The Ir(I) complexes of chiral spiro phosphinoâoxazoline ligands (SpinPhox) have demonstrated good to excellent enantioselectivity in the asymmetric hydrogenation (AH) of a variety of (E)-β,β-disubstituted α,β-unsaturated N-methoxy-N-methylamides, affording the corresponding optically active Weinreb amides with up to 97% ee.
New asymmetricconjugatereduction of beta,beta-disubstituted alpha,beta-unsaturated ketones and esters was accomplished with alkoxylhydrosilanes in the presence of chiral rhodium(2,6-bisoxazolinylphenyl) complexes in high yields and high enantioselectivity. (E)-4-Phenyl-3-penten-2-one and (E)-4-phenyl-4-isopropyl-3-penten-2-one were readily reduced at 60 degrees C in 95 % ee and 98 % ee, respectively
Pd-Catalyzed Asymmetric Hydrogenation of C=C Bond of α,β-Unsaturated Ketones
作者:Yong-Gui Zhou、Duo-Sheng Wang、Da-Wei Wang
DOI:10.1055/s-0030-1259725
日期:2011.4
Homogenous palladium-catalyzed asymmetric hydrogenation of C=C double bond of alpha,beta-unsaturated ketones has been developed by using palladium(II) trifluoroacetate/(S)-7,7'-bis[ di(4-methoxyphenyl]phosphino)-1,1'-spirobiindane complex [Pd(OCOCF(3))(2)-(S)-An-SDP] as the catalyst under ambient hydrogen pressure and room temperature with up to 89% ee.
使用钯 (II) 三氟乙酸酯/(S)-7,7'-双[二(4-甲氧基苯基]膦基)-开发了均相钯催化的α,β-不饱和酮的C=C双键不对称氢化1,1'-spirobiindane 络合物 [Pd(OCOCF(3))(2)-(S)-An-SDP] 作为催化剂,在环境氢气压力和室温下具有高达 89% 的 ee。
A New Entry to Pd−H Chemistry: Catalytic Asymmetric Conjugate Reduction of Enones with EtOH and a Highly Enantioselective Synthesis of Warfarin
[reaction: see text] We report here the catalytic asymmetric conjugatereduction of enones using ethanol as a hydride source. The reaction was carried out in the presence of a chiral Pd complex at ambient temperature in ethanol, and the desired products were obtained in high chemical yield and high enantioselectivity. We applied this novel reaction to the catalytic asymmetric synthesis of warfarin (96%