ChemInform Abstract: Thermal Cycloadditions of Dimethyl Acetylenedicarboxylate with Cyclic Enol Ethers. An Entry into Medium Size Oxocyclic Systems.

ChemInform Abstract

Thermal cycloaddition reaction of dimethyl acetylenedicarboxylate (II) with the dihydropyrans (I) or the dihydrofurans (V) produces the bicyclic adducts (III) or (VI) which undergo ring expansion in the presence of Lewis acids or directly upon further heating, forming the macrocyclic dienol ethers (IV) and (VII), together with the by-product (VIII).