Smaller, faster, better: modular synthesis of unsymmetrical ammonium salt-tagged NHC–gold(i) complexes and their application as recyclable catalysts in water

Abstract

Facile access towards a small library of unsymmetrical ammonium salt-tagged N-heterocyclic carbene gold(I) complexes is described, and their application as recyclable catalysts in cyclization reactions of acetylenic carboxylic acids and amides to lactones and lactams, respectively, in aqueous media is demonstrated. Catalyst 1ab was applied in the synthesis of 2-epi-clausemarine A (16).