Palladium-catalysed imidoylative spirocyclization of 3-(2-isocyanoethyl)indoles

A palladium-catalysed construction of spiroindolines through dearomative spirocyclization of 3-(2-isocyanoethyl)indoles has been developed. 2 '-Aryl-, vinyl-, and alkyl-substituted spiroindolines could be accessed under mild conditions with excellent functional group tolerance. C1-tethered oxindole- and indole-spiroindoline bisheterocycles were generated in high yields via alkene/allene insertion and an imidoylative spirocyclization cascade. Additionally, a tandem dearomatization of two different indoles was realized with N-(2-bromobenzoyl)indoles as the electrophilic coupling partner of 3-(2-isocyanoethyl)indoles, affording polyindoline - spiroindoline bisheterocyclic scaffolds conveniently. Under the catalysis of Pd(OAc)(2) and a spinol-derived phosphoramidite ligand, chiral spiroindolines were successfully accessed with up to 95% yield and 85% ee.

Automated summary

A palladium-catalysed construction of spiroindolines has been developed through dearomative spirocyclization of 3-(2-isocyanoethyl)indoles, yielding a variety of spiroindolines and bisheterocyclic compounds with high yields and enantioselectivity.