1,3-Dipolar Cycloaddition of Nitrile Imine with Carbon Dioxide: Access to 1,3,4-Oxadiazole-2(3<i>H</i>)-ones
作者:Chun-Xiao Guo、Wen-Zhen Zhang、Ning Zhang、Xiao-Bing Lu
DOI:10.1021/acs.joc.7b00963
日期:2017.7.21
Efficient synthesis of 1,3,4-oxadiazole-2(3H)-one was achieved by CsF/18-crown-6 mediated 1,3-dipolar cycloaddition of nitrile imine and 2.0 MPa of CO2. CsF/18-crown-6 played a key role in enhancing the reactivity of CO2 as a 1,3-dipolarophile. The practical utility of this transition-metal-free approach to 1,3,4-oxadiazole-2(3H)-one is highlighted by the convenient synthesis of a commercial herbicide
cycloaddition of nitrile imines with 3-alkenyl-oxindoles was catalyzed by a new chiral Mg(ClO4)2 complex of an N,N′-dioxide ligand. The reaction is so far the sole catalytic synthesis of spiro-pyrazoline-oxindole derivatives. A wide variety of substrates were explored to obtain good yields (up to 98%) and excellent enantioselectivities (up to 99%). This cycloaddition expands the scope of propargyl anion type 1
In this paper, a [3 + 2] cycloaddition of Baylis–Hillmanadducts and nitrilimines has been achieved under mild reaction conditions, providing a concise approach to access biologically important pyrazoline derivatives.
[3 + 2] cycloaddition of para-quinone methides with nitrile imines under mild conditions has been achieved. The corresponding spiro-pyrazoline-cyclohexadienone products were constructed in good to excellent yields (up to 97% yield) with high regioselectivity. This straightforward protocol exhibits good functional group tolerance and scalability and provides the spiro-pyrazoline-cyclohexadienones.
[3 + 2]-Cycloaddition of <i>in Situ</i> Generated Nitrile Imines and Acetylene for Assembling of 1,3-Disubstituted Pyrazoles with Quantitative Deuterium Labeling
作者:Vladimir V. Voronin、Maria S. Ledovskaya、Evgeniy G. Gordeev、Konstantin S. Rodygin、Valentine P. Ananikov
DOI:10.1021/acs.joc.8b00155
日期:2018.4.6
methodology for the preparation of 1,3-disubstituted pyrazoles from in situ generated nitrile imines and acetylene is reported. The reactions are performed in a simple two-chamber reactor. One part of the reactor is loaded with hydrazonoyl chloride precursors of active nitrile imine species and a base. The other part is used to generate acetylenefrom CaC2 and water. Partitioning of the reactants improves