116296-33-4Relevant academic research and scientific papers
Catalyst- And Silane-Controlled Enantioselective Hydrofunctionalization of Alkenes by Cobalt-Catalyzed Hydrogen Atom Transfer and Radical-Polar Crossover
Ebisawa, Kousuke,Izumi, Kana,Ooka, Yuka,Kato, Hiroaki,Kanazawa, Sayori,Komatsu, Sayura,Nishi, Eriko,Shigehisa, Hiroki
, p. 13481 - 13490 (2020)
The catalytic enantioselective synthesis of tetrahydrofurans, which are found in the structures of many biologically active natural products, via a transition-metal-catalyzed hydrogen atom transfer (TM-HAT) and radical-polar crossover (RPC) mechanism is described herein. Hydroalkoxylation of nonconjugated alkenes proceeded efficiently with excellent enantioselectivity (up to 94% ee) using a suitable chiral cobalt catalyst, N-fluoro-2,4,6-collidinium tetrafluoroborate, and diethylsilane. Surprisingly, the absolute configuration of the product was highly dependent on the steric hindrance of the silane. Slow addition of the silane, the dioxygen effect on the solvent, thermal dependence, and DFT calculation results supported the unprecedented scenario of two competing selective mechanisms. For the less-hindered diethylsilane, a high concentration of diffused carbon-centered radicals invoked diastereoenrichment of an alkylcobalt(III) intermediate by a radical chain reaction, which eventually determined the absolute configuration of the product. On the other hand, a more hindered silane resulted in less opportunity for a radical chain reaction, instead facilitating enantioselective kinetic resolution during the late-stage nucleophilic displacement of the alkylcobalt(IV) intermediate.
6-azabicyclo[3.2.1]octanes via copper-catalyzed enantioselective alkene carboamination
Casavant, Barbara J.,Hosseini, Azade S.,Chemler, Sherry R.
supporting information, p. 2697 - 2702 (2014/09/29)
Bridged bicyclic rings containing nitrogen heterocycles are important motifs in bioactive small organic molecules. An enantioselective copper-catalyzed alkene carboamination reaction that creates bridged heterocycles is reported herein. Two new rings are
Regio- and enantioselective aminofluorination of alkenes
Kong, Wangqing,Feige, Pascal,De Haro, Teresa,Nevado, Cristina
supporting information, p. 2469 - 2473 (2013/03/29)
Enantio- and regioselective: The intramolecular enantioselective aminofluorination of unactivated olefins was achieved by using a chiral iodo(III) difluoride salt. A highly regioselective aminofluorination of styrenes to access 2-fluoro-2-phenylethanamines was also developed. Copyright
Synthesis, characterization, and reactivity of arylpalladium cyanoalkyl complexes: Selection of catalysts for the α-arylation of nitriles
Culkin, Darcy A.,Hartwig, John F.
, p. 9330 - 9331 (2007/10/03)
A new coupling process, the palladium-catalyzed α-arylation of nitriles, was developed by exploring the structure and reactivity of arylpalladium cyanoalkyl complexes. Complexes of 1,2-bis(diphenylphosphino)benzene (DPPBz), 1,1′-bis(di-i-propylphosphino)ferrocene (DiPrPF), racemic-2,2′-bis(diphenylphosphino)-1,1′-binaphthyl (BINAP), and diphenylethylphosphine (PPh2Et) were prepared. Coordination to palladium through the α-carbon was observed for DPPBz-ligated complexes and for complexes of primary and benzylic nitrile anions. However, the anion of isobutyronitrile was coordinated to palladium through the cyano-nitrogen when the complex was ligated by DiPrPF. The isobutyronitrile anion displaced a phosphine ligand to form a C,N-bridged dimer when generated from PPh2Et-ligated palladium. These results suggest that the nitrile anion preferentially coordinates to palladium through the carbon atom in the absence of steric effects. Thermolysis of the arylpalladium cyanoalkyl complexes led to reductive elimination that formed α-aryl nitriles. The high yields and short reaction times observed for BINAP-ligated complexes suggested that BINAP-ligated palladium catalysts might be appropriate for the arylation of nitriles. Initial results on a palladium-catalyzed process for the direct coupling of aryl bromides and primary, benzylic, and secondary nitrile anions to form α-aryl nitriles in good yields are reported. Copyright
