3,8-双乙酰基次卟啉二甲酯的合成

以氯化血红素(Ⅰ)为原料,经过溴化氢-冰醋酸加成反应、羟基亲核取代反应和无水氯化氢催化酯化反应制得3,8-双-(1-羟基乙基)次卟啉二甲酯(Ⅲ),然后通过琼斯试剂氧化反应制备了3,8-双乙酰基次卟啉二甲酯(Ⅳ)。 考察了血红素与溴化氢-冰醋酸饱和溶液反应过程中温度和时间对3,8-双-(1-羟基乙基)次卟啉二甲酯(Ⅲ)产率的影响;改进了酯化反应的实验条件;选用了廉价易得、选择性较好的羟基选择性氧化剂。 实验结果表明,当反应温度为35 ℃、反应时间为25 h时,血卟啉(Ⅱ)的产率最高,为98.5%;当催化剂为无水氯化氢时产物(Ⅲ)的产率最高,为72.1%;使用琼斯试剂做氧化剂使实验成本大大降低。 通过1H NMR、MS和IR测试技术对产物结构进行了表征。     

Transesterification of Ethylene Carbonate with Dimethyl Terephthalate over Various Metal Acetate Catalysts

IntroductionDimethyl carbonate(DMC) is known to be a novelbuilding block in organic synthesis. As an environmen-tally benign compound and a unique intermediate,DMC has attracted much attention[1,2]. Among the va-rious methods for synthesizing DMC, the tra…     

Interaction of dimethyl carbonate with anilines in the presence of potassium methylate: Kinetics and the role of the base

The kinetic patterns of the reaction between dimethyl carbonate and anilines in the presence of a potassium methylate as a catalyst were studied. The mechanism of aminolysis was clarified, which includes the detachment of the proton from the amino group of aniline and the subsequent attack of the resulting anion on the carbonyl group of dimethyl carbonate. It is shown that when the reaction occurs in the dimethyl carbonate-methanol 3:1 system, the process can be described as an irreversible first-order reaction in the aniline though the target reaction is complicated by side interaction between potassium methylate and dimethyl carbonate. The rate constants of the target reaction with substituted anilines and of the side reaction in the temperature range of 70-90°C were determined. It is shown that the influence of the substituent on the reaction rate is described by the Hammett equation, with the constant of the reaction series being positive and the best correlation being achieved for σ-scale. The results obtained are consistent with the proposed mechanism of the reaction and are explained by the facilitation of the aniline deprotonation with increasing acceptor properties of the substituent. Effective activation energies for the reaction of various anilines with dimethyl carbonate are found.     

New method of dimethyl sulfide synthesis

The synthesis of dimethyl sulfide consists in the reaction of dimethyl disulfide with methanol in the presence of solid catalyst, aluminum γ-oxide. The yield of dimethyl sulfide grows with growing temperature, contact time, and content of methanol in the reaction mixture. At 350–400°C, molar ratio methanol-dimethyldisulfide 2.0–2.5, and total conversion of the reagents the yield of dimethyl sulfide reached 95 mol%.     

Conversion of dimethyl disulfide in the presence of zeolites

Dimethyl disulfide conversion in the presence of zeolites was studied at atmospheric pressure and T = 190–350°C. For all catalysts, the products of the reaction at T = 190°C—methanethiol, dimethyl sulfide, and hydrogen sulfide—result directly from dimethyl disulfide. The relative reaction rate and the dimethyl sulfide selectivity decreases in the order HZSM-5 ≥ CoHZSM-5 > HNaY > NaX, NaY. The methanethiol formation selectivity changes in the reverse order. The highest methanethiol selectivity at T = 190°C is shown by the sodium zeolites; the highest dimethyl sulfide selectivity, by the high-silicz zeolite HZSM-5. Raising the reaction temperature increases the reaction rate and changes the process route: at high temperatures, dimethyl disulfide decomposes to methanethiol, which then condenses to yield dimethyl sulfide and hydrogen sulfide. The observed regularities are explained in terms of the different acidic properties of the zeolite surfaces.     

