Pd-catalyzed oxidative coupling reaction was of great importance in the aromatic C--H activation and the for-mation of new C-O and C--C bonds. Sanford has pioneered practical, directed C-H activation reactions em-ploy...Pd-catalyzed oxidative coupling reaction was of great importance in the aromatic C--H activation and the for-mation of new C-O and C--C bonds. Sanford has pioneered practical, directed C-H activation reactions em-ploying Pd（OAc）2 as catalyst since 2004. However, until now, the speculated reactive Pd（Ⅳ） transient intermedi-ates in these reactions have not been isolated or directly detected from reaction solution. Electrospray ionization tandem mass spectrometry （ESI-MS/MS） was used to intercept and characterize the reactive Pd（Ⅳ） transient inter-mediates in the solutions of Pd（OAc）2-catalyzed oxidative coupling reactions. In this study, the Pd（IV） transient in-termediates were detected from the solution of Pd（OAc）2-catalyzed oxidative coupling reactions by ESI-MS and the MS/MS of the intercepted Pd（IV） transient intermediate in reaction system was the same with the synthesized au-thentic Pd（Ⅳ） complex. Our ESI-MS（/MS） studies confirmed the presence of Pd（Ⅳ） reaction transient intermedi-ates. Most interestingly, the MS/MS of Pd（Ⅳ） transient intermediates showed the reductive elimination reactivity to Pd（Ⅱ） complexes with new C-O bond formation into product in gas phase, which was consistent with the proposed reactivity of the Pd（Ⅳ） transient intermediates in solution.展开更多
N-Phosphoryl peptide libraries were constructed by transformation from homo-oligopeptide libraries, which was synthesized by self-assembly of amino acids with the assistance of phosphorus oxychloride. Electrospray ion...N-Phosphoryl peptide libraries were constructed by transformation from homo-oligopeptide libraries, which was synthesized by self-assembly of amino acids with the assistance of phosphorus oxychloride. Electrospray ionization mass spectrometry (ESI-MS) was used to monitor the reaction.展开更多
High-throughput lipidomic profiling provides a sensitive approach for discovering minor lipid species. By using an advance in electrospray ionization tandem mass spectrome- try, a large set of phospholipid molecular s...High-throughput lipidomic profiling provides a sensitive approach for discovering minor lipid species. By using an advance in electrospray ionization tandem mass spectrome- try, a large set of phospholipid molecular species （126 species） with high resolution were identified from Arabidopsis seedling; of them 31 species are newly identified （16 are unique in plants）, including 13 species of phosphatidic acid （PA）, nine phosphati- dylcholine, six phosphatidylinositol and three phosphatidylser- ine. Further analysis of the lipidomic profile reveals dynamics of phospholipids and distinct species alterations during seedling development. PA molecules are found at the lowest levels in imbibition and follow an increasing trend during seedling growth, while phosphatidylethanolamine （PE） molecules show the opposite pattern with highest levels at imbibition and a general decreasing trend at later stages. Of PA molecular species, 34：2-, 34：3-, 36：4, 36：5-, 38：3- and 38：4-PA increase during radicle emergence, and 34：2- and 34：3-PA reach highest levels during hypocotyl and cotyledon emergence from the seed coat. Conversely, molecular species of PE show higher levels in imbibition and decrease in later stages. These results suggest the crucial roles of specific molecular species and homeostasis of phospholipid molecules in seedling growth and provide insights into the mechanisms of how phospholipid molecules are involved in regulating plant development.展开更多
文摘Pd-catalyzed oxidative coupling reaction was of great importance in the aromatic C--H activation and the for-mation of new C-O and C--C bonds. Sanford has pioneered practical, directed C-H activation reactions em-ploying Pd（OAc）2 as catalyst since 2004. However, until now, the speculated reactive Pd（Ⅳ） transient intermedi-ates in these reactions have not been isolated or directly detected from reaction solution. Electrospray ionization tandem mass spectrometry （ESI-MS/MS） was used to intercept and characterize the reactive Pd（Ⅳ） transient inter-mediates in the solutions of Pd（OAc）2-catalyzed oxidative coupling reactions. In this study, the Pd（IV） transient in-termediates were detected from the solution of Pd（OAc）2-catalyzed oxidative coupling reactions by ESI-MS and the MS/MS of the intercepted Pd（IV） transient intermediate in reaction system was the same with the synthesized au-thentic Pd（Ⅳ） complex. Our ESI-MS（/MS） studies confirmed the presence of Pd（Ⅳ） reaction transient intermedi-ates. Most interestingly, the MS/MS of Pd（Ⅳ） transient intermediates showed the reductive elimination reactivity to Pd（Ⅱ） complexes with new C-O bond formation into product in gas phase, which was consistent with the proposed reactivity of the Pd（Ⅳ） transient intermediates in solution.
文摘N-Phosphoryl peptide libraries were constructed by transformation from homo-oligopeptide libraries, which was synthesized by self-assembly of amino acids with the assistance of phosphorus oxychloride. Electrospray ionization mass spectrometry (ESI-MS) was used to monitor the reaction.
基金supported by National Natural Science Foundation (31130060, 31161130532)
文摘High-throughput lipidomic profiling provides a sensitive approach for discovering minor lipid species. By using an advance in electrospray ionization tandem mass spectrome- try, a large set of phospholipid molecular species （126 species） with high resolution were identified from Arabidopsis seedling; of them 31 species are newly identified （16 are unique in plants）, including 13 species of phosphatidic acid （PA）, nine phosphati- dylcholine, six phosphatidylinositol and three phosphatidylser- ine. Further analysis of the lipidomic profile reveals dynamics of phospholipids and distinct species alterations during seedling development. PA molecules are found at the lowest levels in imbibition and follow an increasing trend during seedling growth, while phosphatidylethanolamine （PE） molecules show the opposite pattern with highest levels at imbibition and a general decreasing trend at later stages. Of PA molecular species, 34：2-, 34：3-, 36：4, 36：5-, 38：3- and 38：4-PA increase during radicle emergence, and 34：2- and 34：3-PA reach highest levels during hypocotyl and cotyledon emergence from the seed coat. Conversely, molecular species of PE show higher levels in imbibition and decrease in later stages. These results suggest the crucial roles of specific molecular species and homeostasis of phospholipid molecules in seedling growth and provide insights into the mechanisms of how phospholipid molecules are involved in regulating plant development.
