A Gold Carbene Manifold to Prepare Fused γ-Lactams by Oxidative Cyclisation of Ynamides.

Gold-catalysed oxidative cyclisation reactions of ynamides offer great promise in γ-lactam synthesis but are limited by preferential over-oxidation to form α-keto imides. Evaluating the factors that might limit N-cyclisation pathways led to effective gold-catalysed conditions that allow access to different fused γ-lactams on changing the ynamide N-substituent and accommodate previously incompatible substitution patterns. New and efficient methods for the synthesis of functionalised 3-aryl indoles and cyclohepta[c]pyrrol-1-one derivatives are presented. These conditions illustrate the complementarity of gold catalysis to other metals.