Gold-catalyzed synthesis of 2-substituted, 2,3-disubstituted and 1,2,3-trisubstituted indoles in [bmim]BF4

Article abstract of DOI:10.1055/s-2007-982572

Cyclization of 2-alkynylanilines in the presence of NaAuCl ₄·H₂O using [bmim]BF₄ as the reaction medium afforded 2-substituted indoles in high yields. The catalyst system was best recycled using n-Bu₄NAuCl₄. 2,3-Disubstituted indoles could be prepared from 2-alkynylanilines and 3-buten-2-one through a one-flask annulation-alkylation sequence and 1,2,3-trisubstituted indoles were obtained from the same starting materials via an aza-Michael addition-annulation- alkylation process. Georg Thieme Verlag Stuttgart.