1,2- vs 1,4-Addition of Acylbenzotriazoles to α,β-Unsaturated Aldehydes and Ketones. A Novel Route to 3-Alkyl-4,6-diaryl-3,4-dihydropyran-2-ones

Lithiation of aliphatic 1-acylbenzotriazoles with subsequent reaction with alpha,beta-unsaturated ketones and aldehydes affords either 3,4,6-trisubstituted 3,4-dihydropyran-2-ones or 1,3-dienes depending on the carbonyl reagent used. Substituent effects on product yield and isomer ratio are discussed.