Synthesis and photochromism of Δ2,2′-BI-(2H-1,4-benzothiazine)

Δ^2,2′-Bi- (2H-1,4-benzothiazine) (4), the parent ring system of a group of amino-acid pigments (trichosiderins) from red hair and feathers, has been synthesized by a simple and novel method involving air oxidation of 2H-1,4-benzothiazine, generated in situ by treatment of 1-(o-aminophenylthio)-2,2-diethoxyethane (1). This procedure yields only the yellow trans-isomer 4, which in solution exhibits marked photochromism, being reversibly converted into the red unstable cis-form 5 on brief irradiation with sunlight.     

Synthesis of 2-(2-imidazolinyl) substituted 2,3-dihydro-4H-1,4-benzothiazine and 3,4-dihydro-2H-1,4-benzoxazines

An investigation into the synthesis of benzoxazine, benzoxathiane and benzothiazine derivatives of 2-(2-imidazolinyl)-1,4-benzodioxane has been carried out.     

1,4-二氢-5H-(二硝基亚甲基)-四唑(DNMT)的合成、晶体结构和热行为研究

利用1-氨基-1-肼基-2,2-二硝基乙烯(AHDNE)和亚硝酸钾在酸性水溶液中合成出了高能富氮化合物1,4-二氢- 5H-(二硝基亚甲基)-四唑(DNMT), 并在水溶液中培养出DNMT•2H2O单晶. 该晶体属正交晶系, 空间群为Pnma, 晶胞参数为: a＝10.392(2) Å, b＝15.809(4) Å, c＝5.0640(11) Å, V＝832.0(3) Å3, Dc＝1.629 g•cm－3, μ＝0.163 mm－1, F(000)＝432, Z＝4, R1＝0.0311, wR2＝0.0885. 运用Gaussian 03程序, 在6-311＋＋G**基组水平上, 用HF和B3LYP两种方法对DNMT分子进行了几何全优化和相应的电荷、轨道能量分析. 理论计算和热分析结果表明DNMT呈现较差的热稳定性.     

A New Synthetic Approach Towards the Synthesis of 2-(3-Aryl-2H-1,4-benzthiazin-2-yl)-3-aryl-2H-1,4-benzothiazines

Synthesis of 2-(3-Aryl-2H-1,4-benzthiazin-2-yl)-3-aryl-2H-1,4-benzothiazines (3 a-e) from 3-aryl-5(4H)-isoxazolones (1 a-e) and 2-aminothiophenol (2).     

Synthesis and antiinflammatory activity of the sulfoxides of 4-[3-(dimethylamino)propyl] - 3,4- dihydro- 2-(1-hydroxyethyl)-3-phenyl-2H-1,4-benzothiazine

Oxidation of 4-[3-(dimethylamino)propyl]-3,4-dihydro-2-(1-hydroxyethyl)-3-phenyl-2H-1,4-benzothiazine, hydrochloride (I) with hydrogen peroxide yielded a mixture of two sulfoxides (II). Since this mixture exhibited antiinflammatory activity, the two components (Isomers A and B) were prepared in purified form by oxidation of I with N-chlorosuccinimide and hydrogen peroxide, respectively. Isomer A was more potent than Isomer B in the carrageenin-induced edema test.     

Synthesis of 2H-1,4-thiazin-3(4H)-one 1-oxide and 2H-1,4-thiazin-3-(4H)-one 1,1-dioxide,structural analogs of uracil

The synthesis of 1,4-thiazine 1-oxide and 1,1-dioxide analogs of the antibiotic emimycin is described. Reaction of methylthioglycolate with 1-bromo-2,2-diethoxyethane gave methyl (2,2-diethoxyethylthio)acetate ( 2 ). Treatment of 2 with methanolic ammonia followed by cyclization furnished 2H-1,4-thiazin-3(4H)-one ( 5 ). Oxidation of 5 with m-chloroperoxybenzoic acid converted it to 2H-1,4-thiazin-3(4H)-one 1-oxide ( 6 ). Oxidation of 2 with potassium permanganate, followed by treatment with methanolic ammonia, and cyclization gave 2H-1,4-thiazin-3(4H)-one 1,1-dioxide.     

