title: A combined experimental and theoretical study of the polar [3 + 2] cycloaddition of electrophilically activated carbonyl ylides with aldehydes and imines.
abstract: Numerous 2,5-diaryl-1,3-dioxolane-4,4-dicarbonitriles and 2,4-diphenyl-1,3-oxazolidine-5,5-dicarbonitriles have been synthesized by [3 + 2] cycloaddition reactions between carbonyl ylides generated from epoxides and aldehydes or imines. In contrast to the use of aldehydes (3,4,5-trimethoxybenzaldehyde, piperonal, 1-naphthaldehyde, indole-3-carboxaldehyde, furan-2-carboxaldehyde, and thiophene-2-carboxaldehyde), the reactions performed with imines (N-(phenylmethylene)methanamine, N-(1,3-benzodioxol-5-ylmethylene)propylamine, N-(1,3-benzodioxol-5-ylmethylene)butylamine, and N-(1,3-benzodioxol-5-ylmethylene)benzylamine) proceed diastereoselectively. The effect of microwave irradiation on the outcome of the reaction was studied. The mechanism of these [3 + 2] cycloaddition reactions has been theoretically investigated using DFT methods. These cycloadditions, which have one-step mechanisms, consist of the nucleophilic attack of the aldehyde oxygen or imine nitrogen on the carbonyl ylide. For the reaction with aldehydes, a back-donation effect is responsible for the unexpected reverse charge transfer found at the transition structure. The analysis of the reactivity indexes indicates that the large electrophilic character of the carbonyl ylides induces them to act as strong electrophiles in these polar [3 + 2] cycloaddition reactions.
authors.affiliation: Chimie et Photonique Moléculaires, UMR 6510 CNRS, Université de Rennes 1, Campus Scientifique de Beaulieu, 35042 Rennes, France.
authors.forename: Ghenia
authors.initials: G
authors.lastname: Bentabed-Ababsa
authors.forename: Aicha
authors.initials: A
authors.lastname: Derdour
authors.forename: Thierry
authors.initials: T
authors.lastname: Roisnel
authors.forename: Jose A
authors.initials: JA
authors.lastname: Sáez
authors.forename: Patricia
authors.initials: P
authors.lastname: Pérez
authors.forename: Eduardo
authors.initials: E
authors.lastname: Chamorro
authors.forename: Luis R
authors.initials: LR
authors.lastname: Domingo
authors.forename: Florence
authors.initials: F
authors.lastname: Mongin