1572-99-2Relevant articles and documents
One-pot synthesis of α-alkylated nitriles with carbonyl compounds through consecutive aldol reaction/hydrogenation using a hydrotalcite-supported palladium nanoparticle as a multifunctional heterogeneous catalyst
Motokura, Ken,Fujita, Noriaki,Mori, Kohsuke,Mizugaki, Tomoo,Ebitani, Kohki,Kaneda, Kiyotomi
, p. 5507 - 5510 (2005)
α-Alkylation of various nitriles with carbonyl compounds successfully proceeded using a hydrotalcite-supported palladium nanoparticle as a multifunctional catalyst. The alkylated nitriles were formed through aldol reaction at base sites on the hydrotalcite surface followed by hydrogenation by molecular hydrogen on the palladium nanoparticle.
Asymmetric base-free michael addition at room temperature with nickel-based bifunctional amido-functionalized N-heterocyclic carbene catalysts
Rao, Mitta Nageswar,Haridas, Meera,Gangwar, Manoj Kumar,Rajakannu, Palanisamy,Kalita, Alok Ch.,Ghosh, Prasenjit
, p. 1604 - 1615 (2015)
A series of nickel-based chiral bifunctional catalysts (1d-3d) with N-heterocyclic carbene (NHC) ligands derived from (1R)-(-)-menthol, (1S)-(-)pinene, and (1R)-(+)-camphor have been successfully designed for asymmetric Michael addition reactions under base-free conditions. The NHC complexes, namely, [1-R-3-{N-(phenylacetamido)}imidazol-2-ylidene]2Ni [R = (1S)-menthyl (1d), (1S)-pinane (2d), and (1R)-isobornyl (3d)], bearing chiral ancillaries on the amido-functionalized side arms of the NHC ligands, performed the bifunctional catalysis of the asymmetric base-free Michael addition reaction of the α-methyl cyano ester substrates ethyl 2-cyanopropanoate (4), isopropyl 2-cyanopropanoate (5), and tert-butyl 2-cyanopropanoate (6) with the activated olefinic substrates methyl vinyl ketone (7) and acrylonitrile (8) in 63-98 % yields with enantiomeric excess (ee) values of 2-75 % at room temperature in 8 h. More interestingly, only the longest of the three catalysts, the menthol derivative 1d, showed significant chiral induction of up to 75 % ee; this has been attributed to the reduction of the steric influence owing to the relatively distant dispositions of the chiral ancillaries from the catalytically active metal center that arise as a consequence of the cis geometries of 1d-3d. A series of nickel-based chiral bifunctional catalysts with N-heterocyclic carbene ligands derived from readily available and inexpensive (1R)-(-)-menthol, (1S)-(-)pinene, and (1R)-(+)-camphor synthons successfully catalyze asymmetric base-free Michael addition reactions under ambient conditions.
Regioselective Copper-Catalyzed Oxidative Coupling of α-Alkylated Styrenes with Tertiary Alkyl Radicals
Wang, Cong,Liu, Rui-Hua,Tian, Ming-Qing,Hu, Xu-Hong,Loh, Teck-Peng
supporting information, p. 4032 - 4035 (2018/07/15)
A radical-mediated oxidative cross-coupling of readily accessible α-alkylated styrenes with 1,3-dicarbonyl compounds utilizing a combination of Cu(OAc)2 and air as a catalytic system is described. Rather than requiring α-halocarbonyl compounds, this efficient approach enables direct installation of tertiary functionalized alkyl motifs to olefins with simple carbonyl derivatives. The novel protocol is characterized with high allylic selectivities via a competing β-H elimination. Both radical-clock and -trapping experiments provided clear-cut evidence for the intermediacy of an α-keto carbon-centered radical.
Catalytic Anti-Markovnikov Transformations of Hindered Terminal Alkenes Enabled by Aldehyde-Selective Wacker-Type Oxidation
Kim, Kelly E.,Li, Jiaming,Grubbs, Robert H.,Stoltz, Brian M.
supporting information, p. 13179 - 13182 (2016/10/22)
A new strategy for the functionalization of sterically hindered terminal olefins is reported. Alkenes bearing quaternary carbons at the allylic or homoallylic position are readily oxidized to the corresponding aldehydes by palladium/copper/nitrite catalysis. A broad range of functional groups including esters, nitriles, silyl ethers, vinylogous esters, ketones, lactones, and β-ketoesters are tolerated under the reaction conditions. The crude aldehyde products can be transformed further, enabling direct conversion of hindered terminal alkenes to various other synthetically useful functional groups, resulting in formal anti-Markovnikov hydroamination, among other transformations.
