4,5-Dimethyl-2-Iodoxybenzenesulfonic Acid Catalyzed Site-Selective Oxidation of 2-Substituted Phenols to 1,2-Quinols

Organocatalytic Enantioselective Synthesis of Bicyclo[2.2.2]octenones via Oxaziridinium Catalysed ortho ‐Hydroxylative Phenol Dearomatization**

Hydroxylative dearomatization reactions of phenols (HPD) offer an efficient way to assemble complex, biologically relevant scaffolds. Despite this, enantioselective hydroxylative phenol dearomatizations for the construction of bicyclo[2.2.2]octenones are classically limited to stoichiometric chiral reagents, and a practical, enantioselective catalytic method has remained elusive. Herein, we describe a highly enantioselective, organocatalytic tandem o‐HPD‐[4+2] reaction. Our methodology utilizes a chiral oxaziridinium organocatalyst, that is available in both enantiomeric forms, to afford dearomatized products in high enantioselectivity over a range of phenol substitution patterns. This approach was applied to the highly enantioselective synthesis of (+)‐biscarvacrol (99 : 1 e.r.) and (−)‐bis(2,6‐xylenol) (94 : 6 e.r.). The practicality of our conditions was demonstrated at gram‐scale, using an amine precatalyst, accessible in a single synthetic step.

Dearomatization of Electron-Deficient Phenols to ortho-Quinones: Bidentate Nitrogen-Ligated Iodine(V) Reagents

Despite their broad utility, the synthesis of ortho-quinones remains a significant challenge, in particular, access to electron-deficient derivatives remains an unsolved problem. Reported here is the first general method for the synthesis of electron-deficient ortho-quinones by direct oxidation of phenols. The reaction is enabled by a novel bidentate nitrogen-ligated iodine(V) reagent, a previously unexplored class of compounds which we have termed Bi(N)-HVIs. The reaction is extremely general and proceeds with excellent regioselectivity for the ortho over para isomer. Functionalization of the ortho-quinone products was examined, resulting in a facile one-pot synthesis of catechols, as well as the incorporation of a variety of heteroatom nucleophiles. This method represents the first synthetic application of Bi(N)-HVIs and demonstrates their potential as a platform for the further development of highly reactive, but also highly tunable, I(V) reagents.

Palladium-Catalyzed Dearomative syn-1,4-Carboamination with Grignard Reagents

A protocol for palladium-catalyzed dearomative functionalization of simple, nonactivated arenes with Grignard reagents has been established. This one-pot method features a visible-light-mediated [4+2] cycloaddition between an arene and an arenophile, and subsequent palladium-catalyzed allylic substitution of the resulting cycloadduct with a Grignard reagent. A variety of arenes and Grignard reagents can participate in this process, forming carboaminated products with exclusive syn-1,4-selectivity. Moreover, the dearomatized products are amenable to further elaborations, providing functionalized alicyclic motifs and pharmacophores. For example, naphthalene was converted into sertraline, one of the most prescribed antidepressants, in only four operations. Finally, this process could also be conducted in an enantioselective fashion, as demonstrated with the desymmetrization of naphthalene.