New enantiopure bis(thioether) and bis(sulfoxide) ligands from benzothiophene

The C-2-symmetric compound 2,3,2',3'-tetrahydro-2,2'bi(benzo[b]thiophenyl) and three diastereomeric bis(oxide) derivatives can be synthesized in a few steps from benzo[b]thiophene by oxidative homocoupling of (R)-2,3-dihydrobenzo[b]thiophene I-oxide. This new family of enantiopure bis(thioether) and bis(sulfoxide) ligands forms stable chelating Pd-II complexes. The fused pentacyclic structure of the complexes imparts a rigid chiral environment around the metal centre. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005).