Mechanistic Investigations of Cooperative Catalysis in the Enantioselective Fluorination of Epoxides
作者:Julia A. Kalow、Abigail G. Doyle
DOI:10.1021/ja207256s
日期:2011.10.12
studies of the (salen)Co- and amine-cocatalyzed enantioselective ring opening of epoxides by fluoride. The kinetics of the reaction, as determined by in situ (19)F NMR analysis, are characterized by apparent first-order dependence on (salen)Co. Substituent effects, nonlinear effects, and reactivity with a linked (salen)Co catalyst provide evidence for a rate-limiting, bimetallic ring-opening step. To account
本报告描述了(salen)Co 和胺共催化的环氧化物对映选择性开环的机理研究。通过原位 (19)F NMR 分析确定的反应动力学特征在于对 (salen)Co 的明显一级依赖性。取代基效应、非线性效应和与连接的 (salen) Co 催化剂的反应性为限速双金属开环步骤提供了证据。为了解释这些不同的数据,我们提出了一种机制,其中活性亲核氟物质是形成静止状态二聚体的氟化钴。胺助催化剂与 (salen) Co 的轴向连接促进二聚体解离,并且是观察到的协同性的起源。在这些研究的基础上,我们表明在比率、周转次数、氟化物开环反应的底物范围可以通过使用连接的salen框架来实现。报道了将该催化剂系统应用于快速(5 分钟)氟化以生成已知 PET 示踪剂 F-MISO 的未标记类似物。
Discovery of 4-<i>tert</i>-Butyl-2,6-dimethylphenylsulfur Trifluoride as a Deoxofluorinating Agent with High Thermal Stability as Well as Unusual Resistance to Aqueous Hydrolysis, and Its Diverse Fluorination Capabilities Including Deoxofluoro-Arylsulfinylation with High Stereoselectivity
作者:Teruo Umemoto、Rajendra P. Singh、Yong Xu、Norimichi Saito
DOI:10.1021/ja106343h
日期:2010.12.29
groups to CF(3) groups, in high yields. 1k also converts C(=S) and CH(3)SC(=S)O groups to CF(2) and CF(3)O groups, respectively, in high yields. In addition, 1k effects highly stereoselective deoxofluoro-arylsulfinylation of diols and amino alcohols to give fluoroalkyl arylsulfinates and arylsulfinamides, with complete inversion of configuration at fluorine and the simultaneous, selective formation of
Discovery of Quinoxaline-Based P1–P3 Macrocyclic NS3/4A Protease Inhibitors with Potent Activity against Drug-Resistant Hepatitis C Virus Variants
作者:Desaboini Nageswara Rao、Jacqueto Zephyr、Mina Henes、Elise T. Chan、Ashley N. Matthew、Adam K. Hedger、Hasahn L. Conway、Mohsan Saeed、Alicia Newton、Christos J. Petropoulos、Wei Huang、Nese Kurt Yilmaz、Celia A. Schiffer、Akbar Ali
DOI:10.1021/acs.jmedchem.1c00554
日期:2021.8.26
revealed the interplay between the P2 and P4 groups, which influenced inhibitor binding and the overall resistance profile. Optimizing inhibitor interactions in the S4 pocket led to PIs with excellent antiviral activity against clinically relevant PI-resistant HCV variants and genotype 3, providing potential pan-genotypic inhibitors with improved resistance profiles.
as cyclopentene oxide and cycloheptene oxide the corresponding fluorohydrins were isolated in 80% and 82% yield with 65% and 62% ee, respectively. In case of ring opening under similar conditions of the racemic styrene oxide or phenyl glycidyl ether 83% and 75% of the fluorohydrins with fluorine in the primary position were isolated with 74% ee and 65% ee, respectively. Tetrahydronaphthalene oxide yielded
在化学计量或化学计量稍低的雅各布森对映纯(salen)氯化铬络合物A存在下,用不同的氟化试剂对五个内消旋和三个外消旋环氧化物进行不对称开环,得到了相应的旋光性邻位氟代醇。氟化银被用作氟化物来源之一无论是在卜存在4 Ñ + ħ 2 ˚F 3 -在乙醚或乙腈。从氧化环己烯(起始后者反应1)显示出在所形成的最大fluorohydrin 72%ee的2以90%的产率分离。从其他介观-环氧化合物,例如环戊烯氧化物和环庚烯氧化物,分离相应的氟代醇,产率分别为80%和82%,ee分别为65%和62%。在外消旋的苯乙烯氧化物或苯基缩水甘油醚的类似条件下开环的情况下,分别以74%ee和65%ee分离出83%和75%的氟醇,其中氟位于主要位置。四氢萘氧化物产生反式-(23%ee)和顺式-2-氟-3,4-苯并环己烯醇(2%ee)的2:1混合物,表明存在竞争的S N 2和S N 1型开环。其他环氧化物,例如环辛烯
Enzymatic preparation of (1S,2R)- and (1R,2S)-stereoisomers of 2-halocycloalkanols
作者:Olga O. Kolodiazhna、Anastasy O. Kolodiazhna、Oleg I. Kolodiazhnyi
DOI:10.1016/j.tetasy.2012.11.011
日期:2013.1
The stereoisomers of cis-2-halocycloalkanols were resolved by a kinetically controlled transesterification with vinyl acetate in the presence of lipases in organic media. High enantioselectivities (ee >98%) and good isolated yields were obtained for all substrates using the appropriate lipase. Burkholderia cepacia lipase was the most efficient enzyme for the resolution of these substrates. The enantiomeric purities of the compounds were defined by derivatization with Mosher's acid and the absolute configurations were determined by chemical correlation. (C) 2012 Elsevier Ltd. All rights reserved.