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.