Ketenimine intermediates generated by the addition of copper acetylides to sulfonylazides are trapped by nitrile imines (generated from hydrazonoyl chlorides and triethylamine) to afford tetrasubstituted pyrazoles in moderate to good yields.
Facile One-Pot Transformation of Primary Alcohols into 3-Aryl- and 3-Alkyl-isoxazoles and -pyrazoles
作者:Eiji Kobayashi、Hideo Togo
DOI:10.1055/s-0039-1690102
日期:2019.10
Abstract Various primary alcohols were smoothly transformed into 3-aryl- and 3-alkylisoxazoles in good yields in one pot by successive treatment with PhI(OAc)2 in the presence of TEMPO, NH2OH, and then NCS, followed by reaction with alkynes in the presence of Et3N. Similarly, various primary alcohols were smoothly transformed into 3-aryl- and 3-alkylpyrazoles in good yields in one pot by successive
An operationally simple and convenient synthesis method toward a series of diverse spiro[4.4]thiadiazole derivatives via double [3 + 2] 1,3-dipolarcycloaddition of nitrilimines generated in situ from hydrazonyl chlorides with carbon disulfide has been achieved undermild reaction conditions.
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