Recent advances in the use of Pentamethylphenyl (Ph*) Ketones in organic synthesis

Pentamethylphenyl (Ph*) ketones have gained prominence as versatile and valuable motifs in organic synthesis. The presence of the two ortho-methyl groups forces the aromatic ring to adopt a twisted conformation relative to the carbonyl group, and gives Ph* ketones a distinctive and unconventional reactivity profile, differentiating them from traditional aromatic ketones. The main goal of this feature article is to demonstrate how the properties of Ph* ketones facilitate innovative chemical transformations. A range of applications is explored, concentrating on hydrogen borrowing catalysis, but also including acceptorless dehydrogenation, dynamic kinetic resolution and reduction chemistry and showcasing the exceptional potential that these compounds exhibit. Furthermore, a detailed review of strategies for cleaving the Ph* group into a variety of functional derivatives is presented, highlighting their broad synthetic utility.