Ligand Effect and Control of E- and Z-Selectivity in the Silver-Catalyzed Synthesis of 4-Bromooxazolines

The stereospecific intramolecular hydroamination of alkynyl trichloroacetimidates catalyzed by bis(pyridyl)silver(I) complexes to form 1,3‐oxazolines and oxazines has been investigated in greater detail. The rate of the reaction is profoundly influenced by the electronic character of the pyridyl ligand; leading to optimized conditions whereby reactions can be completed at ambient temperature with catalyst loadings as low as 1 mol%, while maintaining stereoselectivity towards the (Z)‐isomer. Further investigations into establishing the role of the ligand, and the synthesis of (E)‐isomer, are also presented.