4H-3,1-benzoxazines. 2. Synthesis of 2,4-substituted 1,2-dihydro-4H-3,1-benzoxazines

The reactions of o-aminophenylcarbinols with carbonyl compounds have been studied. Optimum conditions have been developed for the synthesis of 2-(5-X-2-furyl)-1,2-dihydro-4H-3,1-benzoxazines. It was found that 2,2-disubstituted 1,2-dihydro-4H-3,1-benzoxazines are unstable and are converted upon heating in the presence of acylating agents to 4H-3,1-benzoxazines.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 842–847, June, 1988.     

Synthesis and rearrangement of 4-imino-4H-3,1-benzoxazines

Summary N-Acylanthranilamides react with dibromotriphenylphosphorane in the presence of triethylamine as HBr captor to give 4-imino-4H-3,1-benzoxazines in good yields. If the reaction is carried out without acid acceptor, N-acetylanthranilamides yield 2-methyl-4-quinazolones, whereas N-benzoylanthranilamides give 2-phenyl-4-imino-4H-3,1-benzoxazines. It has also been found that 2-methyl-4-imino-4H-3,1-benzoxazines rearrange under the influence of HCl or HBr into the respective 2-methyl-4-quinazolones; 2-phenyl-4-imino-4H-3,1-benzoxazines, however, do not undergo such a rearrangement.

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Synthese und Umlagerung von 4-Imino-4H-3,1-benzoxazinen

Zusammenfassung Die Umsetzung von N-Acyl-anthranilsäure-amiden mit Triphenyldibromphosphoran in Gegenwart von Triethylamin als HBr-Akzeptor führt mit guten Ausbeuten zu 4-Imino-4H-3,1-benzoxazinen. Wird die Reaktion ohne säurebindendes Mittel durchgeführt, dann entstehen aus N-Acetyl-anthranilsäure-amiden 2-Methylchinazolone-4, jedoch erhält man aus N-Benzoylanthranilsäure-amiden 2-Phenyl-4-imino-4H-3,1-benzoxazine. 2-Methyl-4-imino-4H-3,1-benzoxazine erleiden unter dem Einfluß von HBr oder HCl eine Umlagerung in entsprechende 2-Methylchinazolone-4, während 2-Phenyl-4-imino-4H-3,1-benzoxazine zu einer solchen Umlagerung nicht befähigt sind.

     

Studies of 4H-3,1-benzoxazines

Bromination of 2,4-substituted 1,2-dihydro-4H-benzoxazines with bromine in acetic acid was conducted. It was shown that either the corresponding 6,8-dibromo-1,2-hydrobenzoxazines or the products of their dehydrogenation — 6,8-dibromobenzoxazines, are primarily formed as a function of the structure of the dihydrobenzoxazine and the concentration of bromine in the reaction mixture. The structure of 6,8-dibromo-2-(5-nitrofuryl-2)-4, 4-diphenyl-1,2-dihydro-4H-3,1-benzoxazine was investigated by XSA. A stacking interaction between the nitrofuran fragment of one molecule and the condensed benzene ring of the other was detected in the crystal.See [1] for Communication 12.Kuban State Technological University, Krasnodar 350072. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1391–1397, October, 1997.     

Investigation of 4H-3,1-benzoxazines

The alkylation and acylation of 2,4-disubstituted 1,2-dihydro-4H-3,1-benzoxazines were used to obtain N-methyl and N-acetyl derivatives of these compounds for the first time.¹H NMR was used to reveal several conformational features of these compounds relative to their donor—acceptor properties at positions 2, 3, and 4 of the heterocycle.Communication 11, see [2].Kuban State Technological University, 350072 Krasnodar. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 841–846, June, 1997.     

Research on 4H-3,1-benzoxazines. 8. Synthesis and properties of 4H-3,1-benzoxazinium chlorides

A mechanism for the acylation of substituted o-aminophenylcarbinols with carboxylic acid chlorides and the formation of 2-alkyl(aryl, furyl)-4H-3,1-benzoxaziniun chlorides is proposed. The nitration and introduction of a sulfur atom into the heterocyclic ring of the 4H-3,1-benzoxazinium salts were investigated.For communication 7 see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 537–541, April, 1993.     

4H-3,1-Benzoxazin-4-ones methoxy-substituted 2-(2-arenesulfonylaminophenyl)-4H-3,1-benzoxazin-4-ones

Methoxy-substituted 2-(2-tosylaminophenyl)-4H-3,1-benzoxazin-4-one and 2-phenyl-4H-3,1-benzoxazin-4-one were synthesized. Their UV, IR, and luminescence spectra were studied. The position of the methoxy group affects the strength of the intramolecular hydrogen bond (IHB). The luminescence properties of methoxy-substituted 2-(2-tosylaminophenyl)-4H-3,1-benzoxazin-4-ones are associated with the strength of the IHB. The luminescence maximum is shifted to the short-wave region with strengthening of the IHB, and the luminescence intensity increase simultaneously.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1028–1032, August, 1971.The authors thank Yu. S. Ryabokobylko and A. O. Zisman for measuring the absorption spectra in the IR and UV regions.     

