Allylsilane-vinylcopper reagents: Palladium-mediated coupling with alkenylhalides. Synthesis and photochemical [2+2] cyclization of (+/-)-Ipsdienol

Reaction of phenyldimethylsilyl-copper with 1,2-propadiene followed by Pd-0 catalyzed coupling of the resulting copper intermediate with alkenyl halid es affords allylsilane-containing dienes in high yield. Coupling with vinyl bromide gives 2-phenyldimethylsilylmethylbuta-1,3-diene which is an isopre nyl building block for the synthesis of (+/-)-Ipsenol and (+/-)-Ipsdienol, the aggregation pheromones of the Ips bark beetle. The photochemical [2+2] cyclization of Ipsdienol was also studied.