Regioselectivity of the monohalogenation of 4-allyl-3-allylamino-1,2,4-triazole-5-thione

Khripak, S. M.; Slivka, Mikhailo; Vilkov, R. V.; Usenko, R. N.; Lendel, V. G.

doi:10.1007/s10593-007-0126-6

Cited by 16 publications

(13 citation statements)

References 7 publications

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“…The bromine atoms occupy a mutual +sc-conformation to one another (torsional angle Br(1)-C(10)-C(11)-Br (2) Hence the bromination of the N-allylisatin 1 at room temperature in glacial acetic acid occurs exclusively via a classical addition of halogen to the double bond. Bearing in mind that the course of a similar reaction is sometimes significantly affected by the solvent and temperature used [18,19] we additionally carried out this synthesis in carbon tetrachloride at -20ºC. However, in this case only compound 4 was formed.…”

Section: _______mentioning

confidence: 99%

“…In particular, it is well known that successful halocyclizations can accompany the formation of heterocyclic systems of this type, i.e. those containing five-membered rings mutually annelated [2,[18][19][20][21][22][23][24]. On the other hand, it turns out that not each six-membered 1-N-allyl-substituted Alk _______ *We have shown that the reaction of 1-allyl-3-(2-hydroxyethyl)-1H-quinazoline-2,4-dione with molecular bromine in glacial acetic acid also occurs with addition of the halogen to the allyl double bond, i.e.…”

Section: _______mentioning

confidence: 99%

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4-hydroxy-2-quinolones 170*. synthesis and bromination of N-allylisatin

Украинец

Bereznyakova

Gorokhova

et al. 2009

Chem Heterocycl Comp

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Independently of the reaction conditions N-allylisatin forms only the 2,3-dibromo derivative upon treatment with molecular bromine in contrast to N-allyl-substituted quinolin-or pyrid-2-ones which readily undergo halocyclization to the corresponding 2-bromomethyl oxazoles.Decolorization of bromine is one of the widest known analytical reactions for alkenes but does not always prove to be due to the conventional addition of halogen to an unsaturated bond. With the existence of certain structural features such reactions can be accompanied by the formation of novel 5-, 6-and even 7-membered rings thanks to which they are often referred to as bromo-or halocyclizations [2][3][4][5][6][7].This type of chemical reaction occurs in the bromination of N-allyl-substituted 4-hydroxy-2-quinolones which is, in principle, a simple method for preparing 4R-2-bromomethyl-1,2-dihydrooxazolo[3,2-a]quinolines [8][9][10]. For evaluating the synthetic potential of this interesting reaction and to work out a fuller and more proven idea of the actual mechanism occurring in these chemical processes there is much value in the accumulation and subsequent analysis of experimental material including the maximum use of a broad range of model compounds.This report is a part of such an investigation, the aim of which was a study of the behavior of N-allylisatin 1 (with a structural similarity to 4-hydroxy-2-quinolones) under conditions of bromination using molecular bromine. According to a known outline [11], the alkylation of isatin 2 principally needs its conversion to a sodium salt and used sodium ethylate in absolute ethanol or, indeed, NaH in anhydrous DMF. Preference is usually given to the latter variant since, in this case, the initial separation of the salt is not essential. However, from our data, the use of this method is far from always justified. At least with allyl bromide this reaction is much more conveniently carried out using the system DMSO/K 2 CO 3 . The N-alkylation occurs very rapidly at room temperature and in virtually quantitative yield.

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Section: _______mentioning

confidence: 99%

Section: _______mentioning

confidence: 99%

4-hydroxy-2-quinolones 170*. synthesis and bromination of N-allylisatin

Украинец

Bereznyakova

Gorokhova

et al. 2009

Chem Heterocycl Comp

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“…Following this logic, dihydrothiazoles should be formed most easily and this is, in fact, confirmed in numerous experiments [8][9][10]. However, in that regard, quite ambiguous information is sometimes encountered in the literature.…”

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confidence: 77%

4-hydroxy-2-quinolones 196. synthesis and bromination of 1-allyl-3-(2-hydroxyethyl)-1h,3h-quinazoline-2,4-dione

Украинец

Моспанова

Туров

et al. 2011

Chem Heterocycl Comp

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The alkylation of 3-(2-hydroxyethyl)-1H,3H-quinazoline-2,4-dione and subsequent bromination of its 1-allyl derivative have been studied. The data obtained has been compared with the results of similar studies on a series of other, related compounds. A rule has been formulated which allows a prediction of 1-allyl-substituted 2-oxo azaheterocycles bromination route based upon the way in which their initial alkylation by allyl bromide in the system DMSO-K 2 CO 3 occurs.The bromination of cyclic compounds containing ortho located allyl and carbonyl groups can occur in two ways, viz. as a trivial addition of bromine to the allyl double bond or as a halocyclization accompanied by adding of a new bromomethyl-substituted oxazole heterocycle to the existing molecular system. Unfortunately, to this time there have been no criteria which permit a reliable prediction of such reactions direction and allow to carry out a targeted synthesis of these or related derivatives. We do not rule out that this question will be resolved in time but, for now, synthetic chemists often spend considerable time and effort in deducing the correct structure of the products formed after bromination.

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“…5-Substituted 4-allyl-1,2,4-triazole-3-thiones react with bromine to give a fused five-membered ring [1,2]. We have used 1 H NMR spectroscopy to show that the bromination of 4-allyl-5-methyl-1,2,4-triazole-3-thione (1) in acetic acid proceeds with formation of a 10:1 mixture of 6-bromomethyl-3-methyl-5,6-dihydro-1H-[1,3]thiazolo[2,3-c][1,2,4]triazolium bromide (2) and 6-bromo-3-methyl-6,7-dihydro-1H,5H-[1,2,4]triazolo [3,4-b][1,3]thiazinium bromide (3).…”

Section: New Example Of a Dihydrothiazinementioning

confidence: 99%