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
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)。
Cascade enantioselective synthesis of γ-aryl-γ-butyrolactones with a delayed stereoselective step
作者:Anil V. Karnik、Suchitra S. Kamath
DOI:10.1016/j.tet.2008.01.077
日期:2008.3
Enantioselective synthesis of gamma-aryl-gamma-butyrolactones is achieved using (S)-1-phenylethylamine as a chiral auxiliary. The synthesis involves cascade formation-destruction-formation of the chiral centre with a delayed stereoselective step. The actual stereoselective step has been found to be intramolecular nucleophilic attack on a diastereotopic carbocation formed, thereby resulting in the formation of non-racemic gamma-aryl-gamma-butyrolactones. (C) 2008 Elsevier Ltd. All rights reserved.
Nickel-Catalyzed Asymmetric Hydrogenation of γ-Keto Acids, Esters, and Amides to Chiral γ-Lactones and γ-Hydroxy Acid Derivatives
A highly efficient asymmetric hydrogenation of a series of γ-keto acid derivatives, including γ-keto acids, esters, and amides, using a Ni-(R,R)-QuinoxP* complex as the catalyst has been developed to afford chiral γ-hydroxy acid derivatives with excellent enantioselectivities, up to 99.9% ee. This method provides not only an economical one-pot approach for the synthesis of chiral γ-lactones but also
使用 Ni-( R , R )-QuinoxP* 配合物作为催化剂,开发了一系列 γ-酮酸衍生物(包括 γ-酮酸、酯和酰胺)的高效不对称氢化,以提供手性 γ-具有优异对映选择性的羟基酸衍生物,高达 99.9% ee。该方法不仅为合成手性 γ-内酯提供了一种经济的一锅法,而且还提供了 ( S )-去甲氟西汀(一种神经血清素再摄取抑制剂和药物合成的重要中间体)。