A straightforward, two-step synthesis of chromeno2,3-cpyrazol-4(lH)-ones, thieno2',3':5,6pyrano2,3-cpyrazol-4(lH)-ones, and lbenzo-thieno2',3':5,6pyrano2,3-cpyrazol-4(lH)-ones, respectively, is presented. Hence, treatment of 1-substituted or 1,3-disubstiruted 2-pyrazolin-5-ones with 2-fluorobenzoyl chloride, 2-chlorobenzoyl chloride, 3-chlorothiophene-2-carbonyl chloride, or 3-chloro-l-benzothiophene-2-carbonyl chloride using calcium hydroxide in refluxing 1,4-dioxane gave the corresponding 4-aroylpyrazol-5-ols, which were successfully cyclized into the fused ring systems (NaH/DMF). The N-unsubstituted title compounds were obtained upon treatment of l-(4-methoxybenzyl) protected congeners with trifluoroacetic acid. Detailed NMR spectroscopic investigations (1~H, 13~C, 15~N) with the obtained compounds were undertaken.
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