Alkyl substituted metal alkylalkoxyhydroborate reducing agents, and processes for production and use of the same

Alkyl substituted metal hydroborate reducing agents are produced by reacting a borane or mono- or di-alkylborane with greater than 10%, based on the molar content of the borane, of a metal alkoxide, metal alkylthiolate, metal alkylamide, halogenated metal alkoxide, halogenated metal alkylthiolate or halogenated alkylamide.

FIELD OF THE INVENTION 
The present invention relates to reducing agents, and more particularly to 
alkyl substituted metal hydroborate reducing agents. 
BACKGROUND OF THE INVENTION 
Alkali metal borohydrides have been commercially recognized as powerful 
nucleophilic reducing agents. The first such borohydride to be recognized 
was lithium triethylborohydride, which has been found to reduce most 
organic functional groups in a matter of minutes under very mild 
conditions at room temperature. Other lithium mono- and 
di-alkylborohydrides have since been prepared and have been determined to 
have suitable reducing characteristics for various organic functional 
groups. One commercially available reducing agent in this category is 
lithium 9-boratabicyclo(3.3.1)nonane (hereinafter "Li9-BBNH"). This 
reagent is prepared by reacting lithium hydride with 9-BBN in 
tetrahydrofuran as a solvent. The reaction is extremely slow, taking 48 
hours at 25.degree. C. In industry, this reaction is typically carried out 
at 65.degree. C. for a period of 24 hours. 
The prolonged high temperature reflux required to produce such lithium 
mono- and di-alkylborohydrides greatly limits the structural range of 
products resulting. This is because mono- and di-alkylboranes readily 
disproportionate within hours at reflux temperatures. 
In addition to requiring long preparation times and resulting in a small 
variety of products, such known lithium mono- and di-alkylborohydrides do 
not make efficient use of the metal hydride moiety included therein when 
used to reduce organic functional groups. For example, the reducing agent 
lithium triethylborohydride (LiEt.sub.3 BH) reacts with a reducible 
functional group to produce the byproduct triethylborane. This byproduct 
then reacts with the remaining lithium triethylborohydride to form 
LiEt.sub.3 BH:BEt.sub.3. This latter compound is relatively inactive. In 
effect, the reducing agent serves as its own inactivator and therefore 
requires at least a 100% excess for reduction. The conventional reducing 
agent Li9-BBNH behaves similarly, reacting with many organic compounds to 
liberate less reactive 9-BBN. 
Finally, an additional drawback of such conventional lithium mono- and 
di-alkylborohydride reducing agents is that they must be inactivated prior 
to recovery of the desired reduction product, which usually entails an 
oxidative workup that many organic compounds can not tolerate. 
SUMMARY OF THE INVENTION 
The present invention is directed to alkyl substituted metal hydroborate 
reducing agents produced by reacting alkylboranes with metal salts. In a 
preferred embodiment of the invention, mono- or di-alkylboranes are 
reacted with metal alkoxides, metal alkylthiolates, metal alkylamides, 
halogenated metal alkoxides, halogenated metal alkylthiolates, or 
halogenated metal alkylamides. 
The present invention is also directed to processes for producing alkyl 
substituted metal hydroborate reducing agents of the formula X.sub.i 
M[R.sub.l R.sub.m B(AR.sub.j R.sub.k).sub.p+1-r H.sub.r ].sub.n-i by 
reacting an alkylborane having the formula R.sub.l R.sub.m BH.sub.p with a 
metal salt of the formula X.sub.i M(AR.sub.j R.sub.k).sub.n-i, wherein: 
X is a halogen; 
M is a metal; 
A is selected from the group consisting of oxygen, sulfur and nitrogen; 
R.sub.j, R.sub.k, R.sub.l, and R.sub.m are each hydrocarbons selected from 
the group consisting of hydrogen, C1-C24 alkyl, aryl, arylalkyl, 
monocyclic, polycyclic, and heterocyclic radicals, wherein R.sub.j and 
R.sub.k may share a covalent bond, and R.sub.l and R.sub.m may share a 
covalent bond; 
i equals an integer between 0 and 2;; 
n equals an integer between 1 and 4, provided that i and n are limited by 
the valence of the metal; 
j and k each equal an integer between 0 and 1, provided that the sum of j 
and k is at least 1; 
l and m each equal an integer between 0 and 1, provided that the sum of l 
and m is at least 1 when A is oxygen; 
p equals 3 minus the sum of l and m; and 
r equals an integer between 0 and 3. 
