Pyrazolo!l,5-c quinazolines

Reaction of 2-isothiocyanato-/ra/w-cinnamaldehyde (110) with hydrazine gave the pyrazolo[l,5-c]quinazolines (111), presumably via the corresponding hydrazone and conjugate addition to the pyrazoline followed by cyclization [76JCS(P1)653]. 

Diazoxindole (305) adds DMAD to give 83% of the pyrazolo[l,5-c]quinazoline (307), presumably via 306.188... 

The pyrazolylaniline (176) condenses with benzaldehyde to give the pyrazolo[l,5-c]-quinazoline (177). It also reacts in low yield with formaldehyde but other aliphatic aldehydes fail to react. With formic acid or acid chlorides, it gives the fully aromatic derivatives (178 Scheme 55) (63JOC1336). 

Pyrazolopyrimidinones C NMR, 5, 308 methylation, 5, 310 synthesis, 5, 329 Pyrazolopyrimidinones, thioxo-synthesis, 5, 324 Pyrazoloquinazolines synthesis, 5, 317, 322 Pyrazolo[l, 5-a]quinazolines synthesis, 5, 273 Pyrazolo[l, 5-c]quinazolines synthesis, S, 324 Pyrazolo[2,3-a]quinazolines synthesis, 3, 378 Pyrazoloquinazolinones synthesis, 5, 342 Pyrazolo[4,3-/]quinazolinones synthesis, S, 273 Pyrazolo[4,3-g]quinazolinones synthesis, S, 273 Pyrazolo[3,4-/]quinolines synthesis, S, 273 Pyrazolo[4,3-/]quinolines synthesis, S, 273 Pyrazolo[l,5-a]quinoxalines synthesis, 5, 339 Pyrazolo[3,4-fc]quinoxalines synthesis, S, 272... 

Varano F, Catarzi D, Colotta V et al (2008) Novel AMPA and kainate receptor antagonists containing the pyrazolo[l, 5-c]quinazoline ring system Synthesis and structure-activity relationships. Bioorg Med Chem 16 2617-2626... 

Some tricyclic systems have been prepared by intramolecular cyclization from A-aryl-pyrazoles carrying substituents both in the pyrazole ring at C-5 and in the phenyl ring at the o-position. Thus pyrazolo[l,5-n]quinazolines (563) (69JHC947) and pyrazolo[l,5-n]-[l,4]benzodiazepines (564) (77JHC1163, 77JHC1171) can be prepared from suitable precursors. 

Synthesis of 9-substituted tetrahydroazepinopurines as asmarine analogs has been described <03T6493>. In relation to adenosine receptor antagonists, new derivatives of pyrazolo[4,3-c][l,2,4]triazolo[l,5-c]pyrimidines have been synthesized <03IMC1229, 4287>. A one-pot synthesis of l,2,4-triazolo[l,5-c]quinazoline thiones 65, consisting of a domino cyclization of 2-isothiocyanatobenzonitrile 63 with hydrazides 64 has been published <03EJO182>. 

Acylation and metallation studies on monomers, dimers, trimers, and tetramers containing linked thiophen, pyridine, pyrimidine, furan, benzofuran, benzothiophen, and indole moieties have been published/ Deuteriation, halogenation, and diazo-coupling reactions of 2-oxo- and 2-thioxo-l,2-dihy-dropyrimidinium salts have been studied and compared with results for 2,2-dialkyl-1,2-dihydropyrimidinium and 2,3-dihydro-1,4-diazepinium salts in order to demonstrate the effect of an adjacent 0x0- or thioxo-group on the properties of a 1,5-diazopentadienium system/ Vilsmeier formylation of, and tautomerism in, 2-hydroxypyrazolo[5,l-h]quinazolone and l-phenylpyrazolo[5,l-A]-quinazoline-2,9-dione have been studied/ The pyrazolo[3,4-c]pyrazole (71) has been methylated and acetylated, the major products being (72)/ ... 

Alternatively, (217) react with activated methylene synthons in the presence of potassium bicarbonate to afford transient C=N adducts (218) which revert to the 4-amino-5-(/ ,/ -di substituted vinyl)triazoles (219) or (220). Recyclization of these products (219) or (220) affords (215). Similar transformations of l-substituted-l/7-pyrazolo[3,4-J]pyrimidines (77CPB535), pyrido[2,3-t/]py-rimidines (75CPB2939, 78CPB3242), and quinazolines <79CPB286l> have also been reported. 

A microwave-assisted three-component coupling reaction of 5-amino-3-phenyl-pyrazole, a cychc 1,3-dicarbonyl compound and an aromatic aldehyde has been described by Chebanov and co-workers [121]. Depending on the apphed reaction conditions a series of 4-aryl-3-phenyl-l,4,6,7,8,9-hexahydro-l// pyrazolo[3,4-h] quinolin-5-ones 80, 9-p-tolyl-6,6-dimethyl-2-phenyl 5,6,7,9-tetrahydro-pyrazolo [5,l-h]quinazolin-8-ones 81, or 4-aryl-5a-hydroxy-4,5,5a,6,7,8-hexahydropyra-zolo[4,3-c]quinolizin-9-ones 82 can be formed (Scheme 61). 

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