Selective skeletal editing of polycyclic arenes using organophotoredox dearomative functionalization

Reactions that lead to destruction of aromatic ring systems often require harsh conditions and, thus, take place with poor selectivities. Selective partial dearomatization of fused arenes is even more challenging but it can be a strategic approach to creating versatile, complex polycyclic frameworks. Herein we describe a general organophotoredox approach for the chemo- and regioselective dearomatization of structurally diverse polycyclic aromatics, including quinolines, isoquinolines, quinoxalines, naphthalenes, anthracenes and phenanthrenes. The success of the new method for chemoselective oxidative rupture of aromatic moieties relies on precise manipulation of the electronic nature of the fused polycyclic arenes. Experimental and computational results show that the key to overcoming the intrinsic thermodynamic and kinetic unfavorability of the dearomatization process is an ultimate hydrogen atom transfer (HAT) step, which enables dearomatization to predominate over the otherwise favorable aromatization pathway. We show that this strategy can be applied to rapid synthesis of biologically valued targets and late-stage skeletal remodeling en route to complex structures.

Iridium(III)-Catalyzed Two-Fold C−H Alkylation of BINOLs with Allyl Alcohols

Ir(III)-catalyzed C−H alkylation of BINOL units has been well examined by allyl alcohols as coupling partners. Under the advantage of pyridine guiding group, the efficient protocol allows the rapid synthesis...

Synthesis of Cyclohexanones by a Tandem Photocatalyzed Annulation

The rapid synthesis of cyclic scaffolds is of high importance to the chemistry community. Strategies for the convergent synthesis of substi-tuted carbocycles and heterocycles remain underexplored despite the plethora of applications that these cyclic motifs have in the phar-maceutical and materials industries. Reported herein is a tandem carbene and photoredox-catalyzed process for the convergent synthesis of substituted cycloalkanones via a formal [5+1] cycloaddition. Featuring two distinct photoredox cycles and a novel α-oxidation of ben-zylic ketones, this reaction offers a mild approach to construct two contiguous C–C bonds and eliminates the need for strong bases or expensive metal catalysts. The utility of this method is highlighted through various product diversification reactions that allow access to a range of important cyclic scaffolds.