Synthetic, Structural and Vibrational Spectroscopic Studies in Bismuth(III) Halide/N,N′-Aromatic Bidentate Base Systems. IV. Bismuth(III) Halide/N,N′-Bidentate Ligand (1 : 1) Systems

Abstract

The generation of a number of 1,2-diarylcyclopropane-1,2-diols is reported. Reaction of these in situ with acid gives, primarily, an α,β-unsaturated ketone in which the aryl substituent attached to the double bond is that which is best able to stabilize a benzylic cation. It is proposed that the reaction proceeds by O-protonation of the cyclopropane-1,2-diol, followed by loss of water and opening of the resulting cyclopropyl cation and final deprotonation. Such initial O-protonation contrasts with the C-protonation normally observed in the acidolysis of cyclopropanols and other dialkyl- and alkylaryl-cyclopropane-1,2-diols.