Nickel-Catalyzed Cyclization/Thiocarbonylation of Alkene-Tethered indoles with sulfonyl Chlorides: Synthesis of Thioester-Substituted Indolo[2,1-a]isoquinolines

A novel and straightforward procedure for the synthesis of thioester-substituted indolo[2,1-a]isoquinolines has been established. The reaction proceed via nickel-catalyzed cyclization/thiocarbonylation from alkene-tethered indoles and sulfonyl chlorides. Very good compatibility toward a wide range of functional groups was observed, both aryl and alkyl sulfonyl chlorides were well tolerated. With Mo(CO)₆ as a convenient and solid CO surrogate, and by using sulfonyl chloride as an abundant and cheap sulfur source, a variety of thioester-substituted indolo[2,1-a]isoquinolines were obtained in moderate to high yields.