An efficient, novel method for the synthesis of substituted tetrahydrocarbazoles using catalyzed sulfanilic acid in methanol solvent.

The synthesis of substituted and condensed indoles has attracted considerable attention due to their importance as building blocks for many therapeutically useful materials and the wide ranging biological activity of both synthetic and naturally occurring derivatives1. Tetrahydrocarbazoles condensed with indole, furan, pyrimidine, pyrazoline, and thiophene,moieties have been known to processes wide spectrum biological activities.There has been many methods of synthesis which includes cyclization of diphenylhydrazone of cyclohexane-1,2-dione or 2-phenylhydrazono cyclohexanone via Fischer indole synthesis2. However the Bischler synthesis served as one of the simplest and attractive method to obtain tetra hydrocarbazoles and carbazoles by the condensation of α-halocyclohexanones with aromatic amines3. Improved method for the synthesis of tetrahydrocarbazoles by the Bischler reaction was also reported. Hence in this work, we report the application of sulfanilic acid as a catalyst for efficient One-Pot Fischer phenyl hydrazine whith cyclohexanone synthesis of tetrahydrocarbazoles and by using methanol solvent in summary, involving rapid mild and high yielding product with good purity and excellent yields and also for the simple synthesis of new hetrocycles via modifications of existing methodologies and their biological activities.(Figure1)