alpha-amino ketyl radical generation via hydrogen atom transfer catalysis

The applications of a-amino ketyl radicals in the synthesis of valuable and potentially biologically-active molecules is currently limited; this is due to the need for strong (Ered > –2 V vs SCE) reductants, such as large excesses of samarium(II) iodide, to generate these versatile intermediates. Here we present an operationally-simple, straightforward approach to access -amino ketyl radicals via photoredox-mediated hydrogen atom transfer catalysis. This highly selective strategy allows for direct access to g oxo-d-amino esters, a prominent scaffold in a wide range of pharmaceuticals and biologically active molecules, from readily available and bench-stable amino alcohols and conjugated olefins. Preliminary mechanistic investigations support the key role of phenylboronic acid to enhance both the efficiency, and the selectivity of the reaction.