反应详情

Scheme 15 shows the synthesis of 5-(2-(4-chloro-2-fluorophenyl)-1H-imidazol-4-yl)-1-isopropyl-3-methyl-1H-1,2,4-triazole 44 from 4-chloro-2-fluorobenzonitrile 38. Addition of hydroxylamine to the nitrile of 38 gave 4-chloro-2-fluoro-N-hydroxybenzimidamide 39. Michael addition of 39 to ethyl propiolate gave ethyl 3-(4-chloro-2-fluorobenzimidamidooxy)acrylate 40. Heating 40 in diphenyl oxide gave cyclized imidazole, ethyl 2-(4-chloro-2-fluorophenyl)-1H-imidazole-4-carboxylate 41. Saponification of the ester of 41 with aqueous sodium hydroxide in tetrahydrofuran gave 2-(4-chloro-2-fluorophenyl)-1H-imidazole-4-carboxylic acid 42. Reaction of 42 with N′-isopropylacetohydrazonamide 6 and coupling reagent HBTU in DMF gives intermediate, 2-(4-chloro-2-fluorophenyl)-N-(1-(2-isopropylhydrazinyl)ethylidene)-1H-imidazole-4-carboxamide 43 which cyclizes upon heating to give 44.