The alkyl substituted metal hydroborate reducing agents of the present 
invention tend to disproportionate, yielding a heterogeneous reducing 
agent system that behaves as a homogeneous reducing agent. The reducing 
agents of the present invention are easily prepared, and can be derived by 
allowing the reaction of the present invention to proceed for from 1 to 6 
hours at room temperature. 
Because the long time duration, high temperature reflux required for 
production of prior known alkali metal borohydrides is not required to 
produce the reducing agents of the present invention, the reducing agents 
of the present invention are much less expensive to produce. The reducing 
agents of the present invention are quite powerful, however, reducing a 
broad variety of organic functional groups in time intervals ranging from 
less than 5 minutes to less than 24 hours. The byproducts of reduction are 
easily removed from the reduced product solution. The reducing agents of 
the present invention are also "efficient" in use of the available 
hydride, avoiding the above-noted problem of self-inactivation common with 
previously known alkali metal borohydrides.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
The alkyl substituted metal hydroborate reducing agents of the present 
invention are the reaction products of: a borane or mono- or 
di-alkylborane with a metal salt. The metal salt may be a metal alkoxide, 
a metal alkylthiolate or a metal alkylamide. Additionally, halogenated 
versions of these metal salts may be used. The reducing agents of the 
present invention and reaction to produce the same is represented by the 
following equation: 
EQU R.sub.l R.sub.m BH.sub.p + X.sub.i M(AR.sub.j R.sub.k).sub.n-i 
.fwdarw.X.sub.i M[R.sub.l R.sub.m B(AR.sub.j R R.sub.k).sub.p+1-r H.sub.r 
].sub.-i (1) 
wherein: 
X is a halogen; 
M is a metal; 
A is selected from the group consisting of oxygen, sulfur and nitrogen; 
R.sub.j, R.sub.k, R.sub.l and R.sub.m are each hydrocarbons selected from 
the group consisting of hydrogen, C1-C24 alkyl, aryl, arylalkyl, 
monocyclic, polycyclic, and heterocyclic radicals, wherein R.sub.j and 
R.sub.k may share a covalent bond, and R.sub.l and R.sub.m may share a 
covalent bond; 
i equals an integer between 0 and 2;; 
n equals an integer between 1 and 4, provided that i and n are limited by 
the valence of the metal; 
j and k each equal an integer between 0 and 1, provided that the sum of j 
and k is at least 1; 
l and m each equal an integer between 0 and 1, provided that the sum of l 
and m is at least 1 when A is oxygen; 
p equals 3 minus the sum of l and m; and 
r equals an integer between 0 and 3. 
Metal Salts 
Suitable metal salts for Equation 1 are metal alkoxides (i.e., when A in 
Equation 1 is oxygen), metal alkylthiolates (when A is sulfur) or metal 
alkylamides (when A is nitrogen), or mixtures of these. Additionally, 
halogenated metal alkoxides, alkylthiolates and alkylamides are suitable 
for use. Preferred halogenated metal salts contain fluorine, chlorine, 
bromine, iodine or astatine. 
The metal salt may contain one or two hydrocarbon moieties, which as used 
herein includes hydrogen, C1-C24 alkyl, aryl, arylalkyl, monocyclic, 
bicyclic, polycyclic, and heterocyclic radicals. When two hydrocarbon 
moieties are included, the two moieties may be either identical or 
different, and may share a covalent bond. Preferred alkyl radicals are 
methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, t-butyl, 
n-pentyl, isopentyl, hexyl, heptyl, octyl, nonyl, and decyl radicals. 
