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Selective Asymmetric Transfer Hydrogenation of α‐Substituted Acetophenones with Bifunctional Oxo‐Tethered Ruthenium(II) Catalysts
Author(s) -
Yuki Yamato,
Touge Taichiro,
Nara Hideki,
Matsumura Kazuhiko,
Fujiwhara Mitsuhiko,
Kayaki Yoshihito,
Ikariya Takao
Publication year - 2018
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.201701227
Subject(s) - chemistry , ruthenium , catalysis , bifunctional , transfer hydrogenation , selectivity , halogen , formylation , solvent , nitro , medicinal chemistry , combinatorial chemistry , bifunctional catalyst , substrate (aquarium) , chemoselectivity , organic chemistry , alkyl , oceanography , geology
A practical method for the asymmetric transfer hydrogenation of α‐substituted ketones was developed utilizing oxo‐tethered N ‐sulfonyldiamine‐ruthenium complexes. Reduction by HCO 2 H and HCO 2 K in a mixed solvent of EtOAc/H 2 O 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 HCO 2 H and Et 3 N. 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.