Mercaptomethylpyrazolopyrimidine (2) was synthesized and reacted with ethyl chloroacetate to afford ethyl pyrazolpyrimidinylmethylmercapto acetate (3), which in turn was converted into the corresponding carbohydrazide 4. Carbohydrazide 4 reacts with a variety of reagents to give different pyrazolopyrimidines (5–12). Chloromethyl-pyrazolopyrimidine (1) reacts with chloropyridine to give compound 13, which was subjected in a series of reactions to give new compounds 14–20.

Mercaptomethylpyrazolopyrimidine (2) was synthesized and reacted with ethyl chloroacetate to afford ethyl pyrazolpyrimidinylmethylmercapto acetate (3), which in turn was converted into the corresponding carbohydrazide 4. Carbohydrazide 4 reacts with a variety of reagents to give different pyrazolopyrimidines (5–12). Chloromethyl-pyrazolopyrimidine (1) reacts with chloropyridine to give compound 13, which was subjected in a series of reactions to give new compounds 14–20.

3-Amino-4,6-dimethylthieno[2,3-b]pyridine-2-carboxaldehyde was prepared and from it various functionalised thieno[2,3-b; 4,5-b']dipyridines were synthesised, using the Friedländer and related reactions. Ethyl 2,7,9- trimethylthieno[2,3-b; 4,5-b']dipyridine-3-carboxylate was transformed into a variety of thieno[2,3-b; 4,5-b']dipyridine systems with heterocyclic rings attached at C-3 or fused at C2–C3.

Chloroacylation of 3-amino-2-phenylpyrazole-4-carboxamide (2) using chloroacetyl-(propionyl) chloride affording 6-chloromethyl(ethyl)-1-phenylpyrazolo[3,4-d]pyrimidin-4[5H]-one (3) or (6). Chlorine atom in compound (3) or (6) underwent nucleophilic substitution reaction with primary or secondary amines to give 6-alkyl(aryl)aminomethyl(ethyl)-1-phenylpyrazolo[3,4-d]pyrimidin-4[5H]-one (4a-g,7a-f). When arylaminomethyl( ethyl)pyrazolopyrimidine was treated with formaline (30%) solution in ethanol, underwent Mannich reaction to afford imidazopyrazolopyrimidines (5a-e) and pyrazolopyrimidopyrimidines (8a-e). Chloromethylpyrimidine derivative 3 was converted into the corresponding mercaptomethylpyrazolopyrimidene 9, Which cyclized using bromomalononitrile or phenacyl bromide into pyrazolopyrimidothiazine 11,12

Chloroacylation of 3-amino-2-phenylpyrazole-4-carboxamide (2) using chloroacetyl-(propionyl) chloride affording 6-chloromethyl(ethyl)-1-phenylpyrazolo[3,4-d]pyrimidin-4[5H]-one (3) or (6). Chlorine atom in compound (3) or (6) underwent nucleophilic substitution reaction with primary or secondary amines to give 6-alkyl(aryl)aminomethyl(ethyl)-1-phenylpyrazolo[3,4-d]pyrimidin-4[5H]-one (4a-g,7a-f). When arylaminomethyl( ethyl)pyrazolopyrimidine was treated with formaline (30%) solution in ethanol, underwent Mannich reaction to afford imidazopyrazolopyrimidines (5a-e) and pyrazolopyrimidopyrimidines (8a-e). Chloromethylpyrimidine derivative 3 was converted into the corresponding mercaptomethylpyrazolopyrimidene 9, Which cyclized using bromomalononitrile or phenacyl bromide into pyrazolopyrimidothiazine 11,12

Chloroacylation of 3-amino-2-phenylpyrazole-4-carboxamide (2) using chloroacetyl-(propionyl) chloride affording 6-chloromethyl(ethyl)-1-phenylpyrazolo[3,4-d]pyrimidin-4[5H]-one (3) or (6). Chlorine atom in compound (3) or (6) underwent nucleophilic substitution reaction with primary or secondary amines to give 6-alkyl(aryl)aminomethyl(ethyl)-1-phenylpyrazolo[3,4-d]pyrimidin-4[5H]-one (4a-g,7a-f). When arylaminomethyl( ethyl)pyrazolopyrimidine was treated with formaline (30%) solution in ethanol, underwent Mannich reaction to afford imidazopyrazolopyrimidines (5a-e) and pyrazolopyrimidopyrimidines (8a-e). Chloromethylpyrimidine derivative 3 was converted into the corresponding mercaptomethylpyrazolopyrimidene 9, Which cyclized using bromomalononitrile or phenacyl bromide into pyrazolopyrimidothiazine 11,12

1-Morpholin-4-yl-5,6,7,8-tetrahydroisoquinoline-4-carbonitrile (2) was synthesized from 3-amino- 1-thioxo-5,6,7,8-tetrahydro-1H-isothiochromene-4-carbonitrile (1) and used as starting material to synthesize many thienotetrahydroisoquinolines (4),which in turn were used in the synthesis of many pyrimidothienotetrahydroisoquinolines.

1-Morpholin-4-yl-5,6,7,8-tetrahydroisoquinoline-4-carbonitrile (2) was synthesized from 3-amino- 1-thioxo-5,6,7,8-tetrahydro-1H-isothiochromene-4-carbonitrile (1) and used as starting material to synthesize many thienotetrahydroisoquinolines (4),which in turn were used in the synthesis of many pyrimidothienotetrahydroisoquinolines.

1-Morpholin-4-yl-5,6,7,8-tetrahydroisoquinoline-4-carbonitrile (2) was synthesized from 3-amino- 1-thioxo-5,6,7,8-tetrahydro-1H-isothiochromene-4-carbonitrile (1) and used as starting material to synthesize many thienotetrahydroisoquinolines (4),which in turn were used in the synthesis of many pyrimidothienotetrahydroisoquinolines.

3,4-Dimethyl-5,6-disubstited-thieno[2,3-c]pyridazines (5a-d, 6, and 7) have been synthesized. 5-Amino-3,4- dimethylthieno[2,3-c]pyridazine-6-carbonitrile (5b) was used as a key intermediate in the synthesis of novel pyrimido[4’,5’:4,5]thieno[2,3-c]pyridazine derivatives (8-12) and 1,2,4-triazolo[1»,5»:1’,6’]pyrimido[4’,5’:4,5]thieno[2,3-c]pyridazine (14, 15).