Synthesis and stereochemistry of stereoisomeric 1,3‐benzoxazino‐1,3‐ and ‐3,1‐benzoxazines

Lázár, László; Fülöp, Ferenc; Bernáth, G.; Kàlmán, Alajos; Argay, Gyula

doi:10.1002/jhet.5570280510

Cited by 10 publications

(4 citation statements)

References 18 publications

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“…NMR measurements revealed that the tautomeric equilibrium of 15 in CDCl 3 at 300 K was practically totally shifted toward the open form 15A, while the phenyl-substituted compound 14 was found to participate under similar conditions in a three-component tautomeric equilibrium involving the trans (14B: 56.7%) and the cis (14C: 8.5%) cyclic diastereomers besides the Schiff base (14A: 34.8%). These data are in accordance with earlier observations on the predominance of the open form in the tautomeric equilibria of the condensation products of 1,2-and 1,3-aminoalcohols and salicylaldehyde, which is explained by the stabilization caused by the strong intramolecular hydrogen bonds [21,22].…”

Section: Introductionsupporting

confidence: 93%

“…OH) capable of coupling with the amino group of the ring-closed tautomers via an appropriate agent, this reaction can be a second ring closure with another aldehyde. This type of transformation was exploited earlier in the preparation of 1,3-O,N-heterocycle-condensed 1,3-oxazines by subsequent cyclization of the aminoalcohols with salicylaldehyde and another aldehyde [21][22][23].…”

Section: Resultsmentioning

confidence: 99%

“…Treatment of compound 1 4 with 40% formalin or ethanolic acetaldehyde solution resulted in the formation of phenyl-substituted naphthoxazino-benzoxazines 16 and 17 as crystalline products, whereas the similar transformations of 15 failed. The difference in cyclization behavior between 14 and 15 can be explained on the basis of the better crystallization ability of the pentacyclic products 1 6 and 17 formed from 14, which causes a continuous shift of the tautomeric equilibrium toward the predominant cyclic tautomer 14B [21,22]. In contrast, Stankevich et al related the successful formation of oxazolobenzoxazines in analogous reactions to the increased ratio of the cyclic form in the tautomeric equilibria of the 2-(o-hydroxyphenyl)-oxazolidine intermediates [23].…”

Section: Resultsmentioning

confidence: 99%

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Transformation reactions of the betti base analog aminonaphthols

Szatmári

Hetényi

Lázár

et al. 2004

Journal of Heterocyclic Chem

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By means of simple or domino ring-closure reactions of 1-(α-aminobenzyl)-2-naphthol (Betti base: 1), 1-aminomethyl-2-naphthol (2) and 2-(α-aminobenzyl)-1-naphthol (reverse Betti base: 3) with phosgene, ethyl benzimidate, 2-carboxybenzaldehyde, levulinic acid, salicylaldehyde/formalin or salicylaldehyde/acetaldehyde, naphth[1,2-e][1,3]oxazine and naphth[2,1-e][1,3]oxazine derivatives were prepared. All of the nitrogen-bridged polycyclic derivatives of 1 and 3 containing a number of centers of asymmetry were formed with nearly complete diastereoselectivity. Considerable differences were observed in the ringclosing abilities of the unsubstituted and phenyl-substituted aminonaphthols 1 and 2 and of the regioisomeric compounds 1 and 3.

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Section: Introductionsupporting

confidence: 93%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Transformation reactions of the betti base analog aminonaphthols

Szatmári

Hetényi

Lázár

et al. 2004

Journal of Heterocyclic Chem

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“…The ring−chain tautomerism of the 1,3- X,N heterocycles can be advantageously exploited in different areas of organic synthesis. The selectivity of certain transformations can be explained on the basis of the ring−chain tautomeric equilibration of the intermediates, followed by a shift in the equilibrium . Oxazolidines and tetrahydro-1,3-oxazines can be used as aldehyde or ketone sources in the Hantzsch and Pictet−Spengler reactions …”

Section: Introductionmentioning

confidence: 99%

Ring−Chain Tautomerism of 2-Aryl-Substituted cis- and trans-Decahydroquinazolines

et al. 2002

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In CDCl(3) at 300 K, 2-aryl-substituted cis- and trans-3-isopropyldecahydroquinazolines and trans-3-phenyldecahydroquinazolines proved to be three-component (r(1)[bond]o[bond]r(2)) ring[bond]chain tautomeric mixtures, whereas only ring-closed tautomers could be detected for the 3-methyl-substituted analogues. The proportions of the ring-chain tautomeric forms at equilibrium were strongly influenced by the N-substitutents and the cis-trans ring junction and could be described by the equation log K(X) = rho sigma(+) + log K(X=H). These are the first examples among 2-aryl-1,3-N,N-heterocycles of a three-component ring-chain tautomeric equilibrium characterized by a Hammett-type equation. The stabilities of the ring-closed forms of cis- and trans-2-aryldecahydroquinazolines and the corresponding 3,1-benzoxazines were found to increase in the following sequence of the heteroatom at position 3: NPh < N-i-Pr < O < NMe.

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Fused‐Skeleton Saturated Six‐Membered 1,3‐N,O, N,N and N,S Heterocycles. Fused‐Skeleton Aryl‐Substituted Saturated Isoindolones

Bernáth

1994

Bulletin des Soc Chimique

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In the introduction, a brief survey is given of the main types of fused-skeleton saturated six-membered 1,3-heterocycles serving as model compounds in our earlier investigations and as starting compounds in the present studies. The synthesis and conformational analysis of aryl-substituted fused-skeleton saturated 1 ,boxazines and of aryl-substituted hetero-condensed saturated isoindolones are treated. cis-trans isomerization in the saturated isoindolone moiety of the resulting tricyclic, tetracyclic and pentacyclic systems is discussed in connection with the ring-closure reactions of cis-and trans-1 ,Zdisubstituted 1,2-and 1,3-difunctional alicyclic compounds to give alicycle-fused six-membered 1,3-heterocycles. The cycloaddition reactions of dihydro-1,3 and 3,l-oxazines and the conformations of the alicycle-fused tetrahydrooxazine-azetidinone derivatives obtained are presented. Methods are given for the preparation of saturated thiazolo-and thiazino[2,3-b]quinazolinones. Unambiguous, mainly one-pot syntheses for the preparation of 1,3-heterocycles by a retro Diels-Alder method are discussed.

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Synthesis and stereochemistry of stereoisomeric 1,3‐benzoxazino‐1,3‐ and ‐3,1‐benzoxazines

Cited by 10 publications

References 18 publications

Transformation reactions of the betti base analog aminonaphthols

Transformation reactions of the betti base analog aminonaphthols

Ring−Chain Tautomerism of 2-Aryl-Substituted cis- and trans-Decahydroquinazolines

Fused‐Skeleton Saturated Six‐Membered 1,3‐N,O, N,N and N,S Heterocycles. Fused‐Skeleton Aryl‐Substituted Saturated Isoindolones

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