples include —P(Ph)2CH2CH2P(Ph)2-, —As(Ph)2CH2CH2As(Ph2)—, —P(Ph)2CH2CH2C(CF3)2O—, binaphtholate dianions, pinacolate dianions, —P(CH3)2(CH2)2P(CH3)2—, and —OC(CH3)2(CH3)2CO—. Preferred bidentate ligands are —P(Ph)2 CH2CH2P(Ph)2- and —P(CH3)2(CH2)2P(CH3)2—. Tridentate ligands include, but are not limited to, (CH3)2NCH2CH2P(Ph)CH2CH2N(CH3)2. Other preferred tridentate ligands are those in which any three of X1, X2, L1, L2, L3, R1, and R2 (e.g., X1, L1, and L2) are taken together to be cyclopentadienyl, indenyl, or fluorenyl, each optionally substituted with C2-C20 alkenyl, C2-C20 alkynyl, C1-C20 alkyl, C5-C20 aryl, C1-C20 alkoxy, C2-C20 alkenyloxy, C2-C20 alkynyloxy, C5-C20 aryloxy, C2-C20 alkoxycarbonyl, C1-C20 alkylthio, C1-C20 alkylsulfonyl, or C1-C20 alkylsulfinyl, each of which may be further substituted with C1-C6 alkyl, halide, C1-C6 alkoxy or with a phenyl group optionally substituted with halide, C1-C6 alkyl, or C1-C6 alkoxy. More preferably, in compounds of this type, X, L1, and L2 are taken together to be cyclopentadienyl or indenyl, each optionally substituted with vinyl, C1-C10 alkyl, C5-C20aryl, C1-C10 carboxylate, C2-C10 alkoxycarbonyl, C1-C10 alkoxy, or C5-C20 aryloxy, each optionally substituted with C1-C6 alkyl, halide, C1-C6 alkoxy or with a phenyl group optionally substituted with halide, C1-C6 alkyl or C1-C6 alkoxy. Most preferably, X, L1 and L2 may be taken together to be cyclopentadienyl, optionally substituted with vinyl, hydrogen, methyl, or phenyl. Tetradentate ligands include, but are not limited to O2C(CH2)2P(Ph)(CH2)2P(Ph)(CH2)2CO2, phthalocyanines, and porphyrins.
For example, m is zero, and L2 and R2 are taken together to form a cycle. Catalysts of this type are commonly called “Grubbs-Hoveyda” catalysts, and have the structure of formula (IIa)




wherein Q is selected from hydrocarbylene, substituted hydrocarbylene, heteroatom-containing hydrocarbylene, and substituted heteroatom-containing hydrocarbylene, wherein two or more substituents on adjacent atoms within Q may also be taken together to form an additional, optionally substituted cyclic structure. For example, Grubbs-Hoveyda catalysts may have the structure of formula (IIb)





Further examples of Grubbs-Hoveyda-type catalysts include the following:




wherein L1, X1, X2, and M are as described for any of the other groups of catalysts.

In addition to the catalysts that have the structure of formula (II), as described above, other transition metal carbene complexes may be used in the reactions disclosed herein, including:
neutral ruthenium or osmium metal carbene complexes containing metal centers that are formally in the +2 oxidation state, have an electron count of 16, are penta-coordinated, and are of the general formula (IX);
neutral ruthenium or osmium metal carbene complexes containing metal centers that are formally in the +2 oxidation state, have an electron count of 18, are hexa-coordinated, and are of the general formula (X)
cationic ruthenium or osmium metal carbene complexes containing metal centers that are formally in the +2 oxidation state, have an electron count of 14, are tetra-coordinated, and are of the general formula (XI); and
cationic ruthenium or osmium metal carbene complexes containing metal centers that are formally in the +2 oxidation state, have an electron count of 14, are penta-coordinated, and are of the general formula (XII)




wherein: X1, X2, L1, L2, n, L3, R1, and R2 are as defined for any of the previously defined four groups of catalysts; r and s are independently zero or 1; t is an integer in the range of zero to 5; Y is any non-coordinating anion (e.g., a halide ion, BF4−, etc.); Z1 and Z2 are independently selected from —O—, —S—, —NR2—, —PR2—, —P(═O)R2—, —P(OR2)—, —P(═O)(OR2)—, —C(═O)—, —C(═O)O—, —OC(═O)—, —OC(═O)O—, —S(═O)—, and —S(═O)2—; Z3 is any cationic moiety such as —P(R2)3, or —N(R2)3; and any two or more of X1, X2, L1, L2, L3, n, Z1, Z2, Z3, R1, and R2 may be taken together to form a cyclic group, e.g., a multidentate ligand, and wherein any one or more of X1, X2, L1, L2, n, L3, Z1, Z2, Z3, R1, and R2 may be attached to a support.
As is understood in the field of catalysis, suitable solid supports for any of the catalysts described herein may be of synthetic, semi-synthetic, or naturally occurring materials, which may be organic or inorganic, e.g., polymeric, ceramic, or metallic. Attachment to the support will generally, although not necessarily, be covalent, and the covalent linkage may be direct or indirect, if indirect, typically through a functional group on a support surface.
Non-limiting examples of catalysts that may be used in the reactions of the invention include the following, which for convenience are identified throughout this disclosure by reference to their molecular weight:










In the foregoing molecular structures and formulae, Ph represents phenyl, Cy represents cyclohexyl, i-Pr represents isopropyl, Et represents ethyl, t-Bu represents tertiary butyl, and py represents pyridine (coordinated through the N atom).
Further examples of catalysts useful in the reactions of the invention include the following: ruthenium (II) [1,3-bis-(2,4,6-trimethylphenyl)-2-imidazolidinylidene]dichloro (phenylmethylene) (triphenylphosphine) (C830); ruthenium (II) dichloro (tricyclohexylphosphine) (o-isopropoxyphenylmethylene) (C601), and ruthenium (II) (1,3-bis-(2,4,6,-trimethylphenyl)-2-imidazolidinylidene) dichloro (phenylmethylene) (bis 3-bromopyridine (C884)).
The transition metal complexes used as catalysts herein can be prepared by several different methods, such as those described by Schwab et al. (1996) J. Am. Chem. Soc. 118:100-110, Scholl et al. (1999) Org. Lett. 6:953-956, Sanford et al. (2001) J. Am. Chem. Soc. 123:749-750, U.S. Pat. No. 5,312,940 and U.S. Pat. No. 5,342,909. Also see U.S. Patent Publication No. 2003/0055262 to Grubbs et al. filed Apr. 16, 2002 for “Group 8 Transition Metal Carbene Complexes as Enantioselective Olefin Metathesis Catalysts”, International Patent Publication No. WO 02/079208 application Ser. No. 10/115,581 to Grubbs, Morgan, Benitez, and Louie, filed Apr. 2, 2002, for “One-Pot Synthesis of Group 8 Transition Metal Carbene Complexes Useful as Olefin Metathesis Catalysts,” commonly assigned herewith to the California Institute of Technology. Preferred synthetic methods are described in International Patent Publication No. WO 03/11455A1 to Grubbs et al. for “Hexacoordinated Ruthenium or Osmium Metal Carbene Metathesis Catalysts,” published Feb. 13, 2003.
Reactants:
The olefinic substrate comprises at least one internal olefin, and may have 2 or more internal olefins. For example, the olefinic substrate may comprise in the range of 2 to about 15, 2 to about 10, or 2 to about 5 internal olefins. By “internal olefin” is meant an olefin wherein each of the olefinic carbons is substituted by at least one non-hydrogen substituent. The non-hydrogen substituents are selected from hydrocarbyl, substituted hydrocarbyl, heteroatom-containing hydrocarbyl, substituted heteroatom-containing hydrocarbyl, and functional groups. The internal olefin is therefore at least disubstituted, and may further include additional non-hydrogen substituents such that the internal olefin is tri- or tetra-substituted. Each of the substituents on the internal olefinic carbons may be further substituted as described supra. The internal olefin may be in the Z- or E-configuration. When the olefinic substrate comprises a plurality of internal olefins, the olefinic substrate may comprise a mixture of internal olefins (varying in stereochemistry and/or substituent identity), or may comprise a plurality of identical internal olefins.
The olefinic substrate may be a single compound or a mixture of compounds. The olefinic substrate may be hydrophobic or hydrophilic, although in a preferred embodiment, the olefinic substrate is hydrophobic.
For example, the olefinic substrate may be represented by the formula (RI)(RII)C═C(RIII)(RIV), wherein RI, RII, RIII, and RIV are independently selected from H, hydrocarbyl, substituted hydrocarbyl, heteroatom-containing hydrocarbyl, substituted heteroatom-containing hydrocarbyl, and functional groups, provided that at least one of RI or RII and at least one of RIII or RIV is other than H. In a preferred embodiment, either RI or RII and either RIII or RIV is H, such that the internal olefin is di-substituted.
As another example, the olefinic substrate is an ester of glycerol (a “glyceride”), and has the structure of formula (I)