Aminomercuration-demercuration of dimethyl(chloroalkyl)alkenylsilanes as a route to azasilacycloalkanes

3,3-Dimethyl-1-phenyl-1-aza-3-silacyclopentane and 3,3,5-trimethyl-1-phenyl-1-aza-3-silacyclopentane were obtained by the reaction of dimethyl(chloromethyl)vinylsilane and dimethyl(chloromethyl)allylsilane with aniline in THF in the presence of mercury acetate followed by reduction with sodium borohydride. Aminomercuration-demercuration of dimethyl(3-chloropropyl)vinylsilane and dimethyl(3-chloropropyl)allylsilane results in the corresponding 3-chloropropylphenylaminoalkyl derivatives. Dimethyl(3-chloropropyl)(2-phenylaminopropyl)-silane undergoes cyclization under the same reaction conditions giving 2,4,4-trimethyl-1-phenyl-1-aza-4-silacycloheptane in low yield. Competitive nucleophilic substitution of the chloroalkyl group of initial silanes by aniline affords dimethyl(phenylaminoalkyl)alkenylsilanes.     

Practical and high stereoselective synthesis of 3-(arylmethylene)isoindolin-1-ones from 2-formylbenzoic acid

Practical and high stereoselective synthesis of 3-(arylmethylene)isoindolin-1-ones is reported. The synthetic method involves the preparation of dimethyl isoindolin-1-one-3-yl-phosphonates by a ‘one-pot’ three-component reaction of 2-formylbenzoic acid with 4-methoxybenzylamine or aminoacetaldehyde dimethyl acetal and dimethyl phosphite under solvent and catalyst free-conditions, followed by a Horner reaction with several aryl aldehydes.     

Reactions of diols with dimethyl carbonate in the presence of W(CO)6 and Co2(CO)8

Dimethoxyalkanes and dimethyl alkanediyl biscarbonates were synthesized by reactions of diols with dimethyl carbonate in the presence of tungsten and cobalt carbonyls. Optimal reactant and catalyst ratios and reaction conditions were found to ensure selective formation of dimethoxyalkanes or dimethyl alkanediyl biscarbonates.     

The Reaction of Ethyl Bromoacetate with Dimethyl Sulfoxide

The reaction of excess dimethyl sulfoxide with ethyl bromoacetate has been shown to produce ethyl glyoxylate, hydrogen bromide, and dimethyl sulfide. The yield of glyoxylate at first was reduced because the dimethyl sulfide reacted with bromoacetate to form trimethylsulfonium bromide and ethyl (methylmercapto) acetate, presumably via carbethoxymethyldimethylsulfonium bromide. These side reactions were diminished in a thin-film reactor, but the result was not satisfiable, the yield was 51%, and the side reactions were prevented by addition of methyl bromide, which rapidly consumed the dimethyl sulfide with formation of trimethylsulfonium bromide. Addition of 1, 2-epoxy-3-phenoxypropane removed the hydrogen bromide, thereby preventing the deleterious effects casued by its reduction of dimethyl sulfoxide to dimethyl sulfide. In this way has been developed a convenient preparation of ethyl glyoxylate in yields averaging about 70%. Identification and stoichiometry of the reaction products are presented.     

多取代芳香族化合物的合成 5.卤素-苯硒基取代的丁二烯和丁炔二酸二甲酯的环加成-芳构化串连反应

本文报道用环加成－芳构化串连反应制备多取代芳香族化合物的方法。将１－氯－２－卤－３－苯硒基－１，３－丁二烯（５）与丁炔二酸二甲酯进行Ｄｉｅｌｓ－Ａｌｄｅｒ反应时，能直接生成多取代的芳香族化合物４－苯硒基－５－卤代邻苯二甲酸二甲酯（４）。若用２－卤素－３－苯硒基－１，３－丁二烯（１）与丁炔二酸二甲酯进行Ｄｉｅｌｓ－Ａｌｄｅｒ反应，只得到正常的加成产物４－苯硒基－５－卤素－１，４－环己二烯－１，２－二甲酸二甲酯（３），需再用ＤＤＱ处理，才得到多取代芳香族化合物（４）。     

