Study On Ring Expansion Reaction Of Cyclic N-Sulfimines And Diazo Compounds As Well As Cascade Reaction Of Ortho-hydroxymethzyl Phenols And α,β-unsaturated Dizao Compounds

In the first part of this dissertation, the synthetic methods of seven-membered sulfonamides which were reported in the recent years are reviewed. Most of these methods needed expensive transition metal as the catalysts. Therefore, developping an efficient method for synthesis of seven-membered sulfonamides is highly desirable.In the second part, 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 is very simple and functional-group tolerant to manipulate valuable seven-membered enesulfonamides via a tandem similar Tiffeneau-Demjanov rearrangement and intramolecular proton transfer tautomerization process. Moreover, this ring-expansion reaction could be carried out in a one-pot fashion and scaled up to gram-scale from aryl aldehyde without the need to isolate the tosylhydrazone.In the third part, a cascad reaction of α, β-unsaturated tosylhydrazones and ortho-hydroxymethzyl phenols toward N-benzylpyrazoles has been developed. First, pyrazoles were constructed by self-cyclization reaction of α, β-unsaturated dizao compounds generated in situ from α, β-unsaturated tosylhydrazones, then the N-benzylpyrazoles were obtained from the reation between pyrazoles and orthohydroxymethzyl phenols. A new method to construct N-benzylpyrazoles has been developed.