3 research outputs found
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
Palladium and Lewis-Acid-Catalyzed Intramolecular Aminocyanation of Alkenes: Scope, Mechanism, and Stereoselective Alkene Difunctionalizations
An expansion of methodologies aimed
at the formation of versatile
organonitriles, via the intramolecular aminocyanation of unactivated
alkenes, is herein reported. Importantly, the need for a rigid tether
in these reactions has been obviated. The ease-of-synthesis and viability
of substrates bearing flexible backbones has permitted for diastereoselective
variants as well. We demonstrated the utility of this methodology
with the formation of pyrrolidones, piperidinones, isoindolinones,
and sultams. Furthermore, subsequent transformation of these motifs
into medicinally relevant molecules is also demonstrated. A double
crossover <sup>13</sup>C-labeling experiment is consistent with a
fully intramolecular cyclization mechanism. Deuterium labeling experiments
support a mechanism involving <i>syn</i>-addition across
the alkene
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