Enantio- and diastereoselective construction of vicinal quaternary and tertiary carbon centers by catalytic Michael reaction of α-substituted β-keto esters to cyclic enones

Abstract

A catalytic enantio- and diastereoselective Michael reaction was achieved to construct vicinal quaternary and tertiary carbon centers in one step. Using 5 mol % of La(O- i-Pr) 3 and 10 mol % of a new N-linked-BINOL type ligand, the reaction of α-substituted β-keto esters to cyclic enones provided the corresponding Michael adducts in up to quantitative yield with a diastereomeric ratio up to 86/14 and enantiomeric excess up to 86% for the major isomer. An alternative catalyst preparation method using La(OTf) 3 instead of La(O- i-Pr) 3 was also examined.