Quinazolines addition reactions

Quinazoline-2,4( 1 H,3H)-dione, 7-nitro-synthesis, 3, 110 Quinazolihediones mass spectra, 2, 22 polymers, 1, 298 Quinazoline-2,4( 1 H,3 H)-diones synthesis, 3, 106 O-trimethylsilylation, 3, 91 Quiriazolines addition reactions, 3, 73... 

Treatment of (22) with hot aqueous sodium hydroxide gave 3-(2-aminophenyI)-1,2,4-triazole (208). Evidence that this latter reaction involved an initial attack of hydroxide ion at the 5-position arose from the isolation of 3-(2-benzamidophenyl)-l,2,4-triazole (209) upon the action of hot base on 5-phenyI-[l,2,4]triazoIo[4,3-c]quinazoline (210). Apparently, under these rearrangement conditions, hydrolysis of the intermediate amide, for example (209), is faster than ring closure to the [1,5-c] isomer. Similar ring opening reactions were observed with the [1,5-c] series, a system which also underwent typical alkenic addition reactions at the C(5)—N(6) double bond (70JOC3448). 

Diprotonated pyrimidines, quinoxalines, and quinazolines (HetAr +CH=CH2) have been reported to exhibit an unusual regioelectronic effect that controls the addition reaction thus, depending on the ring position of the vinyl substituent, either conjugate or Markovnikov addition occurs on reaction with benzene, giving rise to either HetArCH2CH2Ph or HetArCH(Ph)-Me. The mode of addition has been shown to correlate well to NBO calculated charges. ... 

The first group is the s-block metal alkoxides. There are a few reports on application of them in the catalytic reactions. Zhao et al. have examined stereoselective addition of quinazolines, 77, to terminal alkynes, 78, under mild conditions catalyzed by KO Bu (reaction 7.10) [58]. Bunlaksananusorn and co-workers also used KO Bu for the addition (reaction 7.11) of ketones, 80, and nitriles, 81, to vinylic silanes, phosphines and thio derivatives, 82, within 60-90% yield efficiently [59]. 

He P, Nie YB, Wu J, Ding MW (2011) Unexpected synthesis of indolo[l,2-c] quinazolines by a sequential ugi 4CC-Staudinger-aza-Wittig-nucleophihc addition reaction. Oig Biomol Chem 9 1429 1436... 

There is a scattered body of data in the literature on ordinary photochemical reactions in the pyrimidine and quinazoline series in most cases the mechanisms are unclear. For example, UV irradiation of 4-aminopyrimidine-5-carbonitrile (109 R=H) in methanolic hydrogen chloride gives the 2,6-dimethyl derivative (109 R = Me) in good yield the 5-aminomethyl analogue is made similarly (68T5861). Another random example is the irradiation of 4,6-diphenylpyrimidine 1-oxide in methanol to give 2-methoxy-4,6-diphenyl-pyrimidine, probably by addition of methanol to an intermediate oxaziridine (110) followed by dehydration (76JCS(P1)1202). 

In addition to having typical A -oxide reactions, quinazoline 3-oxide also shows the same reactivity as quinazoline toward nucleophilic reagents, but the reaction goes a step further by eliminating water as shown in reaction 2d. Oxidation with hydrogen peroxide... 

In many cases, addition or removal of water proceeds sufficiently slowly that some of the physical properties of unstable species (such as hydrated neutral quinazoline or anhydrous 2-hydroxypteridine) can be observed. In these cases, reaction kinetics can also be examined. Addition of water to pteridine is of special interest in relation to studies of the formation and hydrolysis of Schiflf bases. The reaction proceeds in two reversible stages, 3 4 5 ... 

Heterocyclic structures analogous to the intermediate complex result from azinium derivatives and amines, hydroxide or alkoxides, or Grignard reagents from quinazoline and orgahometallics, cyanide, bisulfite, etc. from various heterocycles with amide ion, metal hydrides,or lithium alkyls from A-acylazinium compounds and cyanide ion (Reissert compounds) many other examples are known. Factors favorable to nucleophilic addition rather than substitution reactions have been discussed by Albert, who has studied examples of easy covalent hydration of heterocycles. 

The key intermediate 2-thioxo-3-phenylquinazohn-4(3H)-one was prepared by adding carbon disulfide and sodium hydroxide solution simultaneously to a vigorously stirred solution of aniline 7 in dimethylsulfoxide over 30 min stirring was then continued for an additional 30 min. Dimethylsulfate was added to the reaction mixture whilst stirring at 5-10°C after which it was stirred for another 2 h and then poured into ice water to obtain a soHd dithiocarbamic acid methylester 6. The compoimd 6 and methylanthranilate 5 when refluxed in ethanol for 18 h yielded the desired 2-thioxo-3-substituted quinazolin-4(3H)-one 4. The product obtained was cycUc and not an open chain thiourea 5a. It was confirmed by its value, high melting point, and its... 

The sensitivity of position 2 in 4-chloroquinazoline for nucleophilic addition was also demonstrated in the reaction with lithium piperidide (73RTC460). Whereas in the amination with potassium amide/liquid ammonia no open-chain intermediate could be isolated, with lithium piperi-dide/piperidine the open-chain compound ort/z6>-(piperidinomethy-leneamino)benzonitrile (78,60%) was obtained, in addition to 4-piperidino-quinazoline (80,19%) (Scheme 11.35). The formation of 80 from 78 involves... 

A quinazoline-2,4-dithione complex [Pd(LH)3(PPh3)] has been isolated from the reaction of the free ligand LH (51) with [Pd(PPh3)4], Unidentate co-ordination of the ligand via a sulphur atom was confirmed from the i.r. spectrum. Oxidative addition with iodine is reported. ... 

However, further a possibility of the formation of several different reaction products in similar processes was reported [97-99]. With the help of microwave irradiation and ultrasonication, the problem of selectivity was also touched in these communications. It was found that three-component reaction of equimolar mixture of 5-amino-Al-arylpyrazole-4-carboxamides, aldehydes, and cyclic (3-diketones in DMF under conventional thermal heating or under microwave irradiation at 150°C yielded pyrazoloquinazolines 68. The treatment at room temperature under ultrasonication gave the same reaction products, although addition of catalytic amounts of hydrochloric acid changed direction and positional isomeric quinazolines 69 were only isolated in this case. 

In the presence of catalytic amounts of both sodium -toluenesulfinate and potassium cyanide, the reaction of benzaldehyde with 4-chloroquinazoline 89 gave 4-benzoylquinazoline 90 in good yield <1998H(47)407>. The reaction involves activation of the benzaldehyde by cyanide addition, and activation of the quinazoline as the 4-toluenesulfonyl derivative. 

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