Alkyl radicals may be either branched or straight chained. 
Suitable aryl moieties include phenyl, benzyl, p-tolyl and ethers such as 
C.sub.6 H.sub.4 OCH.sub.3. Examples of other suitable cyclic radicals are 
radicals of pentane, cyclohexane, napthalene, anthracene, phenanthrene, 
cumene, styrene, o-xylene, isopinocampheyl, and furanes. 
Suitable metals for the metal salts include alkali metals, such as lithium, 
sodium, and potassium, rare metals such as beryllium, magnesium and 
calcium, as well as zinc and aluminum. 
When the metal salt is a metal alkoxide or halogenated metal alkoxide, the 
reducing agent obtained in accordance with the present invention is a 
metal alkyl alkoxy hydroborate. Non-limiting examples of metal alkoxides 
suitable for practice of the present invention are: lithium methoxide, 
sodium methoxide, dichloroaluminum isoprop-oxide, sodium isopropoxide, 
sodium cyclohexoxide, bromomagnesium thexoxide, zinc ethoxide, and 
magnesium bis(n-hexoxide). 
Rather than using an alkoxy metal salt, metal alkylthiolates (i.e., A is 
sulfur in Equation 1) may be used to produce alkyl substituted metal 
alkylthiolate reducing agents. In general, the sulfur versions of the 
alkoxy compounds previously listed are suitable for use with the present 
invention. Examples of particular alkylthiolates found to be suitable 
include sodium methylthiolate, sodium ethylthiolate, lithium 
methylthiolate, chloromagnesium phenylthiolate, dilithium ethane 
dithiolate, and dichloroaluminum propylthiolate. 
Metal alkylamides and halogenated metal alkylamides are also suitable as 
metal salts for use in the present invention (i.e., when A is nitrogen in 
Equation 1). Suitable alkylamides include lithium amide, lithium 
di-isopropylamide, sodium ethaneamide and 
magnesium(pyrrolidineamide).sub.2. 
Alkylboranes 
As used herein, the term alkylboranes refers to boranes, monoalkylboranes, 
and di-alkylboranes. Mono- and di-alkylboranes are suitable for use in 
reacting with metal alkoxides, metal alkylthiolates and metal alkylamides 
to produce the reducing agents of the present invention. Additionally 
borane may be utilized for reaction with metal alkylthiolates and metal 
alkylamides. 
Suitable hydrocarbon moieties for mono- and di-alkylboranes for use in the 
present invention include those hydrocarbon radicals listed above as 
suitable for metal salts of the present invention. Thus, hydrogen, C1-C24 
alkyl, aryl, arylalkyl, monocyclic, bicyclic, and heterocyclic alkyls may 
be used. Most preferably, when the metal salt is a metal alkoxide, the 
hydrocarbon moiety is a C1-C24 alkyl, aryl, arylalkyl, monocyclic, 
polycyclic, mono-heterocyclic, or bi-heterocyclic, wherein one of the 
rings bonded to boron is non-heterocyclic (i.e., a heterocyclic ring 
joined to a non-heterocyclic hydrocarbon ring). When the alkylborane is a 
di-alkylborane, the two alkyl groups may be either identical or different, 
and may share a covalent bond. 
Non-limiting examples of suitable mono- or di-alkylboranes for use in the 
practice of the present invention include 9-boratabicyclo[3.3.1]nonane, 
disiamylborane, methylborane, diisopinocampheylborane, phenylborane, 
monoisopinocampheylborane, dicyclohexylborane, and, for reacting with 
metal alkylthiolates and metal alkylamides, borane. 
Alkyl Substituted Metal Hydroborate Reducing Agents 
The alkyl substituted metal organoboranes of the present invention are 
those produced by reaction of Equation 1, and include alkali metal 
hydroborates and other metal alkylalkoxyhydroborates, alkyl substituted 
metal alkylthiolates and alkyl substituted metal alkylamides, as well as 
alkyl substituted halogenated metal alkoxides, alkylthiolates and 
alkylamides. 