wherein RV, RVI, and RVII are independently selected from hydrogen, hydrocarbyl, substituted hydrocarbyl, heteroatom-containing hydrocarbyl, substituted heteroatom-containing hydrocarbyl, and functional groups, provided that at least one of RV, RVI, and RVII is other than hydrogen and comprises an internal olefin. In a preferred embodiment, the olefinic substrate comprises glycerol esterified with 1, 2, or 3 fatty acids, such that the olefinic substrate is a monoacylglycerol, diacylglycerol, or triacylglycerol (i.e., a monoglyceride, diglyceride, or triglyceride, respectively), or a mixture thereof. Each fatty acid-derived fragment of the olefinic substrate may independently be saturated, monounsaturated, or polyunsaturated, and may furthermore derive (or be derivable) from naturally-occurring fatty acids or from synthetic fatty acids. For example, the olefinic substrate may comprise glycerol esterified with one, two, or three fatty acids that are independently selected from CH3(CH2)nCOOH, where n is 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, or 22, palmitoleic acid, vaccenic acid, erucic acid, oleic acid, alpha-linolenic acid, gamma-linolenic acid, linoleic acid, gadoleic acid, arachidonic acid, docosahexaenoic acid (i.e., DHA), eicosapentaenoic acid (i.e., EPA), and CH3—RVIII—COOH, where RVIII is substituted or unsubstituted C2-C24 alkenylene. The olefinic substrate may be solid (e.g., a fat) or liquid (e.g., an oil).

Preferred olefinic substrates are seed oils, or are compounds that derive from seed oils.
The olefinic substrate may be a compound or mixture of compounds that is derived from a seed oil or glyceride using any one or combination of methods well known in the chemical arts. Such methods include saponification, esterification, hydrogenation, isomerization, oxidation, and reduction. For example, the olefinic substrate may the carboxylic acid or mixture of carboxylic acids that result from the saponification of a monoacylglycerol, diacylglycerol, triacylglycerol, or mixture thereof. In a preferred embodiment, the olefinic substrate is a fatty acid methyl ester (FAME), i.e., the methyl ester of a carboxylic acid that is derived from a glyceride. Sunflower FAME, safflower FAME, soy FAME (i.e., methyl soyate), and canola FAME are examples of such olefinic substrates. In addition, preferred olefinic substrates include seed oil-derived compounds such as methyl oleate.
Sources of unsaturated esters of glycerol include synthesized oils, natural oils (e.g., seed oils, vegetable oils), animal fats, similar sources and any combinations thereof. Representative examples of vegetable oils include canola oil, rapeseed oil, coconut oil, corn oil, cottonseed oil, olive oil, palm oil, peanut oil, safflower oil, sesame oil, soybean oil, sunflower oil, linseed oil, palm kernel oil, tung oil, castor oil, combinations of these, and the like. Representative examples of animal fats include lard, tallow, chicken fat, yellow grease, fish oil, combinations of these, and the like. A representative example of a synthesized oil includes tall oil, which is a byproduct of wood pulp manufacture.
The at least one internal olefin is reacted with ethylene, a cross-metathesis partner, in the cross-metathesis reactions of the invention. Ethylene may be provided in the form of a condensed liquid, but in a preferred embodiment, ethylene is provided in the form of a gas. Typically, the pressure of a gaseous cross-metathesis partner over the reaction solution is maintained in a range that has a minimum of about 10 psi, 50 psi, or 80 psi, and a maximum of about 100 psi, 150 psi, 180 psi, 200 psi, 500 psi, 800 psi, or 1000 psi.
Procedures and Reaction Conditions
The components of the reactions of the invention may be combined in any order, and it will be appreciated that the order of combining the reactants may be adjusted as needed. For example, the catalyst may be added to the olefinic substrate, followed by addition of ethylene. As another example, a flask containing the olefinic substrate may be pressurized with ethylene, followed by addition of the catalyst (as, for example, a concentrated solution in a solvent as described herein). The catalyst may be added to the reaction either as a solid or dissolved in a solvent. The catalyst might be added in any quantities and manner effective for the intended results of the reaction. For example in applications where minimization of catalyst's bimolecular decomposition is desired, predetermined amounts of catalyst can be sequentially added to the reaction mixture at predetermined time intervals.
The reactions of the invention may be carried out in a solvent, and any solvent that is inert towards cross-metathesis may be employed. Generally, solvents that may be used in the cross-metathesis reactions include organic, protic, or aqueous solvents, such as aromatic hydrocarbons, chlorinated hydrocarbons, ethers, aliphatic hydrocarbons, alcohols, water, or mixtures thereof. Example solvents include benzene, toluene, p-xylene, methylene chloride, 1,2-dichloroethane, dichlorobenzene, chlorobenzene, tetrahydrofuran, diethylether, pentane, methanol, ethanol, water, or mixtures thereof. In a preferred embodiment, the reactions of the invention are carried out neat, i.e., without the use of a solvent.
It will be appreciated that the temperature at which a cross-metathesis reaction according to the invention is conducted can be adjusted as needed, and may be at least about −78° C., −40° C., −10° C., 0° C., 10° C., 20° C., 25° C., 40° C., 60° C., 100° C., or 150° C. In a preferred embodiment, the reactions are carried out at a temperature of at least about 40° C., and in another preferred embodiment, the reactions are carried out at a temperature of at least about 60° C.
The reactions of the invention are catalyzed by any of the metathesis catalysts that are described supra. The catalyst is typically added to the reaction medium as a solid, but may also be added as a solution wherein the catalyst is dissolved in an appropriate solvent. It will be appreciated that the amount of catalyst that is used (i.e., the “catalyst loading”) in the reaction is dependent upon a variety of factors such as the identity of the reactants (including the identity of the catalyst), and the reaction conditions that are employed. It is therefore understood that catalyst loading may be optimally and independently chosen for each reaction. In general, however, the catalyst will be present in an amount that ranges from a low of about 0.1 ppm, 1 ppm, or 5 ppm, to a high of about 10 ppm, 15 ppm, 25 ppm, 50 ppm, 100 ppm, 200 ppm, 500 ppm, 1000 ppm, or 10,000 ppm relative to the amount of the olefinic substrate. Catalyst loading, when measured in ppm relative to the amount of the olefinic substrate, is calculated using the equation




