Gold(I)‐Catalyzed Intermolecular Hydroarylation of Alkenes with Indoles under Thermal and Microwave‐Assisted Conditions

An efficient method for intermolecular hydroarylation of aryl and aliphatic alkenes with indoles using a combination of [(PR 3 )AuCl]/AgOTf as catalyst under thermal and microwave‐assisted conditions has been developed. The gold(I)‐catalyzed reactions of indoles with aryl alkenes were achieved in toluene at 85 °C over a reaction time of 1–3 h with 2 mol % of [(PR 3 )AuCl]/AgOTf as catalyst. This method works for a variety of styrenes bearing electron‐deficient, electron‐rich, and sterically bulky substituents to give the corresponding products in good to high yields (60–95 %). Under microwave irradiation, coupling of unactivated aliphatic alkenes with indoles gave the corresponding adducts in up to 90 % yield. Selective hydroarylation of terminal CC bond of conjugated dienes with indoles gave good product yields (62–81 %). On the basis of deuterium‐labeling experiments, a reaction mechanism involving nucleophilic attack of Au(I)‐coordinated alkenes by indoles is proposed.