Silver(I)-Catalyzed Novel Cascade Cyclization Reactions:  Incorporation of Allenes into the Isochromenes

The silver(I)-catalyzed reaction of alkynones with alcohols represents a general tool for the synthesis of 1-allenyl isochromenes. The reaction most probably proceeds via the formation of benzopyrylium cation, which subsequently undergoes nucleophilic attack of an alcohol to give the annulation products.