M. C. Cruz, J. Tamariz
Oct 17, 2005
Citations
1
Influential Citations
27
Citations
Journal
Tetrahedron
Abstract
Abstract The intramolecular cyclization of the β-substituted olefins methyl 2-aryloxy-3-dimethylaminopropenoates 3a–3f 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. These benzofurans were also obtained by direct treatment under MW irradiation of the precursors 1-aryloxypropan-2-ones 7a–7c with DMFDMA, followed by addition of the catalyst, resulting in a route that was one step shorter.