Introduction of Amino Alcohols in the Ring-Opening Reaction of 3-bromo-2,5-dimethylthiophene 1,1-dioxide. A short diastereoselective synthesis of substituted ‘tetrahydrobenzo[<i>a</i>]pyrrolizidines’ (= octahydro-1<i>H</i>-pyrrolo[2,1-<i>a</i>]isoindoles) using<scp>L</scp>-prolinol
作者:Anders Tsirk、Salo Gronowitz、Anna-Britta Hörnfeldt
DOI:10.1002/hlca.19970800512
日期:1997.8.11
Tetrahydrobenzo[a]pyrrolizidines (= octahydro-1H-pyrrolo[2,1-a]isoindoles) and tetrahydrobenzo[a]indo-lizidines, (= decahydropyrido[2,1-a]isoindoles) were prepared stereoselectively in four steps through an amineinduced ring-opening of 3-bromo-2,5-dimethylthiophene 1,1-dioxide (1) with L-prolinol (9), piperidine-2-methanol (10), and piperidine-2-ethanol (11), yielding the dienes (2S)-1-[(2E,4Z)-4-bromohexa-2
四氢苯并[一个]吡咯烷并(=八氢1 ħ吡咯并[2,1-一个]异吲哚)和四氢苯并[一个]吲-lizidines,(= decahydropyrido [2,1-一个]异吲哚)为通过在四个步骤立体选择性地制备胺诱导的3-溴-2,5-二甲基噻吩1,1-二氧化物(1)与L-脯氨醇(9),哌啶-2-甲醇(10)和哌啶-2-乙醇(11)的开环,产生二烯(2 S)-1-[(2 E,4 Z)-4-溴己-2,4-二烯基]吡咯烷-2-甲醇(12),1-[(2 E,4 Z)-4-溴六-2,4-二烯基]哌啶-2-甲醇(13)和1-[((2 E,4 Z)-4-溴-六-2,4-二烯基]哌啶-2-乙醇(14 ; Scheme2),其转化为它们的α,β -不饱和酯之后,环化的的TiCl 4催化的分子内饮食-阿尔德反应(Scheme3)。还讨论了开环反应的机理,包括半经验和从头算。