A new reaction between E-cinnamaldehyde and phenyllithium. Mechanistic studies

Abstract

The reaction of phenyllithium (in excess) with E-cinnamaldehyde gives a surprising tandem addition β-alkylation, which can be successfully used for the synthesis of substituted dihydrochalcones. The mechanism by which these unexpected reactions could occur is unknown and experimental and theoretical studies were carried out as a contribution to its understanding.

The observed concentration effects, the surprising changes in the product distribution upon changes in the reaction conditions, the haptomeric structure of the calculated intermediates and the calculated activation energies are consistent with a reaction pathway in which dimeric phenyllithium attacks the E-cinnamaldehyde without prior deaggregation. Solvated structures were also calculated using a “dielectric continuum” model for solvent effects.