2- Phenylquinazoline-4 -one

Acetanilide, heated with urethane and phosphorus pentoxide, gave 2-methylquinazolin-4-one (see 1) benzanilide similarly furnished the 2-phenyl analog (yields not reported).38 The intermediate is apparently the amidine 55, because this produced 2-phenylquinazolin-4-one, in moderate yield, when heated at 185°C.39... 

Benzamidobenzamide was converted to 2-phenylquinazolin-4-one by heating at 250°C for 1 hr (no yield given).207 Difficulty in closing the ring was experienced when one or both of the amino groups were secondary.208... 

Nitriles and imidates have found little use, so far. Heating propionitrile and 2-aminobenzoic acid at 210°C in a closed vessel gave only a low yield of 2-methylquinazolin-4-one.297 Anthranilic add and 10 of its C-substituted derivatives were refluxed (5-50 hr) with ethyl acetimidate and benzimidate in methanol to give 2-methyl- and 2-phenylquinazolin-4-ones, respectively, in moderate yields three aminopyridine carboxylic acids behaved similarly.298 JV-Phenylbenzimidoyl chloride [PhC(NPh)Cl] and ammonium 2-aminobenzoate, in cold acetone, produced 2,3-diphenylquinazolin-4-one in good yield.299... 

When isatoic anhydride was heated with triethyl orthoformate and aniline for 6 hr at 125°C, a good yield of quinazolin-4-one was obtained, but triethyl orthoacetate did not react.379 Isatoic anhydride reacted with thioamides to give 2-substituted quinazolin-4-ones380 or with benzamidine (7 hr in pyridine at 100°C) to supply a good yield of 2-phenylquinazolin-4-one.381 With urea and thiourea, iV-methylisatoic anhydride furnished 1-methylquinazo-line-2,4-dione and l-methyl-2-thioxoquinazolin-4-one.382... 

Heating isatoic anhydride (246) with Schiff bases in acetic acid gives good yields of the dihydroquinazolin-4-ones (247) these are readily oxidized to the corresponding quinazolin-4-ones (Scheme 99). " Irradiation of the sulphonamide (248) in dichloromethane gives 2-phenylquinazolin-4-one in ca. 70% yield the mechanism of this reaction has been discussed. ... 

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. 

Irradiation of cither A -benzoyl-7V-tosylbenzimidamide in dichloromethane or 4,6-diphenyl-2,2-dioxo-1,2,3,5-oxathiadiazine in dichloromethane containing 5% by volume of ethanol or 2-methylpropan-2-ol at / > 290 nm produces 2-phenylquinazolin-4(3//)-one in 40-71% yields. 

Carbonylation of a complex obtained from A -phenylbenziinidamide and lithium tetra-chloropalladate(II) (LijPdClJ with carbon monoxide affords 2-phenylquinazolin-4(3//)-one in 97% yield. ... 

Heating 3-nitroso-2-phenyl-l//-indole with excess phosphoryl chloride or tosyl chloride in sulfolane at 200 C for 1 h, followed by dilution with water, produces 2-phenylquinazolin-4(3//)-one in 90 or 68% yield, respectively. The ring expansion proceeds via the second-order Beckmann rearrangement of the imino-oxime tautomeric form of 3-nitroso-2-phenyl-l//-indole. °... 

Hydroxy-2-phenylquinazolin-4(3//)-one and 3-hydroxy-2-phenylquinazoline-4(3//)-thione, which can be regarded as tautomeric structures of quinazolin-4-ol and quinazoline-4-thiol 3-oxide, are deoxygenated on heating with iodine and red phosphorus in acetic acid to 2-phenylquinazolin-4(3// )-one and 2-phenylquinazoline-4(3//)-thione, respectively. ... 

Hydroxamic esters 10, derived from 3-hydroxy-2-phenylquinazolin-4(3//)-one, are smoothly converted into 2-phenylquinazolin-4(3//)-one and aldehydes on photolysis or thermoly-sis. i "... 

