Synthesis of 6-halo-5-nitroquinoxalines

The 5-nitro derivatives of 6-haloquinoxalines have been efficiently synthesized by condensation of α-dicarbonyls with 4-bromo- or 4-chloro-3-nitro-1,2-benzenediamines. The novel diamines were readily obtained by reductive cleavage of 5-bromo- and 5-chloro-4-nitro-2,1,3-benzoselenadiazoles. As demonstrated by the synthesis of an imidazo-, a selenadiazolo- and a pyrazinoquinoxaline, the reactive halogen atom ortho to the nitro substituent renders the novel quinoxalines versatile intermediates to further heterocycles.     

Phototransformations of 6-X-5-Nitroquinoxalines

Photophysical properties and photochemical activity of 6-X-5-nitroquinoxalines with electron-donor substituents (X = H, CH₃, Cl, OC₂H₅, NH₂) ortho to the nitro group were studied. The quantum yield of the formation of 5-hydroxyquinoxaline from the corresponding nitro derivative depends on the nature of the substituent and irradiation conditions. Phototransformations can go through nitro-nitrite rearrangement with the participation of two alternative T(n*) levels, depending on the size and electronic effects of the substituent. The latter factor is largely determined by the population on excitation of different charge-transfer states involving the nitro group.     

Reaction of 3-Amino-5H- and 3-Amino-5-sulfanyl-1,2,4-triazoles with 1,2,4-Triazine-5-carbonitriles

Russian Journal of Organic Chemistry - 1,2,4-Triazines with an unsubstituted (1,2,4-triazol-3-yl)amine residue in the C5 position were synthesized by the solvent-free ipso-amination reaction...     

Enantioselective Synthesis of 3-Substituted 3-Amino-2-oxindoles by Amination with Anilines

A chiral N,N′-dioxide-nickel(II) complex-catalyzed asymmetric amination of 3-bromo-3-substituted oxindoles with anilines has been developed. A series of alkyl or aryl 3-amino-indolinones with quaternary stereocenters were obtained in high yields with excellent ee values in one step (up to 99 % yield, up to 96 % ee). The method provided a ready route to optically active intermediates of 3-amino-2-oxindole-based bioactive compounds. Moreover, a possible transition-state model is proposed so as to elucidate the origin of the chirality based on the X-ray crystal structure of the catalyst and the adduct.     

B(C6F5)3催化的醛与烷氧基羟胺的一锅法还原胺化反应

近年路易斯酸B（C₆F₅）₃催化的醛酮还原及胺化反应研究表明,缺电子的路易斯酸B（C₆F₅）₃也可以作为一种"耐水"的催化剂在"有水"条件下进行催化反应.这些研究成果对进一步扩展受限路易斯酸碱对（FLPs）化学的研究领域和应用前景提供了更多可能.本文以硅烷作为还原剂,在路易斯酸B（C₆F₅）₃催化下可在温和条件下实现醛与烷基羟胺类化合物的直接还原胺化反应,并且在还原过程中N-O键不会发生断裂,可中等至高产率地制备各种烷氧基取代的羟胺衍生物.对反应机理研究发现,在中性条件下苯甲醛与苄氧基羟胺的反应仅得到缩合中间产物肟醚,而在HCl或过量H₂O的参与下苯甲醛与苄氧基羟胺的直接还原胺化均可顺利进行;对反应机理的研究表明苄氧基羟胺会与路易斯酸硼烷在过量H₂O的参与下发生质子化,在硅烷的作用下转化成具有一定还原性的"硼氢化胺盐"活性中间体并进而促使中间产物肟醚的还原.对醛与羟胺的直接还原胺化反应研究表明,在"有水"条件下路易斯酸B（C₆F₅）₃不仅仅是一种"耐水"的催化剂,在某些反应中水可能直接影响着催化反应,尤其是对醛酮的直接还原胺化反应.因此,继续深入研究有"水"条件下路易斯酸硼烷参与的催化反应机理不仅对FLPs化学的发展至关重要,对其他相应催化体系的研究也具有重要的参考价值.     

