- Palladium-Catalyzed Stereoselective Aza-Wacker-Heck Cyclization: One-Pot Stepwise Strategy toward Tetracyclic Fused Heterocycles
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Palladium-catalyzed intramolecular tandem cyclization reactions were conducted for the synthesis of densely cis/cis-fused aza-tetracyclic structures. The process involved a palladium(II)-catalyzed aerobic aza-Wacker reaction, followed by a palladium(0)-catalyzed Heck reaction. The effects of the solvent and benzene substitution pattern on the one-pot, two-step cascade reaction were studied systematically, and a probable mechanism was proposed. Strained pentahydrobenzo[f]cyclopenta[hi]indolizin-6-one and racemic γ-lycorane can also be synthesized rapidly using this palladium-catalyzed aza-Wacker-Heck cyclization reaction.
- Chen, Li-Yuan,Chuang, Ta-Hsien,Lai, Chin-Hung,Tang, Rong-Shiow
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supporting information
p. 9337 - 9341
(2020/12/21)
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- Palladium-Catalyzed Regioselective C-H Iodination of Unactivated Alkenes
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A palladium-catalyzed C-H iodination of unactivated alkenes is reported. A picolinamide directing group enables the regioselective functionalization of a wide array of olefins to furnish iodination products as single stereoisomers. Mechanistic investigations suggest the reversible formation of a six-membered alkenyl palladacycle intermediate through a turnover-limiting C-H activation.
- Schreib, Benedikt S.,Carreira, Erick M.
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supporting information
p. 8758 - 8763
(2019/06/13)
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- Boosting Hydrogen Production by Anodic Oxidation of Primary Amines over a NiSe Nanorod Electrode
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For electrocatalytic water splitting, the sluggish anodic oxygen evolution reaction (OER) restricts the cathodic hydrogen evolution reaction (HER). Therefore, developing an alternative anodic reaction with accelerating kinetics to produce value-added chemicals, especially coupled with HER, is of great importance. Now, a thermodynamically more favorable primary amine (?CH2?NH2) electrooxidation catalyzed by NiSe nanorod arrays in water is reported to replace OER for enhancing HER. The increased H2 production can be obtained at cathode; meanwhile, a variety of aromatic and aliphatic primary amines are selectively electrooxidized to nitriles with good yields at the anode. Mechanistic investigations suggest that NiII/NiIII may serve as the redox active species for the primary amines transformation. Hydrophobic nitrile products can readily escape from aqueous electrolyte/electrode interface, avoiding the deactivation of the catalyst and thus contributing to continuous gram-scale synthesis.
- Chong, Xiaodan,Huang, Yi,Liang, Yu,Liu, Cuibo,Zhang, Bin
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supporting information
p. 13163 - 13166
(2018/09/21)
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- Palladium-Catalyzed Aerobic Oxidative Cyclization of Aliphatic Alkenyl Amides for the Construction of Pyrrolizidine and Indolizidine Derivatives
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An efficient palladium-catalyzed aerobic oxidative cyclization has been developed to synthesize a variety of pyrrolizidine and indolizidine derivatives from simple aliphatic alkenyl amides in moderate to good yields. The reaction features the capability of accessing various N-heterocycles and the use of molecular oxygen (1 atm) as the green oxidant.
