Reactions of polymerization-resistant 1,2-dithiolanes with lithiated oxygen heterocycles

Lithiated furans have been found to cleave the S-S bond of polymerization-resistant 1,2-dithiolanes to give the ring opened products in good yields. In the case of lithiated benzofuran, the excess reagent reacted with the normal product to give a mixture. Lithiated dihydrofuran and dihydropyran gave the corresponding ring-opened products that rearranged to spiro-1,3-dithianes during acidic workup. The reaction was applied to the selective synthesis of substrates for intramolecular Diels-Alder reactions. (C) 1998 John Wiley & Sons, Inc.