Synthesis of a series of 3-substituted-10-spiro(1'-cycloalkane)-thiazolo[4,3-a]quinazolin-4-ones is described.

1-Isopropyl-4-piperidone (1) reacts with sulphur and active methylene nitriles to give thienopyridines (2a-c). Compounds 2a, b react with CS2 in pyridine to produce pyridothienopyrimidines (3a, b) which upon methylation with MeI give S-methylated derivatives (4a, b). 3,5-Dibenzylidene-4-piperidone reacts with hydrazine hydrate, phenyl hydrazine, thiourea malononitrile or cyanoacetamide to give pyrazolo[4,3-c]pyridine derivative (6), pyrido[4,3-d]pyrimidine derivative (7), pyrano[3,2-c]pyridine derivative (8) and pyrido[3,2-c]pyridin derivative (9), respectively. Piperidylidene malononitrile (10) reacts with benzaldehyde to give derivative 11 which undergoes an addition reaction with malononitrile to give isoquinolein derivative (12) which is also obtained by reacting 1 with one mole of benzaldehyde and two moles of malononitrile

1-Isopropyl-4-piperidone (1) reacts with sulphur and active methylene nitriles to give thienopyridines (2a-c). Compounds 2a, b react with CS2 in pyridine to produce pyridothienopyrimidines (3a, b) which upon methylation with MeI give S-methylated derivatives (4a, b). 3,5-Dibenzylidene-4-piperidone reacts with hydrazine hydrate, phenyl hydrazine, thiourea malononitrile or cyanoacetamide to give pyrazolo[4,3-c]pyridine derivative (6), pyrido[4,3-d]pyrimidine derivative (7), pyrano[3,2-c]pyridine derivative (8) and pyrido[3,2-c]pyridin derivative (9), respectively. Piperidylidene malononitrile (10) reacts with benzaldehyde to give derivative 11 which undergoes an addition reaction with malononitrile to give isoquinolein derivative (12) which is also obtained by reacting 1 with one mole of benzaldehyde and two moles of malononitrile

In this investigation and in continuance with our previous work in the synthesis of some heterocyclic compounds fused with pyridine moiety, we used 3-amino-4,6-diphenyl-1H-pyrazolo[3,4-b]pyridine (II) as starting material to synthesize many heterocyclic compounds containing pyrazolopyridine moiety.

In this investigation and in continuance with our previous work in the synthesis of some heterocyclic compounds fused with pyridine moiety, we used 3-amino-4,6-diphenyl-1H-pyrazolo[3,4-b]pyridine (II) as starting material to synthesize many heterocyclic compounds containing pyrazolopyridine moiety.

In this investigation and in continuance with our previous work in the synthesis of some heterocyclic compounds fused with pyridine moiety, we used 3-amino-4,6-diphenyl-1H-pyrazolo[3,4-b]pyridine (II) as starting material to synthesize many heterocyclic compounds containing pyrazolopyridine moiety.