Aminoborohydrides. 2. Regiospecific reductions of α,β-unsaturated carbonyl compounds with lithium pyrrolidinoborohydride. A facile conversion of α,β-unsaturated aldehydes and ketones to the corresponding allylic alcohols in high purity

Article abstract of DOI:10.1016/S0040-4039(00)60561-0

Lithium aminoborohydrides (LiABH₃), obtained by the reaction of n-BuLi with amine-boranes, are powerful reducing agents for the reduction α,β-unsaturated aldehydes and ketones to the corresponding allylic alcohols. Thus, lithium pyrrolidinoborohydride (LiPyrrBH₃) and reduces cinnamaldehyde and cyclohexenone to give exclusively cinnamyl alcohol and 2-cyclohexen-1-ol respectively. This 1,2-reduction appears to be general and ester groups are tolerated. The yield of allylic alcohols from this procedure is essentially quantitative.