TY - JOUR
T1 - An efficient synthesis of benzofurans and their application in the preparation of natural products of the genus Calea
AU - Del Carmen Cruz, María
AU - Tamariz, Joaquín
N1 - Funding Information:
We thank Fernando Labarrios for his help in spectrometric measurements and Fabiola Jiménez for her assistance in the experimental work. J.T. gratefully acknowledges Coordinación General de Posgrado e Investigación del Instituto Politécnico Nacional (Grants 200140, 20030147, 20040123, and 20050151), and CONACYT (Grant 43508-Q) for financial support. C.C. thanks CONACYT for a graduate scholarship (120988), and the Ludwig K. Hellweg Foundation for a partial scholarship. J.T. is a fellow of the EDI-IPN and COFAA-IPN programs.
PY - 2005/10/17
Y1 - 2005/10/17
N2 - 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.
AB - 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.
KW - 2-Aryloxy-3-dimethylaminopropenoates
KW - Cyclization
KW - Lewis acid catalysis
KW - Microwaves
KW - Natural 2-acetylbenzofurans
UR - http://www.scopus.com/inward/record.url?scp=24944478098&partnerID=8YFLogxK
U2 - 10.1016/j.tet.2005.08.015
DO - 10.1016/j.tet.2005.08.015
M3 - Artículo
SN - 0040-4020
VL - 61
SP - 10061
EP - 10072
JO - Tetrahedron
JF - Tetrahedron
IS - 42
ER -