Iodine–NH₄OAc mediated regioselective synthesis of 2-aroyl-3-arylimidazo[1,2-a]pyridines from 1,3-diaryl-prop-2-en-1-ones

Abstract

The present protocol describes an efficient, metal-free regioselective synthesis of 2-aroyl-3-arylimidazo[1,2-a]pyridines from 1,3-diaryl-prop-2-en-1-ones and 2-aminopyridine. The iodine-NHOAc promoted reaction offers a novel route in the synthesis of 2-aroyl-3-arylimidazo[1,2-a]pyridines. This protocol offers significant flexibility in accessing medicinally important 2-aroyl-3-arylimidazo[1,2-a]pyridines with various substitution patterns.

Iodine‐Catalyzed C−H Functionalization of Cyclopentenedione with Benzamidine: A Double Dehydrogenative Oxidative Cyclization to Access Fused Imidazoles

“…Based on the control experiments, in situ mass spectrometry analysis of the reaction mixture, and literature precedence, we propose a plausible reaction mechanism in Scheme . Benzamidine hydrochloride 2 a is converted into super nucleophilic benzamidine in the presence of K 2 CO 3 as the base additive.…”

“…Due to the significance of imidazoles in medicinal and pharmaceutical chemistry, it is attractive to synthesize the derivatives of these compounds employing readily available precursors. Das has recently reported synthesis of imidazopyridines from 2‐amino pyridines and 1,3‐diaryl‐prop‐2‐en‐1‐one using a stoichiometric amount of iodine and ammonium acetate combination (Scheme a) . Li and Chen reported the synthesis of tetrasubstituted imidazole derivatives using a catalytic amount of iron and iodine combination (Scheme b & c) .…”

“…Das has recently reported synthesis of imidazopyridines from 2-amino pyridines and 1,3-diaryl-prop-2-en-1-one using a stoichiometric amount of iodine and ammonium acetate combination (Scheme 1a). [6] Li and Chen reported the synthesis of tetrasubstituted imidazole derivatives using a catalytic amount of iron and iodine combination (Scheme 1b & c). [7,8] Al-Mourabit and Nguyen reported a synthesis of fused imidazole using iron and iodine combination from 2-cyclohexeneone and 2-aminopyridine (Scheme 1d).…”

Application of Conjugated Carbonyls in the Synthesis of Heterocycles via Oxidative Cycloaddition and Cyclization Reactions

“…In 2018, Kapoor et al developed a methodology for the synthesis of 2-aroylimidazo[1,2-a]pyridine derivatives by the oxidative coupling between 2-aminopyridines and chalcones (Scheme 21). [26] They demonstrated that the reaction in presence of 1 equiv. of I 2 and 2 equiv.…”

Metal‐Free Synthesis of Furocoumarins: An Approach via Iodine‐Promoted One‐Pot Cyclization between 4‐Hydroxycoumarins and Acetophenones

“…Ghosh and Hajra obtained furocoumarins via a DABCO‐promoted cyclization transformation of 4‐hydroxycoumarins and nitrostyrenes . Iodine has recently emerged as a promising alternative for many transition metals due to its ability to promote a variety of organic transformations . In this communication, we would like to report a new iodine‐promoted one‐pot cyclization transformation between acetophenones and 4‐hydroxycoumarins to achieve corresponding furocoumarins.…”