Gold‐Catalyzed C‐3‐Alkylation of 7‐Azaindoles Through Michael‐Type Addition to α,β‐Enones

The Au III ‐catalyzed reactions of 7‐azaindole derivatives with α,β‐enones are described. Factors that can direct the C ‐3‐ versus N ‐1‐alkylation reaction on the 7‐azaindole nucleus are explored. The Au III ‐catalyzed reaction of 7‐azaindole with β‐unsubstituted α,β‐enones afforded 1‐substituted7‐azaindoles through an aza‐Michael‐type reaction. Incontrast, 6‐substituted 7‐azaindoles underwent regioselective C ‐3‐alkylation through a Na[AuCl 4 ] · 2H 2 O‐catalyzed conjugate addition‐type reaction. Analogously, the Na[AuCl 4 ] · 2H 2 O‐catalyzed reaction of 7‐azaindole derivatives with β‐aryl‐substituted α,β‐enones gave 3‐substituted 7‐azaindoles in moderate‐to‐satisfactory yields. Moreover, the Na[AuCl 4 ] · 2H 2 O‐catalyzed reaction of 1‐substituted 7‐azaindoles with α,β‐enones allowed an easy entry to 1,3‐disubstituted 7‐azaindoles in moderate‐to‐high yields. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)