Stereocontrolled metalloenamine alkylations: application to the asymmetricsynthesis of 4-alkyl-1,2,3,4-tetrahydroisoquinolines

A procedure for the asymmetric synthesis of 4-alkyl-1,2,3,4-tetrahydroisoqu inolines is described. The key step in the synthetic route is a stereocontr olled metalloenamine alkylation using (R)-(+)-phenyl-glycinol methyl ether as the chiral auxiliary. Subsequent N-methylation, hydrogenolysis and cycli zation afforded the target heterocycles with enantiomeric excesses higher t han 99%. (C) 2000 Elsevier Science Ltd. All rights reserved.