- Nickel-Catalyzed Multicomponent Coupling: Synthesis of α-Chiral Ketones by Reductive Hydrocarbonylation of Alkenes
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A nickel-catalyzed, multicomponent regio- and enantioselective coupling via sequential hydroformylation and carbonylation from readily available starting materials has been developed. This modular multicomponent hydrofunctionalization strategy enables the straightforward reductive hydrocarbonylation of a broad range of unactivated alkenes to produce a wide variety of unsymmetrical dialkyl ketones bearing a functionalized α-stereocenter, including enantioenriched chiral α-aryl ketones and α-amino ketones. It uses chiral bisoxazoline as a ligand, silane as a reductant, chloroformate as a safe CO source, and a racemic secondary benzyl chloride or an N-hydroxyphthalimide (NHP) ester of a protected α-amino acid as the alkylation reagent. The benign nature of this process renders this method suitable for late-stage functionalization of complex molecules.
- Chen, Jian,Zhu, Shaolin
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supporting information
p. 14089 - 14096
(2021/09/13)
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- Development of a catalytic platform for nucleophilic substitution: Cyclopropenone-catalyzed chlorodehydration of alcohols
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Cyclopropenone makes the switch: 2,3-Bis-(p-methoxyphenyl)cyclopropenone is a highly efficient catalyst for the chlorodehydration of 20 diverse alcohol substrates (see scheme; X=Cl). With oxalyl chloride as catalytic activator, this nucleophilic substitution proceeded through cyclopropenium-activated intermediates and resulted in complete stereochemical inversion in substrates with chiral centers.
- Vanos, Christine M.,Lambert, Tristan H.
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supporting information; experimental part
p. 12222 - 12226
(2012/02/02)
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- Palladium-catalyzed oxidative arylhalogenation of alkenes: Synthetic scope and mechanistic insights
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This article describes the development of a Pd-catalyzed reaction for the arylhalogenation (halogen = Cl or Br) of diverse α-olefins by oxidatively intercepting Mizoroki-Heck intermediates. These transformations afford synthetically useful 1,2- and 1,1-arylhalogenated products in good yields with good to excellent selectivities that can be modulated by changing the nature of the halogenating reagent and/or the reaction conditions. The selectivity of these reactions can be rationally tuned by (i) controlling the relative rates of oxidative functionalization versus β-hydride elimination from equilibrating PdII-alkyl species and (ii) stabilization of organometallic PdII intermediates through the formation of π-benzyl adducts. These arylhalogenations exhibit modest to excellent levels of stereoselectivity, and the key carbon-halogen bond-forming step proceeds with predominant retention of stereochemistry at carbon.
- Kalyani, Dipannita,Satterfield, Andrew D.,Sanford, Melanie S.
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supporting information; experimental part
p. 8419 - 8427
(2010/08/04)
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- Oxidatively intercepting heck intermediates: Pd-catalyzed 1,2- and 1,1-arylhalogenation of alkenes
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This communication describes the development of two Pd-catalyzed reactions for the arylchlorination of diverse α-olefins by oxidatively intercepting Heck intermediates. Depending on the nature of the oxidant and the reaction conditions, these transformati
- Kalyani, Dipannita,Sanford, Melanie S.
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p. 2150 - 2151
(2008/09/21)
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- Laser Flash, Laser-Drop, and Lamp Photolysis of 1,3-Dichloro-1,3-diphenylpropane. One- versus Two-Photon Reaction Pathways
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Low intensity irradiation of 1,3-dichloro-1,3-diphenylpropane (1) in cyclohexane leads to the formation of 3-chloro-1,3-diphenylpropyl radical (2) through homolytic C-Cl bond cleavage. Radical 2 gives rise to final products typical of free radical reactions. Neither 1,2-diphenylcyclopropanes (6) nor 3-cyclohexyl-1,3-diphenylpropene (20) are obtained under these conditions. Nevertheless, high intensity laser irradiation of the initially formed monoradical 2 leads to the 1,3-diphenylpropenyl radical (3) detected with nanosecond techniques. This intermediate is completely trapped by the cyclohexyl radicals generated in the medium to yield 20. Photolysis of 1 with the laser-drop technique leads to the cyclopropanes 6 as major photoproducts.
- Miranda, Miguel Angel,Perez-Prieto, Julia,Font-Sanchis, Enrique,Konya, Klara,Scaiano
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p. 5713 - 5719
(2007/10/03)
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- Lamp versus laser photolysis of 1,3-dichloro-1,3-diphenylpropane in cyclohexane. Direct observation of 1,3-diphenylpropenyl radical
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Laser photolysis of the title compound leads to two-photon processes indicating the involvement of the 1,3-diphenylpropanediyl biradical (12) and the 1,3-diphenylallyl radical (10).
- Perez-Prieto, Julia,Miranda, Miguel Angel,Font-Sanchis, Enrique,Konya, Klara,Scaiano
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p. 4923 - 4926
(2007/10/03)
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