Chiral Synthesis of Erythrina Alkaloids. I Total Synthesis of (+)-Erysotrine via Asymmetric Diels-Alder Reaction under High Pressure.
作者:Yoshisuke TSUDA、Shinzo HOSOI、Nobuya KATAGIRI、Chikara KANEKO、Takehiro SANO
DOI:10.1248/cpb.41.2087
日期:——
(S)-(+)-3, 4-Dimethoxyphenylalanine methyl ester (1b) was converted, in 3 steps, into (5S)-(-)-8, 9-dimethoxy-1, 5-dimethoxycarbonyl-2, 3-dioxo-2, 3, 5, 6-tetrahydropyrrolo[2, 1-a]isoquinoline (2b). Diels-Alder reaction of 2b with 1-methoxy-3-trimethylsilyloxybutadiene under extremely high pressure (10 kbar), followed by desilylation, gave moderate yields of erythrinan derivatives (11), which were converted, in several steps, into (+)-erysotramidine (23b) and (+)-erysotrine (4), thus accomplishing the first total synthesis of natural Erythrina alkaloids in chiral forms.
(S)-(+)-3,4-二甲氧基苯丙氨酸甲酯 (1b) 分三步转化为 (5S)-(-)-8,9-二甲氧基-1,5-二甲氧基羰基-2,3-二氧代-2,3,5,6-四氢吡咯并[2,1-a]异喹啉 (2b)。在极高压力(10 千巴)下,2b 与 1-甲氧基-3-三甲基硅氧基丁二烯发生 Diels-Alder 反应,然后进行脱硅,得到中等产率的红花楠衍生物 (11),这些衍生物经过几个步骤转化为 (+)-erysotramidine (23b) 和 (+)-erysotrine (4),从而首次完成了天然红花楠生物碱手性形式的全合成。