Synthesis of polysubstituted 3-aminoindenes via rhodium-catalysed [3+2] cascade annulations of benzimidates with alkenes.

A novel Rh-catalysed intermolecular [3+2] cascade cyclization of benzimidates and alkenes has been developed to assemble polysubstituted 3-aminoindenes. The target products are important building blocks for organic synthesis and drug discovery. Cheap and easily available α,β-unsaturated ketones or nitroalkenes are applied as coupling partners. Acyl or nitro groups are easily introduced to 3-aminoindenes at the C-2 position, which makes this reaction particularly attractive for further transformation to synthesize various important building blocks.