4G - Thiophene Derivatives Containing Silicon, Germanium, Tin and Lead

Abstract

2-(Thienyl)silane, 5-methyl- and 5-chloro-2-thienylsilane are prepared in 77–87% yield from the corresponding thienyltrichlorosilyl compounds and lithium aluminium hydride in diethyl ether. Phenylvinyl-(2-thienyl)silane is prepared by reduction of phenyl vinyl(2-thienyl)chlorosilane with lithium aluminium hydride. The reactions of 2-thienylsilanes with tin tetrahalides occur selectively with the replacement of only one hydrogen atom. Thus from the procedure mentioned in the chapter, thienylsilanes 2-thienylchloro and bromo silane as well as the 5-methyl and 5-chloro derivatives are obtained in about 40% yield. The general and most often used method consists in the reaction of 2-thienyllithium derivatives, obtained by metalation of thiophenes with butyllithium or lithium diisopropylamide or halogen–metal exhange of 2-bromothiophenes with alkyllithium derivatives, with trimethylsilyl chloride at low temperature. Trialkylsilylthiophenes are rather stable and can, therefore, be modified by a variety of reactions.