Methyl 2-[(tert-Butoxycarbonyl)amino]-3-hydroxy-3-phenylpropanoate: Synthesis of Erythro (±) Isomer by Reduction and Threo (±) Isomer by Inversion Method

We report an efficient protocol for synthesis of methyl 2-[(tert-butoxycarbonyl) amino]-3-hydroxy-3-phenylpropanoate (Erythro (+/-)) by simple reduction and methyl 2-[(tert-butoxycarbonyl) amino]-3-hydroxy-3-phenylpropanoate (Threo (+/-)) by inversion method. The erythro (+/-) isomer has been obtained in excellent yield (93%) using sodium borohydride in methanol at -40 degrees C. The erythro isomer has been effectively converted into its threo (+/-) with 100% efficiency, by inversion, using methanesulfonyl chloride, cesium acetate and crown ether-18-6. The salient features of this method include cost effectiveness, excellent yields and scope for large-scale synthesis, which makes the method an attractive addition to the applicable methodologies.

Automated summary

An efficient protocol for synthesis of Erythro (+/-) and Threo (+/-) is described, with excellent yields achieved through simple reduction and inversion method. The method is cost-effective, high-yielding, and suitable for large-scale synthesis.