Abstract: Carbonyl-tethered alkylidenecyclopropanes can react with aryl isocyanates in presence of Pd(0)-phosphoramidite catalysts to give seven-membered heterobicyclic products in a formal [3+2+2] cycloaddition process. The reaction involves the formation of a palladium π-allyl complex intermediate (A), which behaves as a formal 1,5-dipole, and can be trapped by externally added isocyanates. This report also includes preliminary assays of asymmetric variants, as well as DFT computational studies that shed some light on the nature of the catalytic cycle.

Abstract: Optically active 2-aminobiaryls are valuable chiral frameworks with broad applications in catalysis, synthetic chemistry, and materials science. Here, we present a simple and practical methodology for their asymmetric synthesis via enantioselective palladium catalyzed C−H arylations or alkenylations of racemic precursors. The methodology utilizes a kinetic resolution strategy, producing two highly valuable enantioenriched axially chiral molecules: the C−C coupling product and the unreacted starting material. Notably, we have established reaction conditions that enable the in situ regeneration of the active Pd(II) catalyst using atmospheric air as the sole oxidant. Finally, we showcase the synthetic utility of this approach by preparing several derivatives relevant to the field of asymmetric catalysis.

External link: https://onlinelibrary.wiley.com/doi/abs/10.1002/anie.202425512