Methods for synthesizing vinylidenes and alkenes

The present disclosure provide synthetic methods for the synthesis of N-substituted vinylidene and alkene compounds in addition to compounds formed from such methods.

TECHNICAL FIELD

This disclosure relates to synthetic methods, and more particularly to methods for preparing nitrogen-substituted vinylidene and alkene compounds.

BACKGROUND

Compounds containing vinylidene and alkene functional groups find many applications such as in the development of pharmaceuticals or in polymer manufacture. For example, vinylidene chloride or fluoride are monomer precursors for the widely used plastics polyvinylidene chloride and fluoride, respectively. Due to their wide applicability in the manufacture of various products, there is a clear need for simple and reliable methods for the synthesis of vinylidene-containing compounds.

SUMMARY

The present disclosure provides methods for the synthesis of N-substituted vinylidene compounds from carbonyl-containing compounds using a simple, one-step process. The synthesized N-substituted vinylidene compounds may then be used in the synthesis of novel materials, for example ionic liquids or polymers.

The details of one or more embodiments of the disclosure are set forth in the description below. Other features, objects, and advantages of the disclosure will be apparent from the description and from the claims.

DETAILED DESCRIPTION

Many modifications and other embodiments disclosed herein will come to mind to one skilled in the art to which the disclosed compounds, compositions and methods pertain having the benefit of the teaching presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the disclosures are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. The skilled artisan will recognize many variants and adaptations of the aspects described herein. These variants and adaptations are intended to be included in the teachings of the disclosure and to be encompassed by the claims herein.

As will be apparent to those of skill in the art upon reading this disclosure, each of the individual embodiments described and illustrated herein has discrete components and features which may be readily separated from and combined with the features of any of the other several embodiments without departing from the scope and spirit of the present disclosure.

All publications mentioned herein are incorporated herein by reference to disclose and described the methods and/or materials in connection with which the publications are cited. The publications discussed herein are provided solely for the disclosure prior to the filing date of the present application. The dates of publication provided herein can be different from the actual publication dates, which can require independent confirmation.

It is also to be understood that the terminology used herein is for the purpose of describing particular aspects only and is not intended to be limited. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the disclosed compounds, compositions, and methods belong. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the specification and relevant art and should not be interpreted in an idealized or overly formal sense unless expressly defined herein.

Definitions

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 “a compound” includes, but is not limited to, two or more such compounds, and the like.

Chemical Definitions

Compounds are described using standard nomenclature. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as is commonly understood by one of skill in the art to which this invention belongs.

The compounds described herein include enantiomers, mixtures of enantiomers, diastereomers, tautomers, racemates and other isomers, such as rotamers, as if each is specifically described, unless otherwise indicated or otherwise excluded by context. In particular, any compound containing an alkene group is inclusive of both the Z and E isomers of the alkene, either alone or as a combination in a mixture, irrespective of the particular configuration shown.

A dash (“-”) that is not between two letters or symbols is used to indicate a point of attachment for a substituent. For example, —(C═O)NH2is attached through the carbon of the keto (C═O) group.

The term “substituted”, as used herein, means that any one or more hydrogens on the designated atom or group is replaced with a moiety selected from the indicated group, provided that the designated atom's normal valence is not exceeded and the resulting compound is stable. For example, when the substituent is oxo (i.e., ═O) then two hydrogens on the atom are replaced. For example, a pyridyl group substituted by oxo is a pyridine. Combinations of substituents and/or variables are permissible only if such combinations result in stable compounds or useful synthetic intermediates. A stable active compound refers to a compound that can be isolated and can be formulated into a dosage form with a shelf life of at least one month. A stable manufacturing intermediate or precursor to an active compound is stable if it does not degrade within the period needed for reaction or other use. A stable moiety or substituent group is one that does not degrade, react or fall apart within the period necessary for use. Non-limiting examples of unstable moieties are those that combine heteroatoms in an unstable arrangement, as typically known and identifiable to those of skill in the art.

“Alkyl” is a straight chain or branched saturated aliphatic hydrocarbon group. In certain embodiments, the alkyl is C1-C2, C1-C3, or C1-C6(i.e., the alkyl chain can be 1, 2, 3, 4, 5, or 6 carbons in length). The specified ranges as used herein indicate an alkyl group with length of each member of the range described as an independent species. For example, C1-C6alkyl as used herein indicates an alkyl group having from 1, 2, 3, 4, 5, or 6 carbon atoms and is intended to mean that each of these is described as an independent species and C1-C4alkyl as used herein indicates an alkyl group having from 1, 2, 3, or 4 carbon atoms and is intended to mean that each of these is described as an independent species. When C0-Cnalkyl is used herein in conjunction with another group, for example (C3-C7cycloalkyl)C0-C4alkyl, or —C0-C4(C3-C7cycloalkyl), the indicated group, in this case cycloalkyl, is either directly bound by a single covalent bond (C0alkyl), or attached by an alkyl chain, in this case 1, 2, 3, or 4 carbon atoms. Alkyls can also be attached via other groups such as heteroatoms, as in —O—C0-C4alkyl(C3-C7cycloalkyl). Examples of alkyl include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, t-butyl, n-pentyl, isopentyl, tert-pentyl, neopentyl, n-hexyl, 2-methylpentane, 3-methylpentane, 2,2-dimethylbutane, and 2,3-dimethylbutane. In one embodiments, the alkyl group is optionally substituted as described herein.

