Synthesis of dimethyl thamnolate and dimethyl hypothamnolate

Methyl 5-hydroxyhaematommate (XIX) and methyl 5-hydroxy-β-orcinolcarboxylate (XII) are conveniently made by the application of paranuclear oxidation using methyl haematommate and methy β-orcinol carboxylate respectively. These undergo preferential acylation of the hydroxyl in the meta (5) position and by employing this property, syntheses of dimethyl thamnolate (XVIII) and dimethyl hypothamnolate (VII) have been accomplished.     

Synthesis of dimethyl sulfomycinamate

[reaction: see text] Dimethyl sulfomycinamate, the oxazole-thiazole-pyridine product generated in the methanolysis of the thiopeptide antibiotic sulfomycin I, is prepared in 13 steps and 8% overall yield by the Bohlmann-Rahtz heteroannulation of 1-(oxazol-4-yl)enamines and methyl 4-(trimethylsilyl)-2-oxobut-3-ynoate.     

Synthesis and cytotoxicity evaluation of diastereoisomers and N-terminal analogues of tubulysin-U

Tubulysins are potent anti-mitotic natural compounds and a scalable and efficient synthetic route for generation of its analogues has been developed and extended to the synthesis of diastereoisomers and N-terminal analogues of tubulysin-U. Structure–activity-relationship studies on these synthetic analogues reaffirmed the significance of native stereochemistry of tubulysins for optimal biological activity and cytotoxicity. However, while modification of Tup stereochemistry has only minor effect on the tubulysins cytotoxicity, Tuv stereochemistry is critically important and modification of either Tuv stereocentre produced a dramatic drop in cytotoxicity.     

Synthesis of dimethyl 4-thiazolidinylphosphine oxides via addition of dimethylphosphine oxide to 3-thiazolines

The addition of dimethylphosphine oxide and its trimethylsiloxyphosphorus(III) derivative, generated in situ, to 3-thiazolines was found to yield dimethyl 4-thiazolidinylphosphine oxides via three different synthetic routes. The structures of two products were confirmed by X-ray analysis; common features include approximate envelope conformations of the five-membered rings and hydrogen bonding of the form N–H· · ·O=P. © 1997 John Wiley & Sons, Inc. Heteroatom Chem 8 : 207–215, 1997.     

Synthesis of vulpinic acids from dimethyl tartrate

A series of vulpinic acids differing by the aryl or heteroaryl groups placed in the ester α-position were prepared by Suzuki-Miyaura cross-coupling involving a common iodide and the corresponding aryl boronates. The preparation of the iodide precursor from (+)-dimethyl l-tartrate required four steps: the esterification of one hydroxyl group, a Dieckmann cyclization allowing the construction of the tetronic acid moiety, a dehydration leading to the installation of the exocyclic double bond and lastly, an N-iodosuccinimide-mediated iodation of the alkene obtained.     

Synthesis of dimethyl adipate from cyclopentanone and dimethyl carbonate over solid base catalysts

A facile route for the synthesis of dimethyl adipate (DAP) from cyclopentanone and dimethyl carbonate (DMC) in the presence of solid base catalysts has been developed.It was found that the intermediate carbomethoxycyclopentanone (CMCP) was produced from cyclopentanone with DMC in the first step,and then CMCP was further converted to DAP by reacting with a methoxide group.The role of the basic catalysts can be mainly ascribed to the activation of cyclopentanone via the abstraction of a proton in the α-position by base sites,and solid bases with moderate strength,such as MgO,favor the formation of DAP.     

Stereoisomers of dimethyl N-phthaloyl-4-bromoglutamate

Fractional crystallization and column chromatography have been used to obtain the enantiomers and diastereoisomeric racemates of diemthy N-phthaloyl-4-bromoglutamate. The steric configurations of these compounds were established by PMR and x-ray diffraction analysis.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2077–2081, September, 1989.     

Synthesis and some transformations of dimethyl anabasylethynephosphonate

A new phosphorylated ynamine, dimethyl anabasylethynephosphonate, was synthesized by reaction of dimethyl chloroacetylenephosphonate with anabasine. Anabasylethynephosphonate obtained was shown to react under mild conditions with primary aromatic amines like p-chloroaniline, p-anisidine, and p-aminoacetophenone, whose pK _b values are in the range of 9–13, to form new asymmetrical phosphorylated acetamidines in high yields. Structure of the compounds obtained was proved by ¹H, ¹³C, and ³¹P NMR spectroscopy.     

Synthesis of dimethyl heterocyclic‐o‐dicarboxylates using dimethyl acetylenedicarboxylate

Dimethyl acetylenedicarboxylate (DMAD) is a very important and useful reagent for the preparation of dimethyl heterocyclic‐o‐dicarboxylates, which are key intermediates in the synthesis of fused pyridazine derivatives. The synthesis of thiopyranes by the Diels‐Alder reaction of dithiocarboxylate derivatives, synthesis of various cyclazines by [2 + 8] cycloaddition reactions, and synthesis of dimethyl pyrazolo[3,4‐b]pyridine‐5,6‐dicarboxylates and polycyclic heterocycles containing the 1,6‐naphthyridine ring system by the reaction of o‐aminonitrile compounds with DMAD are described here.     

