- Palladium on Carbon-Catalyzed Chemoselective Oxygen Oxidation of Aromatic Acetals
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The development of an unprecedented chemoselective transformation has contributed to forming a novel synthetic process for target molecules. Chemoselective oxidation of aromatic acetals has been accomplished using a reusable palladium on carbon catalyst under atmospheric oxygen conditions to form ester derivatives with tolerance of aliphatic acetals and ketals.
- Yasukawa, Naoki,Asai, Shota,Kato, Maho,Monguchi, Yasunari,Sajiki, Hironao,Sawama, Yoshinari
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p. 5604 - 5607
(2016/11/17)
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- Efficient synthesis of alkyl aryl ketones & ketals via palladium-catalyzed regioselective arylation of vinyl ethers
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The combination of Pd(OAc)2 with 1,3-bis(diphenylphosphino) propane (dppp) in ethylene glycol constitutes a high-performance catalytic system for highly regioselective arylation of a range of electron-rich vinyl ethers by aryl bromides to provide, upon hydrolysis, alkyl aryl ketones and cyclic ketals in good yields with up to 3.75 × 105 TON and 15625 h-1 TOF.
- Liu, Mingcui,Hyder, Zeynab,Sun, Yawei,Tang, Weijun,Xu, Lijin,Xiao, Jianliang
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supporting information; experimental part
p. 2012 - 2015
(2010/07/04)
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- Hydrogen-bond-directed catalysis: Faster, regioselective and cleaner heck arylation of electron-rich olefins in alcohols
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A general method for the regioselective Heck reaction of electronrich olefins is presented. Fast, highly regioselective Pd-catalysed α-arylation of electron-rich olefins, vinyl ethers (1a-d), hydroxyl vinyl ethers (1e,f), enamides (1g,h) and a substituted vinyl ether (1i) has been accomplished with a diverse range of aryl bromides (2a-r), for the first time, in cheap, green and easily available alcohols with no need for any halide scavengers or salt additives. The reaction proceeds with high efficiency, leading exclusively to the a-products, in 2-propanol and particularly in ethylene glycol. In the latter, the arylation can be catalysed at a palladium loading of 0.1 mol% and finish in as short a time as 0.5 h. The remarkable performance of the alcohol solvents in promoting a regiocontrol is attributed to their hydrogen-bond- donating capability, which is believed to facilitate the dissociation of halide anions from PdII, and hence, the generation of a key ionic Pd II-olefin intermediate responsible for the a product. This belief is further strengthened by the study of a benchmark arylation reaction in 21 different solvents. The study revealed that exclusive α-regioselective arylation takes place in almost all of the protic solvents, and there is a rough correlation between the α-arylation rates and the solvent parameter ETN. The method is simpler, cleaner and more general than those established thus far.
- Hyder, Zeynab,Ruan, Jiwu,Xiao, Jianliang
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experimental part
p. 5555 - 5566
(2009/06/17)
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- PALLADIUM CATALYSED HECK ARYLATION OR VINYLATION OF 1-SUBSTITUTED OLEFINS
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The present invention relates to a process for preparing arylated or vinylated olefins.
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Page/Page column 13-14
(2008/06/13)
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- The Heck reaction of electron-rich olefins with regiocontrol by hydrogen-bond donors
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No salt please: Halide scavengers AgOTf and TlOAc are not required for the Heck coupling of electron-rich olefins with aryl bromides and chlorides. Using ammonium additives, these reactions can be carried out in either an imidazolium ionic liquid or a common molecular solvent, thus furnishing 1,1′- disubstituted olefins in high yields with excellent regioselectivities. (Chemical Equation Presented).
- Mo, Jun,Xiao, Jianliang
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p. 4152 - 4157
(2007/10/03)
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- Palladium-catalysed direct regioselective synthesis of cyclic ketals from electron-rich olefins and aryl bromides in ionic liquids
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The Heck reaction comprises one of the most important carbon-carbon coupling reactions in organic synthesis. The popularity of the reaction is attributable to the broad availability of aryl halides and to the tolerance of the reaction for a wide variety o
- Hyder, Zeynab,Mo, Jun,Xiao, Jianliang
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p. 1699 - 1704
(2007/10/03)
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- Direct synthesis of protected arylacetaldehydes by tetrakis(phosphane)- palladium-catalyzed arylation of ethyleneglycol vinyl ether
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A range of aryl bromides undergo Heck reaction with ethylene glycol vinyl ether, in the presence of [PdCl(C3H5)]2/ cis,cis,cis-1,2,3,4-tetrakis[(diphenylphosphanyl)methyl]cyclopentane as catalyst, to give regioselectively protected arylacetaldehydes in good yields. The β-arylation products were obtained in with 93-100 % selectivity with electron-poor aryl bromides or heteroaryl bromides. Furthermore, this catalyst can be used at low loading, even for reactions with sterically hindered aryl bromides. The aryl vinyl ether intermediates undergo subsequent ketalisation to give the corresponding 2-benzyl-1,3-dioxolane derivatives. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
- Kondolff, Isabelle,Doucet, Henri,Santelli, Maurice
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p. 765 - 774
(2007/10/03)
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- Direct synthesis of protected arylacetaldehydes by palladium- tetraphosphine-catalyzed arylation of ethyleneglycol vinylether
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Through the use of [PdCl(C3H5)]2/cis,cis, cis-1,2,3,4-tetrakis(diphenylphosphinomethyl) cyclopentane as a catalyst, a range of aryl bromides undergo Heck reaction with ethyleneglycol vinylether to give regioselectively protected arylacetaldehydes in good yields. The β-arylation products were obtained in the range 93-98% selectivity with electron-poor aryl bromides. Furthermore, this catalyst can be used at low loading, even for reactions of sterically hindered aryl bromides. The arylvinyl ethers intermediates undergo subsequent ketalization to give the corresponding 2-benzyl-1,3-dioxolane derivatives.
- Kondolff, Isabelle,Doucet, Henri,Santelli, Maurice
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p. 1561 - 1564
(2007/10/03)
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- Photo-Arbuzov rearrangements of 1-arylethyl phosphites: Stereochemical studies and the question of radical-pair intermediates
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The direct UV irradiation of the 1-arylethyl phosphites 7, 8, and 9 was carried out in acetonitrile, benzene, and cyclohexane, as was the triphenylene-sensitized reaction of 9. Dimethyl 1-phenylethyl phosphite, 7, gives the photo-Arbuzov rearrangement pro
- Bhanthumnavin,Bentrude
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p. 980 - 990
(2007/10/03)
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- The efficient deprotection of acetals and tetrahydropyranyl derivatives of phenols using [Ru(CH3CN)3(triphos)](OTf)2 as a catalyst
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Acetals and tetrahydropyranyl derivatives of phenols are efficiently and highly chemoselectively deprotected in the presence of catalytic amounts of [Ru(CH3CN)3)(triphos)](OTf)2 (triphos = CH3C(CH2PPh2)3), under mild condition, in good to excellent yields.
- Ma,Venanzi
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p. 8071 - 8074
(2007/10/02)
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