Deprotonation and Regioselective Addition of 2H-Pyrazolo[3,4-c]quinolines to Electrophiles

Abstract

The deprotonation and regioselective reaction of 2H-pyrazolo[3,4-c]quinolines with a variety of electrophiles is described. Electrophiles include benzaldehyde, DMF, carbon dioxide, and iodine. This method provides a direct route to a class of pharmacologically interesting compounds.

Ring-Opening of Indoles: An Unconventional Route for the Transformation of Indoles to 1H-Pyrazoles Using Lewis Acid

“…It is well documented that the carbonyl and sulfonyl groups form stable adducts with Lewis acids . Hence, we judiciously introduced the carbonyl or sulfonyl containing directing groups like acyl, benzoyl and tosyl at the N1-position of indoles assuming that the complexation between Lewis acids and these directing groups would induce the C2–N1 bond opening (Scheme c). ,,− Therefore, the decrease in electron density of the C2C3 bond would lead to a cyclization reaction with tosylhydrazones leading to the formation of pyrazoles. They are known to display a wide spectrum of biological activities, including antimicrobial, antifungal, antitubercular, anti-inflammatory, anticonvulsant, anticancer, antiviral, neuroprotective activities. , The pyrazole is a versatile synthetic intermediate and potent medicinal scaffold. , The synthesis of pyrazoles still continues to attract considerable attention because of its applications in pharmaceutical and agrochemical industries.…”

Metalated Indoles, Indazoles, Benzimidazoles, and Azaindoles and Their Synthetic Applications

“…The latter was trapped with N,N-dimethylformamide to form aldehyde 232 in 71% yield (Scheme 69). 118 The functionalization of 4,5-dihydrobenzo[g]indazole 233 via metalation with a hindered magnesium amide has been reported (Scheme 70). Indazole 233 was deprotonated at C3 using commercially available TMPMgCl•LiCl at -30 °C.…”