Synthesis of 5-(4-Pyrazolyl and 4-Isoxazolyl)-1,3-dihydro-2H-1,4-benzodiazepin-2-ones

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Abstract
Reaction of 3-(4-pyrazolyl)anthranil (5) with phenylzinc chloride in the presence of nickel acetylacetonate gave 4-(2-anilinobenzoyl)pyrazole (6). 3-(4-Isoxazolyl)anthranil (11) gave a mixture of 4-(2-anilinobenzoyl)isoxazole (12) and 1-phenyl-4-quinolone (16). The compounds 6 and 12 were readily transformed to the azidoacetanilides (9 and 15), which were cyclized to 1,4-benzodiazepin-2-ones (10 and 19), respectively, via aza-Wittig reaction at room temperature. Treatment of azido derivative (25) with triphenyl phosphine gave the phosphinimine (26), which was eventually cyclized to the 1,4-benzodiazepine (27) in refluxing toluene. In contrast, the phosphinimine (41) prepared from 4-(2-azidoacetamido-3-theonyl)isoxazole (40) failed to cyclize to the condensed thieno-1,4-diazepine (42).
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