Metal‐Free Ring‐Expansion Reaction of Six‐membered Sulfonylimines with Diazomethanes: An Approach toward Seven‐Membered Enesulfonamides

Abstract

Abstract 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 fashion and scaled up to the gram scale by using aryl aldehydes, without the need to isolate the N‐tosylhydrazone.