Reactions of α,β‐Enones with Diazo Compounds,Part 3

Carbonyl ylides arising from ethyl acetodiazoacetate/dimethyl diazomalonate and α,β‐enones with mainly s‐cis conformations underwent disrotatory cyclization to produce dihydrofuran derivatives. This process proved to be sensitive to steric effects. The corresponding ylides arising from rather s‐trans α,β‐enals yielded dioxole derivatives. The mechanisms of the reactions are discussed.