Experimental and Computational Studies on Rh(I)-Catalyzed Reaction of Siloxyvinylcyclopropanes and Diazoesters.

The Rh(I)-catalyzed reaction of siloxyvinylcyclopropanes and diazoesters leads to the formation of siloxyvinylcyclobutane and 1,4-diene derivatives. With [Rh(cod)Cl]2 as the catalyst, the formation of 1,4-diene was favored over the formation of siloxyvinylcyclobutane. By changing the catalyst to [Rh(cod)2OTf], siloxyvinylcyclobutane derivatives are formed with excellent chemoselectivities and in moderate to good yields. The alkene products are also obtained as single E configured isomers. A detailed mechanism for this transformation is proposed on the basis of mechanistic experiments and DFT calculations. The effect of catalysts on the chemoselectivity of these reactions is also examined computationally.