Enantio- and Diastereoselective Synthesis of syn-β-Hydroxy-α-Vinyl Carboxylic Esters via Reductive Aldol Reactions of Ethyl Allenecarboxylate with 10-TMS-9-Borabicyclo3.3.2decane and DFT Analysis of the Hydroboration Pathway

摘要

An enantio- and diastereoselective synthesis of syn-β-hydroxy-α-vinyl carboxylate esters 3 via the reductive aldol reaction of ethyl allenecarboxylate (2) with 10-trimethylsilyl-9-borabicyclo[3.3.2]decane (1R, Soderquist’s borane) has been developed. Density functional theory calculations suggest that the allene hydroboration involves the 1,4-reduction of 2 with the chiral borane 1R, leading directly to dienolborinate Z-(O)-8a.