Trialkyl borohydrides

Asymmetric reduction of ketones. This borohydride reduces even hindered ketones and with high stereoselectivity, as noted with other hindered trialkyl-borohydrides. Thus 2-methylcyclohexanone is reduced to c/y-2-methylcyclohexa-nol (99% isomeric purity). Of even greater interest, the alcohols formed on reduction are consistently enriched in the (R)-enantiomer to the extent of 10-40%. ... 

Trialkyl borohydrides such as Lithium Tri-s-butylborohydride and Potassium Tri-s-butylborohydride are superior reagents for the chemoselective 1,4-reduction of enones. On the other hand, 1,2-reduction can be obtained by using NaBHj in the mixed solvent MeOH-THF (1 9), or with NaBHj in combination with CeCH or other lanthanide salts. ... 

Henkel-Loctite appears to have been careful to avoid the patent minefield laid by 3M and Dow. Their patent strategy in this field has involved mainly the use of metal alkali borohydrides [113,114], or tetralkylboranes [115-117]. In particular, alkali metal trialkyl borohydrides are used, the alkali metal salt being selected from lithinm triethylborohydride, sodium triethylborohydride, potassium triethylborohydride, lithium tri-sec-butylborohydride, sodium tri-sec-butylborohydride, potassium tri-sec-butylborohydride, and lithium triethylborodeuteride. 

Reduction reactions of nickel(If) compounds. The reduction of nickel(II) compounds to yield nickel(0) phosphine complexes has been carried out using a variety of reducing agents such as sodium amalgam, sodium sand, sodium borohydride, sodium naphthalenide and aluminum trialkyls. In some cases the phosphine ligand itself was found to act as the reducing agent. 

Trialkyl borates, generated in situ from sodium borohydride and an alcohol, catalyse reduction of ketones with borohydride. With (-)-menthol as the initiating alcohol, the... 

A valuable route to benzofurazans is provided by deoxygenation of the corresponding benzofuroxan. This may be accomplished either directly using trialkyl phosphites, tributyl-or triphe nyl-phosphine, or indirectly via the quinone dioxime using, for example, methanol and potassium hydroxide, hydroxylamine and alkali, sodium azide in DMSO or ethylene glycol, sodium borohydride, and occasionally thermolysis alone. More detailed discussion of these reactions is included in Section 4.22.3.2.4. 

In compliance with this expectation, neutral formyl complexes have been synthetized ° by a reaction of Re carbonyl cations with hydrides. With very strong hydride donors, like trialkyl- or trialkoxy-borohydrides, anionic formyl complexes have been prepared even from neutral carbonyl compounds. 

Dialkoxyphosphines can be prepared in high yields by rednction of chlorophosphites with sodium borohydride or trialkyl stannanes (6.222). 

From mixed alkylethylboranes, arising from ethyldiboranes, all ethyl-boron groups may be removed as (C2H5)3B by addition of small amounts of borohydrides 8, 20) or aluminum trialkyls (9), or by use of di- or polyolefins at room temperature and reduced pressure. In this way, yields... 

Very unstable trialkyl-lead borohydrides have been made from organoleadalkoxides and diborane at - 78°. 

R3PbOCH3 + 3(BH3>2 4R3PbBH4+2HB(OCH3>2 These trialkyl-lead borohydrides react with methanol to release trialkyl-lead hydrides, and decompose at about — 30° to hexa-alkyldileads i. 

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