  
    ppm
    ⁢
    
      
    
    ⁢
    catalyst
  
  =
  
    
      
        moles
        ⁢
        
          
        
        ⁢
        catalyst
      
      
        moles
        ⁢
        
          
        
        ⁢
        olefinic
        ⁢
        
          
            
          
          ⁢
          
            
          
        
        ⁢
        substrate
      
    
    *
    1
    ,
    000
    ,
    000.
  




Alternatively, the amount of catalyst can be measured in terms of mol % relative to the amount of olefinic substrate, using the equation





  
    mol
    ⁢
    
      
    
    ⁢
    %
    ⁢
    
      
    
    ⁢
    catalyst
  
  =
  
    
      
        moles
        ⁢
        
          
        
        ⁢
        catalyst
      
      
        moles
        ⁢
        
          
        
        ⁢
        olefinic
        ⁢
        
          
        
        ⁢
        substrate
      
    
    *
    100.
  




Thus, the catalyst will generally be present in an amount that ranges from a low of about 0.00001 mol %, 0.0001 mol %, or 0.0005 mol %, to a high of about 0.001 mol %, 0.0015 mol %, 0.0025 mol %, 0.005 mol %, 0.01 mol %, 0.02 mol %, 0.05 mol %, 0.1 mol %, or 1 mol % relative to the olefinic substrate.

In a second embodiment of the invention, the olefin metathesis reaction is carried out by contacting, in the presence of a ruthenium alkylidene metathesis catalyst, an olefinic substrate comprised of a mixture of monoglycerides, diglycerides, and triglycerides, with ethylene, under reaction conditions effective to allow cross-metathesis to occur. The olefinic substrate comprises at least one internal olefin, and the metathesis catalyst has the structure of formula (II)





wherein:

m is zero, 1, or 2;
M is Ru or Os;
n1 and n2 are independently selected from zero and 1;
X1 and X2 are anionic ligands;
R1 and R2 are independently selected from H, hydrocarbyl, substituted hydrocarbyl, heteroatom-containing hydrocarbyl, and substituted heteroatom-containing hydrocarbyl;
L2 and L3 are neutral electron donating ligands; and
L1 is a carbene ligand with the structure of formula (IIIa)




wherein:

Z1 is —N(Ar1)(R9) and Z2 is —N(Ar2)(R9A) or —C(R10)(R11)(R12);

    
    
        Ar1 and Ar2 are independently aryl substituted with at least one group selected from C2-C12 alkyl, C2-C12 alkenyl, C2-C12 alkynyl, C5-C12 aryl, C6-C12 aralkyl, and C6-C12 alkaryl; and
    
    