Methylquinazolin-4(3//)-one was obtained in over 62% yield by reacting the phosphorane (25) with sodium hydride in methyl cyanide. The phos-phorane was readily formed from anthranilamide and prop-2-ynyltriphenyl-phosphonium bromide. When anthranilamide was fused with benzoin and a trace of acid at 150°C, it gave 2-phenylquinazolin-4(3H)-one together with o-iV-(a-benzoyl benzyl)aminobenzamide. The latter was cyclized, with ethyl orthoformate, to l-(a-benzoylbenzyl)quinazolin-4-one. If anthranilamide and benzoin were boiled in benzene with azeotropic removal of water, then the Schiff base (26) was formed. This gave 2-phenylquinazolin-4(3Jf/)-one and benzoic acid on heating alone at 150°C or with ethyl orthoformate. The mechanism of this reaction is not clear unless a retro-benzoin condensation and oxidation are occurring. 

Dihydroquinazolines have been formed by the acid- or base-catalyzed disproportionation of 4-alkoxy(or hydroxy)-3-phenyl-3,4-dihydroquinazo-line-2(l//)-thiones(or -ones). These gave a mixture of 3-phenylquinazolin-4-one-2(liJ)-thione(or -one) and 3-phenyl-3,4-dihydroquinazoline-2(lf/)-thione(or -one). The disproportionation is akin to a Cannizzaro reaction. ... 

In the absence of 7r-deficiency, conditions are milder. 2-Acetamidobenzoic acid and sodium acetate, refluxed for 1 hr in acetic anhydride, gave an excellent yield of 2-methyl-3-phenylquinazolin-4-one.214... 

N-Methylformamide converted 2-aminopyridine-3-carboxylic acid to 3-methylpyrido[2,3-d]pyrimidin-4-one (5 hr at 180°C) in good yield.290 The same reagent also made 3-methyl-6-nitroquinazolin-4-one from 2-amino-5-nitrobenzoic acid in excellent yield some slowly reacting 2-aminobenzoic acids were assisted with phosphoryl chloride.291 A moderate yield of 3-phenylquinazolin-4-one was obtained from the action of formani-lide on 2-aminobenzoic acid (90 min at 140°C).282... 

The unexpected reducing power of formamide was discovered when 2-aminobenzoic acid and that amide were refluxed for 4 hr, giving 2,3-dihydro- l-phenylquinazolin-4-one (m/e 224) instead of 164. The latter was dihydrogenated when boiled with formamide.292 The presence of an isolated double bond in 164 and the severe conditions should explain the result. 

Phenyl isocyanate boiled with 2-methylaminobenzoic acid gave 1-methyl-3-phenylquinazoline-2,4-dione, but methyl isocyanate did not react. On the other hand, methyl isothiocyanate at 145°C (sealed vessel) produced 1,2-dimethyl-2-thioxoquinazolin-4-one, whereas phenyl isothiocyanate gave poor results (yields not stated).314 Anthranilic acid heated with amyl isocyanate gave the ureide, which could be cyclized with acid or base315 however, potassium anthranilate, set aside overnight in ethanolic phenyl isocyanate, gave a moderate yield of 2-thioxo-3-phenylquinazolin-4-one directly.316... 

Venkatesh R, Kasaboina S, Gaikwad HK et al (2015) Design and synthesis of 3-(3-((9H-carbazol-4-yl) oxy)-2-hydroxypropyl)-2-phenylquinazolin-4(3H)-one derivatives to induce ACE inhibitory activity. Eur J Med Chem 96 22-29... 

Bharathi et al. [92] successfully synthesized the Ti02 NPs using aqueous nnono squamosa peel extract (Scheme 5.40). These synthesized Ti02 NPs were characterized using UV, XRD, and TEM and used as a catalyst for 2,3-dihydro-3-methyl-2-phenylquinazolin-4(l//)-one analog synthesis. 

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