Isomerization−Cyclization Approach to the Synthesis of 2-Hydroxy-5-alkylidene-cyclopent-2-enones

Propargyl vinyl ketones that are derived from the addition of 1-lithio-1-methoxymethoxy-2-ynes to morpholino enamides undergo isomerization followed by cyclization to α-methylene cyclopentenones upon exposure to silica gel.