The design of PINO-like hydrogen-atom-transfer catalysts.

Abstract

Phthalimide-N-oxyl (PINO) is a valuable hydrogen-atom-transfer (HAT) catalyst for selective C-H functionalization. To advance and optimize PINO-catalysed HAT reactions, researchers have been focused on modifying the phthalimide core structure. Despite much effort and some notable advances, the modifications to date have centred on optimization ofa single parameter of the catalyst, such as reactivity, solubility or stability. Unfortunately, theoptimization with respect to one parameter is often associated with a worsening of the others. The derivation of a singlecatalyst structure with optimal performance across multiple parameters has therefore remained elusive. Here we present an analysis of the structure-activity relationships of PINO and its derivatives as HAT catalysts, which we hope will stimulate further development of PINO-catalysed HAT reactions and, ultimately, lead to much improved catalysts for real-world applications.