藻胆蛋白生物合成的模型反应I. 藻蓝胆素硫醚键的形成

藻蓝胆素二甲酯2a在氢氧化铵的催化作用下可与巯基乙醇发生加成反应,通过UV-Vis,MS和^1HNMR鉴定了加成物的结构,巯基乙醇是加成在A环的3'-C上,得到3-氢-3'-[β-羟基乙硫基]藻蓝胆素二甲酯3,产率为80%。不仅模拟了藻蓝胆素的硫醚键形成,也进一步证明了它是藻蓝蛋白生物合成的最后一步。利用^1HNMR技术对加成物的构型进行了详细的讨论。     

The reactions of dimethyl 2,5-bis(diazo)-3,4-dikentoadipate with aromatic and heteroaromatic compounds

Heating the title compound with benzene provides a mixture of dimethyl 1,3-dihydroxynaphthalene-2,4-dicarboxylate and 3-carbomethoxy-4-hydroxy-5-phenylpyrone which rearranges on melting to the aforementioned naphthalene derivative. The initial substitution reaction appears to proceed through an intermediary pyronyl cation. The scope of this potential ring annelation reaction has been investigated for a range of aromatic and heteroaromatic compounds. Heating with basic substrates converts the bisdazo compound into dimethyl 4-hydroxypyrazole-3,5-dicarboxylate, while heating with isopropanol yields dimethyl 4,5-dihydroxypyridazine-3,6-dicarboxylate.     

Synthesis of a New Phosphonate Methacrylate Monomer

In this work, a new methacrylate phosphonate monomer synthesis was described according to a two-step reaction. First the monoaddition of thioglycolic acid onto dimethylvinyl phosphonate monomer led to dimethyl–5-carboxymethyl-2-thiaethylphosphonate, a new phosphonate acid compound. This reaction also led to the thioester homologue of dimethyl–5-carboxymethyl-2-thiaethylphosphonate with a 15% yield by reaction of a thioglycolic acid thioester with dimethylvinyl phosphonate. Second, dimethyl carboxy-4-thia-butyl phosphonate reacted with glycidyl methacrylate. This epoxy-acid addition reaction was catalyzed by chromium salt at 70°C and led to the new methacrylate phosphonate monomer. We showed that only the secondary alcohol was obtained via a β addition. The two-step reaction final yield was calculated to be about 85%.     

Reactions of arylaldehydes and N-sulfonated imines with dimethyl acetylenedicarboxylate catalyzed by nitrogen and phosphine lewis bases

[reaction: see text] In the reaction of arylaldehydes or N-sulfonated imines (0.5 mmol) with dimethyl acetylenedicarboxylate (DMAD) (0.6 mmol) catalyzed by pyridine or DMAP (20 mol %), we found that (E)-2-aryl-but-2-enedioic acid dimethyl ester 1 or (E)-2-[aryl-(toluene-4-sulfonylimino)methyl]-but-2-enedioic acid dimethyl ester 2 was formed in good yields at 60 degrees C in THF. A plausible mechanism has been proposed.     

Treatment of dimethyl (+)-L-tartrate with sulfur tetrafluoride

Treatment of dimethyl (+)-L-tartrate (I) with sulfur tetrafluoride results in the formation of an intermediate, 2-fluoro-1,2-bis(methoxycarbonyl)ethyl fluorosulfite (II), which under the action of hydrogen fluoride, present in the reaction mixture, is converted into dimethyl (?)(2S:3S)-2-fluoro-3-hydroxysuccinate (III). The reaction of the latter with SF₄ leads to dimethyl meso-2,3-difluorosuccinate (IV). The structure and configurations of the compounds obtained were established by ¹H and ¹⁹F NMR. Treatment of dimethyl (+)-L-tartrate (I) with sulfur tetrafluoride in the presence of excessive hydrogen fluoride gave dimethyl meso-2,3-difluorosuccinate in 96% yield.     