R9, R9A, R10, R11, and R12 are independently selected from hydrogen, hydrocarbyl, substituted hydrocarbyl, heteroatom-containing hydrocarbyl, and substituted heteroatom-containing hydrocarbyl,
wherein any two of X1, X2, L1, L2, L3, R1, R2, R9, R9A, R10, R11, and R12 may be taken together to form a cycle.
The disclosure for the first embodiment of the invention (e.g., reactants and reaction conditions described supra) also applies for this embodiment.
In a third embodiment of the invention, the olefin metathesis reaction comprises contacting, under reaction conditions effective to prepare a terminal olefin, an olefinic substrate comprising a seed oil or a composition derived from a seed oil and further comprising at least one internal olefin with ethylene in the presence of a ruthenium alkylidene metathesis catalyst comprising an N-heterocyclic carbene ligand, wherein at least about 50% of the metathesis reaction products comprise a terminal olefin and further wherein at least about 50% of the internal olefins initially present in the reaction mixture are converted into terminal olefins. The disclosure for the first embodiment of the invention (e.g., reactants and reaction conditions described supra) also applies for this embodiment.
In a fourth embodiment of the invention, the olefin metathesis reactions comprise contacting, in the presence of a metathesis catalyst, an olefinic substrate comprising at least one internal olefin with ethylene, wherein the metathesis catalyst has the structure of formula (IIA)




wherein:

m is 0, 1, or 2;
n1 and n2 are independently selected from zero and 1;
X1A and X2A are CF3CO2;
R1 and R2 are independently selected from H, hydrocarbyl, substituted hydrocarbyl, heteroatom-containing hydrocarbyl, and substituted heteroatom-containing hydrocarbyl;
L2 and L3 are neutral electron donating ligands; and
L1A is an N-heterocyclic carbene ligand.
The disclosure for the first embodiment of the invention (e.g., reactants and reaction conditions described supra) also applies for this embodiment.
In a fifth embodiment of the invention, the olefin metathesis reactions comprise contacting, under reaction conditions effective to prepare a terminal olefin, an olefinic substrate comprising a seed oil or a composition derived from a seed oil and further comprising at least one internal olefin with ethylene, in the presence of a metathesis catalyst, wherein the metathesis catalyst comprises an N-heterocyclic carbene ligand and is present in an amount that is less than about 50 ppm. The disclosure for the first embodiment of the invention (e.g., reactants and reaction conditions described supra) also applies for this embodiment.
It is to be understood that while the invention has been described in conjunction with the preferred specific embodiments thereof, that the description above as well as the examples that follow are intended to illustrate and not limit the scope of the invention. Other aspects, advantages, and modifications within the scope of the invention will be apparent to those skilled in the art to which the invention pertains.
EXAMPLES
General Procedures
Low Pressure (<200 psi) ethenolyses: Ethenolyses of research grade methyl oleate were set up under an inert atmosphere in a glove box. As an example reaction procedure, a Fisher-Porter bottle equipped with a stir bar was charged with methyl oleate (>99%) from Nu-Check-Prep (Elysian, Minn.) (15.0 g; 50.6 mmol). A solution of olefin metathesis catalyst of an appropriate concentration was prepared in anhydrous dichloromethane (from Aldrich) and the desired volume of this solution added to the methyl oleate. The head of the Fisher-Porter bottle was equipped with a pressure gauge and a dip-tube was adapted on the bottle. The system was sealed and taken out of the glove box to an ethylene line. The vessel was then purged 3 times with ethylene (Polymer purity 99.9% from Matheson Tri Gas), pressurized to the indicated pressure and placed in an oil bath at the indicated temperature. The reaction was monitored by collecting samples into vials at different reaction times via the dip-tube. Immediately after collecting a sample, the reaction was stopped by adding 1 mL of a 1.0 M isopropanol solution of tris-hydroxymethylphopshine (THMP) to the vial. The samples were then heated for at least 1 hour at 60° C., diluted with 1 mL of distilled water, extracted with 1 mL of hexanes and analyzed by gas chromatography (GC).
High pressure (>200 psi) ethenolyses: High pressure ethenolyses of research grade methyl were run according to a procedure analogous to that for low pressure ethenolyses, except that a high-pressure stainless steel reactor (Parr) was used in place of the Fisher-Porter bottles.
GC analytical method: The GC analyses were run using a flame ionization detector (FID). The following conditions and equipment were used:













Column:
Rtx-5, 30 m × 0.25 mm (ID) × 0.25 μm



film thickness.



Manufacturer: Restek


GC and column conditions:
Injector temperature: 250° C.



Detector temperature: 280° C.


Oven temperature:
Starting temperature: 100° C.,



hold time: 1 minute.



Ramp rate 10° C./min to 250° C.,



hold time: 12 minutes.



Carrier gas: Helium


Mean gas velocity:
31.3 ± 3.5% cm/sec (calculated)


Split ratio:
~50:1









Example 1
Ethenolysis of MO
Ethenolysis reactions using various first and second generation Grubbs catalysts were run according to the general procedure. Data are provided in Table 1.







