Prasanjit Ghosh

Synthesis of 6-aryl substituted 4-quinolones via Suzuki cross coupling

A convenient way to introduce aryl functionalization in the 6-position of 4-quinolones is developed via selective bromination and subsequent arylation by Suzuki cross-coupling. Ethyl 4-quinolone 3-carboxylates were subjected to selective bromination at C-6 followed by arylation under microwave irradiation that yielded the desired cross-coupling products within 5 minutes. This approach can expediently be used for library synthesis of the aryl functionalized 4-quinolone derivative, an important class of biologically active compounds.

A green protocol for the Pd catalyzed ligand free homocoupling reaction of arylboronic acids under ambient conditions

A simple, competent, green pathway has been developed for the Pd catalyzed ligand free homocoupling reaction of arylboronic acids in water under ambient conditions. An efficient reaction environment is generated using a combination of Pd(OAc)2 and ‘green additives’, which exhibited excellent activity and results in high yields of the desired coupled products within 15 minutes.

Regiocontrolled Nitration of 4-Quinolones at Ambient Conditions

Abstract Regiocontrolled nitration of 4-quinolone, the highly privileged scaffold, has been developed at ambient conditions. The nitro group can selectively be introduced at diverse positions simply by tuning the reactivity of the moiety. Discrimination is being achieved through the selective functionalization of the free N-H group. The functional group has been screened theoretically with the help of Fukui function and local softness calculation. Theoretical predictions are synchronized well with the experimental findings. Finally, this nitration technique allows quick access to the structurally diverse 4-quinolones. GRAPHICAL ABSTRACT

Green procedure for highly efficient, rapid synthesis of imidazo[1,2-a]pyridine and its late stage functionalization

ABSTRACT We unfold a rapid synthetic protocol for the preparation of imidazo[1,2-a]pyridine in cyclohexane. This methodology includes several advantages like shorter reaction time, catalyst free, broader substrate scope, and good yields of the desired products. Late stage functionalization of imidazo[1,2-a]pyridine has also been performed through C–H bond activation and C–C cross-coupling reactions. GRAPHICAL ABSTRACT

Generation of ArS and ArSe substituted 4-quinolone derivatives using sodium iodide as an inducer

An operationally simple sodium iodide-mediated C-S and C-Se bond formation protocol involving substituted 4-quinolone and thiols/diselenide to generate different ArS/ArSe-substituted 4-quinolone derivatives in excellent yields was developed. The versatility of this methodology has been successfully demonstrated by extension of the suitable reaction conditions to both substrates having different substituents. This regioselective C-H bond activation approach provides a direct access of structurally diverse 3-sulfenylated/selenylated 4-quinolone derivatives. Moreover, this new method proceeds without a transition-metal catalyst and prerequisite NH protection of 4-quinolone derivatives.