Sc(OTf)3‐Catalyzed Tunable Thio‐(3 + 3) Annulation Reactions of Indoline‐2‐thiones with α‐Benzylidene‐β‐tetralones

A Sc(OTf)3‐catalyzed tunable thio‐Michael addition/nucleophilic addition/dehydration reaction of indoline‐2‐thiones with α‐benzylidene‐β‐tetralones was realized, leading to biologically important tetrahydrobenzo[7,8]isothiochromeno[3,4‐b]indoles and thiazino[3,2‐a]indoles in moderate to good yields. Moreover, by extending the reaction time, the dehydrogenated cycloadducts dihydrobenzo[7,8]isothiochromeno[3,4‐b]indoles were also obtained from the reaction of indoline‐2‐thiones with α‐benzylidene‐β‐tetralones.