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Indolyl glycinates (3, 7, and 11) were transformed with t-butoxybis(dimethylamino)methane (Bredereck's reagent) into 3-[(dimethylamino)methylidene]-2,3-dihydropyrazino[1,2-a]indole-1,4-dione (4), 3-(dimethylamino)-2-[(1H-indol-3-ylcarbonyl)amino]propenoate (8), and 2-(1-methyl-1H-indol-2-yl)-1,3-oxazol-5(4H)-one derivative (12). Dipeptides (16a-c) were transformed with Bredereck's reagent into the hydantoin (imidazolidine-2,4-dione) derivatives (17a-c).

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).

(Z)-3-Benzoylamino-4-dimethylamino-2-oxo-3-butene (4), prepared from 1-benzoylamino-2-propanone (3) and N,N-dimethylformamide dimethyl acetal, was converted regioselectively by reaction with a series of hydrazines (5) into 1-substituted 4-benzoylamino-5-methyl-1H-pyrazoles (8). Reactions of 4 with primary amines (10) and with dimethylbarbituric acid (12) afforded the dimethylamine substitution products (11) and (13), respectively. Treatment of the butenone (13) with ammonia furnished tetrahydropyrido[2,3-d]pyrimidine derivative (14).