Quinazoline mercapto

Fusion of 4-hydroxyquinazoIine with phosphorus pentasulfide yields 4-mercaptoquinazoline and, similarly, substituted 2,4-dimercapto-quinazolines have been obtained from the corresponding dihydroxy compounds. The greater reactivity of the 4-mercapto as compared with the 2-mercapto group has permitted the preparation of 4-amino-2-mercaptoquinazolines (see 7a). 

Alkylthio, arylthio, and thioxo. The thioxo group in pyrimidine-2,4-dithione can be displaced by amines, ammonia, and amine acetates, and this amination is specific for the 4-position in pyrimidines and quinazolines. 2-Substitution fails even when a 5-substituent (cf. 134) sterically prevents reaction of a secondary amine at the 4-position. Acid hydrolysis of pyrimidine-2,4-dithione is selective at the 4-position. 2-Amination of 2-thiobarbituric acid and its /S-methyl derivative has been reported. Under more basic conditions, anionization of thioxo compounds decreases the reactivity 2-thiouracil is less reactive toward hot alkali than is the iS-methyl analog. Hydrazine has been reported to replace (95°, 6 hr, 65% 3deld) the 2-thioxo group in 5-hexyl-6-methyl-2-thiouracil. Ortho and para mercapto- or thio- azines are actually in the thione form. ... 

Aminolysis of the 5-substituted-2-mercapto-l,3,4-thiadiazolo[3,2-c]-quinazolinium iodides 119 with butylamine afforded the mesoionic 1,3,4-triazolo[l,5-c]quinazolines 120 [77IJC(B)1110] (Scheme 44). 

Kinetic studies have been carried out on the displacement reactions of various chloroazanaphthalenes with ethoxide ions and piperi-dine. - 2-Chloroquinoxaline is even more reactive than 2-chloro-quinazoline, thus demonstrating the powerfully electrophilic nature of the -carbon atoms in the quinoxaline nucleus. The ease of displacement of a-chlorine in the quinoxaline series is of preparative value thus, 2-alkoxy-, 2-amino-, - 2-raethylamino-, 2-dimethyl-amino-,2-benzylamino-, 2-mercapto-quinoxalines are all readily prepared from 2-chloroquinoxaline. The anions derived from substituted acetonitriles have also been used to displace chloride ion from 2-chloroquinoxaline, ... 

Treatment of 2-mercapto-4(3W)-quinazolinone (52) with hydrazonoyl halides affords 1,3-disubstituted l,2,4-triazolo[4,3-a]quinazolin-5-ones 53 [95H(41)1999]. Hydrazones derived from [(2-methyl-4-quinazolinyl)oxy]acetic acid hydrazide and aldehydes or ketones were shown to give 4-thiazolidinones and pyrazoles under cyclization conditions [95UC(B)537]. 

Quinazolin 2-Hydroxy-4-mercapto-E16a, 766 (Pyrimidin-Ring-schluB)... 

Phenacyl bromides react (86JHC43) with anhydro l-amino-5-aryI-2-mercapto-l,2,4-triazolo[3,2-c]quinazolin-4-ium hydroxides (53) through pyrimidine ring-opening and simultaneous formation of the 1,3,4-thiadiazine nucleus to give 54. Compound 514 was also obtained [86JAP(K)61260085] when 2-hydrazino-5-methyl-6/f-l,3,4-thiadiazine (513) was cyclized with aryloxyacetyl chlorides. 

Alkylation of 2-substituted quinazolin-4(3//)-ones by reaction with sodium hydride in dimethylformamide followed by alkylation provided O-and N-alkyl derivatives. The extent of alkylation at the different sites was reasonably explained in terms of steric properties of the 2-substituents. The silver salt of quinazolin-4(3H)-one and tetra-0-acetyl-) -D-glucopyrano-syl bromide gave a 40% yield of the 0-glycosyl derivative in contrast with the mercury salt, which gave mainly the iV-3-glycosyl derivative. As in the alkylation of mercapto compounds, quinazoline-4(3H)-thione gave the S-glycosyl derivative. If sodium hydroxide was used as base a 56% yield of the... 

Thiazolo[2,3-h]quinazolines [C S-C JV2-CeJ. The cycloaddition reaction of alkah-metal salts of 2-mercapto-4(3/f)-quinazolinones with 3-benzoyl-3-bromopropionic acids and esters gives acids (250) and lactones (251). ... 

A new means of access to 5a,10,14fo,15-tetraazabenzo[a]indeno[l,2-c]anthracen-5-ones 33 and to benzimidazo[l,2-c]quinazoline 34 was reported in 2000 [110]. The preparation of 6-mercapto-benzimidazo[l,2-c]quinazoline (34) was easily ac-... 

A soln. of sulfuryl chloride in chloroform added dropwise with vigorous stirring to a suspension of 2-mercapto-3-phenyl-4-oxo-3,4-dihydroquinazoline in the same solvent, and refluxed 30 min. 2-chloro-3-phenyl-4-oxo-3,4-dihydro-quinazoline. Y 60-80%. F. e. s. M. Pesson and D. Richer, G. r. 260, 603 (1965). 

Specific examples of mercapto compoimds include 2-mercapto-benzothiazole, 2-mercaptobenzoxazole, 2-mercaptobenzimidazole, 2-mercapto-4(3H)-quinazoline, and /S-mercaptonaphthalene (7). 

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... 

Quinoxalino[2 3 -4,5]thiazolo[3,2-a(and 6)]quinazolines.—[C3NS-C4N2-C4-N2-C6-Ce]. The condensation of 2,3-dichloroquinoxaline (355) and 2-mercapto-4-(3 )quinazolinone (356) yields a mixture, separable by preparative thin-layer chromatography, of 5 -quinoxalino[2, 3 -4,5]-thiazolo[3,2-fl]quinazolin-5-one (357) and its [3,2-6] isomer (358). The... 

Updated Entry replacing P-10051 3H-Benzo[dQ]quinazoline-2-thione. 2-Mercapto-lH-perimidine [30837-62-8]... 

Khalil AK (2005) Phase-transfer catalyzed alkylation and cycloalkylation of 2-mercapto-quinazolin-4(3H)-one. Phosphorus Sulfur Silicon Relat elem 180 2533-2541... 

Some new facile syntheses for 2-methyl-3-(o-tolyl)quinazolin-4-one (methaqualone) " and 3-aryl-2-mercapto-quinazolin-4-ones have been announced. The former synthesis can be carried out in high yield in one pot by allowing isatoic anhydride to react sequentially with aniline in toluene and pentane-2,5-dione in ethanolic hydrogen chloride. The latter preparation consists of condensing aryl isothiocyanates with anthranilic acid in hot acetic acid-sodium acetate mixture. 

Benzothiazolo-[2,3-b]> and -[3,2-a]>quinazolines (CjNS>CsN C C ).—2-Mercapto-2 -aminobenzanilides, accessible from isatoic anhydride and... 

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