“Cycloalkyl” is a saturated mono- or multi-cyclic hydrocarbon ring system. When composed of two or more rings, the rings may be joined together in a fused or bridged fashion. Non-limiting examples of typical cycloalkyl groups include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, and cycloheptyl. In one embodiment, the cycloalkyl group is optionally substituted as described herein.

“Alkenyl” is a straight or branched chain aliphatic hydrocarbon group having one or more carbon-carbon double bonds, each of which is independently either cis or trans, that may occur at a stable point along the chain. Non-limiting examples include C2-C4alkenyl and C2-C6alkenyl (i.e., having 2, 3, 4, 5, or 6 carbons). The specified ranges as used herein indicate an alkenyl group having each member of the range described as an independent species, as described above for the alkyl moiety. Examples of alkenyl include, but are not limited to, ethenyl and propenyl. In one embodiment, the alkenyl group is optionally substituted as described herein.

“Alkynyl” is a straight or branched chain aliphatic hydrocarbon group having one or more carbon-carbon triple bonds that may occur at any stable point along the chain, for example, C2-C4alkynyl or C2-C6alkynyl (i.e., having 2, 3, 4, 5, or 6 carbons). The specified ranges as used herein indicate an alkynyl group having each member of the range described as an independent species, as described above for the alkyl moiety. Examples of alkynyl include, but are not limited to, ethynyl, propynyl, 1-butynyl, 2-butynyl, 3-butynyl, 1-pentynyl, 2-pentynyl, 3-pentynyl, 4-pentynyl, 1-hexynyl, 2-hexynyl, 3-hexynyl, 4-hexynyl, and 5-hexynyl. In one embodiment, the alkynyl group is optionally substituted as described herein.

“Alkoxy” is an alkyl group as defined above covalently bound through an oxygen bridge (—O—). Examples of alkoxy include, but are not limited to, methoxy, ethoy, n-propoxy, isopropoxy, n-butoxy, 2-butoxy, tert-butoxy, n-pentoxy, 2-pentoxy, 3-pentoxy, isopentoxy, neopentoxy, n-hexoxy, 2-hexoxy, 3-hexoxy, and 3-methylpentoxy. Similarly, an “alkylthio” or “thioalkyl” group is an alkyl group as defined above with the indicated number of carbon atoms covalently bound through a sulfur bridge (—S—). In one embodiment, the alkoxy group is optionally substituted as described herein.

“Alkanoyl” is an alkyl group as defined above covalently bound through a carbonyl (C═O) bridge. The carbonyl carbon is included in the number of carbons, for example C2alkanoyl is a CH3(C═O)— group. In one embodiment, the alkanoyl group is optionally substituted as described herein.

“Haloalkoxy” indicates a haloalkyl group as defined herein attached through an oxygen bridge (oxygen of an alcohol radical).

“Aryl” indicates an aromatic group containing only carbon in the aromatic ring or rings. In one embodiment, the aryl group contains 1 to 3 separate or fused rings and is 6 to 14 or 18 ring atoms, without heteroatoms as ring members. When indicated, such aryl groups may be further substituted with carbon or non-carbon atoms or groups. Such substitution may include fusion to a 4- to 7- or 5- to 7-membered saturated or partially unsaturated cyclic group that optionally contains 1, 2, or 3 heteroatoms independently selected from N, O, B, P, Si and S, to form, for example, a 3,4-methylenedioxyphenyl group. Aryl groups include, for example, phenyl and naphthyl, including 1-naphthyl and 2-naphthyl. In one embodiment, aryl groups are pendant. An example of a pendant ring is a phenyl group substituted with a phenyl group. In one embodiment, the aryl group is optionally substituted as described herein.