When the metal salt utilizes an alkylthiolate, the alkyl substituted metal 
hydroborate reducing agent produced is the one-to-one addition product of 
the metal alkylthiolate and the alkylborane. No significant amount of 
disproportionation of the reducing agent product is found. However, when 
the metal salt is either a metal alkoxide or metal alkylamide, the 
resulting alkyl substituted metal alkoxide or alkylamide readily 
disproportionates. The reducing agent system represented by these 
disproportionated products behaves as a homogeneous reducing agent 
species, however, as will be shown by the examples following below. 
Non-limiting examples of alkyl substituted metal hydroborate reducing 
agents of the present invention include: lithium 
9-boratabicyclo[3.3.1]-nonane, lithium 
9,9-dimethoxy-9-boratabicyclo[3.3.1]-nonane, dichloroaluminum 
disiamylborohydride, dichloroaluminum disiamyldiisopropoxyborate, lithium 
methylborohydride, lithium methyltrimethoxyborate, sodium 
thexylmonoisopropoxyborohydride, sodium thexyldiisopropoxyborohydride, 
sodium thexyltriisopropoxyborohydride, sodium thexylborohydride, sodium 
diisopinocampheyldicycohexoxyborate, sodium diisopinocampheylborohydride, 
bromomagnesium phenylborohydride, bromomagnesium 
phenylmonothexoxyborohydride, bromomagnesium phenyldithexoxyborohydride, 
bromomagnesium phenyltrithexoxyborate, zinc 
monoisopinocampheylborohydride, zinc monoisopinocampheyltriethoxyborate, 
magnesium dicyclohexylborohydride, magnesium dicyclohexyldinhexoxyborate, 
sodium 9-methyl thiolate-9-boratabicyclo [3.3.1] nonane, NaBH.sub.3 
SCH.sub.3, and lithium 9,9-diisopropylamide 9-boratabicyclo [3.3.1] 
nonane. 
Process for Producing Alkyl Substituted Metal Hydroborates 
To produce the alkyl substituted metal hydroborate reducing agents of the 
present invention, the alkylborane is preferably added to a solution or 
slurry of the metal salt in a hydrocarbon solvent. Non-limiting examples 
of suitable hydrocarbon solvents are: tetrahydrafuran, ethyl ether, 
methylsulfide, cyclohexane, pentane, and mixtures thereof. Preferred 
solvents are tetrahydrafuran and ethyl ether, or hydrocarbon mixtures 
including tetrahydrafuran or ethyl ether. While use of a solvent is 
preferred, in some instances the reactants will act as their own solvents. 
Preferably, the metal salt is present at a concentration of greater than 
10% of the molar concentration of the alkylborane. Most preferably the 
metal salt and the alkylborane are combined in substantially 
stoichiometric ratios. 
The alkyl substituted metal hydroborate reducing agents of the present 
invention are produced by allowing the metal salt and alkylborane to react 
at ambient temperatures. The exact reaction time required will depend on 
the species being reacted, as can be readily determined by one of ordinary 
skill in the art in view of the disclosure contained herein. For most of 
those species disclosed herein, it has been found that the reaction is 
substantially complete within one hour at 25.degree. C. For all of the 
reaction species disclosed herein, it has been found that the reaction is 
substantially complete within a time period of from 1 to 6 hours at 
25.degree. C. The reaction temperature can be elevated to temperatures 
greater than 25.degree. C. to increase the reaction speed, however this is 
not required. 
The alkyl substituted metal hydroborate reducing agent produced by the 
above reaction, or disproportionated products thereof, can be either 
recovered from the solvent as a solid or left in solution for use in 
reducing an organic functionality susceptible to reduction. 
