Chroman-4-one derivatives 1(a-i) were prepared by Pechman condensation of phenol or its substitutions with cinnamic acid by using polyphosphoric acid. These derivatives were reacted with hydrazine hydrate in refluxing ethanol to yield pyrazoline derivatives (2). The utility
A series of N-(5-substituted 1,3,4-thiadiazol-2-yl maleimides (14-18) were prepared by cyclization of corresponding maleamic acids (7-12).These acids were prepared by the reaction of 2-amino-5-aryloxymethyl-1,3,4-thiadiazoles (1-6) with maleic anhydride. The starting amines (1-6) were prepared from different aryloxyacetic acids and thiosemicarbazide. The structure of the prepared compounds was suggested in the light of IR and UV Spectroscopy.
(E)-3-Chloro-4-arylidene-2,3-dimethyl-1-phenylpyrazolidin-5-one 1(a-c) which were used as synthon for synthesis of all target compounds were prepared from the reaction of 3-chloro-2,3-dimethyl-1phenylpyrazolidin-5-one(Chlorophenazone)with aromatic aldehydes by 1,4-Michael addition. 4-Aryl-3-chloro-2,3-dimethyl-1-phenyl-2,3-dihydro-1H-pyrazolo[3,4-d]pyrimidine-6(5H)-one2(a-c) and-6(5H)-thiones 2(d-f)were prepared in low yields(40-50%) by the reaction of 1 (a-c) with urea or thiourea respectively in refluxing ethanol. The refluxing of 1(a-c)with hydrazine hydrate in presence of pyridine afford 3-chloro-4-aryl-2,3-dimethyl-1-phenyl-1,2,3,5-tetrahydropyrazolo[3,4-c]pyrazole 3(a-c). Also, 2-benzyl-4-spiro-5-chloro-1,5-dimethyl-2-phenylpyrazolidin-3-one (4) was obtained via epoxidation of 1(a) by hydrogen peroxide in presence of anhydrous sodium carbonate, the reaction of this spiro compound with hydrazine hydrate gave 3-chloro-2,3-dimethyl-1,4diphenyl-1,2,3,3a-tetrahydropyrazolo[3,4-c]pyrazole (5). Finally, the authentic samples of pyrazole (5) was prepared by the oxidation of 3(a) with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ). The structures of these compounds were confirmed by their physical properties in addition to the IR and UV Spectra.
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