α'-Selective Selenium-catalyzed Allylic C-H Amination of Enol Derivatives.

ABSTRACT

A transition metal-free Se-catalyzed C-H amination protocol for α'-amination of enol derivatives has been developed. This reaction can be used to functionalize a wide variety of oxygen- and halogen-substituted alkenes spanning a vast range of nucleophilicities, giving α'-aminated enol derivatives with high regioselectivity. Amination of E/Z mixtures of alkenes proceeds stereoconvergently to give the (Z)-enol derivatives exclusively. Mechanistic studies revealed that the relative reactivity and α'-regioselectivity of these transformations is determined by substantial resonance donation to the heteroatom-bound carbon in the transition state. These products participate in traditional reactions of enol derivatives, allowing for efficient functionalization of both α- and α'-positions from a single enol derivative with high diastereocontrol.