Oxy- and Chloroarylation Pathways in Gold-Mediated Cyclization of 2-Aminoaryl-3-arylpropargyl-benzenesulfonamides

A one-pot diazotization/gold-mediated cyclization of 2-aminoaryl-3-arylpropargyl-benzenesulfonamides is described. After diazotization, Me2SAuCl triggers an oxy- and/or chloroarylation of the alkyne moiety, resulting in the formation of 3-acylindoles and/or Z-3-(chloromethylene)indolines. Density Functional Theory (DFT) calculations show the significant energetic preference of both processes over an insertion pathway. Notably, a Z-3-(chloromethylene)indoline crystallized with [Cl-Au-Cl],- exhibiting Au & sdot;& sdot;& sdot;H-C short contacts. Golden time: 2-Aminoaryl-3-arylpropargyl-benzenesulfonamides react after diazotization with gold to give 3-acylindoles and/or Z-3-(chloromethylene)indolines. DFT calculations show that the arylAu intermediate evolve via external nucleophilic attack over the alkyne, which is more favorable energetically than an insertion process. One of the Z-3-(chloromethylene)indolines crystallized with [Cl-Au-Cl]- displaying short Au & sdot;& sdot;& sdot;H-C contacts, that are maintained in solution.image