Synthesis of cyclopropyl-substituted 4H-3,1-benzoxazines from 2-amino-phenyl cyclopropyl ketones and 2-cyclopropanoylaminoacylbenzenes

2- and 4-cyclopropyl- and 2,4-dicyclopropyl-substituted 4H-3,1-benzoxazines were synthesized by the intramolecular acid catalyzed heterocyclization of ortho-acylamino-substituted benzyl alcohols, obtained from 2-aminophenyl cyclopropyl ketones and 2-cyclopropanoylaminoacylbenzenes. Translated from Khimiya Geterotsicklicheskikh Soedinenii No. 2, 252-268, February, 2009.     

CuCl/DABCO/4-HO-TEMPO-catalyzed aerobic oxidative synthesis of 2-substituted quinazolines and 4H-3,1-benzoxazines

The Cu/N-ligand/TEMPO catalytic system was first applied to the aerobic oxidative synthesis of heterocycles. As demonstrated, 2-substituted quinazolines and 4H-3,1-benzoxazines were synthesized efficiently from the one-pot reaction of aldehydes with 2-aminobenzylamines and 2-aminobenzyl alcohols, respectively, by employing CuCl/DABCO/4-HO-TEMPO as the catalysts and oxygen as the terminal oxidant.     

2-Aryl-4H-3,1-benzoxazin-4-ones alcoholysis

The reaction of 2-(2-tosylaminophenyl)-4H-3,1-benzoxazine-4-one with alcohols in pyridine gives tosylanthraniloylanthranilic acid esters. The synthesized compounds luminesce in the crystalline state and in solutions at room temperature. The anomalously high Stokesian shift characteristic for this series of compounds is due to intramolecular hydrogen bonding with the participation of the tosylamino group. Interaction of polar solvents and irradiation with UV light lead to cleavage of the hydrogen bond, and as a consequence, to a decrease in the Stokesian shift.     

2-Aryl-4H-3,1-benzoxazin-4-ones nitration

2-(3-Nitrophenyl)-4H-3,1-benzoxazin-4-one is formed in the nitration of 2-phenyl-4H-3,1-benzoxazin-4-one, while 2-(2-tosylamino-5-nitrophenyl)-4H-3,1-benzoxazin-4-one is formed in the nitration of 2-(2-tosylaminophenyl)-4H-3,1-benzoxazin-4-one.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 908–909, July, 1974.     

Fluorine-containing heterocycles: XIX. Synthesis of fluorine-containing quinazolin-4-ones from 3,1-benzoxazin-4-ones

Reactions of fluorine-containing 3,1-benzoxazin-4-ones with ammonium acetate, hydrazine, and heteroaromatic amines gave new 3H-, 3-amino-, and 3-hetarylquinazolin-4-ones, respectively. Differences in the conditions of formation of benzoxazinones from anthranilic acids with different fluorination patterns and in the reactions of fluorinated 3,1-benzoxazinones with nitrogen-centered nucleophiles were revealed.     

Studies of 4H-3,1-benzoxazines. 14. Structure and some properties of 2-[2-hydroxyphenyl(naphthyl)]-1,2-dihydro-4H-3,1-benzoxazines

It has been shown that the condensation of tertiary aminophenylcarbinols with 2-hydroxybenz(naphth)aldehydes gives the corresponding 1,2-dihydrobenzoxazines and their structural Schiff base isomers. The reaction of 2-[2-hydroxyphenyl(naphthyl)]-1,2-dihydro-4H-3,1-benzoxazines with aliphatic aldehydes gives substituted 3,1-benzoxazino[1,2-c][1,3]benz(naphth)oxazines. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1230–1241, August, 2006.     

2-Aryl-4H-3,1-benzoxazin-4-ones. Reduction

The reduction of 2-(2-tosylaminophenyl-4H-3,1-benzoxazin-4-one with zinc dust in acetic acid gives N-(o-tosylaminobenzyl)anthranilic acid, the structure of which was proved by mass spectrometry and the ¹³C NMR spectra.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1619–1621, December, 1977.     

Studies of benzoxazines 16*. Synthesis and reactivity of 2,4-substituted 4H-3,1-benzoxazines

A novel method has been developed for preparation of substituted 4H-3,1-benzoxazines via formation of tetrafluoroborates. The substitution of halogen in 2-(α-haloalkyl)-4,4-diphenyl-4H-3,1-benzoxazines by NH and SH nucleophiles was performed. The effect of electrophilic substitution in the annelated aromatic ring in a series of 2,4-substituted 4H-3,1-benzoxazines has been studied.     

Research on 4H-3,1-benzoxazines. 9. 2-Alkyl(aryl,furyl)-4H-3,1-benzoxazinium perchlorates and their transformations

A new method was developed for obtaining 4,4-diphenyl-4H-3,1-benzoxazinium Perchlorates by acylation of o-aminophenyldiphenylcarbinol with organic acids in the presence of perchloric acid. Weak CH acidity of the exocyclic methyl group of the corresponding perchlorate was observed.For communication 8 see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 542–546, April, 1993.     

