δ-Amination of alkyl alcohols via energy transfer photocatalysis

Abstract

Amino alcohols play a crucial role in the realm of biologically active compounds due to their functional diversity. In this study, we introduce a metal-free energy transfer photocatalytic method for the preparation of 1,4-aminoalcohols from readily available alcohol feedstocks. The key feature of this transformation is the simultaneous generation of a persistent iminyl radical and a transient carbon-centered radical through σ-homolytic cleavage of the O–N bond via energy transfer (EnT). The process involves fragmentation/decarboxylation/1,5-HAT (hydrogen atom transfer), leading to the formation of a C(sp³)-hybridized radical, which undergoes selective radical–radical cross-coupling or a radical chain event to yield the desired products. In addition, the protocol was also found to be suitable for N-tosyl amines, giving rise to 1,4-diamines. Our approach combines experimental mechanistic investigations with detailed computational studies using density functional theory (DFT) to provide insights into the reaction mechanism. This innovative method provides a new approach for preparing δ-amino alkyl alcohols and amines.