Synthesis of chromanes by sequential ‘[3+3]-cyclization/Williamson’ reactions of 1,3-bis(trimethylsilyloxy)-7-chlorohepta-1,3-dienes
摘要:
Functionalized chromanes were prepared by sequential '[3+3]-cyclization/Williamson' reactions of 1,3-bis(trimethylsilyloxy)-7-chlorohepta-1,3-dienes with 1,1,3,3-tetrametboxypropane, 3-silyloxyalk-2-en-1-ones, and 1,1-diacetylcyclopropane. The first step of the sequence involves [3+3] cyclizations of the starting materials to give 2-(3-chloropropyl)phenols. The subsequent cyclization proceeds by intramolecular nucleophilic substitution. 6-(2-Hydroxybenzoyl)chromanes were prepared based on sequential '[3+3]-cyclization/Williamson' reactions of 1,3-bis(trimethylsilyloxy)-7-chlorohepta-1,3-dienes with 3-formylchromones. (c) 2006 Elsevier Ltd. All rights reserved.
Synthesis of chromanes by sequential ‘[3+3]-cyclization/Williamson’ reactions of 1,3-bis(trimethylsilyloxy)-7-chlorohepta-1,3-dienes
作者:Van Thi Hong Nguyen、Bettina Appel、Peter Langer
DOI:10.1016/j.tet.2006.05.076
日期:2006.8
Functionalized chromanes were prepared by sequential '[3+3]-cyclization/Williamson' reactions of 1,3-bis(trimethylsilyloxy)-7-chlorohepta-1,3-dienes with 1,1,3,3-tetrametboxypropane, 3-silyloxyalk-2-en-1-ones, and 1,1-diacetylcyclopropane. The first step of the sequence involves [3+3] cyclizations of the starting materials to give 2-(3-chloropropyl)phenols. The subsequent cyclization proceeds by intramolecular nucleophilic substitution. 6-(2-Hydroxybenzoyl)chromanes were prepared based on sequential '[3+3]-cyclization/Williamson' reactions of 1,3-bis(trimethylsilyloxy)-7-chlorohepta-1,3-dienes with 3-formylchromones. (c) 2006 Elsevier Ltd. All rights reserved.
Synthesis of 3-Alkyl- and 3-Chloroalkyl-2-hydroxybenzoates Based on [3+3] Cyclizations of 4-Alkyl- and 4-Chloroalkyl-1,3-bis(trimethylsilyloxy)buta-1,3-dienes
The TiCl 4 -mediated [3+3] cyclization of 4-alkyl- and 4-chloroalkyl-1,3-bis(trimethylsilyloxy)buta-1,3-dienes with 3-silyl-alk-2-en- 1-ones afforded 3-alkyl- and 3-chloroalkyl-2-hydroxybenzoates, respectively; the latter containing a remote chloride functionality. The TiCl 4 - and TiBr 4 -mediated [3+3] cyclization of 1,3-bis(trimethylsilyloxy)-4-chloroalkylbuta-1,3-dienes with 1,1-diacetylcyclopropane