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Rapid Access of New Pyranocarbazole Derivatives Under Microwave Irradiation

[ Vol. 5 , Issue. 2 ]


Pedavenkatagari N. Reddy and Pannala Padmaja*   Pages 104 - 110 ( 7 )


Background: Pyranocarbazoles exhibit promising biological activities such as mosquitocidal, antimicrobial, anti-inflammatory and antioxidant. Pyranocarbazole derivatives have also been used in the field of medicinal chemistry as a pharmacophore for different therapeutic indications.

Methods: New pyrano[3,2-c]carbazole derivatives have been synthesized by the reaction of carbazole Mannich bases with (E)-N-methyl-1-(methylthio)-2-nitroethenamine under microwave irradiation. This transformation presumably occurs via o-quinone methide-Michael addition-tautomerismintramolecular O-cyclization-elimination sequence of reactions creating new one C-O bond and one C-C bond. The structures of obtained pyranocarbazoles were confirmed by NMR, IR and mass spectra.

Results: Various substituted carbazole Mannich bases such as fluoro-, nitro-, methoxy-, and trimethoxy-derivatives reacted smoothly to give the corresponding pyrano[3,2-c]carbazole derivatives in good yields. The significant features of this reaction include catalyst-free, solvent free, no column chromatographic purification, short reaction time and good yields.

Conclusion: We have developed a simple and efficient synthesis of novel pyrano[3,2-c]carazoles derivatives under microwave irradiation in good yields. It is noteworthy that this reaction results in the formation of two new bonds (one C-C and one C-O) in a single operation.


Hydroxycarbazole, mannich base, o-quinone methide, pyranocarbazoles, therapeutic, microwave.


Department of Chemistry, School of Technology, Gitam University, Telangana-502 102, Centre for Chemical Sciences and Technology, IST, Jawaharlal Nehru Technological University, Hyderabad, Telangana-500085

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