Quinazolines 4-quinazolones

They also state that analytical studies of the oxidation products of dichroine-a indicate that the dichroines are quinazoline derivatives, as already indicated by Koepfli et al. for their alkaloids. With the probable exception of dichroine-a, these bases are active against malaria in chicks in the descending order dichroine-y (1), dichroine- (4) dichroidine quinazolone (40) the figures in brackets are effective doses (mgm./kilo.). There are also two neutral substances present, umbelliferone (dichrin-A) and dichrin-B, m.p. 179-181°. 

The quinazoline ring also gives some anomalous quatemization reactions, which presumably reflect the influence of the unusual 3,4-bond. 3-Methyl-4-quinazolone (71 Y = O) and, more... 

Synthesis from quinazoline precursors was achieved by carrying out a Vilsmeier-Haack reaction on 3-amino-2-methyl-4-quinazolone (96) to give the intermediate diformyl derivative 97 that cyclized to 3-formylpyra-zolo[5,l-b]-quinazolin-9-one (98) [73IJC532 84IJC(B)161]. 

Two new quinazoline alkaloids of unusual structure were obtained from the seed husks of Zanthoxylum arborescens.12 Infrared, H n.m.r., and mass spectroscopy showed that the major alkaloid was a quinazolone containing a phenethyl substituent. The 13C n.m.r. spectrum indicated that an iV-methyl rather than an O- methyl group was present, but the spectroscopic studies did not distinguish between structures (19 R = H) and (20 R = H). The alkaloid was shown to be the iV-phenethyl derivative (20 R = H) by synthesis (Scheme 4), and a minor... 

The azeto[2,l-4]quinazolines 178 (R = OMe or N02) in solution in chloroform or dichloromethane undergo slow oxidation, which is accelerated by light, to the quinazolines 179 (R = OMe or N02). The quinazolones are obtained more efficiently by oxidation of 178 by activated manganese dioxide <1997T13449>. 

The 7V-(o-aminobenzyl)pyrrolidine 267 (n = 0) was obtained from the pyrrolo[2,l-i>]quinazolines 124 and 186 with sodium borohydride. Compounds 330 were also prepared from 205 by reduction with lithium aluminum hydride. - - - When reduction was carried out with sodium borohydride, only the C=N bond was saturated and compounds 332 were formed. The carbonyl group of compounds of type 332 was reduced by lithium aluminum hydride to give compounds of type 330. The C=N bond of compounds of type 333 could not be reduced with sodium borohydride or by catalytic hydrogenation over palladium or Raney nickel. The methoxycarbonyl group of the pyrrolo[2,l-i>]quinazolone 334 was reduced to a hydroxymethyl group with lithium aluminum hydride in tetra-hydrofuran at... 

Tetrahydro-l lW-pyrido 2,l5l quinazoline, 6,7,8,9-tetrahydro-l 1 // pyridof2,l j]quinazolone, deoxyvasicinone, anabasine... 

The past year has seen the publication of Comprehensive Organic Chemistry, one volume of which contains much information on the six-membered ring systems to be reviewed in this article a monograph on the chemistry of condensed pyrazines has also appeared. Reviews on 1,4-thiazines, l,3-benzothiazines," pyridazines, benzo[c]cinnolines, quinazolines, purines, pyrrolo[3,2-c]quino-lines, 1,10-phenanthroline and its complexes, polyaza-phenanthrenes, and 1,9- and 1,10-diaza-anthracenes have been published. Other specialist reviews are devoted to catalytic methods of obtaining pyridine bases pyridine N-oxides the stereochemistry of quinolizines, indolizines, and pyrrolizines benzothiazinone dioxides 2-quinazolones and their cyclic homologues (e.g. 

Anthranilic acid hydrazides (104), prepared from lA and hydrazines,are used as precursors for quinazolines, benzotriazinones, and benzotriazepines. Cyclization of 104 with formic acid gives 3-amino-quinazolone (105) 3-aminoquinazolinedione (106) is obtained from urea and the unsubstituted hydrazide 104(R = = H), while ring closure... 

On the other hand, nitriles are widely used as intermediates in the synthesis of many types of heterocycles [7] and other compounds of interest in medicinal chemistry, for example, 3,4-dihydroisoquinolines [8], imidazoles [9], indoles [10], lactim ethers [11], napthyridines [12], pyridones [13], pyridopyrimidi-nes [14], pyrimidines [15], quinazolines [16], quinazolones [17], quinolines [18], sydnones [19], 1,2,4,5-tetrazines [20], tetrazoles [21,22], 1,2,4-triazoles [20], N-substituted amides [23], amidines [24] and basic esters [25]. 

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... 

Quinazoline methiodide, 29 Quinazoline 3-oxides, 31 Quinazoline-thiones, 31, 51 4-Quinazolone, 3-alkyl-, 31 Quindolines, 103, 134, 144, 146 Quindoline-11-carboxylic acid, 144 Quinindoline, 135, 144 Quinolines, alkoxy-, reactions of, 311 2-alkyl-, reaction with carbenes, 77 aza-effects in, 318 basicity of, 244, 245, 247, 288, 289... 

---