Studies on tetrahydroisoquinolines. XXI. A synthesis of (.+-.)-1-hydroxy-2-methoxyhomoproaporphine and stereochemistry of 4-oxygenated 1,2,3,4-tetrahydroisoquinolines.
作者:HIROSHI HARA、RYUICHI SHIRAI、OSAMU HOSHINO、BUNSUKE UMEZAWA、YOICHI IITAKA
DOI:10.1248/cpb.31.4236
日期:——
Acid treatment of the p-quinol acetate (23), obtained from the phenolic amine (14) gave (±)-2-hydroxy-3-methoxyhomoproaporphine (20) in excellent yield. However, similar treatment of other p-quinol acetates (24 and 25) afforded no cyclized products. Reaction of 24 or 25 with Ac2O-conc. H2SO4 gave two diastereoisomeric 4, 7-diacetates (36a and 36b or 38a and 38b). The stereostructures of 36a and 36b were decided by nuclear magnetic resonance study, while those of 38a and 38b were determined by chemical transformations and X-ray analyses. The stereoselectivity of acetoxylation is discussed.
对从酚胺(14)获得的对苯醌醋酸酯(23)进行酸处理,得到(±)-2-羟基-3-甲氧基同源吡咯啉(20),且收率非常高。然而,对其他对苯醌醋酸酯(24 和 25)进行类似处理则未得到环化产物。将24或25与醋酸酐-浓硫酸反应生成两个非对映体的4,7-二乙酸酯(36a和36b或38a和38b)。36a和36b的立体结构通过核磁共振研究确定,而38a和38b的立体结构则通过化学转化和X射线分析确定。讨论了乙酰氧基化的立体选择性。