The chemistry of 4H-3,1-benzoxazin-4-ones

The present review covers the synthesis and reactions of 4H-3,1-Benzoxazin-4-ones. Only those with carbon substituents at the 2-position are included. Literature corverage includes publications primarily from the mid 1960's to May 1998.     

Synthesis of 2-oxazolidinones by direct palladium-catalyzed oxidative carbonylation of 2-amino-1-alkanols

[reaction: see text] 2-Oxazolidinones 2 are obtained in excellent yields (up to 100%) and with unprecedented catalytic efficiencies (up to 2000 mol of product/mol of catalyst used) by direct PdI2/KI-catalyzed oxidative carbonylation of the readily available 2-amino-1-alkanols 1. Reactions are carried out in MeOH as the solvent at 100 degrees C using a 1/6/5 CO/O2/air mixture (60 atm total pressure at 25 degrees C).     

硒催化2-氨基苄醇氧化羰基化合成1,4-二氢-2H-3,1-苯并噁嗪-2-酮

1,4-二氢-2H-3,1-苯并噁嗪-2-酮作为一种重要的母体骨架广泛存在于生物活性化合物中。此外,在有机合成中它可作为经受热脱羧生成氮杂-邻二亚甲基苯的有效工具。文献报道的合成1,4-二氢-2H-3,1-苯并噁嗪-2-酮的方法有：2-氨基苄醇与光气或其替代物反应,钯或硫催化的2-氨基苄醇与 CO的羰基化反应,钯或硒催化的2-硝基苄醇与 CO的羰基化反应,钯催化的2-叠氮基苄醇直接羰基化反应或2-叠氮基苄醇的氮杂-维悌希(aza-Wittig)/杂累积多烯调节的环合反应,苯并呋喃酮的胺解-霍夫曼重排反应,硼氢化锂还原1,2-二氢-3,1-苯并噁嗪-2,4-二酮,以及2-羟甲基苯基氨基甲酸酯的分子内亲核取代反应。上述合成方法存在原料毒性高或成本高且来源不便、原子经济性低、有腐蚀性废物或 CO2排放、CO利用率低、催化剂昂贵且难以循环使用、反应步骤较多等缺陷,因此发展绿色、高效、经济的合成新途径具有重要意义。本文采用廉价易得的非金属硒作催化剂,用 CO作羰基化试剂, O2作氧化剂,通过硒催化2-氨基苄醇的氧化羰基化反应直接合成了目标产物1,4-二氢-2H-3,1-苯并噁嗪-2-酮。通过考察反应时间、反应温度、催化剂硒的用量、助催化剂种类及用量、CO和 O2的比例及溶剂种类等影响因素,得到了优化的反应条件,目标产物收率最高可达87%。实验证实,该 Se/CO催化体系具有相转移催化功能。反应前硒以粉末形式存在于反应体系中,为多相体系;反应开始后,硒粉参与羰基化反应形成可溶活性化合物,从而成为均相体系;反应完成后硒粉经氧化可重新从反应介质中沉淀析出,又变为多相体系。因此,该体系既实现了高效的均相催化反应,又便于催化剂分离回收,且回收的硒可重复使用,其催化活性基本保持不变。结合相关文献,我们提出了该反应的机理：在助催化剂三乙胺存在下,硒首先与 CO反应原位生成羰基硒,然后羰基硒先后接受2-氨基苄醇中氨基和羟基的亲核进攻生成目标产物,同时释放出硒化氢,硒化氢再被 O2氧化为硒,从而进入下一轮催化循环反应。总之,我们成功开发出一条绿色、高效、经济的1,4-二氢-2H-3,1-苯并噁嗪-2-酮合成新途径。用廉价易得且能循环使用的硒替代贵金属钯作催化剂,用 CO替代剧毒光气或其衍生物作羰基化试剂, O2作氧化剂,硒催化的2-氨基苄醇氧化羰基化反应可顺利进行,以87%的良好收率得到目标产物,具有成本低、原子经济性高、CO利用率高、步骤简短、无腐蚀性废物或温室气体 CO2排放、无光气使用及环境相对友好等优点。     

Direct oxidative cascade cyclisation of 2-aminobenzoic acid and arylaldehydes to aryl 4H-3,1-benzoxazin-4-ones with oxone

This paper presents a methodology of oxidative cascade cyclisation of 2-aminobenzoic acids and arylaldehyde using I₂ as a catalyst and an environmentally benign oxidant oxone. This method displays facile access to a diverse range of substituted aryl 4H-3,1-benzoxazin-4-ones. This synthetic methodology has many advantages such as: (1) easy availability of starting material, (2) transition metal-free condition (3) use of an environmentally benign oxidant.     

Palladium-catalyzed highly regio- and stereoselective synthesis of 4-alkylidene-4H-3,1-benzoxazines from N-acyl-o-alkynylanilines

The highly regio- and stereoselective 6-exo-dig mode cyclization of N-acyl-o-alkynylanilines producing 4-alkylidene-3,1-benzoxazines occurred unpredictably by use of a proper catalyst [Pd(OAc)(2)] and an effective additive (acetic acid) under suitable reaction conditions.