Intramolecular Oxyacylation of Alkenes Using a Hydroxyl Directing Group

Alkene oxyacylation is a new strategy
for the preparation of β-oxygenated
ketones. Now, with Ir catalysis and low-cost salicylate esters, alkene
oxyacylation can be promoted by simple and versatile hydroxyl directing
groups. This paper discusses catalyst optimization, substituent effects,
mechanistic experiments, and the challenges associated with asymmetric
catalysis. Crossover experiments point to several key steps of the
mechanism being reversible, including the most likely enantiodetermining
steps. The oxyacylation products are also prone to racemization without
catalyst when heated alone; however, crossover is not observed without
catalyst. These observations account for the low levels of enantioinduction
in alkene oxyacylation. The versatility of the hydroxyl directing
group is highlighted by demonstrating further transformations of the
products.