Halogen Atom Transfer-Induced Radical Cascades Cyclization of N-(o-Cyanobiaryl)acrylamides with Alkyl Halides via Boryl Radical-Mediated

Abstract

We report a study on the use of ligated boryl radicals for the synthesis of nitrogen-containing polycyclic compounds under photocatalytic conditions through a halogen-atom transfer (XAT) strategy. This approach leverages the fact that alkyl iodides are not capable of directly generating alkyl radical intermediates under photocatalytic conditions. Instead, the transformation proceeds via a XAT pathway involving boron-centered radical intermediates. A range of alkyl halogen (1°, 2° and 3° C-I, C-Br) as well as alkyl iodides derivatives of biologically active molecules (Such as Ibuprofen, Citronellol, Geraniol, Cholesterol, Estrone et. al.) are applicable in the strategy. Finally, a scale-up synthesis and late-stage modification in Sonogashira cross-coupling reactions of structurally complex molecules demonstrate the practicability of this methodology.