Reverse Polarity Reductive Functionalization of Tertiary Amides via a Dual Iridium Catalyzed Hydrosilylation & SET Strategy

16 July 2020, Version 1
This content is a preprint and has not undergone peer review at the time of posting.

Abstract

A new strategy for the mild generation of synthetically valuable α-amino radicals from robust tertiary amide building blocks has been developed. By combining Vaska’s complex-catalyzed tertiary amide reductive activation and photochemical single electron reduction into a streamlined tandem process, metastable hemiaminal intermediates were successfully transformed into nucleophilic α-amino free radical species. This umpolung approach to such reactive intermediates was exemplified through coupling with an electrophilic dehydroalanine acceptor, resulting in the synthesis of an array of α-functionalized tertiary amine derivatives, previously inaccessible from the amide starting materials. The utility of the strategy was expanded to include secondary amide substrates, intramolecular variants and late stage functionalization of an active pharmaceutical ingredient. DFT analyses were used to establish the reaction mechanism and elements of the chemical system that were responsible for the reaction’s efficiency.

Keywords

Vaska reduction
photocatalysis
iminium ion
umpolung
α-amino radical

Supplementary materials

Title
Description
Actions
Title
TOC-vaska
Description
Actions
Title
Vaska-photoredox-SI
Description
Actions

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