An efficient asymmetric synthesis of Sitagliptin, a new DPP-IV inhibitor for the treatment of type 2 diabetes mellitus has been developed. The beta-amino acid fragment of Sitagliptin was prepared by asymmetric Michael addition of the corresponding α, β-unsaturated ester to (R)-(α-methylbenzyl)benzylamine followed by a two-step elaboration to obtain N-boc beta-amino ester. Hydrolysis of the ester and coupling with the triazolopiperazine afforded Sitagliptin after cleavage of the N-boc group and salt formation. The overall yield was 31% over nine steps.