The alkyl substituted metal hydroborates of the present invention have been 
found to be powerful reducing agents for a wide variety of organic 
functional groups that are susceptible to reduction. For example, the 
reducing agents of the present invention have been found to reduce 
aldehyde, ketone, acid chloride and lactone functionalities within five 
minutes at 25.degree. C. Ester functionalities have been found to be 
reduced within one-half hour at 25.degree. C. Epoxides are reduced within 
six hours at 25.degree. C. Alkylbromides and iodides are also reduced 
rapidly (0.5 to 2 hours) by the reducing agents of the present invention, 
while alkylchlorides are also reduced within 24 hours at 25.degree. C. 
Tertiary amide and nitrile functionalities, however, are inert to the 
reducing agents of the present invention over a period of 48 hours. The 
boron derivative produced by reducing organic functionalities with the 
reducing agents of the present invention can be readily removed by 
extraction, chelation, or filtration, as will be readily determined by 
those with skill in the art based on the disclosure contained herein. 
Additional Reducing Agents From Boronic and Borinic Acids and Esters 
The boron derivative produced by reduction with the alkyl substituted metal 
hydroborate reducing agents of the first embodiment of the present 
invention described above are boronic acids and esters, or borinic acids 
and esters, (when the metal salt utilized is a metal alkoxide) or 
alkylthiol boranes (when the metal salt is a metal alkylthiolate), or 
alkylamidoboranes (when the metal salt is a metal alkylamide). As noted 
above, these borane byproducts are readily removed from the reduction 
reaction mixture by filtration, chelation, or extraction. 
In a further aspect of the present invention, it has been found that these 
borane derivatives may be further reacted with metal hydrides or metal 
halides to produce further reducing agents, hereinafter referred to as the 
second embodiment of reducing agents. These reducing agents can be 
represented by the following formula: 
EQU x.sub.i MH.sub.j-i +(R'A).sub.t B R.sub.n R.sub.p H.sub.r .fwdarw.X.sub.i 
M[R.sub.n R.sub.p B(R'A).sub.4-n-p-m H.sub.m ].sub.j-i (2) 
X is a halogen (F, Cl, Br, I, At); 
i equals an integer between 0 and 4; 
M is a metal selected from the group consisting of Li, Na, K, Be, Mg, Ca, 
Zn and Al; 
j equals an integer between 0 and 4; 
A is selected from the group consisting of oxygen, sulfur and nitrogen; 
t equals 1 or 2; 
R', Rn, Rp, are each hydrocarbons selected from the group consisting of 
C1-C24; 
alkyl, aryl, arylalkyl, monocyclic, polycylic and heterocyclic radicals; 
n and p each equal 0 or 1; 
r equals 3 minus the sum of t, n and p; and 
m equals an integer between 0 and 3. 
Preferred boronic acids, boronic esters, borinic acids and borinic esters 
are those that will react with the metal hydride or metal halide to form a 
tetravalent boron reducing agent. Again, as for the first preferred 
embodiment of the present invention, the boron reducing agent tends to 
disproportionate, yielding products including between zero and three 
alkoxy, alkylthiol and alkylamido moeties. These disproportionated species 
act as a single, homogeneous reducing system. 
The metal halide or metal hydride and the borane derivative are preferably 
reacted in the presence of a suitable hydrocarbon solvent, including those 
previously disclosed for the first preferred embodiment of the present 
invention. Preferred solvents include tetrahydrafuran or ethyl ether. The 
reaction is essentially complete within from one to six hours at room 
temperature. 
EXAMPLES 
The following experiments to produce reducing agents in accordance with the 
first preferred embodiment of the present invention were carried out under 
an inert atmosphere of nitrogen using oven or flame dried equipment. Each 
experiment was carried out at 25.degree. C., unless otherwise noted. 