The term “heterocycle” refers to saturated and partially saturated heteroatom-containing ring radicals, where the heteroatoms may be selected from N, O, and S. The term heterocycle includes monocyclic 3-12 members rings, as well as bicyclic 5-16 membered ring systems (which can include fused, bridged, or spiro bicyclic ring systems). It does not include rings containing —O—O—, —O—S—, and —S—S— portions. Examples of saturated heterocycle groups including saturated 4- to 7-membered monocyclic groups containing 1 to 4 nitrogen atoms [e.g., pyrrolidinyl, imidazolidinyl, piperidinyl, pyrrolinyl, azetidinyl, piperazinyl, and pyrazolidinyl]; saturated 4- to 6-membered monocyclic groups containing 1 to 2 oxygen atoms and 1 to 3 nitrogen atoms [e.g., morpholinyl]; and saturated 3- to 6-membered heteromonocyclic groups containing 1 to 2 sulfur atoms and 1 to 3 nitrogen atoms [e.g., thiazolidinyl]. Examples of partially saturated heterocycle radicals include, but are not limited, dihydrothienyl, dihydropyranyl, dihydrofuryl, and dihydrothiazolyl. Examples of partially saturated and saturated heterocycle groups include, but are not limited to, pyrrolidinyl, imidazolidinyl, piperidinyl, pyrrolinyl, pyrazolidinyl, piperazinyl, morpholinyl, tetrahydropyranyl, thiazolidinyl, dihydrothienyl, 2,3-dihydro-benzo[1,4]dioxanyl, indolinyl, isoindolinyl, dihydrobenzothienyl, dihydrobenzofuryl, isochromanyl, chromanyl, 1,2-dihydroquinolyl, 1,2,3,4-tetrahydro-isoquinolyl, 1,2,3,4-tetrahydro-quinolyl, 2,3,4,4a,9,9a-hexahydro-1H-3-aza-fluorenyl, 5,6,7-trihydro-1,2,4-triazolo[3,4-a]isoquinolyl, 3,4-dihydro-2H-benzo[1,4]oxazinyl, benzo[1,4]dioxanyl, 2,3,-dihydro-1H-benzo[d]isothazol-6-yl, dihydropyranyl, dihydrofuryl, and dihydrothiazolyl. Bicyclic heterocycle includes groups wherein the heterocyclic radical is fused with an aryl radical wherein the point of attachment is the heterocycle ring. Bicyclic heterocycle also includes heterocyclic radicals that are fused with a carbocyclic radical. Representative examples include, but are not limited to, partially unsaturated condensed heterocyclic groups containing 1 to 5 nitrogen atoms, for example indoline and isoindoline, partially unsaturated condensed heterocyclic groups containing 1 to 2 oxygen atoms and 1 to 3 nitrogen atoms, partially unsaturated condensed heterocyclic groups containing 1 to 2 sulfur atoms and 1 to 3 nitrogen atoms, and saturated condensed heterocyclic groups containing 1 to 2 oxygen or sulfur atoms.

“Heteroaryl” refers to a stable monocyclic, bicyclic, or multicyclic aromatic ring which contains from 1 to 3, or in some embodiments 1, 2, or 3 heteroatoms selected from N, O, S, B, and P (and typically selected from N, O, and S) with remaining ring atoms being carbon, or a stable bicyclic or tricyclic system containing at least one 5, 6, or 7 membered aromatic ring which contains from 1 to 3, or in some embodiments from 1 to 2, heteroatoms selected from N, O, S, B, or P, with remaining ring atoms being carbon. In one embodiments, the only heteroatom is nitrogen. In one embodiment, the only heteroatom is oxygen. In one embodiment, the only heteroatom is sulfur. Monocyclic heteroaryl groups typically have from 5 to 6 ring atoms. In some embodiments, bicyclic heteroaryl groups are 8- to 10-membered heteroaryl groups, that is groups containing 8 or 10 ring atoms in which one 5-, 6-, or 7-membered aromatic ring is fused to a second aromatic or non-aromatic ring, wherein the point of attachment is the aromatic ring. When the total number of S and O atoms in the heteroaryl group excess 1, these heteroatoms are not adjacent to one another. In one embodiment, the total number of S and O atoms in the heteroaryl group is not more than 2. In another embodiment, the total number of S and O atoms in the heteroaryl group is not more than 1. Examples of heteroaryl groups include, but are not limited to, pyridinyl, imidazolyl, imidazopyridinyl, pyrimidinyl, pyrazolyl, triazolyl, pyrazinyl, furyl, thienyl, isoxazolyl, thiazolyl, oxadiazolyl, oxazolyl, isothiazolyl, pyrrolyl, quinolinyl, isoquinolinyl, tetrahydroisoquinolinyl, indolyl, benzimidazolyl, benzofuranyl, cinnolinyl, indazolyl, indolizinyl, phthalazinyl, pyridazinyl, triazinyl, isoindolyl, pteridinyl, purinyl, triazolyl, thiadiazolyl, furazanyl, benzofurazanyl, benzothiophenyl, benzothiazolyl, benzoxazolyl, quinazolinyl, quinoxalinyl, naphthyridinyl, and furopyridinyl.

