A new method for the chemoselective reduction of aldehydes and ketones using boron tri-isopropoxide, B(OiPr)3: Comparison with boron tri-ethoxide, B(OEt)3

Abstract

A chemoselective Meerwein-Ponndorf-Verley reduction process of various aliphatic and allylic α,β-unsaturated aldehydes and ketones is described. This chemoselective reduction is catalysed by boron triisopropoxide B(Oi Pr)3. Kinetics of reduction of aldehydes and ketones to corresponding alcohols were also examined and rate constant of each carbonyl compounds were measured. Rate constant and reduction yield of each carbonyl compounds in the presence of B(Oi Pr)3 were compared with those in the presence of B(OEt)3. The alcohols that are the reduction product were analysed by GC-MS. The rate constants and alcohol yields were found to be higher with B(OEt)3 than with B(Oi Pr) 3. The mechanism proposed involves a six-membered transition state in which both the alcohol and the carbonyl are coordinated to the same boron centre of a boron alkoxide catalyst. © Indian Academy of Sciences.