The Palladium-Catalyzed Aerobic Kinetic Resolution of Secondary Alcohols: Reaction Development, Scope, and Applications
作者:Davidâ C. Ebner、Jeffreyâ T. Bagdanoff、Ericâ M. Ferreira、Ryanâ M. McFadden、Danielâ D. Caspi、Raissaâ M. Trend、Brianâ M. Stoltz
DOI:10.1002/chem.200902172
日期:2009.12.7
and tert‐butyl alcohol greatly enhances reaction rates, promoting rapid resolutions. The use of chloroform as solvent allows the use of ambient air as the terminal oxidant at 23 °C, resulting in enhanced catalyst selectivity. These improved reaction conditions have permitted the successful kineticresolution of benzylic, allylic, and cyclopropyl secondary alcohols to high enantiomeric excess with good‐to‐excellent
已经开发出第一个钯催化的仲醇对映选择性氧化反应,利用容易获得的二胺(-)-金雀花石作为手性配体,分子氧作为化学计量氧化剂。关于碱基和氢键供体作用的机制见解导致了对原始系统的一些改进。也就是说,碳酸铯和叔丁醇的添加大大提高了反应速率,促进了快速分辨率。使用氯仿作为溶剂允许在 23 °C 下使用环境空气作为终端氧化剂,从而提高催化剂选择性。这些改进的反应条件使得能够以良好至优异的选择性因子成功地将苄基、烯丙基和环丙基仲醇动力学拆分为高对映体过量。该催化剂体系也已应用于内消旋二醇的去对称化,提供高产率的对映体富集的羟基酮。
Hot water-promoted cyclopropylcarbinyl rearrangement facilitates construction of homoallylic alcohols
作者:Pei-Fang Li、Cheng-Bo Yi、Jin Qu
DOI:10.1039/c5ob00305a
日期:——
H2O–1,4-dioxane and without an additional catalyst, the rearrangements of various types of cyclopropylcarbinols were attempted. It was found that the reactions generally gave homoallylic alcohols in good to very high chemical yields. Rearrangements of bicyclic or tricyclic cyclopropylcarbinols readily gave the desired ring-expanded cyclic homoallylic alcohols which are difficult to synthesize by other
Asymmetric transfer hydrogenation of α,β-unsaturated, α-tosyloxy and α-substituted ketones
作者:Philip Peach、David J. Cross、Jennifer A. Kenny、Inderjit Mann、Ian Houson、Lynne Campbell、Tim Walsgrove、Martin Wills
DOI:10.1016/j.tet.2005.11.036
日期:2006.2
Asymmetric transferhydrogenation of cyclic and acyclic α,β-unsaturatedketones catalysed by η6-p-cymene/ruthenium(II) and η5-pentamethylcyclopentadienyl/rhodium(III) complexes have been investigated. Cyclicα,β-unsaturatedketones appeared to be more suitable substrates for the synthesis of enantiomerically pure allylic alcohols than do acyclic α,β-unsaturatedketones. A proposed mechanism for the
环状和无环α的不对称转移氢化,β不饱和酮由η催化6 - p -cymene /钌(II)和η 5 -五甲基/铑(III)络合物进行了研究。环状α,β-不饱和酮似乎比无环α,β-不饱和酮更适合用于合成对映体纯的烯丙基醇。讨论了一种由α-甲苯磺酰氧基和卤素取代的苯乙酮形成4-苯基-[1,3]-二氧戊环-2-酮的机理。提出了进一步研究减少α-甲苯磺酰氧基苯乙酮范围和α-取代酮的动态动力学拆分的结果。
Are bis(pyridine)iodine(<scp>i</scp>) complexes applicable for asymmetric halogenation?
作者:Daniel von der Heiden、Flóra Boróka Németh、Måns Andreasson、Daniel Sethio、Imre Pápai、Mate Erdelyi
DOI:10.1039/d1ob01532j
日期:——
chiral trans-chelating bis(pyridine)iodine(I) complexes in the development of substrate independent, catalytic enantioselective halofunctionalization has been explored herein. Six novel chiral bidentate pyridine donor ligands have been designed, routes for their synthesis developed and their [N–I–N]+-type halogen bond complexes studied by 15N NMR and DFT. The chiral complexes encompassing a halogen
对映体纯卤化分子作为合成中间体在药物、香料、香精、天然产物、杀虫剂和功能材料的构造中具有极其重要的作用。对映选择性卤代官能化仍然知之甚少,缺乏普遍适用的程序。本文探讨了手性反式螯合双(吡啶)碘( I )配合物在开发与底物无关的催化对映选择性卤代官能化中的适用性。设计了六种新型手性双齿吡啶供体配体,开发了它们的合成路线,并由15研究了它们的 [N-I-N] +型卤素键配合物N核磁共振和密度泛函。包含卤素键稳定的碘鎓离子的手性配合物显示能够有效地将碘鎓转移到烯烃;然而,没有对映选择性。立体选择性的缺乏被证明源于具有可比能量的多个配体构象的可用性和手性配体的空间影响不足。手性催化剂对底物的预组织似乎是对映选择性卤代官能化的必要条件。
Asymmetric Reduction of Cyclic Enones to Allylic Alcohols
作者:Jérôme Hannedouche、Jennifer A. Kenny、Tim Walsgrove、Martin Wills
DOI:10.1055/s-2002-19747
日期:——
Asymmetric transfer hydrogenation of cyclic enones results in highly enantioselective reduction to cyclic allylic alcohols.