Regioselective Hydroamidation of α,β-Unsaturated Esters Enabled by Lewis Acid/Iron Relay Catalysis
Hoonchul Choi, Dongwook Kim, Sukbok Chang
Abstract
Achieving precise regioselectivity in the hydroamination of alkenes is in high demand yet remains a longstanding challenge, particularly when electronically competing β-substituents are present. Here, we report a dual boron/iron catalytic system that enables the unprecedented hydroamidation of α,β-unsaturated esters to exclusively access α-amidated esters under mild conditions. The strategy harnesses the Lewis acidity of B(C 6 F 5 ) 3 to rapidly generate reactive silyl ketene acetal intermediates, which are subsequently intercepted by in situ generated iron nitrenoids. Central to this cooperative activation mode is the dual role of the chloride anion in modulating both boron and iron catalytic reactivity. This protocol is operationally simple, requiring no tailored ligands, light, or electrochemical setup, and proceeds efficiently with only 1 mol % of boron and iron catalysts. The system exhibits a broad scope of unsaturated esters, tolerating β-aryl, -alkyl, -silyl, -perfluoroalkyl, and -boryl groups. This work lays the foundation for universal α-selective hydrofunctionalization strategies across electronically complex substrates.