Abstract Irradiation of β-phenylethynyl-α-diazo-β-ketoester with 300 or 350 nm light results in efficient and regioselective Wolff rearrangement producing only the product of alkynyl group migration. Addition of alcohols to the resulting α-oxoketene yields α-phenylethynyl-β-diester, which undergoes rapid (τ< 1 min) tautomerization to 1, 1-dicarbalkoxyallene. The latter then adds second molecule of alcohol in Michael fashion to form the final product, 2-(1-alkoxy- ...
