- Selective Asymmetric Transfer Hydrogenation of α-Substituted Acetophenones with Bifunctional Oxo-Tethered Ruthenium(II) Catalysts
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A practical method for the asymmetric transfer hydrogenation of α-substituted ketones was developed utilizing oxo-tethered N-sulfonyldiamine-ruthenium complexes. Reduction by HCO2H and HCO2K in a mixed solvent of EtOAc/H2O allowed for the selective synthesis of halohydrins from 2-bromoacetophenone (98%) and 2-chloroacetophenone (>99%), leading to suppressed undesired side reactions stemming from formylation under the typical reaction conditions using an azeotropic 5:2 mixture of HCO2H and Et3N. A range of functional groups, such as halogens, methoxy, nitro, dimethylamino, and ester groups, were well tolerated, highlighting the potential of this method. Nearly complete selectivity with a preferable ee was maintained even with a substrate/catalyst (S/C) ratio of 5000. This catalyst system was also effective for the asymmetric reduction of α-sulfonated ketones without eroding the leaving group. (Figure presented.).
- Yuki, Yamato,Touge, Taichiro,Nara, Hideki,Matsumura, Kazuhiko,Fujiwhara, Mitsuhiko,Kayaki, Yoshihito,Ikariya, Takao
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supporting information
p. 568 - 574
(2017/12/13)
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- Carbon-13 NMR Spectra of Some 4-Substituted Phenacyl Chlorides and Iodides
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The 13C NMR signals for some 4-substituted phenacyl chlorides and iodides were assigned.The carbonyl carbons exhibit upfield shifts compared with those of the corresponding 4-substituted acethophenones; in the chlorinated derivatives a downfield shift is observed for the α-methylene carbons, while a reverse effect occurs in the iodinated compounds.The chemical shifts of the aromatic ring carbons are in close agreement with those calculated using substituent chemical shifts.KEY WORDS 13C NMR 4-substituted pheacyl chlorides and iodides
- Olivato, Paulo Roberto,Guerrero, Sandra Alvarez,Rittner, Roberto
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p. 179 - 180
(2007/10/02)
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