Development of a Scalable Synthesis of (<i>S</i>)-3-Fluoromethyl-γ-butyrolactone, Building Block for Carmegliptin’s Lactam Moiety

Abstract

Several new routes are reported for the synthesis of (S)-3-fluoromethyl-γ-butyrolactone. An asymmetric hydrogenation-based synthesis was chosen as the enabling route to produce the lactone on a 10-kg scale. A superior stereoselective route starting from (S)-tert-butyl glycidyl ether which afforded the desired lactone in three steps with ∼50% overall yield was finally selected for further development and production.