Convenient synthesis of 1,4-thiazane-3-carboxylic acid derivatives.
作者:KAZUO SAKAI、NAOTO YONEDA
DOI:10.1248/cpb.29.1554
日期:——
A convenient method to synthesize 1, 4-thiazane-3-carboxylic acid derivatives was established. Condensation of L-cysteine methyl ester (2a) with monochloroacetone (3a) followed by reduction with sodium borohydride yielded methyl (3R, 5S)-5-methyl-1, 4-thiazane-3-carboxylate (6a) and its (5R)-methyl isomer (7a) in a ratio of 3.1 : 1. The use of cysteine isopropyl ester (2c) instead of methyl ester (2a) gave the corresponding (5S)-methyl isomer (6e) more stereoselectively. The reaction of chloromethyl ethyl ketone (3b) or α-bromoacetophenone (3c) with 2a gave the corresponding 5-substituted-1, 4-thiazane-3-carboxylates. Hydrolysis and oxidation of 6a yielded cycloalliin (1a).
建立了一种合成 1,4-噻嗪-3-羧酸衍生物的简便方法。L-半胱氨酸甲酯(2a)与一氯丙酮(3a)缩合,然后用硼氢化钠还原,得到(3R, 5S)-5-甲基-1, 4-噻嗪-3-羧酸甲酯(6a)及其(5R)-甲基异构体(7a),两者的比例为 3.1 :1.使用半胱氨酸异丙酯 (2c) 代替甲酯 (2a),可以更立体选择性地得到相应的 (5S)- 甲基异构体 (6e)。氯甲基乙基酮(3b)或α-溴苯乙酮(3c)与 2a 反应生成相应的 5-取代-1,4-噻嗪-3-羧酸盐。6a 经水解和氧化后得到环木菠萝苷 (1a)。