Benzofurans. Improved syntheses of bufuralol, 7-ethyl-2-(2-<i>tert</i>-butylamino-1-hydroxyethyl)benzofuran, and 1″-oxobufuralol, 7-acetyl-2-(2-<i>tert</i>-butylamino-1-hydroxyethyl)benzofuran
作者:S. Ananda Weerawarna、Michael Guha-Biswas、Wendel L. Nelson
DOI:10.1002/jhet.5570280535
日期:1991.8
An improved laboratory scale synthesis of bufuralol (1) and 1″-oxobufuralol (4) was accomplished. The intermediate benzofurans were prepared via aromatization of 2,3-dihydrobenzofurans or by a one-step acidcatalyzed cyclization from 2,2-diethoxyethyl 4-bromo-6-ethyl-2-formylphenyl ether (23). Base-catalyzed cyclization of 3-(5-bromo-3-ethyl-2-hydroxyphenyl)-1.2-epoxypropane (16) provided the key intermediate
实现了改进的实验室规模的布富拉尔(1)和1''-氧代布富拉尔(4)的合成。中间体苯并呋喃是通过2,3-二氢苯并呋喃的芳构化反应或通过由2,2-二乙氧基乙基4-溴-6-乙基-2-甲酰基苯基醚进行一步酸催化环化反应制得的(23)。3-(5-溴-3-乙基-2-羟基苯基)-1.2-环氧丙烷的碱催化环化反应(16)提供了关键中间体5-溴-7-乙基-2-羟甲基-2,3-二氢苯并呋喃(17)。完成了对苯并呋喃环系统的C-2和C-7位置的选择性官能化,以提供1和4。