The polymer-bound palladium-catalyzed cross-coupling reaction of allylic alcohols with hypervalent iodomum salts to form carbun-ca~n bonds was achieved at room temperature under extremely mild and aqueous conditions even in the absence of base with very high activity in the Stille coupling reaction. The polymeric catalyst can be easily separated from a reaction mixture and reused more than 10 times with no decrease in activity ยฉ 1997 Elsevier Science Ltd.
The formation of a carbon-carbon bond by palladium-catalyzed coupling of aryl or vinyl halides with olefms, known as the Heck reaction, has become a powerful tool in organic chemistry. ~ In the case of allylie alcohols, palladium-catalyzed reaction of organic halides usually affords f-substituted kctons or aldehydes rather than the 13-substituted allyhe alcohols. 2 Jeffery 3 reported that in the presence of a stoichiometric amount of silver acetate or silver carbonate, a highly selective formation of the substituted allylic alcohols can be achieved. Cacchi 4 reported that Pd(0)catalyzed reaction of aUylic alcohols with triflates in the presence of EhN provided two isomeric substituted allylic alcohols. Tamaru 5 utilized O-substituted allylic alcohols to direct the Pd(0)-catalyzed coupling without elimination of proton adjacent to the oxygen-bearing carbon. Finally, I have found that the coupling reaction of hypervalent iodonium salts 6 with allylic alcohols in the presence of polymer-bound palladium catalyst affords the substituted aUylic alcohols as the sole products under mild conditions with high catalytic efficiency.
Recently, I reported that palladium-catalyzed cross-coupling reactions using polymer-hound palladium catalyst. 7 In connection with my programs to ufdize polymer-hound palladium catalyst in palladium-catalyzed cross-coupling reactions, I have investigated the coupling of allylie alcohols with hypervalent iodonium salts.
Hybrid catalysts combining the attributes of conventional homogeneous catalysts with the experimental simpli-