Platinum(ii)–phosphole complexes: synthesis and evaluation as enyne cycloisomerisation catalysts

Abstract

A series of platinum(II)–monophosphole complexes has been synthesized and used in enyne cycloisomerisations in order to study the effect of the ligand on the catalytic activity and selectivity. Reactions were performed on various N- or C-tethered 1,6-enynes and in the absence or in the presence of nucleophiles. For the most efficient cationic Pt(II)-complexes, it was also evidenced that the counterion and/or the solvent could have an influence on both the efficiency and the selectivity in the competition between the 5-exo-dig and the 6-endo-dig processes.