Asymmetric synthesis of chiral beta-amiNo acids

摘要

The invention herein is directed to a process for the preparation of ethyl 3S-amino-4-pentynoate which involves treating 3-(trimethylsilyl)-2-propynal with L-phenylglycinol in toluene to produce alpha S-[[3-(trimethylsilyl)-2-propynylidene amino]benzenethanol; reacting alpha S-[[3-(trimethylsilyl)-2-propynylidene]amino]benzenethanol with BrZnCH2CO2t-Bu in THF/NMP to produce 1,1-dimethylethyl 3S-[(2-hydroxy-1S-phenylethyl)amino]-5-(trimethylsilyl)-4-pentynoate; reacting the 1,1-dimethylethyl 3S-[(2-hydroxy-1S-phenylethyl)amino]-5-(trimethylsilyl)-4-pentynoate with sodium periodate to form 1,1-dimethylethyl 3S-[(phenylmethylene)amino]-5-(trimethylsilyl)-4-pentynoate; hydrolyzing 1,1-dimethylethyl 3S-[(phenylmethylene)amino]-5-(trimethylsilyl)-4-pentynoate to produce 1,1-dimethylethyl 3S-amino-5-(trimethylsilyl)-4-pentynoate; transesterifying 1,1-dimethyl 3S-amino-5-(trimethylsilyl)-4-pentynoate and desilylating to produce ethyl 3S-amino-4-pentynoate.