Fully atom-economic access to spiro-cyclic skeletons through photoredox-induced hydrogen transfer/Giese addition/dearomative cyclization/protonation cascade

Abstract

Herein, we report a fully atom-economic and highly step-economic cascade dearomatization with non-activated phenyl and other hetero-aryl rings for access to aniline-tethered spiro-lactams with broad substrate scopes. This protocol involves a photoredox-induced hydrogen transfer/Giese addition/dearomative cyclization/protonation cascade and enables the introduction of two moieties of a C(sp³)–H bond of N-methylaniline into N-benzyl-acrylamide. Interestingly, dearomative products of the pyridine ring can be further transformed into pentacyclic alkaloid skeletons in a fully atom-economic fashion again.