DABCO Mediated Sulfur Activation‐Intramolecular De‐Nitration Strategy for the Synthesis of Novel Dihydrothiochromeno[4,3‐<i>c</i>]pyrazoles
Deepika, Avijit Kumar Paul, Chandi C. Malakar, Ajay Bansal, Virender Singh
Abstract
Abstract A facile and highly efficient metal‐free approach has been unfolded for the synthesis of novel dihydrothiochromeno[4,3‐ c ]pyrazoles using elemental sulfur as a powerful sulfurating reagent. This method includes sp 2 C−H functionalization followed by sp 2 C−NO 2 group displacement using elemental sulfur as an odourless sulfur source activated by DABCO in DMSO. Using the developed synthetic strategy, a library of 29 novel dihydrothiochromeno[4,3‐ c ]pyrazoles, incorporating two pharmacologically important scaffolds has been synthesized in 52–76% yield with a broad substrate scope. A sensible mechanistic proposal has been projected based on control experiments.