We report the optimization of a neglected reaction for the rapid and direct conversion of oxazoles into N-substituted imidazoles. The utility of this microwave-promoted reaction for diversity-oriented synthesis is demonstrated in the preparation of >40 N-substituted imidazoles, including α-imidazolyl esters.

The imidazoles 1a-g add to the CC-double bond of the iminium ion 2 with rate constants as predicted by the equation log k = s(N)(N + E). Unfavourable proton shifts from the imidazolium unit to the enamine fragment in the adduct 3 account for the failure of imidazoles to take part in iminium-activated aza-Michael additions to enals.

[reaction: see text] A simple, high-yielding synthesis of 2,4,5-trisubstituted imidazoles from 1,2-diketones and aldehydes in the presence of NH(4)OAc is described. Under microwave irradiation, alkyl-, aryl-, and heteroaryl-substituted imidazoles are formed in yields ranging from 80 to 99%. Short syntheses of lepidiline B and trifenagrel illustrate the utility of this approach.

An olefin cross-metathesis method applicable for the preparation of 4-(alk-1-en-1-yl)-1H-imidazoles was developed. The optimized conditions afforded a high-rate, selective, and high yielding reaction that comprise traditionally unreactive imidazole kernel as substrate. A variety backbone functionalized imidazoles were synthesized in good to yields by using this method.

We describe here a tandem catalytic route to prepare imidazoles in a single operation from aryl iodides, imines and CO. The reaction involves a catalytic carbonylation of aryl halides with imines to form 1,3-dipoles, which undergo spontaneous 1,3-dipolar cycloaddition. Overall, this offers an alternative to coupling reactions to construct the (hetero)aryl-imidazole motif, where variation of the...

We describe here a tandem catalytic route to prepare imidazoles in a single operation from aryl iodides, imines and CO. The reaction involves a catalytic carbonylation of aryl halides with imines to form 1,3dipoles, which undergo spontaneous 1,3-dipolar cycloaddition. Overall, this offers an alternative to coupling reactions to construct the (hetero)aryl-imidazole motif, where variation of the ...

A survey of the pertinent literature reveals that aryl imidazoles have been found to possess a wide spectrum of biological activity such as antibacterial [1], antirheumatoid arthritis [2], antitubercular [3], antiviral [4], anti-inflammatory [5] and anticancer activities [6-8]. Specifically, it has been revealed from the literature that imidazoles fused with indole nucleus possess various biolo...

A one-pot, two step synthesis of highly substituted imidazoles has been carried out in good to excellent yields for the first time via a cascade intermolecular aza-SN2'-intramolecular aza-Michael addition involving a variety of Morita-Baylis-Hillman acetates of nitroalkenes and amidines in the presence of DABCO at room temperature. The synthetic and biological utility of the products has been d...

N-aryl imidazoles play an important role as structural and functional units in many natural products and biologically active compounds. Herein, we report a photocatalytic route for the C-N cross-coupling reactions over a Cu/graphene catalyst, which can effectively catalyze N-arylation of imidazole and phenylboronic acid, and achieve a turnover frequency of 25.4 h(-1) at 25°C and the irradiation...

A variety of heteroaromatic compounds, such as substituted pyridines, pyrazoles, indoles, 2-substituted imidazoles, 2-substituted imidazoles, 2-arylbenzazoles and pyrimidin-2(1H)-ones are synthesized by oxidative aromatization using the activated carbon and molecular oxygen system. Mechanistic study focused on the role of activated carbon in the synthesis of 2-arylbenzazoles is also discussed. ...