Lithium amidoborane, a highly chemoselective reagent for the reduction of α,β-unsaturated ketones to allylic alcohols

Lithium amidoborane (LiNH2BH3, LiAB for short), is capable of chemoselectively reducing alpha,beta-unsaturated ketones to the corresponding allylic alcohols at ambient temperature. A mechanistic study shows that the reduction is via a double hydrogen transfer process. The protic H(N) and hydridic H(B) in amidoborane add to the O and C sites of the carbonyl group, respectively.