Diphosphine sulfides derived from 2,2′-biphosphole: novel chiral S,S ligands for palladium-catalyzed asymmetric allylic substitution

Diphosphine sulfides derived from 2,2′-biphosphole have been efficiently synthesized in an enantiomerically pure form by a four step synthetic sequence. These S,S-ligands were used for the first time in Pd-catalyzed asymmetric allylic alkylation. Good yields and enantiomeric excess up to 73% were obtained.