Unprecedented negishi coupling at C-br in the presence of a stannyl group as a convenient approach to pyridinylstannanes and their application in liquid crystal synthesis

Abstract

The 2-bromo-5(or 6)-tri-n-butylstannylpyridines, prepared from dibromopyridines and i-PrMgCl at room temperature, undergo Negishi coupling with either alkyl or arylzinc chlorides. The new alkyl- and aryl-substituted pyridylstannanes produced are shown to be suitable for further functionalization by Stille coupling. A group of new liquid crystalline materials with aromatic cores comprised of pyridine and thiophene rings were prepared utilizing these new pyridinylstannanes as key intermediates.