The synthesis of disubstituted chiraldieneligands (3aR,6aR)- and (3aS,6aS)-10 with a pentalene backbone from the corresponding bicyclo[3.3.0]octa-1,4-diones 7 is described. The latter were accessible by enzymatic resolution of the racemic diol rac-5 and subsequent Swern oxidation. The efficiency of the ligands 10 in the rhodium-catalyzed1,4-addition of arylboronic acids 12 to cyclic and acyclic