Ethyl‐2‐Cyano‐2‐(2‐Nitrophenylsulfonyloximino)Acetate (ortho‐NosylOXY) Mediated One‐Pot Racemization Free Synthesis of Ureas, Carbamates, and Thiocarbamates via Curtius Rearrangement

This is the authors' abstract. We don't add key points for this paper.

Direct conversion of carboxylic acids to ureas, carbamates, and thiocarbamates in a single pot via Curtius rearrangement is accomplished. One recently established coupling reagent, Ethyl‐2‐cyano‐2‐(2‐nitrophenylsulfonyloximino)acetate ( o rtho‐NosylOXY, I ), is successfully used for the racemization free synthesis of ureas, di‐peptidyl ureas, and carbamates with moderate to good yield (82–69%). This single‐pot hassle‐free procedure works with a diverse range of N‐protecting groups Fmoc, Boc, and Cbz. Various amine, including aromatic, methyl esters of amino acids, t‐butylamine, alcohols, and thiols, are used as nucleophiles. A detailed NMR‐based mechanism study is incorporated here. Racemization suppression, easy removal of by‐products, and less waste generation make this methodology useful.