Abstract Nitrobenzenes carrying an ortho substituent are selectively methylated at the free ortho position by reaction with dimethylsulfonium methylide. The importance of the ortho substituent is demonstrated by the failure of the methylation of nitrobenzene and 3-and 4- nitroanisole. This is explained by the out-of-plane geometry of the nitro group in the ortho- substituted derivative, which enables a specific interaction between the ylide and the nitro ...