Synthesis of gasoline from syngas via dimethyl ether

Zeolite H-TsVM has been loaded with palladium by different methods. The properties of the resulting catalysts in gasoline synthesis from syngas via dimethyl ether depend on the way in which palladium was introduced. The catalysts have been characterized by ammonia temperature-programmed desorption (TPD), temperature-programmed reaction with hydrogen, and X-ray photoelectron spectroscopy. According to ammonia TPD data, use of a palladium ammine complex instead of palladium chloride reduces the concentration of strong acid sites and raises the concentration of medium-strength acid sites, thereby reducing the yield of C1–C4 hydrocarbons and increasing the yield of gasoline hydrocarbons. At T = 340°C, P = 100 atm, and GHSV = 2000 h^?1, the dimethyl ether conversion is 98–99%, the gasoline selectivity is >60%, the isoparaffin content of the product is ～61%, and the arene content is not higher than 29%.     

聚甲氧基二甲醚的合成及其物理化学性质表征

聚甲氧基二甲醚（H₃CO（CH₂O）_nCH₃, PODE_n或DMM_n, n ≥ 2）具有独特的物理化学性质;作为一种柴油添加剂,可以有效提高油品燃烧效率并达到节能减排的目的。首先合成了一系列聚合度n为2、3、4和5单一组分的聚甲氧基二甲醚,采用NMR、FT-IR、Raman和DFT计算等手段对每个聚甲氧基二甲醚单体的化学结构进行表征,并对其在298.15-323.15K温度的密度和黏度进行了测试。结果表明,聚甲氧基二甲醚的密度和黏度随着温度的升高而逐渐降低,随着聚合度的增加而逐渐升高。同时,聚甲氧基二甲醚PODE_n（n =2-5）的闪点和倾点以及溶解热和凝固热均随着聚合度的增加而提高。     

Synthesis and solid-state structures of dimethyl 2,2'-bithiophenedicarboxylates

The syntheses of dimethyl 2,2'-bithiophene-4,4'-dicarboxylate (3), dimethyl 2,2'-bithiophene-3,4'-dicarboxylate (4), and dimethyl 2,2'-bithiophene-3,3'-dicarboxylate (5) are described. Single-crystal X-ray structural analysis of these compounds shows that the thiophene rings in 3 and 4 are nearly coplanar (dihedral angle close to 0 degrees ) and they adopt the anti sulfur conformation in the solid state. Further, the structure of 4 is in agreement with our previous suggestion that there is an electrostatic stabilization of the planar structure due to attraction of the 3-carbonyl oxygen to the sulfur of the distal ring. In 5, however, the thiophene rings are nearly perpendicular (dihedral angle 75 degrees ), indicating considerable steric hindrance between the two large ester groups at the 3- and 3'-positions. Unlike compounds 3 and 4, where the thiophene rings have the sulfur atoms anti, the sulfur atoms in 5 are completely syn. This is the first instance where a bithiophene has been shown to adopt a conformation where the sulfur atoms are completely syn. The solid-state conformations of 3, 4, and 5 are in agreement with ab initio theoretical calculations on these compounds; particularly, the planar conformations of 3 and 4 reflect the previously calculated low rotation barriers of these molecules.     

氨基多元膦酸水处理剂的合成及性能分析

以N.N-二甲基甲酰胺、三氯化磷为主要原料合成了氨基多元膦酸水处理剂-二甲基甲叉二膦酸.并对其缓蚀阻垢能力进行了考察.试验表明:二甲基甲叉二膦酸具有很好的缓蚀效果,在与Zn2+复配或采用预膜处理后其缓蚀性能更为优越.对碳酸钙、硫酸钙和磷酸钙具有很好的抑制能力,即使在Ca2+浓度较高体系也有较好的阻垢效果.     

分子筛催化剂催化合成聚甲氧基二甲醚

以甲醇、甲缩醛和三聚甲醛为原料,考察了分子筛孔道结构、晶粒粒径、酸性及反应体系对合成聚甲氧基二甲醚反应性能的影响,并筛选出最佳反应条件。结果表明,HMCM-22分子筛具有良好的催化性能。在最佳反应条件下,以甲醇与三聚甲醛为原料,DMM2~8的选择性为65.1%;而以甲缩醛和三聚甲醛为原料,DMM2~8的选择性则达到90.6%。NH3-TPD结果表明,弱酸位有利于三聚甲醛解聚为甲醛,中强酸位促进长链分子生成,而强酸位导致DMM为主要产物。     

4-(2,6-二甲基苯氧基)邻苯二腈的合成与物理光学研究

合成出一种具有荧光性质的小分子有机分子,用1HNMR,IR和元素分析进行了表征.研究了该有机分子的荧光性质,在浓度为1×10-3mol/L时,激发波长为340nm,发射波长是459nm;浓度对发射光谱的峰位和强度有影响.     

Synthesis of dimethyl sulfide in the presence of zeolites

In the presence of zeolites, dimethyl sulfide is produced either through CH₃OH interaction with H₂S or via CH₃SH decomposition. In accordance with their activities, in both reactions, zeolites arrange in the same sequence: HZSMHNaY>NaXNaY. Realization of the reaction CH₃OH+H₂S is more difficult compared to methanethiol decomposition.

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CH₃OH H₂S CH₃SH. : HZSMHNaY>NaXNaY. CH₃OH+H₂S , .

     

Synthesis of dimethyl esters of protoporphyrin ix and pemtoporphyrin

The dimethyl esters of protoporphyrin IX and pemtoporphyrin were synthesized by cyclization ofa,c-biladienes to the corresponding porphyrins, which contain -diethylaminoethyl groups as potential vinyl substituents, and subsequent Hofmann degradation of them to vinylporphyrins in high yields.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 202–206, February, 1973.