Ligand effects in homogeneous Au catalysis

A cationic gold(I) complex as a general catalyst for the intermolecular hydroamination of alkynes: application to the one-pot synthesis of allenes from two alkynes and a sacrificial amine

Two very distinct chemical reactions, yet a single catalyst: A gold complex promotes the formation of tertiary enamines from a variety of terminal and internal alkynes. Subsequent addition of a terminal alkyne to the reaction mixture affords allenes (see scheme).

Au-catalyzed synthesis of 5,6-dihydro-8H-indolizin-7-ones from N-(pent-2-en-4-ynyl)-beta-lactams

Au-catalyzed synthesis of 5,6-dihydro-8H-indolizin-7-ones from readily available N-(pent-2-en-4-ynyl)-beta-lactams is developed. In this reaction, a 5-exo-dig cyclization of the beta-lactam nitrogen to the Au-activated C-C triple bond is followed by heterolytic fragmentation of the amide bond, forming a highly nucleophilic acyl cation. An expedient formal synthesis of indolizidine 167B was easily achieved using this new method.