The asymmetric hydrogenation of aromatic γ‐ and δ‐keto esters into optically active hydroxy esters or diols under the catalysis of a novel DIPSkewphos/3‐AMIQ–Ru^II complex was studied. Under the optimized conditions (8 atm H₂ , Ru complex/t‐C₄H₉OK=1:3.5, 25 °C) the γ‐ and δ‐hydroxy esters (including γ‐lactones) were obtained quantitatively with 97–99 % ee. When the reaction was conducted under somewhat harsh conditions (20 atm H₂ , [t‐C₄H₉OK]=50 mm, 40 °C), the 1,4‐ and 1,5‐diols were obtained predominantly with 95–99 % ee. The reactivity of the ester group was notably dependent on the length of the carbon spacer between the two carbonyl moieties of the substrate. The reaction of β‐ and ϵ‐keto esters selectively afforded the hydroxy esters regardless of the reaction conditions. This catalyst system was applied to the enantioselective and regioselective (for one of the two ester groups) hydrogenation of a γ‐ϵ‐diketo diester into a trihydroxy ester.

中文翻译：

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γ-和δ-酮基酯不对称加氢成羟基酯或二醇的化学选择性控制

研究了在新型DIPSkewphos / 3-AMIQ-Ru ^II配合物的催化下芳族γ-和δ-酮酯的不对称氢化为旋光羟基酯或二醇。在最佳条件下（8 atm H ₂  ，Ru络合物/ t- C ₄ H ₉ OK = 1：3.5，25°C），用97–99定量获得了γ-和δ-羟基酯（包括γ-内酯）。 ％  ee。当反应在某些苛刻的条件下（20 atm H ₂  ，[ t -C ₄ H ₉ OK] = 50 m m，40°C）进行时，得到的1,4-二醇和1,5-二醇主要是95 –99％  ee。酯基的反应性特别取决于底物的两个羰基部分之间的碳间隔基的长度。不论反应条件如何，β-和β-酮酸酯的反应选择性地提供羟基酯。该催化剂体系用于γ-ϵ-二酮二酯加氢成三羟基酯的对映选择性和区域选择性（对于两个酯基之一）。