Design and synthesis of versatile ligand precursors based on phosphonium ylides for palladalactam formation and catalytic investigation

Abstract

A new series of ligand precursors designed for the synthesis of palladalactams has been developed. These precursors are easily accessible through a one-step reaction involving 2-chloro-N-phenylacetamide and a wide choice of various monophosphines, offering tunable electronic and steric properties within the ligand framework. The stability of both ligand precursors and resulting palladalactams in ambient air enhances their practical applicability. A newly synthesized palladalactam, featuring an electron-donating triethylphosphine moiety on the anionic phosphonium ylide ligand scaffold exhibited promising catalytic activities in the Mizoroki–Heck coupling reaction between aryl chlorides and alkenes. Theoretical calculations further affirmed that the ligand system in the complex is the most electron-donating, forming the strongest Pd–C bond compared to other complexes with alternative phosphine moieties.