TABLE 1







Comparison of first and second generation catalysts in


ethenolysis of MO.a



















Conver-
Selec-







Temp
Time
sion
tivity
Yield

TOF


Entry
Catalyst
(° C.)
(min)
(%)b
(%)c
(%)d
TONe
(min−1)f


















1
C823
40
120
58
93
54
5,400
45


2
C823
60
30
54
89
48
4,800
160


3
C601
40
30
51
94
48
4,800
160


4
C848
40
120
64
44
28
2,800
23


5
C848
60
<15
64
44
28
2,800
>190


6
C627
40
30
60
33
20
2,000
67


7
C627
60
<15
68
47
32
3,200
>210





aGeneral conditions: neat MO, 150 psi ethylene, catalyst loading = 100 ppm


bConversion = 100 − [(final moles of MO) * 100/(initial moles of MO)]


cSelectivity = (moles of ethenolysis products) * 100/(moles of total products)


dYield = (moles of ethenolysis products) * 100/(initial moles of MO) = Conversion * Selectivity/100


eTON = Yield * [(moles of MO)/(moles of Cat.)]


fTOF = TON/Time






Example 2
Ethenolysis of MO
Ethenolysis reactions using various catalysts were run according to the general procedure. Data are provided in Table 2.







TABLE 2







Comparison of various catalysts in the ethenolysis of MO

















Loading
Time
Conversion
Selectivity
Yield

TOF


Entry
Cat.
(ppm)
(min)
(%)
(%)
(%)
TON
(min−1)


















 1a
C848
100
120
64
44
28
2,800
23


 2b
C848
100
<15
64
44
28
2,800
>190


 3a
C627
100
30
60
33
20
2,000
67


 4b
C627
100
<15
68
47
32
3,200
>210


 5a
C782
100
<15
38
71
27
2,700
>180


 6b
C782
100
<15
53
60
32
3,200
>210


 7a
C712
100
30
70
56
39
3,900
130


 8b
C712
100
<15
79
71
56
5,600
>373


 9a
C712
35
<15
69
57
39
11,000
>733


10c
C712
100
360
87
80
70
7,000
19


11c
C712
25
360
51
63
32
12,800
36


12a
C933
100
60
69
55
38
3,800
63


13a
C933
10
60
61
36
22
22,000
367


14a
C866
100
30
49
94
46
4,600
150


15b
C866
100
<15
43
88
38
3,800
>250


16c
C866
100
<30
39
92
36
3,600
>120


17c
C866
500
<15
86
94
81
1,620
>110


18d
C697
100
1260
66
53
35
3,560
<3


19e
C697
100
390
79
72
57
5,710
15


20f
C697
100
120
81
67
54
5,410
45


21a
C785
100
1380
58
55
32
3,200
<3


22b
C785
100
180
78
73
57
5,640
31


23b
C859
100
240
77
66
51
5,200
22


24g
C859
100
30
76
61
46
4,680
156


25a
C859
100
1200
71
59
42
4,200
<4


26a
C879
100
390
51
69
35
3,570
9


27b
C879
100
240
59
90
53
5,370
22


28b
C965-p
100
30
58
45
26
2,500
84


29b
C824
100
30
35
86
30
2,990
100


30a
C606
100
1,320
61
92
56
5,600
4


31a
C606
50
1,200
61
93
57
11,400
10


32a
C578
100
<30
73
73
53
5,300
>177


33a
C578
35
60
75
75
56
16,000
267


34a
C578
10
<30
42
83
35
35,000
>1,167


35a
C646
100
360
46
94
43
4,200
12


36a
C838
100
1320
60
90
54
5,440
4


37g
C577
100
300
74
84
62
6,330
21


38b
C577
100
1380
67
90
60
6,150
<5


39a
C767-m
100
30
37
32
12
1,150
38


40a
C811
100
15
62
34
21
2,100
140


41a
C916
100
15
65
45
29
2,900
194


42b
C827
100
120
75
64
48
4,790
40





aneat MO; 40° C.; 150 psi ethylene.


bneat MO; 60° C.; 150 psi ethylene.


cneat MO; 25° C.; 800 psi ethylene.


dneat MO; 40° C.; 180 psi ethylene.


eneat MO; 60° C.; 180 psi ethylene.


fneat MO; 80° C.; 180 psi ethylene.


gneat MO; 80° C.; 150 psi ethylene






Example 3
Ethenolysis of MO
Ethenolysis reactions using various catalysts were run according to the general procedure. Data are provided in Table 3.







