A Facile Preparation of Geometrically Pure Alkenyl, Alkynyl, and Aryl Conjugated Z-Alkenes: Stereospecific Synthesis of Bombykol

Ni- and Pd-catalyzed cross coupling reactions of 2-alkenyl, 2-alkynyl, and 2-aryl substituted (1Z)-1-bromoalkene with alkyl Grignard reagents gave 1-alkyl substituted (1Z,3E)-diene, (1Z)-en-3-yne, and (1Z)-2-arylethene, each in good yield. When (trimethylsilyl)methylmagnesium chloride was used as the Grignard reagent, conjugated Z-allylsilane was produced. Bombykol, (10E,12Z)-10,12-hexadecadien-1-ol, a sex pheromone of female moss, Bombyx mori, was synthesized stereospecifically.