Example 1 
##STR1## 
The above reaction was carried out in a 1 liter round bottom flask with 
reflux condenser and septum inlet. Methanol, 12.62 mL (312 mmol) was 
diluted with 351.7 mL of tetrahydrofuran, THF. To this stirred solution, 
312 mmoles of n-butyl lithium (124.8 mL of a 2.5M solution in hexanes) was 
added at 0.degree. C., yielding a total of 500 mL of a well suspended 
slurry of lithium methoxide, a, LiOMe. The reflux condenser was replaced 
with a simple distillation setup and approximately 100 mL of solvent was 
removed at atmospheric pressure and 65.degree. C. This process removes 
dissolved butane and allows the final solution of the borohydride to be 
standardized with a hydride meter. This slurry was added via double ended 
needle to 38.13 g (312 mmol) of solid 9-borabicyclo[3.3.1]nonane, b, 9-BBN 
in a 1 liter flask. The contents of the flask quickly pass into solution 
at 25.degree. C. within one hour, with a small amount of precipitate 
formed. The final solution has a milky appearance due to its 
concentration. This solution was transferred into a 500 mL volumetric 
flask, and THF was added to bring the total volume to 500 mL. After 
cooling overnight the solution was standardized using a hydride meter and 
found to be 0.56M in hydride, corresponding to a yield of 89.7%. This 
solution was analyzed using .sup.11 B NMR (Bruker 250 MHz) and found to be 
a mixture of lithium 9-boratabicyclo[3.3.1]-nonane, c, and lithium 
9,9-dimethoxy-9-boratabicyclo[3.3.1]nonane, d. 
Example 2 
##STR2## 
Isopropanol (0.766 mL, 0.601 g, 10 mmol) was diluted to 10 mL with 9.23 mL 
of n-hexanes. To this stirred solution, 10 mL of a 1M solution of ethyl 
aluminum dichloride was added slowly at 0.degree. C. Gas was evolved with 
each drop. This reaction resulted in a slurry of 10 mmol of 
dichloroaluminum isopropoxide, a, as an approximate 0.5M solution in 
hexanes. To this slurry was added a solution of disiamylborane, b, in 
ethyl ether, 10 mL of a 1M solution. After one hour at 25.degree. C. the 
mixture was analyzed and found to contain dichloroaluminum 
disiamylborohydride, c, and dichloroaluminum disiamyldi-isopropoxyborate, 
d, and to be devoid of starting material disiamylborane, b. 
Example 3 
##STR3## 
Solid lithium methoxide, a, (0.418 g, 11 mmol) was diluted with 10 mL of 
ethyl ether. To this stirred slurry was added 20 mL of a 0.5M solution of 
freshly prepared methyl borane, b. The mixture was stirred for two hours 
at 25.degree. C. Analysis of the mixture via .sup.11 B NMR revealed both 
lithium methylborohydride, c, and lithium methyltrimethoxyborate, d, and 
an absence of the starting material methyl borane, b. 
Example 4 
##STR4## 
Solid sodium isopropoxide, a, (0.902 g, 11 mmol) was mixed with 10 mL THF. 
Thexylborane, b, (ThxBH.sub.2) (0.98 g, 10 mmol) in 9 mL of THF/Methyl 
Sulfide was added to the slurry and stirred for one hour. Analysis 
indicated the formation of various products: sodium 
thexylmonoisopropoxyborohydride, c, sodium thexyldiisopropoxy-borohydride, 
d, sodium thexyltriisopropoxyborate, e, and sodium thexylborohydride, f, 
and the complete disappearance of starting material thexylborane, b. 
Example 5 
##STR5## 
Ten milliliters of a previously prepared slurry of THF containing 1.34 g of 
sodium cyclohexoxide, a, (10 mmols) was added to a flask containing solid 
diisopinocampheyl-borane, b, (2.86 g, 10 mmol), free of solvent. The 
mixture was stirred and an additional 10 mL of THF was added. The solid 
Ipc.sub.2 BH quickly broke up and dissolved, however, another precipitate 
formed concurrently with this and was believed to be the compound sodium 
diisopinocampheyldicyclohexoxyborate, d. Analysis of the mixture revealed 
an absence of the starting borane, b, and the formation of sodium 
diisopinocampheyl-borohydride, c. 
