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181.
John R. Stutzman Carl A. Luongo Scott A. McLuckey 《Journal of mass spectrometry : JMS》2012,47(6):669-675
Protonated angiotensin II and protonated leucine enkephalin‐based peptides, which included YGGFL, YGGFLF, YGGFLH, YGGFLK and YGGFLR, were subjected to ion/ion reactions with the doubly deprotonated reagents 4‐formyl‐1,3‐benzenedisulfonic acid (FBDSA) and 1,3‐benzenedisulfonic acid (BDSA). The major product of the ion/ion reaction is a negatively charged complex of the peptide and reagent. Following dehydration of [M + FBDSA‐H]? via collisional‐induced dissociation (CID), angiotensin II (DRVYIHPF) showed evidence for two product populations, one in which a covalent modification has taken place and one in which an electrostatic modification has occurred (i.e. no covalent bond formation). A series of studies with model systems confirmed that strong non‐covalent binding of the FBDSA reagent can occur with subsequent ion trap CID resulting in dehydration unrelated to the adduct. Ion trap CID of the dehydration product can result in cleavage of amide bonds in competition with loss of the FBDSA adduct. This scenario is most likely for electrostatically bound complexes in which the peptide contains both an arginine residue and one or more carboxyl groups. Otherwise, loss of the reagent species from the complex, either as an anion or as a neutral species, is the dominant process for electrostatically bound complexes. The results reported here shed new light on the nature of non‐covalent interactions in gas phase complexes of peptide ions that can be used in the rationale design of reagent ions for specific ion/ion reaction applications. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
182.
《Journal of Coordination Chemistry》2012,65(2):296-306
New six-coordinate ruthenium(III) complexes [RuX(EPh3)2(L)] (X = Cl or Br; E = P or As; L = chalcone thiosemicarbazone) have been prepared by reacting [RuX3(EPh3)3] (X = Cl or Br; E = P or As) with chalcone thiosemicarbazones in benzene under reflux. The new complexes have been characterized by analytical and spectroscopic (IR, electronic, mass, and EPR) data. The redox behavior of the complexes has also been studied. Based on the above data, an octahedral structure has been assigned for all the complexes. The new complexes exhibit catalytic activity for carbon–carbon coupling reactions. 相似文献
183.
Eosin Y as a Direct Hydrogen‐Atom Transfer Photocatalyst for the Functionalization of C−H Bonds 下载免费PDF全文
Xuan‐Zi Fan Dr. Jia‐Wei Rong Hao‐Lin Wu Quan Zhou Dr. Hong‐Ping Deng Jin Da Tan Cheng‐Wen Xue Dr. Li‐Zhu Wu Dr. Hai‐Rong Tao Dr. Jie Wu 《Angewandte Chemie (International ed. in English)》2018,57(28):8514-8518
Eosin Y, a well‐known economical alternative to metal catalysts in visible‐light‐driven single‐electron transfer‐based organic transformations, can behave as an effective direct hydrogen‐atom transfer catalyst for C?H activation. Using the alkylation of C?H bonds with electron‐deficient alkenes as a model study revealed an extremely broad substrate scope, enabling easy access to a variety of important synthons. This eosin Y‐based photocatalytic hydrogen‐atom transfer strategy is promising for diverse functionalization of a wide range of native C?H bonds in a green and sustainable manner. 相似文献
184.
Clément Ghiazza Vincent Debrauwer Dr. Cyrille Monnereau Lhoussain Khrouz Dr. Maurice Médebielle Dr. Thierry Billard Dr. Anis Tlili 《Angewandte Chemie (International ed. in English)》2018,57(36):11781-11785
The first visible‐light‐mediated synthesis of trifluoromethylselenolated arenes under metal‐free conditions is reported. The use of an organic photocatalyst enables the trifluoromethylselenolation of arene diazonium salts using the shelf‐stable reagent trifluoromethyl tolueneselenosulfonate at room temperature. The reaction does not require the presence of any additives and shows high functional‐group tolerance, covering a very broad range of starting materials. Mechanistic investigations, including EPR spectroscopy, luminescence investigations, and cyclic voltammetry allow rationalization of the reaction mechanism. 相似文献
185.
The use of dimedone in green chemistry has been described for the synthesis of selective heterocyclic motifs which are both pharmacologically and industrially important. The objective of this review is to summarize some of the selected recent advances of dimedone in the synthesis of organic compounds utilizing green chemistry procedures. 相似文献
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An Ylide Transformation of Rhodium(I) Carbene: Enantioselective Three‐Component Reaction through Trapping of Rhodium(I)‐Associated Ammonium Ylides by β‐Nitroacrylates 下载免费PDF全文
Xiaochu Ma Dr. Jun Jiang Siying Lv Wenfeng Yao Yang Yang Dr. Shunying Liu Dr. Fei Xia Prof. Dr. Wenhao Hu 《Angewandte Chemie (International ed. in English)》2014,53(48):13136-13139
The chiral RhI–diene‐catalyzed asymmetric three‐component reaction of aryldiazoacetates, aromatic amines, and β‐nitroacrylates was achieved to obtain γ‐nitro‐α‐amino‐succinates in good yields and with high diastereo‐ and enantioselectivity. This reaction is proposed to proceed through the enantioselective trapping of RhI‐associated ammonium ylides by nitroacrylates. This new transformation represents the first example of RhI‐carbene‐induced ylide transformation. 相似文献