由于需要开发有效的反应,用可持续溶剂(如加压 CO 2 )替代源自化石燃料的普通有机溶剂,因此对 CO 2作为溶剂的适用性的研究变得越来越重要。在我们之前对大体积底物的脂肪酶催化反应的溶剂工程研究中,CO 2膨胀液体(通过溶解加压 CO 2膨胀的液体)中的反应转化率高于没有 CO 2 的液体中的转化率。本研究展示了对 CO 2的详细检查-膨胀液体作为溶剂用于脂肪酶催化的外消旋 1-四氢萘酚、2-四氢萘酚和取代的 1-四氢萘酚类似物的动力学拆分,因为手性取代的四氢萘酚类似物是重要的药物中间体。CO 2膨胀液体在保持优异的对映选择性(E > 200)的同时,将反应速率提高了无 CO 2反应的 40 倍。外消旋 1-四氢萘酚和 2-四氢萘酚的制备规模反应成功地产生了相应的 (R)-乙酸酯和 (S)-醇,具有高产率和优异的对映选择性(高达 ee >99%)。
Bringing “N” into the game: The direct chemoselective nitrogenation of unactivated alkenes can be achieved through oxidative selenium catalysis (see scheme). This method provides a broad variety of allylic imides in yields of up to 89 % using N‐fluorobenzenesulfonimide (NFSI) as the terminal oxidant and nitrogen source. Furthermore, an unprecedented selenium‐catalyzed vinylic C(sp2)–H nitrogenation
Silylation-Based Kinetic Resolution of Monofunctional Secondary Alcohols
作者:Cody I. Sheppard、Jessica L. Taylor、Sheryl L. Wiskur
DOI:10.1021/ol2012617
日期:2011.8.5
The nucleophilic small molecule catalyst (−)-tetramisole was found to catalyze the kineticresolution of monofunctional secondaryalcohols via enantioselective silylation. Optimization of this new methodology allows for selectivity factors up to 25 utilizing commercially available reagents and mild reaction conditions.
Catalytic Asymmetric Intermolecular Bromoesterification of Unfunctionalized Olefins
作者:Lijun Li、Cunxiang Su、Xiaoqin Liu、Hua Tian、Yian Shi
DOI:10.1021/ol501542r
日期:2014.7.18
An asymmetric intermolecular bromoesterification of unfunctionalized olefins catalyzed by (DHQD)2PHAL is described. Optically active bromoesters can be obtained with up to 92% ee.
Tandem InCl<sub>3</sub>-Promoted Hydroperoxide Rearrangements and Nucleophilic Additions: A Straightforward Entry to Benzoxacycles
作者:Alexandra E. Bosnidou、Agathe Fayet、Cristina Cheibas、Oscar Gayraud、Sophie Bourcier、Gilles Frison、Bastien Nay
DOI:10.1021/acs.joc.3c00845
日期:2023.7.7
The acid-catalyzed rearrangement of organic peroxides is generally associated with C–C-bond cleavages (Hock and Criegee rearrangements), with the concomitant formation of an oxocarbenium intermediate. This article describes the tandem process between a Hock or Criegee oxidative cleavage and a nucleophilic addition onto the oxocarbenium species (in particular a Hosomi–Sakurai-type allylation), under
Method of preparing a composition containing hygromycin A and epi-hygromycin
申请人:Pfizer Products Inc.
公开号:EP1369490A1
公开(公告)日:2003-12-10
A method of preparing a composition containing hygromycin A and epi-hygromycin, wherein the ratio of hygromycin A to epi-hygromycin is at least 10:1, which comprises fermenting Streptomyces hygroscopicus in media having a pH less than 6.9 at a temeperature ranging from 25°C to 35°C.
一种制备含百日咳霉素 A 和表-百日咳霉素的组合物的方法,其中百日咳霉素 A 与表-百日咳霉素的比例至少为 10:1,该方法包括在 pH 值小于 6.9 的培养基中,在 25°C 至 35°C 的温度范围内发酵吸湿链霉菌。