Vinylidene compounds are those which incorporate the functional group RaRbC═CH2, where the connectivity of the central carbon to Raand Rbcan be through carbon atoms or heteroatoms. The most well-known vinylidene compounds are vinylidene chloride (Cl2C═CH2) and vinylidene fluoride (F2C═CH2), which are the respective parent monomers of polyvinylidene chloride (PVDC) and polyvinylidene fluoride (PVDF). Vinylidene compounds where Raand Rbare connected through carbons are rare with the exception of isobutylene ((CH3)2C═CH2), a key intermediate for a variety of organic compounds including methyl tert-butyl ether (MTBE) and poly(isobutylene) (“butyl rubber”). Other small hydrocarbon vinylidene molecules are known, including 2-methyl-1-butene and 1,1-diphenylethylene. Vinylidene compounds where at least one substituent group is connected to the central carbon through either at least one oxygen and/or nitrogen atom have limited examples (e.g., 2-methoxypropene, 2-(dimethylamino)propene, 1,1-dimethoxyethene, and 1-(dimethylamino)-1-methoxyethene). More commonly, greater substitution is present in such molecules, therefore making them not fit within the strict definition of a vinylidene. Those connected through two oxygen atoms are called “ketene acetals”, which have been known since the 1920s (1) and find use as intermediates in a multitude of organic reactions, including the preparation of alpha-amino acids and controlled polymerizations (2-6). Analogous species where the central carbon atom is connected through two nitrogen atoms are known as ketene aminals (7,8). It is known that the adjacent electronegative atoms (either nitrogen or oxygen) in these ketene molecules influence the behavior and activate the methylene carbon of the alkenyl segment.

However, such molecules could prove to be incredibly valuable for a variety of uses, especially in pharmaceuticals, catalysis, and energetic applications. While 1,1-diaminoethene (DAE) and similar compounds exist in the literature, the work is primarily theoretical/computational studies focused on electronic structure calculations and energetics (9-16). The only experimental reactions that have been demonstrated and with DAE and α,β-unsaturated carbonyl derivatives, which cyclize to form pyrimidines or other N-containing ring systems (17, 18). Pyrimidines naturally occur in several nucleotides and are used in synthetic barbiturates and HIV drugs. N,N,N′,N′-tetramethylethene-1,1-diamine (TMDA) has been utilized in cumulene (—C═C═C—) synthesis from coupling with 1,1′-dihaloalkane (19). TMDA has also been used to modify unsaturated ring systems via cycloaddition (20, 21). TMDA in the presence of a sulfonyl halide group forms substituted thiete-dioxide rings (22). TMDA and bis-alkylmercaptomethyleneimides were shown to form isothioureas and 1-aza-butadiene derivatives (23). Diaminoalkenes and thioureas have been explored as nucleophilic catalysts for reactions including ring-opening polymerizations of lactones, epoxies, and isocyanates (24,25). Diaminoalkenes are most commonly found within the substructures of ligands and complexes (26). Amidines, an isomer of diaminoalkenes, have also exhibited catalytic activity in a variety of reactions (27). Generally, metal vinylidenes have also been shown to catalyze various organic reactions (28). N-vinyl azole derivatives have been reported, from the reaction of azoles with 1,1-dihaloalkenes (29,30). N-heterocyclic olefins bear structural similarity to these aforementioned compounds, wherein the N-atoms connected to the C═C segment are within a heterocycle, and have also been demonstrated as diverse catalysts (31, 32).

Despite these fundamental studies of the nitrogen-analogs of ketene acetals (i.e., ketene aminals) and foundational investigation of simple 1,1′-diaminoethene derivatives, few analogs of this form include complex or cyclic substituents on the nitrogen atoms or are synthetically accessible. In fact, no N-mediated vinylidenes are shown in the literature summarizes 1,1-bis(nitrogen-functionalized) alk-1-enes (25).

1,1′-carbonyldiimidazole (CDI), 1,1′-thiocarbonyldiimidazole (TCDI), and 1,1′-sulfinylbis(1H-imidazole) have all been demonstrated to react with various substrates, serving as imidazole or carbonyl transfer agents (33). Ogata et al. investigated the reaction between aldehydes and ketones with 1,1′-thionyldiimidazole (TDI), which resulted in imidazole transfer and yielded diimidazole and monoimidazole products from several derivatives. While thionyl or thiocarbonyl transfer reactions via TDI or TCDI are well known, only CDI is an inexpensive, common, and versatile substrate with diverse reaction potential, even though the aforementioned work did not observe reactions between CDI and aldehydes or ketones. Since this early work, the continued study of CDI has gravitated toward the synthesis of asymmetric carbamides and carbamates, as one imidazole moiety of CDI can be displaced by alcohols and amines (29, 34, 35). Additionally, the catalyzed reactions of CDI with benzaldehydes, or corresponding benzaldehyde dimethyl acetals, have been shown to produce 1,1′-(phenylmethylene)diimidazole compounds (36). 1,1′-carbonyldiazole compounds are powerful synthetic tools (37) but have not been demonstrated in the synthesis of heterocyclic N,N′vinylidene or HKA compounds.

