Nitroimidazoles: Part XVII. 5-Aminoimidazoles

Abstract

2-Benzoyl-1-methyl-5-nitroimidazole (I) undergoes-reduction over Raney nickel catalysed to the amine (2), which is transformed into the p-chIorobenzamide (3), the acylthioureas (4 and 6) and the sulphonylthiourea (5). Alkaline hydrolysis of 4 affords the thiourea (7), Hydrogenation of the p-nitrobenzayl analogue (10) of 1 and condensation of the product with dimeihylformamide dimethylacetal leads to the bis-amidine (II). Catalytic reduction of the nitrosulphone (12) affords unstable 2-methanesulphonyl-1-methyI-S-aminoimidazole (13) forming stable acyl derivatives (14a-g) and thioureas U5a and 15b). Reaction of 13 with p-nitrobenzaldehydc furnishes in low yield an anomalous product considered to be 19, which probably results via the benzylidene-bisimidazole(16)and the tricyclic condensed pyridines(17and 18). 2-Meihunesulphinyl-1-metbyl-5-aminoimidazole arising from the nitro derivative (20a) is characterised as the acylthioureas (20b and 20c). Likewise the reduction product of 1-methylsulphonyl-3-(1-methyl-5-nitro-2-imidazoly])-2-irnidazolidinone (21a) has been isolated as the acetyl derivative (21b).