title: [3+2] versus [4+2] cycloadditions of quinone monoimide with azadienes: a Lewis acid-free access to 5-amino-2,3-dihydrobenzofuranes.
abstract: The reaction between p-quinone monoimide 1a and various azadienes 2 is described in the absence of a Lewis acid promoter. When alpha,beta-unsaturated hydrazones are substituted by proton or alkyl groups, 2,3-dihydrobenzofuranes 4, a motif that is present in numerous biologically active products, are obtained in moderate to excellent yields. The regio- and stereoselectivity of this reaction has been proved by a complete NMR study, including 1H-15N correlations.
authors.affiliation: Laboratoire de Chimie Thérapeutique, EA 3741, Ecosystèmes et Molécules Bioactives, Faculté de Pharmacie, Université Claude Bernard Lyon 1, 8 Avenue Rockefeller, 69373 Lyon Cedex 08, France.
authors.forename: Thierry
authors.initials: T
authors.lastname: Lomberget
authors.forename: Fabien
authors.initials: F
authors.lastname: Baragona
authors.forename: Bernard
authors.initials: B
authors.lastname: Fenet
authors.forename: Roland
authors.initials: R
authors.lastname: Barret