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.