Beneficial Effect of ortho-Methoxy Groups in the Asymmetric Ring Opening of meso Epoxides with Silicon Tetrachloride Catalyzed by Chiral ortho-Methoxyphenyldiazaphosphonamide Lewis Bases Response to the Communication by G. Buono et al.

The reported ability of chiral phosphonamide 1 to effect the enantioselective opening of meso epoxides with silicon tetrachloride has not withstood experimental verification by Denmark's group. Having reexamined the ring-opening of cyclooctene oxide, Denmark and co-workers found a serious discrepancy between their results (81-83 % recovery of the epoxide and an essentially racemic product) and those reported by Buono et al. (77 % yield and >99 % ee).