1,3-Cycloadditions of 3,5-dichloro-2,4,6-trimethylbenzonitrile oxide to 1,1-diphenylallene

Abstract

The reaction of 3,5-dichloro-2,4,6-trimethylbenzonitrile oxide with excess of 1,1-diphenylallene in various solvents gives two isomeric monoadducts. Further reaction of one of these with the nitrile oxide gives a diadduct. Products were identified by spectroscopic properties and chemical behaviour. Kinetics were measured in CCl₄, in EtOH, and in mixtures of the two solvents, in the temperature range 40–70 °C. The solvent effect on the rates is small; activation entropies are in the range –34 to –22 cal mol^–1 K^–1. A concerted mechanism of 1,3-cycloaddition is favoured for the three reactions.