Asymmetric Cyclizative Dimerization of (ortho-Alkynyl Phenyl) (Methoxymethyl) Sulfides with Palladium(II) Bisoxazoline Catalyst.
Cheng PengTaichi KusakabeShoko KikkawaTomoyuki MochidaIsao AzumayaYogesh Daulat DhageKeisuke TakahashiHiroaki SasaiKeisuke KatoPublished in: Chemistry (Weinheim an der Bergstrasse, Germany) (2018)
The first example of an asymmetric cyclization-dimerization of (ortho-alkynyl phenyl) (methoxymethyl) sulfides with a palladium(II) bisoxazoline (box) catalyst has been developed. The box ligand enhances the alkynophilicity of benzothienyl palladium(II) intermediate A and thus promotes coordination of the second alkyne substrate, leading to the dimerization. The characteristic properties of the box ligand were supported by density functional theory (DFT) calculations of the intermediate. Axially chiral bibenzothiophenes were obtained in good yields with good enantioselectivities.