Regio- and stereoselective double alkylation of beta-enamino esters with organolithium reagents followed by one-pot reduction: convenient method for the synthesis of tertiary gamma-amino alcohols

An easy, high yielding and stereoselective procedure for the preparation of tertiary -amino alcohols starting from -enamino esters is presented. In this procedure, the double alkylation of -enamino esters with organolithium reagents is followed by one-pot reduction with sodium borohydride in methanol/acetic acid. A hypothesis of mechanism is given, explaining the observed diastereoselectivity through molecular modeling. The configuration of the products was determined by 1H-NMR spectroscopy coupled with conformational analysis.