The present disclosure demonstrates the formation of azole-mediated vinylidene products (e.g., several 1,1′-(ethene-1,1-diyl)diazoles and 1,1′-(prop-1-ene-1,1-diyl)diimidazole), and methods for their synthesis via reaction of symmetric carbamides with at least 3 equivalents of paraformaldehyde (PFA) (or dimethoxymethane or 1,3,5-trioxane) and acetaldehyde, respectively. The principal demonstration of the C═C bond formation is the reaction of CDI with at least 3 equivalents of PFA to form 1,1′-vinylidene-diimidazole (VDI). This transformation was expanded and confirmed to apply in other cases under similar reaction conditions, including the reaction of at least 3 equivalents of PFA with 1,1-carbonyldi(2-methylimidazole) or 1,1′-carbonyldi(1,2,4-triazole) to form the corresponding 1,1′-(ethene-1,1-diyl)bis(2-methyl-1H-imidazole) or 1,1′-(ethene-1,1-diyl)bis(1H-1,2,4-triazole) derivatives, respectively. Similarly, the reaction of 1 equivalent of CDI with at least 3 equivalents of acetaldehyde yields 1,1′-(prop-1-ene-1,1-diyl)bis(1H-imidazole).

The transformations described herein could allow for alternative chemistries related to catalysis or carbamide-based pharmaceutical development and drug delivery. Carbamides are contained within fungicides (i.e., prochloraz), barbiturates, as well as anti-inflammatory, anti-microbial, and anti-convulsant compounds (38-41). This chemistry could be utilized in the design and expansion of pharmaceuticals containing these functional features, or employed in the grafting or tethering of pharmaceuticals for investigative drug delivery methodologies. Furthermore, the described vinylidene derivatives are polymerizable, leading to new forms of poly(azoles) or cationic poly(azolium) polyelectrolytes with an unprecedented architecture and controllable ionizable content, in contrast to the architectures of poly(vinylimidazole), poly(vinylimidazolium), (i.e., poly(ionic liquids)) and ionenes (42, 43). Cationic polyelectrolytes and ionenes find use in a range of applications, including batteries, biocompatible materials, as antimicrobial/antifungal substrates, and in separation processes (44, 45).

Methods for Synthesizing Compounds of Formula I or Formula III

The present disclosure provides methods for synthesizing vinylidene or alkene compounds substituted at their open valencies with one or more nitrogen containing substituents. “Vinylidene” as used herein refers to a 1,1-ethenediyl (C═CH2) moiety.

Thus, in one aspect, the present disclosure provides a method for synthesizing a compound of Formula VI

the method comprising reacting a compound of Formula II

with a compound of Formula VII

or an acetal derivative or a polyacetal derivative thereof, at elevated temperature to form the compound of Formula VI;

R1is selected from hydrogen, alkyl, cycloalkyl, heterocycle, aryl, heteroaryl, OR3, SR3, and NR4R5, each of which may be optionally substituted with one or more Z groups;

R3is selected from alkyl, cycloalkyl, heterocycle, aryl, and heteroaryl, each of which may be optionally substituted with one or more Z groups;

R4and R5are independently selected from hydrogen, alkyl, cycloalkyl, heterocycle, aryl, and heteroaryl, each of which may be optionally substituted with one or more Z groups; or

R4and R5may be brought together with the nitrogen to which they are attached to form a heterocycle ring or a heteroaryl ring, wherein said heterocycle ring or heteroaryl ring may be optionally substituted with one or more Z groups;

R6and R7are independently selected hydrogen, alkyl, cycloalkyl, heterocycle, aryl, and heteroaryl, each of which may be optionally substituted with one or more Z groups; or

R6and R7may be brought together with the nitrogen to which they are attached to form a heterocycle ring or a heteroaryl ring, wherein said heterocycle ring or heteroaryl ring may be optionally substituted with one or more Z groups;

R20is selected from hydrogen, alkyl, cycloalkyl, heterocycle, aryl, and heteroaryl, each of which may be optionally substituted with one or more Z groups; and

An “acetal derivative” as used herein refers to a compound having the formula R20CH(OR21)(OR22), wherein R21and R22may each be selected from alkyl, cycloalkyl, heterocycle, aryl, and heteroaryl, each of which may be unsubstituted or optionally substituted as defined herein, or wherein R21and R22are brought together with the atoms to which they are attached to form an optionally substituted heterocycle ring, and R10is as defined herein. Representative acetal derivatives may include dimethoxymethane and diethoxyethane. A “polyacetal derivative” as used herein refers to a compound having two or more monomeric units having the structure —O—CHR20—O—, wherein R20is as defined herein. In some embodiments, the polyacetal derivative may comprise a trioxolane, for example 1,3,5-trioxolane or paraldehyde. In some embodiments, the polyacetal derivative may comprise a polymer, for example paraformaldehyde.

