Preparation by Addition to Alkenes

Preparation. - By Addition to Alkenes. Triethylborane and phenyl-borinic acid have been found to catalyse hydroalumination of alkenes, and reaction of the intermediate alane with atmospheric oxygen efficiently furnished alcohols resulting from anti-Markovnikov hydration.1 Procedures for the preparation of methylborane and dimethylborane and their use in the synthesis of 

By Reduction of Carbonyl Compounds. Use of high (10 kbar) pressures has been shown to effect trialkylstannane reductions of ketones in the absence of radical initiators or Lewis acids.10 Zinc borohydride has been demonstrated to be a mild reducing agent for the conversion of benzenethiol esters into alcohols in good yield. Use of mixed solvents containing methanol has been found to confer some chemoselectivity upon reductions with lithium borohydride and permits enhanced rates of reduction of esters, lactones, and 

Reagent i, anti-selective Me NHB(OAc)3, CHgCN, AcOH or Pr SiHCI syn -selective Bu jAlH, THF, -78 °C 

Aldols possessing a 2-(1-trimethylsilyl)vinyl substituent give high yields of the corresponding 1,2-syn reduction product with lithium triethylborohydride regardless of the substitution pattern at C-3. The same workers have demonstrated that removal of the silyl group from the C-2 vinylic substituent cleanly inverts the stereochemistry 

Interest in microbial transformations of ketones continues to flourish and a wide range of substrates may now be reduced with impressive optical yields and frequently high chemical yields (cf.8, 210 9 239). Baker s yeast appears to be the most popular 

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Preparation by Addition to Alkenes.- Low-activity boranes in the presence of rhodium complexes (e.g. catecholborane-Wilkinson s... 

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