拉帕替尼新中间体的合成

通过使用市售的5-溴糠醛与2-甲磺酰基乙胺进行亲和加成得到席夫碱,该席夫碱通过还原氢化、氨基保护和与硼酸酯反应,得到一种拉帕替尼的新中间体5-((苄基(2-(甲基磺酰基)乙基)氨基)甲基)呋喃-2-基硼酸,四步反应总收率为66.32%。     

Characterization of chlorovinylcobalamin,a putative intermediate in reductive degradation of chlorinated ethylenes

The first X-ray structure of a vinylcobalamin is reported. Chlorovinylcobalamin is formed in the reaction of cob(I)alamin with chloroacetylene. Subsequently, cob(I)alamin catalyzes the reduction of chlorovinylcobalamin to vinylcobalamin in the presence of excess titanium(III)citrate. Introduction of a chlorine onto the vinyl group of vinylcobalamin greatly changes its reduction potential. These results are discussed with respect to vitamin B12-catalyzed dechlorination of perchloroethylene, a pollutant on the priority list of the EPA.     

A novel transformation of O-methyldalbergin

O-methyldalbergin and related 4-phenylcoumarins are markedly different from ordinary coumarins in their behaviour towards alkali. They are stable in boiling alkali and on addition of mercuric oxide yield coumarilic acids. Phenyl-coumarilic acids undergo decarboxylation readily when boiled with aqueous alcoholic mercuric chloride to yield phenyl substituted coumarones.     

Characterization of the arene-oxidizing intermediate in ToMOH as a diiron(III) species

We report the generation and characterization of a diiron(III) intermediate formed during reaction with dioxygen of the reduced hydroxylase component of toluene/o-xylene monooxygenase from Pseudomonas sp. OX1. The decay rate of this species is accelerated upon mixing with phenol, a substrate for this system. Under steady-state conditions, hydrogen peroxide was generated in the absence of substrate. The oxidized hydroxylase also decomposed hydrogen peroxide to liberate dioxygen in the absence of reducing equivalents. This activity suggests that dioxygen activation may be reversible. The linear free energy relationship determined from hydroxylation of para-substituted phenols under steady-state turnover has a negative slope. A value of rho < 0 is consistent with electrophilic attack by the oxidizing intermediate on the aromatic substrates. The results from these steady and pre-steady-state experiments provide compelling evidence that the diiron(III) intermediate is the active oxidant in the toluene/o-xylene monooxygenase system and is a peroxodiiron(III) transient, despite differences between its optical and M?ssbauer spectroscopic parameters and those of other peroxodiiron(III) centers.     

A unique and novel cyclopropylmethyl cation intermediate: a DFT study

Some physical organic aspects of the intermediates that result from the interaction between phenylmethylenecyclopropane (substituted derivatives are important in synthesizing cyclobutenes) and platinum and palladium halides have been studied using B3LYP. Geometrical aspects, values of atom polarizable tensor charges (APT), effect of substituents, selected transition states activation barriers, and molecular orbital calculations are presented. These calculations suggest a novel organometallic cyclopropylmethyl cation, which is characterized by the presence of a highly polarized and unusually long sigma bond between the benzylic carbon and coordinating halogen atom.     

A novel transformation in the quadrone series

A remakable reaction of the substituted bicyclo [3,3,0] oct-3-ene-2-one ($\text{2e}$) with the sodium enolate of malonic ester is described.     

Thermochromism of a novel organic compound in the solid state via crystal-to-crystal transformation

A novel thermochromic organic compound, 1,5-bis(hydroxyethylamino)-2,4-dinitrobenzene (BDB), was synthesized and characterized using X-ray diffraction, differential scanning calorimetry, visible and infrared spectroscopy. It was observed that BDB exists in two different crystal structures of A- and B-forms at room temperature. In each crystal structure, there exist intra- and intermolecular hydrogen bonds between hydroxy, amino, and nitro groups. As the temperature is increased, the color of BDB crystalline powder changes from yellow to orange. The yellow color was recovered for a specific period of time when it is cooled again, indicating that thermochromism of BDB in the solid state is reversible. Both crystals of A- and B-forms are transformed to the C-form crystal at the transition temperature. From the results of X-ray diffraction, thermal data, and infrared spectra, it is suggested that the thermochromism of BDB originates from the crystal-to-crystal transition accompanying with the configurational transformation between nitro-form and acid-form via intramolecular hydrogen transfer.     

