Application of a one-pot lipase resolution strategy for the synthesis of chiral γ- and δ-lactones
作者:Ahmed Kamal、Mahendra Sandbhor、Ahmad Ali Shaik
DOI:10.1016/s0957-4166(03)00281-7
日期:2003.6
one-pot method was illustrated by the oxidation of these chiral diols to respective chiral γ-butyrolactone and δ-lactones. Lipase from Pseudomonas cepacia, immobilized on ceramic afforded the product with highenantiomeric excess in good yields undermild reaction conditions. This approach has been used to develop a convenient enantioselective route for several γ- and δ-lactones using achiral and corresponding
High turnover: An highlyefficientcatalyticasymmetrichydrogenation of δ‐aryl‐δ‐ketoesters has been realized by using the chiral spiroiridium catalyst (R)‐1. Chiral 1,5‐diol products are obtained with excellent enantioselectivity and turnover numbers (TONs) as high as 100 000. TOF=turnover frequency.
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)。
Remote Ester Group Leads to Efficient Kinetic Resolution of Racemic Aliphatic Alcohols via Asymmetric Hydrogenation
A highly efficient method for kineticresolution of racemic aliphatic alcohols without conversion of the hydroxyl group has been realized; the method involves hydrogenation mediated by a remote ester group and is catalyzed by a chiral iridium complex. This powerful, environmentally friendly method provides chiral δ-alkyl-δ-hydroxy esters and δ-alkyl-1,5-diols in good yields with high enantioselectivities
From Diols to Lactones under Aerobic Conditions using a Laccase/TEMPO Catalytic System in Aqueous Medium
作者:Alba Díaz-Rodríguez、Iván Lavandera、Seda Kanbak-Aksu、Roger A. Sheldon、Vicente Gotor、Vicente Gotor-Fernández
DOI:10.1002/adsc.201200892
日期:2012.12.14
An efficient catalyticsystem to oxidize quantitatively aliphatic diolsusing Trametes versicolor laccase and TEMPO has been developed in aqueousmedium. Oxidations have occurred in a non-stereoselective fashion but with complete regio- and/or monoselectivity, obtaining lactones with excellent purity after simple extraction. This catalyticsystem has been demonstrated to be scalable, compatible with