The synthesis of 4,~-dimethylene-3, 3, 6, 6-tetramethyl-l-thiacycloheptane (IV) was accomplished via a double Wittig reaction with 3, 3, 6, 6-tetramethyl-l-thiacycloheptane-4, 5- dione (111). The synthesis of 2, 3-diisopropyl-1, 3-butadiene (VIII) from 2, 3-diisopropyl-1, 4- butanediol (XI) was accomplished via a modification of the Chugaev reaction. The chemical and spectroscopic properties of 2, 3-di-t-butyl-1, 3-butadiene (I), of dienes IV and VIII, and ...