Molecular iodine mediated transition-metal-free oxidative dehydrogenation of 4,7-dihydropyrazolo[3,4-b]pyridines

Abstract

A transition-metal-free Iodine-K₂CO₃ catalyzed efficient oxidation of 4,7-dihydropyrazolo[3,4-b]pyridines has been developed for the practical synthesis of corresponding pyrazolo[3,4-b]pyridines. The method is suitable for synthesis of variously substituted pyrazolo[3,4-b]pyridines as it is free from tedious purification steps and gives pure products in high yields. Molecular iodine (I₂), being inexpensive, environmentally benign, and easy‐to‐handle reagent, was used to carry out the dehydrogenation under mild reaction conditions.

Graphical Abstract

Keywords:

• Oxidative dehydrogenation
• 4,7-dihydropyrazolo[3,4-b]pyridine
• pyrazolo[3,4-b]pyridine
• Iodine-K₂CO₃
• environmentally benign
• transition-metal-free protocol

Acknowledgements

We are thankful to University Grant Commission, New Delhi for providing financial support in the form of Rajiv Gandhi National, Senior Research Fellowship to Suresh Kumar. Thanks are also due to Council of Scientific and Industrial Research, New Delhi for providing financial assistance in the form of Senior Research Fellowship to Gulshan Singh. We are also thankful to SAIF, Panjab University, Chandigarh for spectral studies.

Supporting information

Full experimental details regarding ¹H and ¹³C NMR spectra can be found in supplementary content section of this article’s webpage.