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.
Regioselective 1,3-dipolar cycloaddition of nitrilimines to 2-methyl-2-vinyl oxirane
作者:Muhammet Yıldırım、Yaşar Dürüst
DOI:10.1016/j.tet.2011.03.017
日期:2011.5
1,3-Dipolarcycloaddition of in situ generated C,N-diaryl nitrilimines to 2-methyl-2-vinyl oxirane gives rise to the regioselective formation of novel 5-(2-methyloxiranyl)-4,5-dihydropyrazole derivatives in moderate to good yields. The structures and stereochemistries of the new cycloadducts were confirmed by spectroscopic/physical methods including X-ray diffraction data.
[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.
A general and practicalmethod for the synthesis of 5-trifluoromethylpyrazoles is reported that occurs by the coupling of hydrazonyl chlorides with environmentally friendly and large-tonnage industrial feedstock 2-bromo-3,3,3-trifluoropropene (BTP). This exclusively regioselective [3 + 2] cycloaddition of nitrile imines and with BTP is catalyst-free and operationally simple and features mild conditions
Substrate-Switched Chemodivergent Pyrazole and Pyrazoline Synthesis: [3 + 2] Cycloaddition/Ring-Opening Rearrangement Reaction of Azadienes with Nitrile Imines
作者:Liang Tu、Limei Gao、Qiang Wang、Zhixing Cao、Rong Huang、Yongsheng Zheng、Jikai Liu
DOI:10.1021/acs.joc.1c02998
日期:2022.3.4
new reaction model of benzofuran-derived azadienes (BDAs), an unprecedented synthesis of biologically important pyrazoles has been achieved through a tandem [3 + 2] cycloaddition/ring-opening rearrangement reaction of BDAs with nitrile imines. The nature and type of substrates are found to act as a chemical switch to trigger two distinct reaction pathways. A minor modification to the substrates allows