Lewis Acid-Catalyzed Carbofunctionalization of Uncommon ,-Diacyliminium Ions: Controlling Regio- and Enantioselectivity.

The tricyclic azepino[1,2-]indole acetates , readily accessible by visible-light-driven catalytic photooxygenation of cyclohepta[]indoles , are convenient precursors to novel and uncommon cyclic ,-diacyliminium ions . 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) as catalysts. Employing Sc(OTf)/pybox complexes as a chiral catalyst system, regio- and enantioselective asymmetric alkylations with silyl enol ethers were achieved.