In some embodiments, the molar ratio of the compound of Formula VII to the compound of Formula II is about 2:1, 2.5:1, 3:1, 3.5:1, or 4:1. In typical embodiments, the molar ratio of the compound of Formula VII to the compound of Formula II in the reaction is about 3:1.

In some embodiments, the compound of Formula II is reacted with the compound of Formula VII at a temperature of about 50° C. or more, about 60° C. or more, about 70° C. or more, about 80° C. or more, about 90° C. or more, about 100° C. or more, about 110° C. or more, or about 120° C. or more. In some embodiments, the compound of Formula II is reacted with the compound of Formula VII at a temperature of about 50° C., 55° C., 60° C., 65° C., 70° C., 75° C., 80° C., 85° C., 90° C., 95° C., 100° C., 105° C., 110° C., 115° C., 120° C. or more. In some embodiments, the compound of Formula II is reacted with the compound of Formula VII at a temperature from about 50° C. to about 120° C., for example from about 60° C. to about 120° C., about 70° C. to about 120° C., about 80° C. to about 120° C., about 90° C. to about 120° C., about 100° C. to about 120° C., about 110° C. to about 120° C., about 50° C. to about 110° C., about 60° C. to about 110° C., about 70° C. to about 110° C., about 80° C. to about 110° C., about 90° C. to about 110° C., about 100° C. to about 110° C., about 50° C. to about 100° C., about 60° C. to about 100° C., about 70° C. to about 100° C., about 80° C. to about 100° C., about 90° C. to about 100° C., about 50° C. to about 90° C., about 60° C. to about 90° C., about 70° C. to about 90° C., about 80° C. to about 90° C., about 50° C. to about 80° C., about 60° C. to about 80° C., about 70° C. to about 80° C., about 50° C. to about 70° C., about 60° C. to about 70° C., or about 50° C. to about 60° C.

In some embodiments, the compound of Formula II may be reacted with the compound of Formula VII for a period of time of about 1 hour, about 2 hours, about 3 hours, about 4 hours, about 5 hours, about 6 hours, about 12 hours, about 18 hours, about 24 hours, about 36 hours, about 48 hours or more. In typical embodiments, the compound of Formula II may be reacted with the compound of Formula VII for about 24 hours.

In another aspect, the present disclosure provides a method for synthesizing a compound of Formula I

the method comprising reacting a compound of Formula II

with paraformaldehyde at elevated temperature to form the compound of Formula I;

R1is selected from hydrogen, alkyl, cycloalkyl, heterocycle, aryl, heteroaryl, OR3, SR3, and NR4R5, each of which may be optionally substituted with one or more Z groups;

R3is selected from alkyl, cycloalkyl, heterocycle, aryl, and heteroaryl, each of which may be optionally substituted with one or more Z groups;

R4and R5are independently selected from hydrogen, alkyl, cycloalkyl, heterocycle, aryl, and heteroaryl, each of which may be optionally substituted with one or more Z groups; or

R4and R5may be brought together with the nitrogen to which they are attached to form a heterocycle ring or a heteroaryl ring, wherein said heterocycle ring or heteroaryl ring may be optionally substituted with one or more Z groups;

R6and R7are independently selected hydrogen, alkyl, cycloalkyl, heterocycle, aryl, and heteroaryl, each of which may be optionally substituted with one or more Z groups; or

R6and R7may be brought together with the nitrogen to which they are attached to form a heterocycle ring or a heteroaryl ring, wherein said heterocycle ring or heteroaryl ring may be optionally substituted with one or more Z groups; and

“Paraformaldehyde” as used herein refers to a polyoxymethylene polymer having the formula

wherein n may range from 5 to 500, more typically ranging from 8 to 100. Paraformaldehyde is a readily obtainable material that is available from numerous chemical suppliers.

In some embodiments, the molar ratio of paraformaldehyde to the compound of Formula II is about 2:1, 2.5:1, 3:1, 3.5:1, or 4:1 based upon the molecular weight of the monomeric unit of paraformaldehyde (MW=30.03). In typical embodiments, the molar ratio of paraformaldehyde to the compound of Formula II in the reaction is about 3:1 based upon the molecular weight of the monomeric unit of paraformaldehyde.