Example 6 
##STR6## 
Tertiary hexanol (2,3-dimethyl-2-butanol, HOThx), 1.02 g, 10 mmol, was 
diluted to a 1M solution with THF (9.2 mL). To this stirred solution, 3.33 
mL of a 3.0M solution of methyl magnesium bromide in diethyl ether was 
added dropwise while the solution was maintained at 0.degree. C. This 
results in a clear solution of bromomagnesium thexoxide, a. A 1.0M 
solution of phenylborane, b, in hexanes(9.5 mL, 9.5 mmol) was added 
rapidly to this solution, and a small amount of precipitate formed. 
.sup.11 B NMR indicated the presence of the following compounds: 
bromomagnesium phenylborohydride, c, bromomagnesium phenyl 
monothexoxyborohydride, d, bromomagnesium phenyldithexoxyborohydride, e, 
and bromomagnesium phenyltrithexoxyborate, f, and an absence of the 
starting material phenylborane, b. 
Example 7 
##STR7## 
Freshly prepared monoisopinocampheylborane, b, (1.5 g, 10 mmol) as a 1.0M 
solution in ethyl ether was added via double ended needle to solid zinc 
ethoxide, a, 1.7 g, 11 mol. To this slurry, 10 mL of THF was added, and 
the mixture stirred for 6 hours. Analysis of the solution revealed the 
presence of zinc monoisopinocampheylborohydride, c, and zinc 
monoisopinocampheyltriethoxyborate, d, and the absence of starting 
material monoisopinocampheyl borane, b. 
Example 8 
##STR8## 
Ten milliliters of THF was added to 10 mmol, 2.26 g of solvent free 
magnesium bis (n-hexoxide), a, previously prepared from magnesium hydride 
and n-hexanol in ethyl ether. The slurry was stirred for one hour and 
transferred via double ended needle to a flask containing 10 mmol, 1.78 g 
of solidified dicyclohexylborane, b, in ethyl ether, methyl sulfide, and 
excess cyclohexene. The solid quickly broke up and dissolved. Analysis of 
the solution revealed the presence of magnesium dicyclohexylborohydride, 
c, and magnesium dicyclohexyldin-hexoxyborate, d, and the absence of 
starting material dicyclohexylborane, b. 
Example 9 
##STR9## 
The above reaction was carried out using the procedure of Example 1, except 
that sodium methoxide was used in place of lithium methoxide. A clear 
solution resulted within an hour at 25.degree. C. The solution was 
analyzed using .sup.11 B NMR, and was found to include equal amounts of 
sodium 9-boratabicyclo-[3.3.1]nonane, c, and sodium 
9,9-dimethoxy-9-boratabicyclo-[3.3.1]nonane, d. 
Example 10 
##STR10## 
The above reaction was carried out using the procedure of Example 1, except 
that sodium methyl thiolate, a, was used in place of lithium methoxide. A 
clear solution resulted within an hour at 25.degree. C. The solution was 
analyzed using .sup.11 B NMR, and was found to include sodium 9-methyl 
thiolate-9-boratabicyclo[3.3.1]nonane, c, in the non-disproportionated 
form. 
Example 11 
##STR11## 
The above reaction was carried out using the procedure of Example 10, 
except that borane, b, was used in place of 9-BBN. A clear solution 
resulted within an hour at 25.degree. C. The solution was analyzed using 
.sup.11 B NMR, and was found to include NaBH.sub.3 SCH.sub.3, c, in the 
non-disproportionated form. 
Example 12 
##STR12## 
The above reaction was carried out using the procedure of Example 1, except 
that lithium diisopropylamide, a, was used in place of lithium methoxide. 
A clear solution resulted within an hour at 25.degree. C. The solution was 
analyzed using .sup.11 B NMR, and was found to include a mixture of 
lithium 9-boratabicyclo[3.3.1]nonane, c, and lithium 9,9-diisopropylamide 
9-boratabicyclo[3.3.1]nonane, d. 
While the preferred embodiments of the invention have been described and 
examples thereof provided, it will be appreciated that various changes can 
be made therein by those of ordinary skill in the art based on the 
disclosure herein, without departing from the spirit and scope of the 
present invention. Thus it is intended that the scope of letters patent 
granted hereon be limited only by the definitions of the appended claims.