title: Polar [3 + 2] cycloaddition of ketones with electrophilically activated carbonyl ylides. Synthesis of spirocyclic dioxolane indolinones.
abstract: The [3 + 2] cycloaddition reaction between carbonyl ylides generated from epoxides and ketones (ethyl pyruvate, ethyl phenylglyoxylate, isatin, N-methylisatin and 5-chloroisatin) to give substituted dioxolanes and spirocyclic dioxolane indolinones was investigated. The effect of microwave irradiation on the outcome of the reaction was studied. The thermal reaction between 2,2-dicyano-3-phenyloxirane and N-methylisatin was theoretically studied using DFT methods. This reaction is a domino process that comprises two steps. The first is the thermal ring opening of the epoxide to yield a carbonyl ylide intermediate, whereas the second step is a polar [3 + 2] cycloaddition to yield the final spiro cycloadducts. The cycloaddition presents a low stereoselectivity and a large regio- and chemoselectivity. Analysis of the electrophilicity values and the Fukui functions of the reagents involved in the cycloaddition step allowed the chemical outcome to be explained.
authors.affiliation: Chimie et Photonique Moléculaires, UMR 6510 CNRS, Université de Rennes 1, Bâtiment 10A, Case 1003, Campus Scientifique de Beaulieu, F-35042, Rennes Cedex, 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: Luis R
authors.initials: LR
authors.lastname: Domingo
authors.forename: Florence
authors.initials: F
authors.lastname: Mongin