Reduction of 3, 4-di (1-adamantyl)-1, 2-dithiete (2) with LiEt 3 BH, followed by treatment with MeI, gave (E)-1, 2-di (1-adamantyl)-1, 2-bis (methylthio) ethene (7-E) in 87% yield. Configuration of the double bond part of 7-E was determined by X-ray diffraction analysis. Treatment of 2 with MeLi and then with MeI also gave the same alkene 7-E in 90% yield, whereas treatment of 2 with MeLi followed by acidification afforded thermally labile (E)-1, ...