Cyclisation reactions of 2-substituted benzoylphosphonates with trialkyl phosphites via nucleophilic attack on a carbonyl-containing ortho substituent

Dimethyl 2-acetoxy- and dimethyl 2-benzoyloxy-benzoylphosphonate undergo cyclisation and deoxygenation in the presence of excess trimethyl phosphite to give dimethyl (3-methyl-1-benzofuran-2-yl)phosphonate and dimethyl (3-phenyl-1-benzofuran-2-yl)phosphonate, respectively. The reaction pathway has been shown to involve phosphite attack on initially formed tricyclic dioxaphospholane intermediates with the subsequent loss of two molecules of trimethyl phosphate. In the absence of additional trimethyl phosphite the initially formed tricyclic dioxaphospholane intermediates lose one molecule of trimethyl phosphate and then undergo a novel rearrangement to give β-ketophosphonates. The mechanism for this reaction helps explain some previously reported epoxide rearrangements. In contrast, the initially formed anionic intermediate from the reaction of dimethyl 2-benzoyloxymethylbenzoylphosphonate with trimethyl phosphite undergoes decomposition to give a carbene intermediate which is trapped by the trimethyl phosphite to give an ylidic phosphonate.     

Determination of carbamate, phenylurea and phenoxy acid herbicide residues by gas chromatography after potassium tert-butoxide/dimethyl sulphoxide/ethyl iodide derivatization reaction

The usefulness of the potassium tert-butoxide/dimethyl sulphoxide/ethyl iodide reaction with carbamate and phenylurea herbicides, and its application to phenoxy acids as a way to prevent hazards and toxicity of the sodium hydride/dimethyl sulphoxide/methyl iodide reaction was studied. Using factorial design optimization of this reaction was carried out. A solid-phase extraction method using dimethyl sulphoxide as eluent on-line with this reaction was developed to determine these herbicides in water samples by gas chromatography-mass spectrometry. Relative standard deviation values were lower than 10% for most of the herbicides in multicomponent trace determinations. Detection limits were in the 0.110-0.652 ng L(-1) concentration range. The validity of the method was confirmed by recovery studies from natural water samples.     

The diels-alder reaction of 5-aminopyrazole-4-carbonitrile with dmad: Synthesis and structural determination of dimethyl 2-(p-toluenesulfonylamino)-3-cyano-4-imino-1,4-dihydropyridine-5,6-dicarboxylate

The Diels-Alder reaction of 5-amino-1-(p-toluenesulfonyl)pyrazole-4-carbonitrile with dimethyl acetylenedi-carboxylate was carried out in the presence of potassium carbonate in dimethyl sulfoxide. The reaction gave dimethyl 2-(p-toluenesulfonylamino)-3-cyano-4-imino-1,4-dihydropyridine-5,6-dicarboxylate. The product was formed by transformation of the original Diels-Alder adduct followed by rearrangement of the p-toluenesul-fonylamino group into the 2-position of the pyridine ring. The structure of the product was irrefutably established by X-ray crystallography. This reaction is the first example of a pyrazole ring serving as the diene in a [4 + 2] cycloaddition reaction.     

Benzyl radical addition reaction through the homolytic cleavage of a benzylic C-H bond

Direct generation of a benzyl radical by C-H bond activation of toluenes and the addition reaction of the resulting radical to an electron deficient olefin were developed. The reaction of dimethyl fumarate with toluene in the presence of Et(3)B as a radical initiator at reflux afforded 2-benzylsuccinic acid dimethyl ester in good yield.     

Reaction between naphthols and dimethyl acetylenedicarboxylate in the presence of phosphites. Synthesis of stable oxa-2 lambda 5-phosphaphenanthrenes,and benzochromene derivatives

The reaction of dimethyl acetylenedicarboxylate (DMAD) with 2-naphthol in the presence of trimethyl or triphenyl phosphite leads to stable dimethyl oxa-2 lambda 5-phosphaphenanthrene derivatives in good yields. The reaction of DMAD and trimethyl phosphite in the presence of 1-naphthol or 8-hydroxyquinoline leads to dimethyl 2-(dimethoxyphosphoryl)-3-(1-hydroxy-2-naphthyl)succinate or dimethyl 2-(dimethoxyphosphoryl)-3-(8-hydroxyquinolin-7-yl)-succinate in excellent yields. Using triethyl phosphite and DMAD in the presence of 2-naphthol or 1-naphthol produces methyl 3-oxo-2,3-dihydro-1H-benzo[f]chromene-1-carboxylate or methyl 2-oxo-3,4-dihydro-2H-benzo[h]-chromene-4-carboxylate in excellent yields.