Ligand‐Dependent Chemoselectivity in Gold‐Catalyzed Reactions between Anthranils and Diynamides. Formation of Spiro Azacyclic Compounds versus 1‐Imino‐1<i>H</i>‐Indene‐3‐Carboximidamides

Gold‐catalyzed reactions between anthranils and diynamides have been investigated, and their reaction chemoselectivity relies on the types of gold catalysts. With the same anthranil/diynamide mixtures, the use of PPh 3 AuCl/AgNTf 2 leads to formation of spiro azacyclic compounds, whereas P( t ‐Bu) 2 ( o ‐biphenyl)AuCl/AgNTf 2 preferably yields 1‐imino‐1 H ‐indene‐3‐carboximidamides instead. In the PPh 3 AuCl/AgNTf 2 system, an indole intermediate at low temperature for X‐ray diffraction study is isolated; this isolable indole species requires anthranil and gold catalyst for efficient formation of spiro azacyclic products. In the case of P( t ‐Bu) 2 ( o ‐biphenyl)AuCl/AgNTf 2 , the mechanism of its resulting 1‐imino‐1 H ‐indene‐3‐carboximidamides is postulated based on literature reports.