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11.
The reaction between salicylic acid and dialkyl phosphite was traced by electrospray ionization mass spectrometry and ^31P NMR. All reactants, unstable intermediates and products were detected. The mechanism was proposed based on ESI-MS results and ^31P NMR profiles. 相似文献
12.
磷酰氨基酸的酯交换反应研究 总被引:1,自引:0,他引:1
本文利用^3^1P NMR , 对比研究了磷酰化组氨酸与其它磷酰化氨基酸和一级醇的磷上酯交换的反应速度,实验表明磷酰化组氨酸的反应速度最快. 由此提出了以下机理:由于咪唑环的参与,磷可以形成六配位过渡态,从而加快了反应速度. 相似文献
13.
Yu-Fen Zhao De-Qing Zhang Chu-Biao Xue Jia-Ning Zeng Gai-Jiao Ji 《Journal of mass spectrometry : JMS》1991,26(5):510-513
Positive ion fast atom bombardment mass spectrometry of N-diisopropyloxyphosphoryl dipeptides and tripeptides showed a novel cleavage pattern in that only the N-phosphoryl fragment ions gave intense peaks while the C-terminal series of ions was suppressed. The base peak was the N-phosphoryl imino ion responding to the N-terminal residue. These advantages are superior to those of other types of N-protecting groups. 相似文献
14.
N-phosphorylamino acids are chemically active species that have many biomimic activities. alpha-COOH in amino acids and peptides behaviors rather differently than beta-COOH in many biochemical processes and takes a more important role in the origin of life. Activity differences between alpha-COOH and beta-COOH in the peptide formation of phosphoryl amino acids are studied by 1D, 2D NMR techniques and by ab initio and density functional theory (DFT) calculations in this paper. Phosphoryl dipeptide is formed directly from phosphoryl aspartic acids without any coupling reagents. Only the alpha-dipeptide ester is observed by 1D (1)H, (13)C, and (31)P NMR and 2D NMR. In the ab initio and DFT calculations, the pentacoordinate phosphorane intermediates containing five-membered rings are predicted to be more favored than those with six-membered rings. Both the experimental results and the theoretical calculations suggest that only the alpha-COOH group is activated by N-phosphorylation in N-phosphorylaspartic acid under mild conditions. 相似文献
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17.
Yang Jiang Ru-Gang Zhong Bo Tan Yan-Mei Li Yu-Fen Zhao 《Phosphorus, sulfur, and silicon and the related elements》2013,188(4):831-837
The reactivity of N -phosphoryl f -alanine differs from N -phosphoryl g -alanine and N -phosphoryl n -amino butyric acid enormously. N -phospho- f -alanine could self-activate to yield N -phosphopeptides either in aqueous or nonaqueous media, but not g - or n -amino acid analogues. The mechanism of the reaction is discussed. 相似文献
18.
Two novel tricoordinate phosphorous saccharides, methyl 4,6-O-benzylidene- α -D-glucopyranoside 2,3-cyclic phosphite ethyl ester 3 and its mannoside analogue 5 were synthesized by the reaction of protected pyrannosides (1 and 4) with ethyl dichlorophosphite 2. Addition of 2,3-butanedione to 3 resulted in the formation of pentacoordinate phosphorous compound 6. 相似文献
19.
A nest-shaped cluster [(C4H9)4N]2[WOSe3Cu3Br1.67Cl1.33] (1) and a cage-shaped cluster [(C4H9)4N]3[WSe4Cu3Br2Cl2] (2) were synthesized and their structures were determined by single-crystal X-ray diffraction. It was found that cluster 1 showed better optical limiting properties under an 8 ns pulsed laser at 532 nm but poorer optical limiting properties under a 35 ps pulsed laser compared with its analogue [(C4H9)4N]2[MoOS3Cu3BrCl2]. The influence of the peripheral ligands of the cluster to the optical limiting properties was also discussed. 相似文献
20.
Yan-Chun Guo Jing Li Jiao-Li Ma Zhi-Ran Yu Hai-Wei Wang Wen-Juan Zhu Xin-Cheng Liao Yu-Fen Zhao 《中国化学快报》2015,26(6):755-758
Two series of thieno[2,3-d]pyrimidine derivatives were designed and synthesized, in which bioactive a-aminophosphonate subunits were introduced at the N3 position through an N–N bond connection.The in vitro cytotoxic activity of the novel compounds was tested against human esophageal carcinoma cells(EC109), human hepatocarcinoma cells(Hep G2), human gastric carcinoma cells(MGC-803),respectively, by the MTT method. The evaluation results revealed that compounds 6mb, 6mf, 6mg, 6nd and 6nh exerted the most potent inhibition against Hep G2, MGC-803 and EC109 cells, respectively. In particular, compound 6mg presented excellent inhibitory effect against Hep G2(91.2%) and MGC-803(94.4%) cells. 相似文献