Search

1,4-Disubstituted 5-hydroxy-1H-pyrazoles (9), (12), and (13) were prepared in two steps from hydrazines (2a-k) and 3-(dimethylamino)propenoates (1), (4), and (5). First, acid-catalyzed treatment of enaminones (1), (4), and (5) with (hetero)arylhydrazines (2a-k) afforded the corresponding dimethylamine substitution products, hydrazones (3') and enehydrazines (6) and (7). Under acidic conditions, intermediates (3'), (6), and (7) did not undergo cyclization into the pyrazole derivatives. However, heating 3', 6, and 7 in a mixture of methanol and triethylamine furnished the desired products in 65-98% yields.

Methyl (E)-2-[(benzyloxycarbonyl)amino]-3-cyanopropenoate (4) was, as a versatile multifunctional reagent, transformed with hydrazine and monosubstituted aromatic and heteroaromatic hydrazines under various conditions into derivatives of pyridazine (6), pyrrole (7), imidazole-2,4-dione (9), and pyrazole (13).

The reaction of amines (4a-g) with ethyl (2E)-3-N,N-dimethylamino-2-(5-ethoxy-l-phenyl-1H-pyrazol-3-yl)propenoate (3), prepared in two steps from ethyl (4,5-dihydro-5-oxo-l-phenyl-1H-pyrazol-3-yl)acetate (1), gave ethyl (2E)-2-(5-ethoxy-1-phenyl-1H-pyrazol-3-yl)-3-(substituted amino)propenoates (5a-g). The reaction of compound (3) with 2-aminopyridine (4h), 3 amino-1H-pyrazole (4i), 2H-pyran-2-one (6a), and 5,5-dimethylcyclohexane-1,3-dione (6b) afforded 3-(pyrazol-3-yl)pyridopyrimidinone (7a), 6-(pyrazol-3-yl)pyridopyrimidinone (7b), 3-(pyrazol-3-yl)pyranopyrandione (7c), and 3-(pyrazol-3-yl)-chromenedione (7d), respectively.

Ethyl (2E)-3-dimethylamino-2-[(4Z)-4-dimethylaminomethylidene-5-oxo-1-phenyl-4,5-dihydro-1H-pyrazol-3-yl]propenoate (3) was transformed with N-nucleophiles into ethyl 3-oxo-2-phenyl-3,5-dihydro-2H-pyrazolo[4,3-c]pyridine-7-carboxylates (6, 7, 9, 12, and 14).

Alkyl [(Z)-4-dimethylaminomethylidene-5-oxo-1-phenyl-4,5-dihydrolH-pyrazol-3-yl]acetate (4) was transformed with N- and C-nucleophiles into alkyl [4-(substituted amino)methylidene-4,5-dihydro-1H-pyrazol-3-yl]acetates (7) and alkyl (4-heteroarylmethylidene-4,5-dihydro-1H-pyrazol-3-yl)acetates (8), respectively. Compounds (7) cyclize by heating with DMFDMA in DMF into 2H-pyrazolo[4,3-c]pyridine-7-carboxylates (9).

A synthesis of new 2-substituted 1H-perimidines by the reaction of 1-[(methylthio)thiocarbonylmethyl]azinium salts and 1,8-diaminonaphthalene is described. Reaction of these perimidine derivatives with several electrophiles is also reported., Authors wish to thank Comision Interminlsterial de Ciencla y Tecnologia (CICYTI for financ ial support.

Reaction of 1-[(1,3,5-thiadiazol-2-yl)]-methylpyridinium derivatives with diverse electrophiles produced disubstituted heteroarylmethylpyridinium ylides. Only with phenyl isothiocyanate 1,3-dipolar cycloaddition was observed

A series of new N-[(methylthio)thiocarbonylmethyl] azinium salts has been synthesized by reaction of carbon disulphide and methyl iodide with the corresponding phenacylazinium salt in a two-phase system followed by acid treatment of the ylide thus obtained. Condensation of dithioster derivatives with o-phenylenediamines gave N-(benzimidazolylmethyl) azinium salts in good yields., Authors wish to thank Comión Asesora de lnvestigación Científica y Técnica (C.A.I.C.Y.T.) for financial support.