Reactivity of nitro- and nitroso-arenes with vinyl grignard reagents: synthesis of 2-(trimethylsilyl)indoles

The reaction of nitrosoarenes and 1 -(trimethylsilyl)vinylmagnesium bromide in dibutyl ether represents a useful tool for the synthesis of 2-(trimethylsilyl)indoles by cyclisation of benzene derivatives. The use of more common ethers as the solvent leads to large amounts of azo and azoxy derivatives. Conversely, the reaction of nitroarenes and 1-(trimethylsilyl)vinylmagnesium bromide gives conjugate addition products. The reasons for this behaviour are discussed.