- Water-initiated hydrocarboxylation of terminal alkynes with CO2and hydrosilane
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This work discloses a Cu(ii)-Ni(ii) catalyzed tandem hydrocarboxylation of alkynes with polysilylformate formed from CO2and polymethylhydrosiloxane that affords α,β-unsaturated carboxylic acids with up to 93% yield. Mechanistic studies indicate that polysilylformate functions as a source of CO and polysilanol. Besides, a catalytic amount of water is found to be critical to the reaction, which hydrolyzes polysilylformate to formic acid that induces the formation of Ni-H active species, thereby initiating the catalytic cycle.
- Wang, Meng-Meng,Lu, Sheng-Mei,Paridala, Kumaraswamy,Li, Can
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supporting information
p. 1230 - 1233
(2021/02/09)
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- The Development of a Stereoselective Method for the Synthesis of Tetrasubstituted Derivatives of α,β-Unsaturated Carboxylic Acids
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Alkenes possessing four different carbon-linked substituents are the main structural motif of many biologically active compounds. The derivatives of (2E)-3-(3-methoxyphenyl)-2-methylpent-2-enoic acid ((E)-2c) are suitable precursors for the synthesis of Tapentadol, a novel centrally acting analgesic. It was found that the Ni-carbometallation reaction of disubstituted alkyne 8 with CO2and an Et2Zn allows for efficient and practical preparation of (E)-2c as a single (E)-regioisomer in 89% of isolated yield. The influence of the size of the aliphatic substituent of alkyne and the steric hindrance of the organozinc reagent on stereochemical course of the carbometallation reaction was evaluated. Finally, air-stable Ni(dme)Cl2was proposed as an alternative to widely used Ni(cod)2catalyst.
- Rzymkowski, Jan,Pi?tek, Anna
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p. 665 - 673
(2016/09/21)
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- Solvent and ligand partition reaction pathways in nickel-mediated carboxylation of methylenecyclopropanes
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Methylenecyclopropanes are carboxylated with gaseous carbon dioxide in the presence of a stoichiometric amount of a nickel complex; the reaction pathways are significantly influenced by the reaction solvent and the amine ligand. The Royal Society of Chemi
- Murakami, Masahiro,Ishida, Naoki,Miura, Tomoya
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p. 643 - 645
(2008/02/10)
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- Cp2ZrCl2-mediated three-component coupling reactions of CO2, ethylene (or alkynes), and electrophiles leading to carboxylic acid derivatives
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Zirconacycles 1 and 2 can be simply generated from Cp2ZrCl 2, EtMgBr, and an atmospheric pressure of CO2. The treatment of Cp2ZrCl2 with EtMgBr followed by exposure to CO2 generates zirconacycle 1, which can react with various electrophiles to give a variety of carboxylic acid derivatives. Unsaturated zirconacycles 2 can also generated from Cp2ZrCl2, EtMgBr, alkynes, and CO2. Complexes 2 react with electrophiles to give α,β-unsaturated acids stereoselectively.
- Yamashita, Kohei,Chatani, Naoto
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p. 919 - 922
(2007/10/03)
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- Iodo-aryl carbonates for use in methods in radiography
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A method for using iodo-aryl carbonates, such as for example, p-iodo-benzyl carbonates, p-iodo-sec-phenethyl carbonates, p-iodo-phenethyl carbonates, p-iodo-phenyl carbonates, 3-(p-iodophenyl)propyl carbonates, 3-(p-iodophenyl)butyl carbonates, 2-(p-iodobenzyl)butyl carbonates and 2-(p-iodobenzyl)-n-hexyl carbonates, to provide radiopaques for various radiography purposes in connection with such techniques as X-ray applications including myelography, salpingography, lymphography and bronchography. The method first comprises selecting a compound generally categorized as a carbonate and having the general formula STR1 wherein R represents an alkyl group having from 1 to 10 carbon atoms and R' represents an iodinated phenyl linked directly to the ester oxygen or through an alkyl chain consisting of 1 to 3 carbon atoms. An effective amount of a pharmaceutically acceptable carbonate, as defined herein, is then placed into the subject body cavity and the particular X-ray or other study performed of this area.
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- Iodine containing organic carbonates for use as radiographic agents
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Iodo-aryl carbonates, such as for example, p-iodo-benzyl carbonates, p-iodo-sec-phenethyl carbonates, p-iodo-phenethyl carbonates, p-iodo-phenyl carbonates, 3-(p-iodophenyl)propyl carbonates, 3-(p-iodophenyl)butyl carbonates, 2-(p-iodobenzyl)butyl carbonates and 2-(p-iodobenzyl)-n-hexyl carbonates, for use as radiographic media in connection with such techniques as x-ray applications including myelography, salpingography, lymphography and bronchography. An effective quantity of iodinated organic carbonate provides x-ray contrast, and the compounds of the invention may be characterized generally as carbonates having the general formula STR1 wherein R represents an alkyl group having from 4 to 10 carbon atoms and R' represents an iodinated phenyl linked to the ester oxygen through an alkyl chain consisting of 1 to 3 carbon atoms.
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