Reaction of zinc enolates derived from 1-aryl-2,2-dibromoalkan-1-ones with tetramethyl 2,2′-(1,4-phenylenedimethylidene)dimalonate,dimethyl 3,3′-(1,4-phenylene)bis(2-cyanoacrylate), and 2,2′-(1,4-phenylenedimethylidene)-bis(malononitrile)

Zinc enolates derived from 1-aryl-2,2-dibromoalkanones reacted with tetramethyl 2,2′-(1,4-phenylenedimethylidene)dimalonate, dimethyl 3,3′-(1,4-phenylene)bis(2-cyanoacrylate), and 2,2′-(1,4-phenylenedimethylidene)bis(malononitrile) to give, respectively, tetramethyl 3,3′-(1,4-phenylene)bis(2-alkyl-2-aroylcyclopropane-1,1-dicarboxylates), dimethyl 3,3′-(1,4-phenylene)bis(2-alkyl-2-aroyl-1-cyanocyclopropane-1-carboxylates), and 3,3′-(1,4-phenylene)bis(2-alkyl-2-aroylcyclopropane-1,1-dicarbonitriles) as a single stereoisomer.     

New approach to the synthesis of 2,2':5',2'-terthiophene-5,5'-and 2,2':5',2':5',2'-quaterthiophene-5,5'-dicarboxylic acids

Chemistry of Heterocyclic Compounds - The reaction of bromosuccinimide with esters of 3-substituted 2,2'-bithiophene-5-carboxylic acids was used to obtain their 5'-bromo derivatives, which...     

Surface modification of poly(2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene) (MEH-PPV) by confined photo-catalytic oxidation

In this study, the surface of π-conjugated polymer, poly(2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene) (MEH-PPV), was successfully modified with the sulfate anion (SO(4-)) groups by the confined photo-catalytic oxidation (CPO). After the surface modification, the water contact angle of MEH-PPV is changed from 95.5° to 82.1° without influence on its optical properties (based on the UV and PL spectra), and the water droplet can be absorbed on the modified MEH-PPV surface without sliding even at substrate tilt angles of 90° and 180°. The CPO on the MEH-PPV surface is able to further expand the use of MEH-PPV for applications. In addition, the water transport test indicates that the modified MEH-PPV can be a candidate for transporting water droplet.     

Synthesis and oxidation of 2,6-dimethyl-3, 5-di(phenoxycarbonyl)-1,4-dihydropyridines

A number of new aryl esters of acetoacetic acid were obtained in the reaction of phenols with diketene in the presence of triethylamine. Reaction of the esters thus obtained with hexamethylenetetramine gave, for the first time, aryl esters of 1,4-dihydropyridine-3,5-dicarboxylic acid, the oxidation of which with chloranil gave the corresponding pyridines.     

Design, synthesis, and 1,3-dipolar cycloaddition of (5R)- [and (5S)]-5,6-dihydro-5-phenyl-2H-1,4-oxazin-2-one N-oxides as chiral (E)-geometry-fixed alpha-alkoxycarbonylnitrones

Optically pure (5R)- [and (5S)]-5,6-dihydro-5-phenyl-2H-1, 4-oxazin-2-one N-oxides [(5R)- and (5S)-2] were designed as chiral (E)-geometry-fixed alpha-alkoxycarbonylnitrones 1. The nitrones (5R)- and (5S)-2 were synthesized by three-step oxidation of (R)- and (S)-phenylglycinols [(R)- and (S)-3], condensation of the resulting (R)- and (S)-2-hydroxylamino-2-phenylethanols [(R)- and (S)-5] with glyoxylic acid, and cyclization of the intermediary nitrones (R)- and (S)-6b. The nitrone (5R)-2reacted with olefins 7-14 under mild conditions to afford the corresponding cycloadducts 15-22 as the main products via the least sterically demanding exo modes. Cycloadduct 30 obtained from (5S)-2 and cyclopentadiene was effectively elaborated to (1S,4S, 5R)-4-benzyloxycarbonylamino-2-oxabicyclo[3.3.0]oct-7-en-3-one (28), the key synthetic intermediate of carbocyclic polyoxin C.     

5-(2-Thienylsulfanyl)thiophene-2-carbaldehyde: Thioacetalization,chloromethylation, and oxidation

5-(2-Thienylsulfanyl)thiophene-2-carbaldehyde reacted with propane-1-thiol and propane-1,3-dithiol in the presence of chloro(trimethyl)silane to give previously unknown 5-[bis(propylsulfanyl)methyl]-2-(2-thienylsulfanyl)thiophene and 2-[5-(2-thienylsulfanyl)thiophen-2-yl]-1,3-dithiane. Chloromethylation of 5-(2-thienylsulfanyl)thiophene-2-carbaldehyde with formaldehyde in a stream of hydrogen chloride in the presence of zinc chloride resulted in the formation of an oligomeric product consisting of thiophene rings connected alternately by sulfur and methylene bridges. The oligomer is formed via fast polycondensation of the primary chloromethylation product with the initial aldehyde. 5-(2-Thienylsulfanyl)thiophene-2-carbaldehyde was oxidized at the sulfide and aldehyde groups with 30% hydrogen peroxide in glacial acetic to produce 5-(2-thienylsulfonyl)thiophene-2-carboxylic acid.