Pd-Catalyzed Enantioselective Tandem C-C Bond Activation/Cacchi Reaction between Cyclobutanones and o-Ethynylanilines

A palladium-catalyzed asymmetric tandem C-C bond activation/Cacchi reaction between cyclobutanones and o-ethynylanilines was reported. The transient chiral sigma-alkylpalladium species generated via enantioselective C(sp(3))-C(sp(2)) bond activation of cyclobutanones promotes cyclization of o-ethynylanilines, leading to one-carbon-tethered chiral indanone-substituted indoles. Two C-C bonds and one C-N bond are created with concomitant formation of an all-carbon quaternary stereocenter. Furthermore, a chiral C2-aryl axis can be created in 2,3-disubstituted indole moiety, leading to indanone-substituted indoles with both central and axial stereogenic elements.

Automated summary

This study demonstrated a palladium-catalyzed asymmetric tandem C-C bond activation/Cacchi reaction between cyclobutanones and o-ethynylanilines, leading to the synthesis of one-carbon-tethered chiral indanone-substituted indoles with multiple new bonds and stereocenters.