The Enantioselective Synthesis of ?-Amino Acids, their ?-hydroxy derivatives, and theN-terminal components of bestatin and microginin
作者:Charles W. Jefford、James McNulty、Zhi-Hui Lu、Jian Bo Wang
DOI:10.1002/hlca.19960790426
日期:1996.6.26
(3R)-3-aminobutanoic acids 12a–e (ee > 99%). Electrophilic hydroxylation of 8 ( 19; Scheme 3), subsequent iodo-esterification ( 21; Scheme 4), and nucleophilic alkylation and phenylation afforded, after saponification and deprotection, a series of 4-substituted (2S, 3R)-3-amino-2-hydroxybutanoic acids 24 including the N-terminal acids 24e ( =3) and 24f ( =4) of bestatin and microginin (de > 95%), respectively
通过甲苯磺酸化,酸酐形成和用NaBH 4还原而得到的L-天冬氨酸被转化为(3S)-3-(甲苯磺酰基氨基)丁烷-4-醇化物(8;方案1)。的Tretment 8用乙醇三甲基碘硅烷,得到Ñ -保护的脱氧碘β -高丝氨酸乙酯9。后者在连续的亲核置换过程中,用二烷基铜锂(10a-e),碱性水解(11a-e)和甲苯磺酰基的还原去除,产生了相应的4-取代的(3 R)-3-氨基丁酸12a。 -e(ee> 99%)。8的亲电羟基化(19;方案3),随后的碘酯化(21;方案4),以及在皂化和脱保护后,进行亲核烷基化和苯基化,得到一系列的4-取代的(2 S,3 R)-3-氨基-2-羟基丁酸24分别包括Bestatin和Microginin(de> 95%)的N端酸24e(= 3)和24f(= 4)。