Auto-tandem catalysis: facile synthesis of substituted alkylidenecyclohexanones by domino (4+2) cycloaddition-elimination reaction.

A catalytic domino reaction producing substituted 2-alkylidenecyclohexanone from 3-oxymethyl-2-siloxy-1,3-butadienes, which can be prepared from Baylis-Hillman adducts, and α,β-unsaturated ketones is described. The process involves two mechanistically distinct reactions, (4+2) cycloaddition and elimination. Both of these reactions are catalyzed by Tf(2)NH.