Gold-Catalyzed N-Alkenylation of Isoxazolines and the Use of Alkenyl Gold Intermediates in the Synthesis of 2-Amino-1-pyrrolines

A gold-catalyzed method for N-alkenylation has been developed for NH-isoxazolines, which are challenging substrates for alternative transition-metal-catalyzed N-functionalization reactions. Generation of a vinyl gold intermediate from the addition of NH-isoxazolines to gold-activated ynamides initiates a diastereoselective [3,3′]-sigmatropic rearrangement to give 2-amino-1-pyrrolines. Optimization of this transformation is described, in addition to reaction scope, the use of chiral auxiliaries for the preparation of chiral nonracemic 2-amino-1-pyrrolines, and mechanistic insight. This method prepares heterocycles that are difficult to access through traditional approaches with an enabling gold-catalyzed disconnection.