- Transition metal-free protodecarboxylation of electron rich aromatic acids under mild conditions
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A mild and practical method for the transition metal-free protodecarboxylation of aromatic acids using readily available and safe sodium persulfate as initiator was described. This environment-friendly decarboxylation approach was performed at 60 °C in ethanol and could easily scale up to the gram level with a good yield. In Particular, the tandem reactions of decarboxylation and halogenation were achieved by the addition of the corresponding halogenating reagents to the reaction system.
- Fang, Jingxian,Wang, Dangui,Deng, Guo-Jun,Gong, Hang
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supporting information
p. 4503 - 4506
(2017/10/30)
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- Reactions of alkynes with [RuCl(cyclopentadienyl)] complexes: The important first steps
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Cyclopentadienyl-ruthenium half-sandwich complexes with η2-bound alkyne ligands have been suggested as catalytic intermediates in the early stages of Ru-catalyzed reactions with alkynes. We show that electronically unsaturated complexes of the formula [RuCl(Cp)(η2-RC=CR')] can be stabilized and crystallized by using the sterically demanding cyclopentadienyl ligand Cp (Cp = η5-l-methoxy-2,4tert-butyl-3-neopentyl-cyclopentadienyl). Furthermore we demonstrate that [RuCl2(Cp)]2 is an active and regioselective catalyst for the [2+2+2] cyclotrimerization of alkynes. The first elementary steps of the reaction of mono(η2- alkyne) complexes containing {RuCl(Cp*)} (Cp* = η5- C5Me5) and (RuCl(Cp)} fragments with alkynes were investigated by DFT calculations at the M06/6-31G* level in combination with a continuum solvent model. Theoretical results are able to rationalize and complement the experimental findings. The presence of the sterically demanding Cp ligand increases the activation energy required for the formation of the corresponding di(η2alkyne) complexes, enhancing the initial regioselectivity, but avoiding the evolution of the system towards the expected cyclotrimerization product when bulky substituents are present. Theoretical results also show that the electronic structure and stability of a metallacyclic intermediate is strongly dependent on the nature of the substituents present in the alkyne.
- Dutta, Barnali,Curchod, Basile F. E.,Campomanes, Pablo,Solari, Euro,Scopelliti, Rosario,Rothlisberger, Ursula,Severin, Kay
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experimental part
p. 8400 - 8409
(2010/09/05)
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- SYNTHESIS OF PHLOROGLUCINOL TRIALKYL ETHERS
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The alkylation of phloroglucinol dialkyl ethers with alcohols or alkyl halides leads, depending on the reaction conditions, either to products of O- or C- alkylation, or to C,O-alkylation products.Reaction conditions were found which enable us to obtain pure phloroglucinol trialkyl ethers.A convenient preparative method for the synthesis of phloroglucinol trialkyl ethers consists in the alkylation of phloroglucinol dialkyl ethers in a two-phase system in presence of phase-transfer catalysts.
- Kirillova, K. M.,Skvortsova, T. A.,Nikonova, L. Z.,Chugunov, Yu. V.,Igonin, V. B.,Mukhtarov, A. Sh.
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p. 427 - 430
(2007/10/02)
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- NICKEL(0)-CATALYZED CYCLOADDITION OF ETHOXYETHYNE WITH CARBON DIOXIDE TO 4,5-DIETHOXY-α-PYRONE
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Ni(0)-phosphine(L) complexes (L=tri-n-alkylphosphines and bis(diphenylphosphino)butane) catalyzed the cycloaddition of ethoxyethyne and carbon dioxide to afford 4,5-diethoxy-α-pyrone regioseletively.
- Tsuda, Tetsuo,Kunisada, Kazuhiro,Nagahama, Norio,Morikawa, Shonei,Saegusa, Takeo
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p. 1575 - 1582
(2007/10/02)
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- Process for preparing a S-trialkoxy benzene
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A 1,3,5-trialkoxy benzene having 1-2 carbon atoms in each of the alkoxy-groups is prepared at high overall yields, with minimal formation of hazardous or polluting by-products, by reacting 1,3,5-tribromo benzene with an alkalimetal alcoholate having 1-3 carbon atoms in the molecule in the presence of a copper salt, e.g. cuprous iodide or cupric chloride, and an aprotic solvent such as e.g. dimethylformamide. The product is readily recovered from the reaction mixture in an overall yield as high as 90%.
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