Gold‐Catalyzed Bicyclic and [3+2]‐Annulations of Internal Propargyl Alcohols with Nitrones and Imines To Yield to Two Distinct Heterocycles
作者:Sayaji Arjun More、Tzu‐Hsuan Chao、Mu‐Jeng Cheng、Rai‐Shung Liu
DOI:10.1002/adsc.202001119
日期:2021.1.19
4‐a]indoles from 1‐oxo‐3‐yn‐4‐ols and nitrones is described; this new bicyclic annulation presents the first examples that internal alkynes can react with nitrones to undergo an oxoarylation route. DFT calculations indicate a [3,3]‐sigmatropic shift of initial alkenylgold intermediates to elude the intermediacy of gold carbenes. We also developed new [3+2]‐annulations of the same 1‐oxo‐3‐yn‐4‐ols with imines
描述了一种由金催化的由1-氧代3-yn-4-醇和硝酮合成的1,3-二氢恶唑并[3,4- a ]吲哚的方法;这种新的双环环化反应是第一个实例,表明内部炔烃可以与硝酮反应进行羰基化反应。DFT计算表明,初始烯基金中间体发生了[3,3]-σ位移,从而避开了金卡宾的中间产物。我们还用亚胺开发了相同的1-oxo-3-yn-4醇与新的[3 + 2]环,有效地生成了oxazolidin-4-yylne衍生物。这些1-oxo-3-ynes的束缚醇可捕获其亚稳的2-azadienium中间体,从而实现新颖的环化反应。我们的机械分析表明,尽管两种产品在结构上相关,但它们是由两个独立的系统生产的。
Metal-free approach for the ʟ-proline mediated synthesis of nitrones from nitrosobenzene
metal-free approach for the ʟ-proline mediated synthesis of nitrones from nitrosobenzene and benzaldehydes has been established. The reaction undergoes very efficiently at room temperature in methanol as a solvent. The reaction is assumed to involve that the initial formation of azomethine ylide and [2 + 3] cycloaddition of nitrosobenzene, followed by the subsequent retro [2 + 3] cycloaddition could offer
1,3-Dipolar Cycloaddition Reactionsof Nitrones to Prop-1-ene-1,3-sultone
作者:Lun-Zu Liu、Li Tian、Guo-Yan Xu、Yong Ye
DOI:10.1055/s-2003-40201
日期:——
The reaction of prop-1-ene-1,3-sultone (1) with a variety of nitrones 2 afforded novel [3+2] cycloaddition products 3, 4, and 5 in good yield. Excellent regio- and stereoselectivity were achieved in the cycloaddition reaction with phenylnitrones.
of a chiral C2-symmetric bis(oxazoline) ligand, its Lewis acid complexes-catalyzed asymmetric 1,3-dipolarcycloaddition reactions of nitrones with electron-deficient dipolarophiles, 3-(2-alkenoyl)-1,3-oxazolidin-2-ones, have been investigated and it was found that the cycloadditions using a Cu(II)-bis(oxazoline) complex under optimized reaction conditions induced extremely high enantioselectivity.
Nitrones as Trapping Reagents of α,β-Unsaturated Carbene Intermediates - [1,2]Oxazino[5,4-<i>b</i>]indoles by a Platinum- Catalyzed Intermolecular [3+3] Cycloaddition
作者:Weibo Yang、Tao Wang、Yang Yu、Shuai Shi、Tuo Zhang、A. Stephen K. Hashmi
DOI:10.1002/adsc.201300338
日期:2013.5.17
Boc‐protected 2‐(3‐methoxy‐1‐propynyl)anilines and nitrones in platinum‐catalyzed reactions deliver [1,2]oxazino[5,4‐b]indoles. Twelve examples with yields of 41–95% are reported. Different substituents like nitro, trifluoromethyl, fluoro, bromo, and ester groups are tolerated. With regard to the mechanism, this reaction probably combines an initial intramolecular cyclization/elimination to vinylcarbenoid
在铂催化的反应中,一些容易获得的Boc保护的2-(3-甲氧基-1-丙炔基)苯胺和硝酮可提供[1,2]恶嗪基[5,4- b ]吲哚。报道了十二个产量为41–95%的例子。可以容忍不同的取代基,例如硝基,三氟甲基,氟,溴和酯基。关于机理,该反应可能结合了最初的分子内环化/消除为乙烯基类胡萝卜素物质,以及随后与硝酮的逐步的分子间[3 + 3]环加成反应。