Captodative olefins: methyl 2-aryloxy-3-dimethyl-aminopropenoates and their application in a new synthesis of benzofurans
作者:Marı́a del Carmen Cruz、Joaquı́n Tamariz
DOI:10.1016/j.tetlet.2004.01.073
日期:2004.3
The beta-substituted captodative olefins methyl 2-aryloxy-3-dimethylaminopropenoates 4a-h were synthesized, via amino-methylenation of the corresponding 2-phenoxyacetic esters 9a-h. Lewis acid promoted intramolecular cyclization of alkenes 4 led to benzofurans 7a-h, in an efficient synthetic approach to the benzofuran frame. (C) 2004 Elsevier Ltd. All rights reserved.
An efficient synthesis of benzofurans and their application in the preparation of natural products of the genus Calea
作者:María del Carmen Cruz、Joaquín Tamariz
DOI:10.1016/j.tet.2005.08.015
日期:2005.10
catalyzed by Lewis acids leads to a short and novel synthesis of benzofurans 2a–2f. When the olefins 4-dimethylamino-3-aryloxy-3-buten-2-ones 4a–4f were used, the cyclization process was faster and provided the corresponding substituted 2-acetylbenzofurans 1a–1f. Among the latter, naturally occurring compounds calebertin (1a), caleprunin A (1b), and caleprunin B (1c) were prepared in good overall yields.