A new method for the enantioselective synthesis of N-Boc-α,α-disubstituted α-amino acids
作者:Rubén Martı́n、Gabriela Islas、Albert Moyano、Miquel A Pericàs、Antoni Riera
DOI:10.1016/s0040-4020(01)00503-8
日期:2001.7
A new method for the enantioselective synthesis of N-Boc-α,α-disubstituted α-amino acids has been developed. The starting materials are diastereomerically pure 3,3-disubstituted allyl alcohols, prepared by DIBAL-H reduction of the corresponding unsaturated esters derived from carbocupration of an acetylenic ester or from Wadsworth–Emmons olefination of a ketone. Sharpless epoxidation of the allylic
开发了N -Boc-α,α-二取代α-氨基酸对映选择性合成的新方法。起始原料是非对映体纯的3,3-二取代的烯丙醇,可通过DIBAL-H还原相应的不饱和酯制得,这些不饱和酯是由乙炔酸酯的羰基化或由Wadsworth-Emmons的酮烯化反应制得的。烯丙醇的无尖锐的环氧化提供了对映体富集的环氧醇,其在Crotti的条件下(N 3 Na / LiClO 4)经历亲核开环,得到3-叠氮基1,2-二醇。氢化和原位保护提供了N -Boc-3-氨基-1,2-二醇,它们被氧化裂解为α,α-二取代的N-Boc-α-氨基酸。通过这种方法已经制备了保护的α-甲基-α-苯基甘氨酸和α-甲基异亮氨酸。