Reactions of Pyrazolo [1, 5-a] pyrimidine Derivatives with Nucleophiles. III. Nucleophilic Addition to 6, 7-Bis (ethoxycarbonyl) pyrazolo [1, 5-a] pyrimidine-3-carbonitrile in the Presence of Triethyloxonium Fluoroborate

Abstract

Nucleophilic additions of phenol and aniline analogs to 6, 7-bis (ethoxycarbonyl) pyrazolo [1, 5-a] pyrimidine-3-carbonitrile (1) in the presence of triethyloxonium fluoroborate are described. For example, though phenol or o-cresol (having no substituent at the para-position) reacted with 1 to give the cyclohexadienylidene derivatives (3, 4), p- or m-cresols, p-methoxyphenol, and α-or β-naphthol gave the corresponding spiro lactones (6, 7, 8, 10 and 12). When 1 was treated with several kinds of aniline analogs, three types of products were obtained. Namely, while aniline or o-toluidine gave the 7-(4-aminophenyl) adducts (13, 15), p-anisidine, p-chloroaniline or p-nitroaniline afforded the 7-anilino derivatives (17, 20 or 21). Treatment of p-toluidine with 1 under the same reaction conditions gave a mixture of the spiro-indole-3 (2H), 7'(4'H)-pyrazolo [1, 5-a] pyrimidin-2-one (22) and the pyrazolo [1', 5' : 1, 2] pyrimido [5, 6-c] quinoline (23).