Two general methods for α-carbalkoxymethylation of both enolizable and nonenolizable (towards the γ-position) α, β-unsaturated ketones have been developed. Method A involves three synthetic steps: photocycloaddition of the starting enone to 1, 1-dimethoxyethylene, hydrolysis-oxidation of the adduct with acetic acid and 30% hydrogen peroxide, and O- alkylation of the resulting mixture of lactone and acid using anhydrous potassium ...