Imidazolsynthesen mit Formamid (Formamid‐Reaktionen, I. Mitteil.)

Abstract

Aus a-Oxy-, r-Ha.logcn-, z-Amino-und untcr reduzierenilen Bedingungen auch aus a-Isonitroso-ketonen entstehsn mit. Formamid 4.5-suhstituierte Iinidazole. Formamid dient ini t'bemcliul3 gleichzeitig als Losungsmitt,el.Bei der Ausarbeitung der Xanthin-Synthese aus Harnsiiure') waren wir auf die giinstigen Eigenschaften des Formamids aufmerksam geworden. Formamid diente dabei als Losungsmittel und bewirkte zugleich Ringoffnung, Formylierung und erneutcn R,ingschluB. In anderen Fallen ist Formamid weiterhin in der Lage, aminierend zu wirken, wie bei der Saureamid-Synthese narh

Novel symmetrically p-benzyl-substituted 4,5-diaryl-imidazole N-heterocyclic carbene-silver(I) acetate complexes – Synthesis and biological evaluation

“…The solvent was decanted and the white precipitate was washed with pentane (2 Â 10 mL) and diethyl ether (3 Â 10 mL) to yield a white powder (95. 5 (3) 4,5-Bis(4-methoxyphenyl)-1H-imidazole was synthesised according to literature [22] to give a yield of 38.5%. The formation of the product was confirmed by NMR.…”

A Rapid and Efficient Access to Polysubstituted Imidazoles viaIodine-Catalyzed Tandem Oxidative Cyclization

“…[5] Traditionally, imidazoles was obtained from cyclo-condensation reactions, such as Brederck reaction [6] involving an addition of α-diketones and α-haloketones to formamide, the cycloaddition of p-tosylmethyl-isocyanide with aldimines (van Lausen's TosMIC chemistry). [7] Recently, many other original methodologies have also reported, such as the direct functionalization of imidazoles rings [8] and acid-based multi-component coupling reactions.…”

Five‐Membered Heterocycles: 1,3‐Azoles

“…A similar synthetic methodology was introduced by Bredereck [27] in which an a-hydroxyketone or an a-haloketone is heated with formamide instead of ammonia or ammonium acetate. Brederecks reaction provides 4-substituted and 4,5-disubstituted imidazoles (Scheme 10.5).…”