N—H Insertion Reactions of Primary Ureas: The Synthesis of Highly Substituted Imidazolones and Imidazoles from Diazocarbonyls.

Abstract

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Modern Organic Synthesis with α-Diazocarbonyl Compounds

“…Janda and co-workers have explored such reactions in solution and in the solid phase with a view to preparing libraries of small heterocycles for application in combinatorial-type screening programs for drug discovery. 489,490 From the initial screening, these workers discovered that primary ureas were excellent substrates in N−H insertion reactions of α-diazo-β-ketoesters catalyzed by rhodium(II) octanoate ( Scheme 193). The best results were obtained using a mixed solvent system of toluene/1,2-dichloroethane (1:1) with slow addition of the catalyst.…”

Brønsted Acid-Catalyzed Synthesis of 1,2,5-Trisubstituted Imidazoles via a Multicomponent Reaction of Vinyl Azides with Aromatic Aldehydes and Aromatic Amines

“…Yield: 81%, 48 mg. White solid, mp = 243−245°C (lit. 19 mp 247−248 °C). R f = 0.3 (PE/EtOAc = 10:1).…”

“…R f = 0.3 (PE/ EtOAc = 10:1). 1 H NMR (400 MHz, CDCl 3 ): δ 7.59 (d,J = 8.2 Hz,2H),7.36 (s,1H),7.29 (dd,J = 8.2,5.0 Hz,4H),4H),7.20 (d,J = 8.2 Hz, 2H), 7.05 (dd, J = 5.8, 2.5 Hz, 2H) ppm; 13 C{ 1 H} NMR (100 MHz, CDCl 3 ): δ 148.0, 140.3 (q, J CF = 1.5 Hz), 134.9, 130.4 (q, J CF = 32.5 Hz), 130.2, 129.3, 128.9, 128.7, 128.6, 128.6, 128.5, 128.4, 128.3, 127.7, 126.5 (q, J CF = 3.7 Hz), 123.5 (q, J CF = 272.5 Hz) ppm; 19 7.31 (s, 1H), 7.25−7.21 (m, 4H), 7.17−7.13 (m, 2H), 7.12−7.07 (m, 2H), 6.87 (dd, J = 5.0, 3.8 Hz, 1H), 6.60 (dd, J = 3.7, 0.9 Hz, 1H) ppm; 13 C{ 1 H} NMR (125 MHz, CDCl 3 ): δ 143. 4, 135.9, 135.1, 132.9, 132.9, 130.4, 129.1, 128.4, 128.3, 128.2, 127.6, 127.3, 126.5, 125.9, 123.4…”