title: An Organocatalytic Cope Rearrangement.
abstract: The first example of an organocatalytic Cope rearrangement is reported. Acyclic and cyclic acyl hydrazides catalyze the rearrangement of 1,5-hexadiene-2-carboxaldehydes via iminium ion formation. A correlation between ring size and catalyst activity was observed for the cyclic hydrazides, with seven- and eight-membered-ring catalysts being the most active. Diazepane carboxylate 5 c (10 mol %) catalyzed the rearrangement of a range of dienes at room temperature in acetonitrile using triflic acid as a co-catalyst. Preliminary proof of principle for asymmetric catalysis was provided by rearrangement of 3,3-dimethyl-7-phenyl-1,5-heptadiene-2-carboxaldehyde in the presence of a novel 7-substituted diazepane carboxylate.
authors.affiliation: Department of Chemistry, McGill University, 801 Sherbrooke W., Montreal, QC, H3A 0B8, Canada.
authors.forename: Dainis
authors.initials: D
authors.lastname: Kaldre
authors.affiliation: Department of Chemistry, McGill University, 801 Sherbrooke W., Montreal, QC, H3A 0B8, Canada. jim.gleason@mcgill.ca.
authors.forename: James L
authors.identifier: 0000-0003-1687-3343
authors.initials: JL
authors.lastname: Gleason
keywords: Cope rearrangements; allylic strain; hydrazides; iminium ions; organocatalysis