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A novel synthesis of pyrazolopyrimidine derivatives was reported wherein 5-amino-1-benzoyl-3-(methylthio)-1H-pyrazole-4-carbonitrile was treated with formic acid, formamide, thioacetamide, carbon disulfide, and phenylisocyanate and phenylisothiocyanate.

3‐Oxime‐4‐phenyl‐1(H)(l,5)benzodiazepin‐2‐one 2 was prepared and treated with malononitrile, arylidenenitriles, and bidentates to give the corresponding spiro‐3,3′‐isoxazolo‐, thiadiazino‐, and triazino‐1,5‐benzodiazepines 3–7. 3‐Bromo‐3‐cyano‐4‐phenyl‐l(H)(l,5)benzodiazepin‐2‐one 9a and 3‐bromo‐3‐cyano‐4‐(4′‐bromophenyl)‐1(H)(l,5)benzodiazepin‐2‐one 9b were synthesized via the bromination of 3‐cyano‐4‐phenyl‐1(H)(l,5)benzodiazepin‐2‐one 8. Compounds 9a,b were reacted with bidentates or cyclopentanone to afford spiro piprazine, quinoxaline, thiazine, thiadiazine, imidazole, and cyclopentafuran derivatives 10–16. Treatment of compound 1 with p‐tolyldiazonium chloride gave 3‐(p‐tolylazo)‐4‐phenyl‐1(H)(1,5)‐benzodiazepin‐2‐one 17, which in turn treated with nitriles, cyclopentanone, and S,S‐acetal derivative to give the corresponding spiro pyrazole, cyclopentapyrazole, and thiadiazole derivatives 18–21.

1,3-Dihydro-4-phenyl-1,5-benzodiazepin-2-one 1 was treated with bromine in 1:1 molar ratio to get the corresponding 3-bromo derivative 2 which in turn reacted with different nucleophiles to get the corresponding 3-substituted derivatives 3–11. The cyclized compounds 4a , 5a , 7a,b , and 9a–c were achieved on refluxing compounds 4, 5, 6a,b , or 8 a–c respectively in diphenyl ether. Compound 1 was benzoylated with benzoyl chloride to give the corresponding 1-benzoyl derivative 12 which reacted with bromine in 1:2 molar ratio to yield the corresponding 3,3-dibromo derivative 13. Spiro benzodiazepines 14a–d–16 were obtained by reacting compound 13 with the proper bidentates. Compound 1 was treated with formaldehyde and secondary amines or thiols to give Mannich bases or sulphides 17–21, respectively.

The reaction of 3-hydroxy-3(2-oxocyclohexyl)indolin-2-one 1 with some active methylene, bidentates, phenylisocyanate, phenylisothiocyanate, carbon disulfide, benzaldehyde, ketoketene S,S-acetal, cyanoketene S,S-acetal, active halo compounds or benzylidenemalononitrile affords a series of new spiro heterocyclic systems.

A new series of pyrano, oxazino, triazolo, oxazolo, furano, and 3-substituted(1,5)benzodiazepines were obtained from thereaction of lH(alkyl)-2,3-dihydro-4-methyl-1,5-benzodiazepin-2-ones with the proper reagents.

Novel heterocyclic compounds were prepared by the reaction of 2-acetyl-2-oxopropylidene s,s-acetal with different amino compounds namely, hydrazine hydrate, phenylhydrazine, guanidine hydrochloride, thiosemicarbazide, o-phenylenediamine, o-aminophenol or o-amino-thiophenol in different molar ratios.

The reaction of anilinomethylenemalononitrile 1 or 1,4-di (malononitrilemethyleneamino) benzene 7 with some reactive halo compounds in a one-pot reaction under PTC conditions affords a new series of pyrrole and pyridinone compounds. The reaction of compounds 1 or 7 with ethyl chloroformate gives the corresponding esters which underwent cyclization on reaction with different amino compounds affording the pyrimidinone derivatives.

The pharmacodynamic properties1-3 of substituted amino pyrazines as well as their importance in the synthesis of pteridine and other polyfused heterocyclic systems is well known4,5. In this investigation we aim to prepare a new series of condensed heterocyclic systems containing the pyrazine nucleus.

The inverse electron demand hetero-Diels-Alder reaction of arylmethylenepyrazolones with enamines results in the selective formation of 3,4-dihydro-2H-pyran derivatives. These cycloadducts under thermodynamic conditions, are transformed via the zwitterion, which can be captured in the presence of tetracyanoethylene (TCE), as the more stable Michael-type adducts. The zwitterion could also be the intermediate for the cyclic adducts.

A novel synthesis of pyrano(2,3-c)(1,5) benzodiazepines from 1H(alkyl)-2,3-dihydro-4-methyl-1,5-benzodiazepln-2-ones and malononitrile or ethyl cyanoacetate is reported.

Cycloaddition of 5-arylidenerhodanine derivatives la-d as α, β unsaturated carbonyl system attached to a heterocyclic nucleus with enamine E as an electron rich dienophile lead to 3,4-dihydro-2H-pyrans 2a-d. The results differed depending on the nature of the substituent of the arylidene group. The introduction of an electron-withdrawing group in the p-position of arylidene moiety should increase the facility of the reaction.

The reaction of the arylidenepyrazolones (1b-d) with l-morpholinocyclohexene (E2) in refluxing acetonitrile leads to the less substituted alkylated enamines 3b-d. On the other hand, the more substituted alkylated enamines 2a-d are formed when 1a-d react under the same conditions with l-piperidinocyclohexene (E1). The nature of the enamine is crucial. Nucleophilic attack of the enamine on the α, β-unsaturated carbonyl system of 1 gives rise to a zwitterionic intermediate which through α -proton loss leads to different Michael-type adducts depending on the enamine.