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 alpha,beta-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 P-unsubstituted alpha,beta-enones afforded 1-substituted 7-azaindoles through an aza-Michael-type reaction. In contrast, 6-substituted 7-azaindoles underwent regioselective C-3-alkylation through a Na[AuCl4]center dot 2H(2)O-catalyzed conjugate addition-type reaction. Analogously, the Na[AuCl4]center dot 2H(2)O-catalyzed reaction of 7-azaindole derivatives with beta-aryl-substituted alpha,beta-enones gave 3-substituted 7-azaindoles in moderate-to-satisfactory yields. Moreover, the Na [AuCl4]center dot 2H(2)O-catalyzed reaction of 1-substituted 7-azaindoles with alpha,beta-enones allowed an easy entry to 1,3-disubstituted 7-azaindoles in moderate-to-high yields. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)