In some embodiments, the compound of Formula II is reacted with paraformaldehyde at a temperature of about 50° C. or more, about 60° C. or more, about 70° C. or more, about 80° C. or more, about 90° C. or more, about 100° C. or more, about 110° C. or more, or about 120° C. or more. In some embodiments, the compound of Formula II is reacted with paraformaldehyde at a temperature of about 50° C., 55° C., 60° C., 65° C., 70° C., 75° C., 80° C., 85° C., 90° C., 95° C., 100° C., 105° C., 110° C., 115° C., 120° C. or more. In some embodiments, the compound of Formula II is reacted with paraformaldehyde at a temperature from about 50° C. to about 120° C., for example from about 60° C. to about 120° C., about 70° C. to about 120° C., about 80° C. to about 120° C., about 90° C. to about 120° C., about 100° C. to about 120° C., about 110° C. to about 120° C., about 50° C. to about 110° C., about 60° C. to about 110° C., about 70° C. to about 110° C., about 80° C. to about 110° C., about 90° C. to about 110° C., about 100° C. to about 110° C., about 50° C. to about 100° C., about 60° C. to about 100° C., about 70° C. to about 100° C., about 80° C. to about 100° C., about 90° C. to about 100° C., about 50° C. to about 90° C., about 60° C. to about 90° C., about 70° C. to about 90° C., about 80° C. to about 90° C., about 50° C. to about 80° C., about 60° C. to about 80° C., about 70° C. to about 80° C., about 50° C. to about 70° C., about 60° C. to about 70° C., or about 50° C. to about 60° C.

In some embodiments, the compound of Formula II may be reacted with paraformaldehyde for a period of time of about 1 hour, about 2 hours, about 3 hours, about 4 hours, about 5 hours, about 6 hours, about 12 hours, about 18 hours, about 24 hours, about 36 hours, about 48 hours or more. In typical embodiments, the compound of Formula II may be reacted with paraformaldehyde for about 24 hours.

The above reaction may be performed in any reaction vessel that is appropriate for the type of reagents/reactants and solvents used and the scale of the reaction performed. In embodiments where the reaction is performed at a temperature above the boiling point of the solvent or any of the reagents used, the reaction may be performed in a pressure reactor, for example a standard glass pressure reactor, a fisher porter tube or vessel, or a metal pressure reactor. Suitable reaction vessels are commercially available and may be readily selected by one of ordinary skill in the art for the particular conditions to be applied. In some embodiments, the reaction may be performed under microwave irradiation in order to induce the elevated temperature required; in such embodiments the reaction may be performed in a microwave synthesizer. Microwave synthesizers are commercially available from multiple suppliers.

In some embodiments, NR4R5is selected from:

In some embodiments, NR4R5is selected from:

Representative examples of compounds of Formula II include, but are not limited to:

Representative examples of compounds of Formula I or Formula VI as produced by the present methods include, but are not limited to:

A Representative example of a compound of Formula VI as provided by the present methods includes, but is not limited to:

In another aspect, a compound of Formula I-a is provided:

wherein X1, X2, X3, X4, X5, and X6are each selected from N, CH, or C—Z, wherein at least one of X1, X2, X3, X4, X5, and X6in Formula I-a is C—Z, wherein no more than one of X1, X2, and X3, in Formula I-a is N, wherein no more than one of X4, X5, X6in Formula I-a is N, and Z is as defined herein.

In another aspect, a compound of Formula VI-a is provided:

wherein X1, X2, X3, X4, X5, and X6are each selected from N, CH, or C—Z, wherein at least one of X1, X2, X3, X4, X5, and X6in Formula I-a is C—Z, wherein no more than one of X1, X2, and X3, in Formula I-a is N, wherein no more than one of X4, X5, X6in Formula I-a is N, and Z is as defined herein.

Uses of Compounds of Formula I

Uses of the compounds of Formula I may be readily identified by those of ordinary skill in the art. Representative examples are provided below that are in no way meant to limit the potential applications of the compounds synthesized by the methods described herein.

In one aspect, the compounds of Formula I as prepared herein may be use in the preparation of cationic derivatives which may find use as ionic liquids or in the preparation of charged polymers. Compounds of Formula I may be, for example, alkylated at available nitrogen positions under standard alkylating conditions or may be substituted with an aryl or heteroaryl group using cross-coupling conditions such as the Buchwald-Hartwig coupling that would be readily known to those of skill in the art.

Thus in one representative aspect, compounds of Formula III are provided:

and one or more anions balancing the charge of the compound of Formula III;

wherein R10and R11are independently selected from alkyl, cycloalkyl, aryl, or heteroaryl, each of which may be optionally substituted with one or more Z groups;

wherein no more than one of X1, X2, and X3in Formula III are N;

wherein no more than one of X4, X5, and X6in Formula III are N;

and all other variables are as defined herein.

Representative examples of compounds of Formula III include, but are not limited to:

In another aspect, compounds of Formula III-a are provided:

and one or more anions balancing the charge of the compound of Formula III-a;

wherein all variables are as defined herein.

In another representative aspect, compound of Formula IV are provided:

and one or more anions balancing the charge of the compound of Formula IV;

wherein all variables are as defined herein.

In another representative aspect, compound of Formula IV-a are provided:

and one or more anions balancing the charge of the compound of Formula IV-a;

wherein all variables are as defined herein.

