Facile and Efficient Synthesis of Hydrophenanthren-1(2H)-ones and Naphtho[2,1-c]furan-3(1H)-ones by a Palladium-Catalyzed Aryne Annulation Strategy

Insights into the Regioselectivity of Metal-Catalyzed Aryne Reactions

The synthetic potential of unsymmetrically substituted aryne intermediates is significantly hindered by regioselectivity issues. Current methods for inducing regioselectivity all rely on substrate control and are focused on non-metallated arynes. Before our initial disclosure, there was no systematic study regarding the regioselectivity of metal-catalyzed aryne reactions. By exploiting ligand control, we have induced regioselectivity in a palladium-catalyzed aryne annulation to form phenanthridinones (up to 9:91 r.r.). Through this study we have investigated: ligand effects, influence of steric perturbation, and the impact of the aryne precursor.

Ligand-Induced Regioselectivity in Metal-Catalyzed Aryne Reactions Using Borylaryl Triflates as Aryne Precursors

The utility of reactions using unsymmetrically substituted aryne intermediates can be negatively impacted by issues with regioselectivity as these reactions are substrate controlled. This leaves no avenues for improving regioselectivity without altering the substrate which has led to numerous reports about how to enhance or reverse this regioselectivity in metal-free aryne reactions by changing the electronics. To the best of our knowledge, no such studies exist for systems with metal-bound aryne intermediates, which often suffer from worse regioselectivities. Herein we report a means of achieving regioselectivity in a metal-catalyzed aryne difunctionalization via catalyst control. Through the use of an unsymmetrical ligand environment, selectivity can be induced (up to 9:91 r.r.). These investigations demonstrate that catalyst design can influence selectivity in metal-catalyzed aryne reactions.

Construction of indazolo[3,2-a]isoquinolines via [3 + 2] cycloaddition of benzynes

A [3 + 2] annulation protocol for the construction of N-substituted indazolo[3,2-a]isoquinolines starting from benzynes and C,N-cyclic azomethine imines was developed. A diverse range of highly functionalized products indazolo[3,2-a]isoquinolines featuring an indazole scaffold can be easily accessed via a one-step reaction under mild conditions, and they show good anti-proliferative activity on cancer cells.

Benzo[c]carbazole derivatives produced by an effective Diels–Alder reaction: synthesis and structure–activity-relationship for surface coating

We demonstrate the use of an effective Diels–Alder reaction to produce a library of heterocyclic, polyaromatic benzo[c]carbazole derivatives with good corrosion inhibitive potency for copper against HCl.

Palladium-catalyzed annulation of arynes by o-halobenzamides: synthesis of phenanthridinones

The palladium-catalyzed annulation of arynes by substituted o-halobenzamides produces N-substituted phenanthridinones in good yields. This methodology provides this important heterocyclic ring system in a single step by simultaneous C-C and C-N bond formation, under relatively mild reaction conditions, and tolerates a variety of functional groups.