Pt(ii)-Chiral diene-catalyzed enantioselective formal [4 + 2] cycloaddition initiated by C–C bond cleavage and elucidation of a Pt(ii)/(iv) cycle by DFT calculations

Abstract

A chiral Pt(II) complex was readily prepared from [PtCl₂(C₂H₄)]₂ and Hayashi's diene. Its dicationic derivative efficiently catalyzed a formal intramolecular [4 + 2] cycloaddition of biphenylenes possessing substituted arylalkynes tethered by an ortho-phenylene moiety at ambient temperature and axially chiral cycloadducts were obtained in excellent yields and ees. A study of the DFT calculations revealed a Pt(II)/(IV) cycle including oxidative addition of biphenylene along with C–C bond cleavage.