I<sub>2</sub>-TBHP-catalyzed one-pot highly efficient synthesis of 4,3-fused 1,2,4-triazoles from N-tosylhydrazones and aromatic N-heterocycles via intermolecular formal 1,3-dipolar cycloaddition
I2-TBHP-catalyzed azomethine imine generation and subsequent regioselective 1,3-dipolarcycloaddition (DC) with aromatic N-heterocycles was developed to afford various 4,3-fused 1,2,4-triazoles in excellent yields. The method is operationally simple and highly efficient with broad functional group tolerance.
Palladium-Catalyzed Amidation of N-Tosylhydrazones with Isocyanides
作者:Fengtao Zhou、Ke Ding、Qian Cai
DOI:10.1002/chem.201102459
日期:2011.10.24
N‐tosylhydrazones: The direct formation of keteniminesfromcarbenes and isocyanides is limited to the reaction of Fischer carbene complexes or some specially stabilized carbenes with isocyanides. A Pd‐catalyzed amidation of N‐tosylhydrazones with isocyanides via a ketenimine intermediate in the presence of water is described. The method offers a general way to synthesize amides from carbonyl compounds through one‐carbon
Reactions of the sodium salts of tosylhydrazones of several heteroaromatic aldehydes with an equimolar amount of acrylonitrile afforded the corresponding cyclopropane derivatives as the major products accompanied by small amounts of pyrazole derivatives. On the other hand, reactions using ten-molar equivalents of acrylonitrile gave pyrazole derivatives as major products.
Metal-Free Ring-Expansion Reaction of Six-membered Sulfonylimines with Diazomethanes: An Approach toward Seven-Membered Enesulfonamides
作者:An-Jie Xia、Tai-Ran Kang、Long He、Lian-Mei Chen、Wen-Ting Li、Jin-Liang Yang、Quan-Zhong Liu
DOI:10.1002/anie.201508804
日期:2016.1.22
A new metal‐free, ring‐expansion reaction of six‐membered N‐sulfonylimines with unstable diazomethanes, generated in situ from the N‐tosylhydrazones, has been developed. This reaction delivers valuable seven‐membered enesulfonamides by a Tiffeneau–Demjanov rearrangement and intramolecular proton transfer tautomerization process. Moreover, this ring‐expansion reaction can be carried out in a one‐pot
Efficient Synthesis of 1,5-Disubstituted Carbohydrazones Using K<sub>2</sub>CO<sub>3</sub> As a Carbonyl Donor
作者:Jun Wen、Chu-Ting Yang、Tao Jiang、Sheng Hu、Tong-Zai Yang、Xiao-Lin Wang
DOI:10.1021/ol500732c
日期:2014.5.2
A novel reaction that generates 1,5-disubstituted carbohydrazones via the carbonylation of tosylhydrazones has been developed. For the first time, the inexpensive, readily available, environmentally friendly, and nongaseous potassium carbonate is used as the carbonyl donor for the transformation. The reaction system exhibited tolerance with various functional groups and affords the desired products