Enantioselective Syntheses of Conformationally Rigid, Highly Lipophilic Mesityl-Substituted Amino Acids
作者:Eva Medina、Albert Moyano、Miquel A. Pericàs、Antoni Riera
DOI:10.1002/(sici)1522-2675(20000510)83:5<972::aid-hlca972>3.0.co;2-9
日期:2000.5.10
N-Boc-protected amino acids substituted with a mesityl (=2,4,6-trimethylphenyl) group were synthesized in enantiomerically pure form, either by asymmetric epoxidation or by aminohydroxylation as the source of chirality. The 3-mesityloxirane-2-methanol 7, easily available in high enantiomer purity by Sharpless epoxidation, was converted into 3-[(tert-butoxy)carbonyl]amino}-3-mesitylpropane-1,2-diol 9 by a regio-
通过不对称环氧化或作为手性来源的氨基羟基化,以对映体纯的形式合成了三个被异丙叉基 (=2,4,6-三甲基苯基) 基团取代的 N-Boc 保护的氨基酸。3-mesityloxirane-2-methanol 7 很容易通过 Sharpless 环氧化以高对映异构体纯度获得,通过区域转化为 3-[(tert-butoxy)carbonyl]amino}-3-mesitylpropane-1,2-diol 9 - 用氨等价物(叠氮化钠或二苯甲基胺)进行立体选择性开环,然后氢化并用 (Boc)2O (Boc=[(叔丁氧基)羰基]) 进行原位处理(方案 3)。9 中的二醇片段的氧化裂解提供了 > 99% ee 的 N-[(叔丁氧基)羰基]-α-均三甲基甘氨酸 1。这种氨基酸也以对映体纯的形式从 2,4 开始制备,6-三甲基苯乙烯 (11) 通过区域选择性 Sharpless 不对称氨基羟基化,然后是