Quinazolinones structure

Acetylation of 2-(l-hydroxyphenylmethyl)quinazolin-4-one (195) with refluxing acetic anhydride gave the expected acetate 196. Refluxing the starting compound (195) or its acetate (196) with acetic anhydride and sodium acetate gave the oxazolo[3,4-a ]quinazolinone (197). Spectral as well as chemical evidence favored the assigned structure(197) rather than the alternative oxazolo-[4,3-fc]quinazolinone structure (198) that could arise as a result of cyclization with N-3 of the quinazoline nucleus (74JOC3828). 

The quinazolinone structure is found in many biologically active compounds methaqualone, mecloqualone, piriqualone, afloqualone, and so on. Methaqualone (MQ, 470), 2-methyl-3-(2-methylphenyl)quinazolin (3H)-one, an hypnotic and anticonvulsive drug, is one of the leading examples of atropisomeric six-membered N-aryl heterocycles. Methaqualone gives stable atropisomers at room temperature due to the three substituents in ortho positions of the N-aryl rotating bond. 

Quinazolin-4(3H)-one, 3-phenyl-reduction, 3, 75 Quinazolinones polymers, 1, 298 reactions, 3, 89 structure, 3, 66-67 synthesis, 2, 96 3, 133 thiation, 3, 89 Quinazolin-4-oties 2,3-disubstituted Grimmel synthesis, 3, 109 mass spectra, 2, 22... 

The ethers (40) are hydrolyzed in high yields, by boiling water (4 hr), to 4-hydroxyquinazoline 1-oxide, and their structures were deduced by methylation followed by reduction to 3-methyl-4(3H)-quinazolinone (Scheme 6). These N-1 oxides show the typical reac-... 

Pyrido[2, l-6]quinazolinone (analogous to 204) and its 2,8-dinitro derivative were brominated by bromine in acetic acid, but the products are of unknown structure. Reaction with a mixture of phosphoryl chloride and... 

Other anthraquinone/azo pigments are obtained by coupling 1-aminoanthraquinone derivatives onto bis-quinazolinone methanes with the following chemical structure 82 ... 

Chemical Name l-Isopropyl-7-methyl-4-phenyl-2(lH)-quinazolinone Common Name -Structural Formula ... 

Carbon-13 N.M.R. Spectroscopy.—The 13C n.m.r. spectra of ten 4-quinazolinones have been reported, and are useful for determining their predominant tautomeric forms and for resolving controversial structural problems.13 Thus, the resonance of C-4 in compound (22), containing a double-bond between C-2 and N-3, appears at ca 1 p.p.m. to lower field (167.7-168.9 p.p.m.) than in compound (23), in which there is a double-bond between N-l and C-2. There is also a significant difference between resonances of C-8a in the two groups of compounds, those in compounds... 

The pyrido[2,l-6]quinazolinone 286 and its 2,8-dinitro derivative 372 (R = H) were brominated with bromine in acetic acid, but the structures of the brominated products were not elucidated. Treatment of 286 with phosphorus pentachloride in phosphoryl chloride at 180- 190 C yielded a trichlorinated product. ... 

The structures of octahydropyrido[2,l-i>]quinazolinone hydrobromide (283 HBr) and the pyrido[2,l-i>]quinazolinium picrate 455 were determined by means of X-ray crystallography. The configuration of the latter was 5a/ ,85, and two conformers were found in the crystal lattice. 

A still unresolved problem is the structure of the often used adducts from phosphorus trihalides and carboxylic acid amides, which might be described by the formulae (8) or (9). With the aid of in situ generated adducts of acid amides and PX3 amidines, isonitriles, quinazolinones, alkyl chlorides, aminomethylenediphosphonic acids, carbamoyl halides, triformylaminomethane, 1,3,4-oxadia-zoles, sulfides (from sulfoxides), nitriles (from primary nitro compounds)" and bromoqui-nolines (from methoxyquinolines)" have been prepared. 

PARP inhibitors have been synthesized (11) and are shown in Figs. 11.4 and 11.5. Some of them have been tested in stroke models with good results in terms of preventing infarction (12-18). Most of the inhibitors are based on the structure of nicotinamide and therefore bind to the nicotinamide site of PARP. Several inhibitors are well known, such as nicotinamide, benzamide, and 3-aminobenzamide (19,20). However, new quinazolinone, phen-anthradinone, and other inhibitors are being investigated. Nicotinamide has a of about 5 xM for PARP (19). Activity is decreased in 6-aminonicotinamide, isonicotinamide, 1-methylnicotinamide, 5-methylnicotinamide, 8-methylnicotinamide, and thionicotinamide (Table 11.1 >... 

Makino et al. described a pathway to quinazolinones utilizing a resin-bound amine, treatment of which with 2-methoxycarbonyl phenylisothiocyanate formed resin 147, which subsequently cydized in the presence of TFA to form the quina-zohnone core structure 151 [190]. Quinazoline alkaloids have been synthesized by cychzation of amidine intermediate 148 [191]. A two-step reaction on a sohd support involving cyclocondensation of ethyl oxalate 149 with benzamide and subsequent cleavage employing trimethylsilyl iodide also provided a quinazohne [192]. 

Andersin, R. and Mesilaakso, M., 1985, Structure elucidation of 6-chloro-2-methyl-4(lH)-quinazolinone, a photodecomposition product of midazolam, J. Pharm. Biomed. Anal., 13, 667-670. 

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