Acylative Cleavage of Ethers Catalyzed by Triorganotin Halides and Palladium(II) Complexes

Benzylic, allylic, and cyclic ethers react with acyl halides under mild conditions in the presence of triorganotin halide and palladium(II) catalysts to give the corresponding esters in good yields. In the case of benzyl ether the other product is the benzyl halide, while in the reaction of allylic ethers the other products are various olefins resulting from the cleavage of the allyl group and an organotin moiety. The reaction is selective to these ethers, while acyclic aliphatic and phenolic ethers are unreactive. By control of the reaction conditions, benzylic and cyclic ethers could be cleaved in the presence of allylic ethers. The utility of the reaction as a deprotective method is demonstrated by the cleavage of a benzylic ether containing olefinic unsaturation. The mechanism of the benzylic and allylic ethers cleavage was studied by carrying out the corresponding stoichiometric reactions with the various palladium(II) complexes proposed in the catalytic cycle.