Quinazoline molecular structure

The crystal and molecular structures of 6,6-dimethyl-3-methylthio-6,7-dihydro[l,2,4]triazino[l,6-c]quinazolin-5-ium-l-olate 461, obtained by condensation of 455 with acetone, confirmed its zwitterionic structure (75CSC295). Analogues of 461 were also prepared for thermolysis studies (74T3997). 

Rastelli, G., Fanelli, F., Menziani, M.C., Cocchi, M. and De Benedetti, P.G. (1991) Conformational analysis, molecular modeling and quantitative structure-activity relationships studies of 2,4-diamino-6,7-dimethoxy-2-substituted quinazoline al-adrenergic antagonists. Journal of Molecular Structure (Theochem), 251, 307—318. 

The crystal and molecular structure of quinazoline was solved in 1976 by X-ray diffraction. Bond lengths and interbond angles of quinazoline (1) [with two crystallographically independent molecules (A and B) in the unit cell], 2-methylquinazolin-4(3/f)-one (2a), ° 2-phenylquinazolin-4(32f)-one (2b)," 2-acetylquinazolin-4(3//)-one (2c), " quinazoline-2,4-diamine monohydrate (3), 5-chloroquinazoline-2,4,6-triamine (4), 2-phenylquinazoline 1,3-dioxide (S). and ( )- , 2-bis(2-methylquinazolin-4-yl)ethene (6) obtained by X-ray crystallography are collected in Table 1. 

Methyl-4-oxoquinazolinyl-2-thiolacetic acid (378), obtained by the reaction of 6-methyl-4-oxoquinazoline-2-thione (377) and chloroacetic acid, upon treatment with acetic anhydride-pyridine, yields a cyclized product confirmed by the molecular ion peak [M] at m/z 232 and for which structure 7-methyl-2//-thiazolo[3,2-n]quinazolin-l,5-dione (379) was assigned on the basis of IR and H-NMR data in preference to possible... 

Battershell, C., Malhotra, D. and Hopfinger, A.J. (1981). Inhibition of Dihydrofolate Reductase Structure-Activity Correlations of Quinazolines Based upon Molecular Shape Analysis. 

Jantschi, L. and Bolboaca, S. (2006) Molecular descriptors family on structure-activity relationships. 5. Antimalarial activity of 2,4-diamino-6-quinazoline sulfonamide derivates. Leonardo Journal of Sciences, 8, 77-88. 

Sun et al. [51] have further reported the scope of the cyclization reaction of privileged scaffolds, IL-tagged diamines 99. Microwave-assisted IL-supported S5mthesis toward dihydro- and tetrahydroquinazoline analogs was demonstrated in Scheme 14 [50]. In order to conshuct quinazoline framework, IL-supported 99 was condensed with one-carbon electrophile aldehydes and isothiocyanates resulting tetrahydroquinazoline 120 and dihydroquinazoline 122, respectively. To extend the scope of this cyclization reaction, treatment of the same starting material with a-ketobenzoic acids or y-ketoaliphatic acid in the presence of acetic acid afforded isoindolo[l,2-a]quinazoles 119 under microwave irradiation (Scheme 14) [51]. Removal of IL support from quinazolines moiety xmder transesterification conditions furnished heterocycles 119, 121, and 123 with varied molecular complexity. The present methods offer more effective platforms to access structurally diverse heterocycles. 

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