Tetrahydrocarbazoles and perhydrocyclohepta[b]indoles undergo a catalytic cascade singlet oxygenation in alkaline medium, which leads to chiral tricyclic perhydropyrido‐ and perhydroazepino[1,2‐a]indoles in a single operation. These photooxygenation products are new synthetic equivalents of uncommon C,N‐diacyliminium ions and can be functionalized with the aid of phosphoric acid organocatalysis.

The tricyclic azepino­[1,2-a]­indole acetates 7, readily accessible by visible-light-driven catalytic photooxygenation of cyclohepta­[b]­indoles 1, are convenient precursors to novel and uncommon cyclic C,N-diacyliminium ions 3. We report here the first Lewis acid-catalyzed C–C bond forming reactions of these species with TMSCN and silyl enol ethers as nucleophiles and utilizing TIPSOTf as well as Sc­(OTf)3 as catalysts. Employing Sc­(OTf)3/pybox complexes as a chiral catalyst system, regio- and enantioselective asymmetric alkylations with silyl enol ethers were achieved.

A short total synthesis of the Kopsia alkaloid (±)-mersicarpine is presented. As the key step, a visible light-induced catalytic cascade photooxygenation was utilized, to convert a 3,3-disubstituted tetrahydrocarbazole intermediate, in...

Tetrahydrocarbazoles and perhydrocyclohepta[b]indoles undergo a catalytic cascade singlet oxygenation in alkaline medium, which leads to chiral tricyclic perhydropyrido‐ and perhydroazepino[1,2‐a]indoles in a single operation. These photooxygenation products are new synthetic equivalents of uncommon C,N‐diacyliminium ions and can be functionalized with the aid of phosphoric acid organocatalysis.