The platinum(II) catalyzed hydroarylation of alkynes has been proposed to proceed via a Friedel-Crafts type mechanism. This involves the electrophilic alkyne activation at the electrophilic Pt(II) center followed by arene addition across the C�C triple bond. The mechanism of the whole catalytic cycle has been studied using the highly electrophilic and stable Pt(PNP)2+ complex fragment (PNP = 2,6-bis(diphenylphosphinomethyl)pyridine). The generated arylalkenyl complexes [Pt(PNP)(E-CH=CHAr)]+ (Ar = C6Me5, C6H2Me3) exhibit key intermediates in alkyne hydroarylation, which were characterized by NMR and X-Ray diffraction. The E-arylalkenyl complexes isomerized slowly to the Z-form. The transformation of the arylalkenyl complexes to the arylalkene (product) complexes by protolysis was found to be a reversible equilibrium and depends on structural and electronic features of the aryl group. The results of these studies are very useful for the design of more efficient hydroarylation catalysts.

Mechanistic insights into platinum(II) catalyzed hydroarylation of alkynes

245th National Meeting (2013)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.