4-quinazolones, 2,3-dihydro

Reaction of the enamine-ester 513 with guanidine in boiling ethanol afforded the quinazolone 517. Hydrogenation of which gave the dihydro derivative 518 (92JHC1375) (Scheme 111). 

Anthranilamides (43) and aldehydes (or their acetals) react when heated or oxidized to give quinazolones 85. The alkaloid dihydro-isoevodiamine (88) was obtained by the same sequence of reactions as evodiamine (57) [cf. Eq. (9)], using formaldehyde instead of formic acid. Ketones give the corresponding 2,2-disubstituted quinazolones (86), while diketones such as acetylacetone lead in an acid catalyzed reaction with anthranilamides (43) or thioanthranilamides to quinazolones of type 87, which are methaqualone analogs (Scheme 15). 

The amino amides 195 were obtained from isatoic or 6-iodoisatoic anhydrides and the esters of amino acids. They were converted by the action of aromatic aldehydes or acetone into derivatives of dihydro-4-quinazolone 196 (ethanol, piperidine, boiling for 1 h, or cone, hydrochloric acid, boiling for 6 h [117] toluene, toluene sulfonic acid, boiling for 0.5 h, [118]). 

Plugar, V. N., Ya. V. Rashkes, and Kh. M. Schakhidoyatov Mass Spectra of 2,3-Polymethylene-3,4-dihydro-4-quinazolones with Substituents at C9. Khim. Prir. Soedin. 1979, 180 (Russ). 

Alkoxymethyl-4-hydroxy-3,4-dihydro-2(lH)-quinazolones from 4,5-epoxy-l,3,4,5-tetrahydro-2H-l,4-benzodiazepin-2-ones... 

Methylene-2-quinazolones. Startg. m. warmed with coned. HCl, whereupon at 65° tert-hnty chloride starts to distil, and heated 1 hr. at 90° after the distillation 3,4-dihydro-3-methyl-4-methylene-2-quinazolone. Y 9S%. F. e. s. A. Brack, A. 730, 166 (1969). 

Enzyme-catalyzed ring closures under mild conditions 4-Imino-3,4-dihydro-2(li )-quinazolones from < -cyanoureas... 

The Niementowski quinazoline synthesis is the condensation of an anthranilic acid (1) with an amide (2) to produce a 4-keto-3,4-dihydro-quinazoline product (3). The reaction occurs under thermal conditions, and reaction temperatures > 100 °C are generally required. This reaction is also often referred to as the Niementowski reaction, and occasionally as the Niementowski 4-quinazolone synthesis or von Niementowski synthesis. ... 

Thiazolo[3,2-a]quinazolines.—[C3NS-C4N2-C6]. A number of thiazolo-[3,2-a]quinazolones have been obtained by the application of conventional cyclization reactions. Thus, the condensation of 2-mercapto-3-phenylquinazolin-4(3/f)-one (301) and phenacyl bromide yields the S -alkylated derivatives (302) which are reduced by sodium borohydride tol,2-dihydro-2-(a-hydroxyphenethyl)mercapto-3-phenylquinazolin-4(3/f)-one (303). Cyclodehydration by acetic anhydride or toluene-p-sulphonic... 

Rafi I, Taylor GA, Calvefe JA, Boddy AV, Balmanno K, Bailey N, Lind M, Calvert AH, Webber S, Jackson RC, Johnston A, Clendeninn N, Newell DR (1995) Clinical pharmacokinetic and pharmacodynamic studies with the nonclassical antifolate thymidylate synthase inhibitor 3,4- dihydro-2-amino-6-methyl-4-oxo-5-(4-pyridylthio)-quinazolone dihydrochloride(AG337) given by 24-hour continuous intravenous infusion. Chn Cancer Res 1 1275-1284... 

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)/ ... 

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