A nordehydroabietyl amide-containing chiral diene for rhodium-catalysed asymmetric arylation to nitroolefins
作者:Ruikun Li、Zhongqing Wen、Na Wu
DOI:10.1039/c6ob02202b
日期:——
A highlyenantioselectiverhodium catalysed asymmetric arylation (RCAA) of nitroolefins with arylboronicacids is presented using a newly developed, C1-symmetric, non-covalent interacted, phellandrene derived, nordehydroabietyl amide-containing chiral diene under mild conditions. Stereoelectronic effects were studied, suggesting an activation of the bound substrate through the secondary amide as a
Zn-Catalyzed Enantio- and Diastereoselective Formal [4 + 2] Cycloaddition Involving Two Electron-Deficient Partners: Asymmetric Synthesis of Piperidines from 1-Azadienes and Nitro-Alkenes
作者:John C. K. Chu、Derek M. Dalton、Tomislav Rovis
DOI:10.1021/jacs.5b00033
日期:2015.4.8
We report a catalytic asymmetricsynthesis of piperidines through [4 + 2] cycloaddition of 1-azadienes and nitro-alkenes. The reaction uses earth abundant Zn as catalyst and is highly diastereo- and regioselective. A novel BOPA ligand (F-BOPA) confers high reactivity and enantioselectivity in the process. The presence of ortho substitution on the arenes adjacent to the bis(oxazolines) was found to
1,4‐Addition of TMSCCl
<sub>3</sub>
to Nitroalkenes: Efficient Reaction Conditions and Mechanistic Understanding
作者:Na Wu、Benoit Wahl、Simon Woodward、William Lewis
DOI:10.1002/chem.201402394
日期:2014.6.16
formation of the 1,4‐addition product, suggesting the reaction proceeds via a transient [Me3Si(alkene)CCl3] species, in which (alkene) indicates an Si⋅⋅⋅O coordinated nitroalkene. The anaerobic catalytic chain is propagated through the kinetic nitronate anion resulting from 1,4 CCl3− addition to the nitroalkene. This is demonstrated by the fact that isolated NBu4[CH2NO2] is an efficient promoter. Use
改进的合成条件允许以良好的产率 (70%) 和优异的纯度制备 TMSCCl 3。NBu 4 X [X=Ph 3 SiF 2 (TBAT)、F(四丁基氟化铵,TBAF)、OAc、Cl 和 Br]类型的化合物作为催化促进剂,用于对一系列环状和非环状硝基烯烃进行 1,4-加成, 在 0–25 °C 的 THF 中,通常具有中等至极好的收率 (37–95%)。TBAT 是最有效的促进剂,而溴化物最不有效。厌氧条件下的多核 NMR 研究(1 H、19 F、13 C 和29 Si)表明将 TMSCCl 3 添加到 TBAT(均为 0.13 M) 在 -20 °C 下,在没有硝基烯烃的情况下,立即导致 Me 3 SiF、Ph 3 SiF 和 NBu 4 CCl 3 的混合物。后者至少在 0 °C 下是稳定的,并且即使在延长的时间后,也不会在 -20 到 0 °C 之间添加硝基烯烃。硝基烯烃在 TMSCCl
Nucleophilic halo-Michael addition under Lewis-base activation
作者:Víctor Laina-Martín、Ignacio Pérez、Jose A. Fernández-Salas、José Alemán
DOI:10.1039/c9cc07068k
日期:——
A simple and general conjugate nucleophilic halogenation is presented. The THTO/halosilane combination has shown the ability to act as a nucleophilic halide source in the conjugate addition to a variety of Michael acceptors. In addition, a straightforward diastereoselective halogen installation using α,β-unsaturated acyloxazolidinones as platforms has been developed.
4-Trifluoromethanesulfonamidyl prolinol tert-butyldiphenylsilyl ether as a highly efficient bifunctional organocatalyst for Michael addition of ketones and aldehydes to nitroolefins
作者:Chao Wang、Chun Yu、Changlu Liu、Yungui Peng
DOI:10.1016/j.tetlet.2009.02.211
日期:2009.5
4-Trifluoromethanesulfonamidyl prolinol tert-butyldiphenylsilyl ether bifunctionalorganocatalyst 3a is a highly efficient catalyst for the asymmetric Michaeladdition reactions of ketones and aldehydes to nitrostyrenes, leading to syn-selective adducts with excellent yields (>99%), high diastereoselectivities (up to 99:1 dr) and excellent enantioselectivities (up to 99% ee). Control experiments suggested that the