The above compounds of Formula III, III-a, IV, and IV-a are cationic and are typically found paired with one or more anions in their natural state. Representative examples of such anions include, but are not limited to, halides (such as chloride, bromide, fluoride, or iodide), hydroxide, bis(trifluoromethanesulfonyl)amide anion, hexafluorophosphate anion, trifluoromethanesulfonate anion, dicyanamide anion, tetrafluoroborate anion, thiocyanate anion, nitrate anion, sulfonate anion, methylsulfate anion, or combinations thereof.

In another aspect, the vinylidene compounds of Formula I described herein may be used in the synthesis of polymers.

Thus in another representative aspect, a polymer is provided comprising one or more monomeric units selected from Formula V, Formula V-a, or combinations thereof:

In another aspect, a polymer is provided comprising one or more monomeric units of Formula V-b:

and one or more anions balancing the charge of the compound of Formula V-b;

wherein all other variables are as defined herein.

A representative polymer includes, but is not limited to, Polymer 1:

wherein X comprises an anion.

EXAMPLES

Representative Synthetic Procedure for Synthesis of 1,1′-(ethene-1,1-diyl)bis(1H-imidazole) (I)

To a 250 mL heavy-walled round-bottom pressure vessel (Ace Glass) was added CDI (10.00 g, 61.7 mmol) and PFA (7.41 g, 247 mmol). The vessel was equipped with a stir bar and acetonitrile (100 mL) was added, and the vessel was sealed with a threaded PTFE cap. The reaction was then heated at 120° C. for 24 h. The reaction mixture was cooled to RT and was precipitated and stirred in 200 mL of DI water for 24 h. The product was isolated via vacuum filtration to yield I as an off-white powder (5.44 g 55%). mp: 185-189° C.;1H NMR (500 MHz, DMSO-d6): δ 7.95 (s, 2H), 7.41 (s, 2H) 6.92 (s, 2H) 6.23 (s, 2H);13C NMR (125 MHz, DMSO-d6): δ 138, 130, 120, 108, 55; HRMS (m/z): [M]+calcd. for C8H8N4, 160.0749; found, 160.0744.

Other representative compounds prepared according to these methods are provided in Scheme 1 below:

Higher order alkene derivatives may be formed according to the procedure described in the following representative scheme:

NMR Characterization of Compounds Prepared

1H- and13C-NMR experiments were collected using a 360 or 500 Hz Bruker Avance NMR Spectrometer, in DMSO-d6, TFA-d, or DCl (in D2O). For all spectra, at least 641H-NMR scans or at least 1500013C-NMR scans were obtained. 2D Spectra, HSQC or HMBC experiments, were employed on the same instrumentation to support these assignments and correlations. Select representative spectra are provided inFIGS.1-14.

IR Characterization

Fourier transform infrared spectroscopy (FT-IR) was performed using a Perkin Elmer ATR-FTIR instrument. In situ FTIR data were collected on a Mettler Toledo ReactIR instrument. Select representative spectra are provided inFIGS.15-18.

Mass Spectrometry

High Resolution Mass Spectrometry

The exact mass and corresponding formulas for the three vinylidene compounds introduced in this work were confirmed using HRMS. These experiments were performed via solid state electron ionization (EI) techniques utilizing an AutoSpec-Ultima™ NT instrument (Scanning Methods Utilized: Magnetic scan: vary magnetic field, over large mass ranges, nominal accuracy. Voltage scan: vary accelerating voltage, over smaller mass ranges, higher accuracy than magnet scanning; Spectra Analyzed: Magnetic scan centroid mode, Voltage scan centroid mode and elemental analysis, Voltage scan continuum mode, with smoothing, with smoothing and center.)

REFERENCES CITED

The compositions and methods of the appended claims are not limited in scope by the specific compositions and methods described herein, which are intended as illustrations of a few aspects of the claims and any compositions and methods that are functionally equivalent are intended to fall within the scope of the claims. Various modifications of the compositions and methods in addition to those shown and described herein are intended to fall within the scope of the appended claims. Further, while only certain representative compositions and method steps disclosed herein are specifically described, other combinations of the compositions and method steps also are intended to fall within the scope of the appended claims, even if not specifically recited. Thus, a combination of steps, elements, components, or constituents may be explicitly mentioned herein; however, other combinations of steps, elements, components, and constituents are included, even though not explicitly stated.

The term “comprising” and variations thereof as used herein is used synonymously with the term “including” and variations thereof and are open, non-limiting terms. Although the terms “comprising” and “including” have been used herein to describe various embodiments, the terms “consisting essentially of” and “consisting of” can be used in place of “comprising” and “including” to provide for more specific embodiments of the invention and are also disclosed. Other than in the examples, or where otherwise noted, all numbers expressing quantities of ingredients, reaction conditions, and so forth used in the specification and claims are to be understood at the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, to be construed in light of the number of significant digits and ordinary rounding approaches.