1979 Volume 27 Issue 11 Pages 2760-2766
A novel method was devised for the asymmetric synthesis of 2-alkylcycloalkanones (10) by metalation and alkylation of chiral cyclic imines (8), using an optically active α-amino acid tert-butyl ester (7) as a chiral source. The present method provides 2-alkylcycloalkanones (10) of unequivocally predictable absolute configuration in quite high enantiomeric purities, allowing easy recovery of the chiral reagent without any racemization for reuse. The present method is also shown to be applicable for the creation of an asymmetric quaternary carbon atom, as exemplified in the synthesis of 2-methyl-2-phenylcycloalkanones (13). The mechanism of the reaction is proposed.
