One-Pot Synthesis of 3-Substiuted Indoles from 2-(2-Nitro-1-phenylethyl)cyclohexanone Derivatives.

Herein, a one-pot synthesis of 3-substituted indoles from 2-(2-nitro-1-phenylethyl)cyclohexanone derivatives catalyzed by Pd/C is reported. The starting materials can be easily prepared by the reaction of substituted ketones and nitroalkenes. The facile experimental procedure comprises the treatment of 2-(2-nitro-1-phenylethyl)cyclohexanone derivatives with H2 as a hydrogen donor in the presence of 10 mol % Pd/C. Subsequently, the exchange of H2 with CH2═CH2 as a hydrogen acceptor affords a variety of 3-substituted indoles in high yields. The formation of intermediate nitrones is essential for a smooth reaction.