蛋氨酸合成酶催化反应研究VII.5-氨基-6-甲基尿嘧啶的合成研究

报道了5-氨基-6-甲基尿嘧啶简便的合成方法。该化合物以6-甲基尿嘧啶（2） 为起始物，经硝化或重氮化分别得到了中间体5-硝基-6-甲基尿嘧啶（3）和5-偶氮 苯基-6-甲基尿嘧啶(4)，化合物3和4经Na_S_2O_4还原，合成产物5-氨基-6-甲基尿 嘧啶（1）。     

蛋氨酸合成酶催化反应研究 VII.5-氨基-6-甲基尿嘧啶的合成研究

报道了 5 氨基 6 甲基尿嘧啶简便的合成方法 .该化合物以 6 甲基尿嘧啶 ( 2 )为起始物 ,经硝化或重氮化分别得到中间体 5 硝基 6 甲基尿嘧啶 ( 3 )和 5 偶氮苯基 6 甲基尿嘧啶 ( 4 ) ,化合物 3和 4经Na2 S2 O4还原 ,合成产物 5 氨基 6 甲基尿嘧啶 ( 1) .     

Reaction of 4-Amino-3-methylthio-5-oxo-6-R-4,5-dihydro-1,2,4-triazines with Sulfonylacetic Acid Nitriles

The reactions of 4-amino-3-methylthio-5-oxo-6-R-4,5-dihydro-1,2,4-triazines with arylsulfonylacetonitriles and with dinitriles of sulfonyldiacetic acid and methylenebis(sulfonylacetic) acid have been studied. 7-Amino-3-R-8-(R'-sulfonyl)-1,4-dihydropyrazolo[5,1-c][1,2,4]triazin-4-ones have been synthesized and these are the first representatives of geminal sulfones in which the heterocyclic ring is bound directly to the sulfur atoms of the sulfonyl groups.     

Studies on the Reaction of Vinyl Triazole Derivatives with Hydroxylamine

Vinyltnazoledenvativeshavebeensynthesized1nthesearchforpotentandbroadspectrumfungicides[l.2:.Theyhavebeenfoundtoinhibitbiosynthesisofergosterolinfungalcells[3"'.Inordertodevelopneu:fungicidesweexpectedtosynthesizeaseriesofnewvinyItnazoledenvativesbythereactionof(Z)-or(E)-4,4-dimethyl-1-aryl-2-(1,2,4-triazo1-l-yl)-1-penten-3-ones(I,-.)withhydroxylaminehydrochloride.ButtheresultindicatedthattheproductsII.-,expectedwerenotobtainedandtheneu'heterocycliccompoundsof1,2-oxazocyclopentanedenvatives(…     

Amination of 4-Azafluorene under Chichibabin Reaction Conditions. Some Chemical Transformations of 1-Amino-4-azafluorene

4-Azafluorene is aminated by sodium amide in dimethylaniline at C₍₁₎. The oxidation of 1-amino-4-azafluorene was studied along with the condensation of this compound with acetic anhydride and its diazotization.     

A Novel Formation of 3,4-Disubstituted Isothiazoles from 5-Amino-6-methylpyrimidinones

3,4-Disubstituted isothiazoles (8a, b, 9a, b, 10, 11, 14a,b) were synthesized from 5-amino-6-methyl-4(3H)-pynmidinone (1) or 1,3-disubstituted 5-amino-6-methyluracils (12a,b) via the formation of isothiazolo[4,3-d] pyrimidines (6, 13a, b) followed by the reaction with alkylamines.     

利用偶联反应光度法测定羟胺体系的研究及应用

利用羟胺与碘反应生成亚硝酸 ,然后与对氨基苯磺酸发生重氮化反应 ,再与 α-萘胺偶联形成偶氮化合物 ,从而建立了测定羟胺的新光度法。方法线性范围为 2 .0× 1 0 - 6 ～1 .5× 1 0 - 5mol/L ,表观摩尔吸光系数为 3.1× 1 0 4 L· mol- 1· cm- 1,应用于水中羟胺和试剂丁二酮肟含量的测定 ,结果满意。     

利用偶联反应光度法测定羟胺体系的研究及其应用

利用羟胺与碘反应生成亚硝酸,然后与对氨基苯磺酸发生重氮化反应,再与α-萘胺偶联形成偶氮化合物,从而建立了测定羟胺的新光度法.方法线性范围为2.0×10-6～1.5×10-5 mol/L,表观摩尔吸光系数为3.1×104 L.mol-1.cm-1,应用于水中羟胺和试剂丁二酮肟含量的测定,结果满意.     

Regularities and Features of the Reaction of 2-Amino-6-nitro- and 2,6-Diaminobenzothiazoles with Ethylene Chlorohydrin

The alkylation of 2-amino-6-nitro- and 2,6-diaminobenzothiazoles by ethylene chlorohydrin has been studied. A comparative analysis has been made of the composition of these reaction mixtures and of those obtained from other 2-aminobenzothiazoles using this reaction. The structure of the synthesized compounds was confirmed using IR and ¹H NMR spectroscopy, mass spectrometry, and X-ray diffraction and via alternative syntheses.