title: Evidence for a concerted [4 + 1]- cycloaddition between electron-rich carbenes and electron-deficient dienes.
abstract: Results from the thermal reactions of deuterated dienes 12-15 provide evidence of the concertedness of the [4 + 1]-cycloaddition between dimethoxycarbene and electron-deficient dienes. Other evidence suggests that the main pathway is a concerted [4 + 1]-cycloaddition rather than a cyclopropanation followed by a vinylcyclopropane rearrangement. Ionic pathways can become competitive when steric or geometrical constraints are present.
authors.affiliation: Département de Chimie, Université de Sherbrooke, 2500 Boul. Université, Sherbrooke, QC, Canada J1K 2R1.
authors.forename: Luc
authors.initials: L
authors.lastname: Boisvert
authors.forename: Francis
authors.initials: F
authors.lastname: Beaumier
authors.forename: Claude
authors.initials: C
authors.lastname: Spino