Prop-2-ynylic carbonates as a1,a2 synthons in palladium catalysed annulation reactions with bifunctional nucleophiles

Prop-2-ynylic carbonates were used as a1, a2 synthons in palladium catalysed annulation reactions with bifunctional nucleophiles. Methods were developed for the synthesis of 3-methylenedihydropyran derivatives and methylenecycloalkane derivatives in good yields. The regiochemistry of such reactions is discussed based upon the proposed mechanism.