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Microwave‐Induced Synthesis and Regio‐ and Stereoselective Epoxidation of 3‐Styrylchromones
Author(s) -
Patonay Tamás,
KissSzikszai Attila,
Silva Vera M. L.,
Silva Artur M. S.,
Pinto Diana C. G. A.,
Cavaleiro José A. S.,
Jekő József
Publication year - 2008
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.200701081
Subject(s) - chemistry , dimethyldioxirane , regioselectivity , stereoselectivity , hydrogen peroxide , organic chemistry , cinchona , ammonium acetate , enantioselective synthesis , solvent , catalysis , high performance liquid chromatography
The microwave‐assisted solvent‐free synthesis of ( E )‐3‐styrylchromones from 3‐formylchromones and phenylmalonic acid on sodium acetate support has been developed; the method affords the styryl derivatives in moderate to good yields and with complete diastereoselectivity. Protocols for the highly regioselective epoxidation of ( E )‐ and ( Z )‐3‐styrylchromones have been elaborated. Treatment of the alkenes with dimethyldioxirane led to the exclusive formation of 3‐(3‐aryloxiran‐2‐yl)chromones with complete diastereoselectivity, whereas treatment with hydrogen peroxide under alkaline conditions afforded the corresponding 2,3‐epoxy‐3‐styrylchromanones as the only products. Epoxidation performed in the presence of chiral, nonracemic cinchona‐alkaloid‐based quaternary ammonium salts allowed the synthesis of enantiomerically enriched 2,3‐epoxy‐3‐styrylchromanones, but with only moderate ee values. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)