TABLE 3







Comparison of C606 and C578 to C848 and C627 in ethenolysis of MOa

















Loading
Time
Conversion
Selectivity
Yield

TOF


Entry
Cat.
(ppm)
(min)
(%)
(%)
(%)
TON
(min−1)


















1
C848
100
120
64
44
28
2,800
23


2
C627
100
30
60
33
20
2,000
67


3
C606
100
1,320
61
92
56
5,600
4


4
C606
50
1,200
61
93
57
11,400
10


5
C578
100
<30
73
73
53
5,300
>177


6
C578
35
60
75
75
56
16,000
267


7
C578
10
<30
42
83
35
35,000
>1,167





aConditions: neat MO; 40° C.; 150 psi ethylene.






Example 4
Ethenolysis of Pure Methyl Oleate with 2ND Generation Catalysts
As in the reaction shown below, methyl oleate was reacted with ethylene and 100 ppm of catalyst C627 according to the general procedure given above. The results are illustrated in the graph shown in FIG. 1.

## Claims

1. A method for synthesizing a metathesis reaction product having a terminal olefin, the method comprising contacting, in the presence of a metathesis catalyst, an olefinic substrate comprised of at least one internal olefin with ethylene, wherein the catalyst is present in an amount that is less than about 1000 ppm relative to the amount of the olefinic substrate, and wherein the metathesis catalyst has the structure of formula (IIa):



wherein:
M is Ru;
X1 and X2 are anionic ligands;
R1 is selected from the group consisting of hydrogen, hydrocarbyl, substituted hydrocarbyl, heteroatom-containing hydrocarbyl, and substituted heteroatom-containing hydrocarbyl;
Q is selected from the group consisting of heteroatom-containing hydrocarbylene and substituted heteroatom-containing hydrocarbylene, wherein M is connected to a heteroatom, wherein a five or six member ring is formed with M and the heteroatom, and wherein two or more substituents on adjacent atoms within Q may be taken together to form an additional, optionally substituted cyclic structure;
n1 is zero or 1;
L1 has the structure of formula (IIIc):






L3 is a neutral electron donating ligand;
wherein Ar1 and Ar2 are independently aryl substituted with at least one group selected from the group consisting of C5-C12 alkyl, C5 -C12 alkenyl, C5-C12 alkynyl, C5-C12 aryl, C6-C12 aralkyl, and C6-C12 alkaryl; α is an optional double bond; and R13, R14, R15, and R16 are independently selected from the group consisting of hydrogen, hydrocarbyl, substituted hydrocarbyl, heteroatom-containing hydrocarbyl, and substituted heteroatom-containing hydrocarbyl, wherein any two or more of Ar1, Ar2, R13, R14, R15, and R16 may be taken together to form a cyclic group, and provided that R14 and R16 are not present if α is present.

2. The method of claim 1, wherein L1 has the structure of formula (IIId):



wherein R22, R23, R27, and R28 are independently selected from the group consisting of C5-C12 alkyl, C5-C12 alkenyl, C5-C12 alkynyl, C5-C12 aryl, C6-C12 aralkyl, and C6-C12 alkaryl, and R24, R25, R26, R29, R30, and R31 are independently selected from the group consisting of hydrogen, C1-C12 alkyl, C2-C12 alkenyl, C2-C12 alkynyl, C5-C12 aryl, C6-C12 aralkyl, and C6-C12 alkaryl.

3. The method of claim 2, wherein R13, R14, R15, R16, R24, R25, R26, R29, R30, and R31 are hydrogen such that L1 has the structure of formula (IIIe):

4. The method of claim 1, wherein R17 and R18 are C5-C12 alkyl.

5. The method of claim 1, wherein the catalyst has the structure of formula (IIb):

6. The method of claim 1, wherein the catalyst is present in an amount that is 100 ppm or less relative to the amount of the olefinic substrate, at least 50% of the metathesis reaction product comprises the terminal olefins, and at least 50% of the internal olefins initially present in the reaction mixture are converted to the terminal olefins.

7. The method of claim 6, wherein at least 70% of the metathesis reaction product comprises the terminal olefins.

8. The method of claim 6, wherein at least 80% of the metathesis reaction product comprises the terminal olefins.

9. The method of claim 6, wherein at least 90% of the metathesis reaction product comprises the terminal olefins.

10. The method of claim 6, wherein at least 60% of the internal olefins initially present in the reaction mixture are converted to the terminal olefins.

11. The method of claim 6, wherein at least 70% of the internal olefins initially present in the reaction mixture are converted to the terminal olefins.

12. The method of claim 6, wherein at least 80% of the internal olefins initially present in the reaction mixture are converted to the terminal olefins.

