Pd-catalyzed sequential distal C–H alkenylation and π-allylic amination of arylacetic acids using MBH acetates: access to macrocyclic lactams

Palladium(ii)-catalyzed directed <i>meta</i>-selective C-H functionalization of arylacetic acids has been accomplished utilizing Morita-Baylis-Hillman (MBH) acetates as the coupling partner to furnish β-aryl MBH acetates that can be converted into 14-membered macrocyclic lactams employing water as the oxygen source <i>via</i> a π-allyl intermediate. The sequential <i>meta</i>/<i>meta</i>' C-H difunctionalization can be accomplished with varied coupling partners. Mechanistic investigations underscore the roles of the nitrile-directing template, palladium(ii)-catalysis and ligand in <i>meta</i>-selectivity. The macrocyclization pathway has been validated through an ¹⁸O-labeling experiment and the photophysical studies reveal distinct fluorescence in the selected macrocycles. In addition, the selected lactams exhibited biocompatibility with Vero cells and dose-dependent cytotoxicity against MCF-7 cells, highlighting their therapeutic potential. The substrate scope, functional group tolerance, selectivity, photophysical and biological properties, and the late-stage functionalization of drug molecules as well as natural product derivatives are important practical features.