Through-space electrostatic control in a novel regiospecific ring transformation of 1,3,4-trisubstituted maleimides

Ring transformation of 1-ethoxycarbonyl-3,4-disubstituted maleimide in alkaline solution yielded exclusively 1,5-disubstituted orotic acid. No hydantoin derivatives were detected. These findings can be best explained by assuming that the initial attack of the hydroxylate anion occurs at C2 and not at C5. X-ray diffraction and quantum chemical investigations indicate that stereospecificity is mainly due to through-space electrostatic effects.     

Cation sensing by a novel triazine-cored intermediate as a fluorescent chemosensor incorporating benzothiazole fluorophore

Research on Chemical Intermediates - In the present work, a new triazine-based intermediate containing bis(2-pyridylmethyl)amine and benzothiazole units was designed and synthesized with the...     

一种新型的糖基型紫外线吸收剂的合成和表征

<正>紫外线是太阳光谱中波长200～400nm部分的电磁波,约占太阳辐射的6%,按波长不同,又可分为UVC(短波紫外线,200～280nm)、UVB(中波红斑效应紫外线,280～320nm)、UVA(长波黑斑效应紫外线,320～400nm)3个区段,其中UVC几乎全部被大气层阻滞,对人体无法造成伤害。     

Unprecedented base-promoted cascade transformation of a pyrimidinone derivative into a novel tricyclic bis-diazepinone

In the presence of strong bases (NaH, DBU, KOH), ethyl 4-chloromethyl-6-methyl-2-oxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate, 4, is transformed into a novel tricyclic compound, diethyl 9-methyl-5-methylene-3,11-dioxo-2,3,4,5,6a,7,10,11-octahydro-1,6-methano[1,3]diazepino[1,7-e][1,3,5]triazocine-6,8(1H)-dicarboxylate, 5, as a result of a cascade reaction.     

Efficient synthesis of sitagliptin phosphate,a novel DPP-IV inhibitor,via a chiral aziridine intermediate

Sitagliptin phosphate, a novel DPP-IV inhibitor of T2DM, has been synthesized via 12 linear steps, in an overall yield of 26%. The key step is the coupling reaction of 2,4,5-trifluorophenylmagnesium bromide with a chiral aziridine derivative, which was prepared from l-homo-serine by simple steps.     

A simple synthesis of 5-fluorouracil by a novel ring transformation reaction

A very simple method for the preparation of 5-fluorouracil ( 1 ) from 1,3-dimethyl-5-azauracil ( 2 ) by a novel ring transformation reaction is reported.     

Characterization of a novel diol column for high-performance liquid chromatography

For the investigation of a diol phase (Inertsil Diol column) in hydrophilic interaction chromatography, urea, sucrose and glycine were used as test compounds. The chromatographic conditions were investigated for optimal column efficiency. The column temperature used in common reversed-phase liquid chromatography could also be used for the separation and the flow-rate should be adjusted to 0.3-0.5 ml/min to optimize column efficiency. It is suggested that the velocity of the hydrophilic interaction is slower than the hydrophobic interaction in RPLC. The addition of trifluoroacetic acid is effective for the retention of glycine, but ineffective for urea and sucrose. The diol phase exhibited sufficient chemical stability even if exposed to water in high percentage, and could be applied with isocratic elution for the separation/analysis of amino acids and glucose.     

Synthesis of a key intermediate of novel galbonolide analogues via efficient construction of a conjugated diene system

The development of an efficient synthetic method enabled multi-gram synthesis of a key intermediate, which is useful for the modification at the C6-functional group of galbonolide analogues. The structure of a key intermediate including a conjugated diene was afforded by Horner-Emmons reaction, alkylation of Weinreb amide with alkyl lithium and a subsequent Wittig reaction.     

Characterization of a novel trace-level impurity in lisinopril using multi-stage mass spectrometry

An impurity in the bulk drug lisinopril was detected by simple reversed-phase high-performance liquid chromatography (HPLC). This trace-level impurity was rapidly identified as 2-(2-oxo-azocan-3-ylamino)-4-phenyl- butyric acid on the basis of the on-line multi-stage mass spectrometric evidence, and the proposed structure was further confirmed by multi-stage mass spectrometry of lisinopril and three related compounds.     

Characterization of novel neopullulanase fromBacillus polymyxa

Bacillus polymyxa CECT 155 produces an extracellular neopullulanase activity that degrades pullulan to panose. This activity was stimulated by the presence of pullulan in the culture, and repressed by glucose. The apparent mol wt determined for the enzyme was 58 kDa. The optimum pH and temperature for neopullulanase activity were pH 6.0 and 50°C, respectively. The enzyme was stable in a pH range of 4.0–8.0, and temperatures up to 60°C. These properties make it suitable for the saccharification processes in the starch industries.