13. The method of claim 1, wherein the catalyst is present in an amount that is 25 ppm or less relative to the amount of the olefinic substrate, at least 50% of the metathesis reaction product comprises the terminal olefins, and at least 50% of the internal olefins initially present in the reaction mixture are converted to the terminal olefins.

14. The method of claim 13, wherein at least 70% of the metathesis reaction product comprises the terminal olefins.

15. The method of claim 13, wherein at least 80% of the metathesis reaction product comprises the terminal olefins.

16. A method for synthesizing a metathesis reaction product having a terminal olefin, the method comprising contacting, in the presence of a metathesis catalyst, an olefinic substrate comprised of at least one internal olefin with ethylene, wherein the catalyst is present in an amount that is less than about 1000 ppm relative to the amount of the olefinic substrate, and wherein the metathesis catalyst has the structure of:

17. The method of claim 1, wherein the olefinic substrate is selected from the group consisting of seed oils, alkyl esters of unsaturated fatty acids, and aryl esters of unsaturated fatty acids.

18. The method of claim 1, wherein the olefinic substrate comprises a mixture of internal olefins selected from the group consisting of monoacylglycerols, diacylglycerols, triacylglycerols, and combinations thereof.

19. A method for synthesizing a metathesis reaction product having a terminal olefin, the method comprising contacting, in the presence of a metathesis catalyst, an olefinic substrate comprised of at least one internal olefin with ethylene, wherein the catalyst is present in an amount that is less than about 1000 ppm relative to the amount of the olefinic substrate, and wherein the metathesis catalyst has the structure of formula (IIa):



wherein:
M is Ru;
X1 and X2 are anionic ligands;
R1 and R2 are independently selected from the group consisting of hydrogen, hydrocarbyl, substituted hydrocarbyl, heteroatom-containing hydrocarbyl, and substituted heteroatom-containing hydrocarbyl;

Q is selected from the group consisting of heteroatom-containing hydrocarbylene and substituted heteroatom-containing hydrocarbylene, wherein M is connected to nitrogen, and wherein two or more substituents on adjacent atoms within Q may be taken together to form an additional, optionally substituted cyclic structure;
n1 is zero or 1;
L1 has the structure of formula (IIIc):






L3 is a neutral electron donating ligand;
wherein Ar1 and Ar2 are independently aryl substituted with at least one group selected from the group consisting of C2-C12 alkyl, C2-C12 alkenyl, C2-C12 alkynyl, C5-C12 aryl, C6-C12 aralkyl, and C6-C12 alkaryl; α is an optional double bond; and R13, R14, R15, and R16 are independently selected from the group consisting of hydrogen, hydrocarbyl, substituted hydrocarbyl, heteroatom-containing hydrocarbyl, and substituted heteroatom-containing hydrocarbyl, wherein any two or more of Ar1, Ar2, R13, R14, R15, and R16may be taken together to form a cyclic group, and provided that R14 and R16 are not present if α is present.

20. The method of claim 19, wherein L1 has the structure of formula (IIId):



wherein R22, R23, R27, and R28 are independently selected from the group consisting of C2-C12 alkyl, C2-C12 alkenyl, C2-C12 alkynyl, C5-C12 aryl, C6-C12 aralkyl, and C6-C12 alkaryl, and R24, R25, R26, R29, R30,and R31 are independently selected from the group consisting of hydrogen, C1-C12 alkyl, C2-C12 alkenyl, C2-C12 alkynyl, C5-C12 aryl, C6-C12 aralkyl, and C6-C12 alkaryl.

21. The method of claim 19, wherein R13, R14, R15, R16, R24, R25, R26, R29, R30, and R31 are hydrogen such that L1 has the structure of formula (IIIe):

22. The method of claim 19, wherein the catalyst has the structure:

23. The method of claim 19, wherein the catalyst is present in an amount that is 100 ppm or less relative to the amount of the olefinic substrate, at least 50% of the metathesis reaction product comprises the terminal olefins, and at least 50% of the internal olefins initially present in the reaction mixture are converted to the terminal olefins.

24. The method of claim 23, wherein at least 70% of the metathesis reaction product comprises the terminal olefins.

25. The method of claim 23, wherein at least 90% of the metathesis reaction product comprises the terminal olefins.

26. The method of claim 23, wherein at least 60% of the internal olefins initially present in the reaction mixture are converted to the terminal olefins.

27. The method of claim 23, wherein at least 80% of the internal olefins initially present in the reaction mixture are converted to the terminal olefins.

28. The method of claim 19, wherein the catalyst is selected from the group consisting of:

29. The method of claim 19, wherein the olefinic substrate is selected from the group consisting of seed oils, alkyl esters of unsaturated fatty acids, and aryl esters of unsaturated fatty acids.