- Lo, Kai-Yip,Ye, Liu,Yang, Dan
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supporting information
p. 1570 - 1575
(2017/08/11)
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- Direct cyanomethylation of aliphatic and aromatic hydrocarbons with acetonitrile over a metal loaded titanium oxide photocatalyst
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A platinum-loaded TiO2 (Pt/TiO2) photocatalyst promoted cyanomethylation of aliphatic hydrocarbons, namely cyclohexane and cyclohexene, with acetonitrile, where the photogenerated hole oxidatively dissociates the C-H bond of both the acetonitrile and the aliphatic hydrocarbons to form each corresponding radical species before their radical cross-coupling. The Pt/TiO2 photocatalyst was more active than the Pd/TiO2 photocatalyst in these reactions. In contrast, the cyanomethylation of benzene was promoted by the Pd/TiO2 photocatalyst or a physical mixture of the Pt/TiO2 photocatalyst and a Pd catalyst supported by Al2O3, while it was hardly promoted by the Pt/TiO2 photocatalyst alone. The temperature dependence of the reaction rate proved that the Pd nanoparticles on the TiO2 photocatalyst thermally function as a metal catalyst. These results clearly suggest that the Pd metal catalyst is necessary for the cyanomethylation of benzene. However, in the cyanomethylation of aliphatic hydrocarbons, the catalytic effect of the metal particles was not observed, meaning that the radical coupling takes place without the metal catalysis. Thus, it is concluded that in the case of the benzene cyanomethylation the Pd nanoparticles play dual roles, as a catalyst to catalyse the substitution reaction of benzene with the cyanomethyl radical, and as an electron receiver to reduce the recombination of the photoexcited electrons and holes in the TiO2 photocatalyst, although they could not contribute as a catalyst to the cyanomethylation of aliphatic hydrocarbons.
- Wada, Emiko,Takeuchi, Tomoaki,Fujimura, Yuki,Tyagi, Akanksha,Kato, Tatsuhisa,Yoshida, Hisao
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p. 2457 - 2466
(2017/07/22)
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- Highly efficient Narasaka-Heck cyclizations mediated by P(3,5-(CF 3)2C6H3)3: Facile access to N-heterobicyclic scaffolds
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N-heterobicyclic scaffolds: Highly efficient palladium-catalyzed cyclizations of oxime esters with cyclic alkenes were used as a general entry to perhydroindole and related scaffolds. The chemistry is reliant upon the use of P(3,5-(CF3)2/
- Faulkner, Adele,Bower, John F.
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p. 1675 - 1679
(2012/04/05)
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- Palladium-catalyzed transformation of cyclobutanone O-benzoyloximes to nitriles via C-C bond cleavage
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Palladium-catalyzed transformation of cyclobutanone O-benzoyloximes to a variety of nitriles is described. The reaction may proceed via two important steps, that is, (i) oxidative addition of the N-O bond of oximes to Pd(0) to give a cyclobutylideneaminopalladium(II) species and (ii) β-carbon elimination of this species to afford a reactive alkylpalladium species. The kind of products is very dependent on the nature of substituents on the cyclobutane ring. The direction of the C-C bond cleavage is controlled by the kind of ligand employed. The sequential reaction composed of the C-C bond cleavage and the subsequent intra- and intermolecular C-C bond formations via the corresponding alkylpalladium species is also demonstrated. For example, an oxime having an alkynyl moiety at a suitable position reacts with a variety of alkenes to afford nitriles bearing dienylcyclopentane moiety in moderate to good yields.
- Nishimura, Takahiro,Nishiguchi, Yoshiki,Maeda, Yasunari,Uemura, Sakae
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p. 5342 - 5347
(2007/10/03)
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- Radical reductive alkylation of enamines: Conversion of the products into alkenes and primary amines
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Procedures for the conversion of tertiary amines, obtained by radical reductive alkylation of enamines, into alkenes (Cope reaction) and primary amines (double β-elimination reaction) are presented.
- Renaud,Betrisey
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p. 3479 - 3491
(2007/10/03)
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- Preparation of 3-Hydroxycyclohexaneacetonitriles
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Preparation of cis-4-tert-butyl-cis-3-hydroxycyclohexaneacetonitrile (2) and the parent cis-3-hydroxycyclohexaneacetonitrile (1) is described.In intermediates leading to 2 severe crowding at axially substituted C(3) leads to unusual reactions, including rapid intramolecular oxonium ion formation at 0-5 deg C, abnormally easy hydride reduction of a nitrile, and formation of an open-chain hemiacetal that is relatively stable to aqueous acid.
- Ayral-Kaloustian, Semiramis,Agosta, William C.
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p. 4880 - 4885
(2007/10/02)
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