56905-18-1Relevant academic research and scientific papers
Photoiodocarboxylation of Activated C=C Double Bonds with CO2 and Lithium Iodide
Mello, Rossella,Arango-Daza, Juan Camilo,Varea, Teresa,González-Nú?ez, María Elena
, p. 13381 - 13394 (2018/11/20)
The photolysis at 254 nm of lithium iodide and olefins 1 carrying an electron-withdrawing Z-substituent in CO2-saturated (1 bar) anhydrous acetonitrile at room temperature produces the atom efficient and transition metal-free photoiodocarboxylation of the C=C double bond. The reaction proceeds well for terminal olefins 1 to form the new C-I and C-C σ-bonds at the α and β-positions of the Z-substituent, respectively, and is strongly inhibited by polar protic solvents or additives. The experimental results suggest that the reaction channels through the radical anion [CO2?-] in acetonitrile, yet involves different intermediates in aqueous medium. The stabilizing ion-quadrupole and electron donor-acceptor interactions of CO2 with the iodide anion play a crucial role in the reaction course as they allow CO2 to penetrate the solvation shell of the anion in acetonitrile, but not in water. The reaction paths and the reactive intermediates involved under different conditions are discussed.
A multicomponent Ni-, Zr-, and Cu-catalyzed strategy for enantioselective synthesis of alkenyl-substituted quaternary carbons
McGrath, Kevin P.,Hoveyda, Amir H.
supporting information, p. 1910 - 1914 (2014/03/21)
The availability of enantiomerically enriched carbonyl-containing compounds is essential to the synthesis of biologically active molecules. Since catalytic enantioselective conjugate addition (ECA) reactions directly generate the latter valuable class of molecules, the design and development of such protocols represents a compelling objective in modern chemistry. Herein, we disclose the first solution to the problem of ECA of alkenyl groups to acyclic trisubstituted enones, an advance achieved by adopting an easily modifiable and fully catalytic approach. The requisite alkenylaluminum reagents are synthesized with exceptional site- and/or stereoselectivity by a Ni-catalyzed hydroalumination process, and the necessary enones are prepared through a site- and stereoselective zirconocene-catalyzed carboalumination/acylation reaction. The all-catalytic procedure is complete within four hours, furnishing the desired products in up to 77 % overall yield and 99:1 enantiomeric ratio. One-two-three punch: Ni-catalyzed alkyne hydroalumination, Zr-catalyzed alkyne carbometalation/acylation, and Cu-catalyzed enantioselective conjugate addition are combined for accessing acyclic organic molecules that contain an alkene-substituted quaternary carbon stereogenic center. The entire process takes less than four hours and affords products in up to 77 % overall yield and 99:1 enantiomeric ratio. Copyright
Estimation of standard reduction potentials of alkyl radicals involved in atom transfer radical polymerization
Bortolamei, Nicola,Isse, Abdirisak A.,Gennaro, Armando
body text, p. 8312 - 8318 (2011/02/23)
The redox properties of some alkyl radicals, which are important in atom transfer radical polymerization both as initiators and mimics of the propagating radical chains, have been investigated in CH3CN by an indirect electrochemical method based on homogeneous redox catalysis involving alkyl halides (RX) and electrogenerated aromatic or heteroaromatic radical anions (D-). Dissociative electron transfer between RX and D- yields an intermediate radical (R), which further reacts with D- either by radical coupling or by electron transfer. Examination of the competition between these reactions, which depends on ED/D-°, allows determination of the standard reduction potential of R as well as the self-exchange reorganization energy λR/R-. The standard reduction potentials obtained for the radicals CH2CN, CH2CO 2Et and CH(CH3)CO2Me are -0.72 ± 0.06, -0.63 ± 0.07 and -0.66 ± 0.07 V vs. SCE, respectively. Quite high values of λR/R- (from 122 to 164 kJ mol-1) were found for all radicals, indicating that a significant change of structure accompanies electron transfer to R.
α-Iodination of Some Aliphatic Acids. Substituent Effect and Optimum Conditions
Ogata, Yoshiro,Watanabe, Shinya
, p. 2831 - 2834 (2007/10/02)
The chlorosulfonic acid promoted α-iodination of some aliphatic acids in 1,2-dichloroethane has been studied.In contrast to the bromination, the effect of substituents on the rate shows not only a polar effect but also a steric effect in view of Taft's equation: , where ρ? = -1.20 and δ = 1.55 at 80 deg C.The transition state is discussed, which involves the electrophilic addition of I2 to a ketene intermediate.Aliphatic acids with less steric hindrance at the α-position, except acetic acid, are α-iodinated in good yields (ca. 80-100percent).The optimumconditions for α-iodination of long-chain aliphatic acids with caprylic acid as a model substrate are described.
