Copper-catalyzed oxidative multicomponent reaction: synthesis of imidazo fused heterocycles with molecular oxygen

Abstract

An oxidative cascade that involves multicomponent reaction comprising a terminal alkyne, 2-amino N-heterocycle, benzyl or allylic bromide with molecular oxygen, delivering densely functionalized imidazo fused heterocycles, is described. This reaction features a cheap catalyst, a green oxidant, and readily available starting materials, which make the overall synthesis applicable in the quick access to relevant pharmaceutical molecules with imidazole derived heterocycles.

Stimuli-Responsive Aggregation-Induced Delayed Fluorescence Emitters Featuring the Asymmetric D–A Structure with a Novel Diarylketone Acceptor Toward Efficient OLEDs with Negligible Efficiency Roll-Off

“…Synthesis and Thermal Stability. The synthesis of new luminogens was enlightened in our previous work, 43,44 as shown in Scheme S1, The key intermediate pipd-BZ-Br was prepared via an efficient iodine-mediated region-selective synthesis akin to the Ortoleva−King reaction, followed by a Buchwald− Hartwig cross-coupling reaction to obtain the new luminogens, and decent yields of the products were achieved. The structures of new luminogens were characterized after purification by vacuum sublimation.…”

Recent developments and perspectives in the copper-catalyzed multicomponent synthesis of heterocycles

“…An efficient synthetic method towards functionalized imidazo fused heterocycles from 2-amino N-heterocycle, terminal alkyne, allyl or benzyl bromide using molecular oxygen was unveiled ( Scheme 29 ). 38 The mentioned protocol consists of many advantages and is assumed to have the synthetic potential for the easy access to diverse bioactive molecules. The optimized reaction condition contained Cu(OTf) 2 as the copper( ii ) source for catalysis, Li 2 CO 3 as base, TEMPO as well as molecular oxygen as the suitable oxidant in toluene.…”

α-Aminoazoles/azines: key reaction partners for multicomponent reactions

“…An interesting multicomponent approach to access imidazole-derived heterocycles 322b was reported by X. Li et al through an oxidative cascade reaction. 197 This Cu(OTf) 2 and Li 2 CO 3 -catalyzed reaction was conducted using terminal alkyne 313, 2-amino N-heterocycle 120, benzyl/allylic bromide 322a and TEMPO (as an oxidant) in toluene under an oxygenated environment at 100 °C ( Scheme 100 ). After 10 h, the target products, densely functionalized imidazo-fused heterocycles 322b, were obtained in moderate to good yields.…”