Another class of C 2 -symmetric bidentate ligands based on the dibenzofuran (BIFOL) or carbazole (BICOL) unit was introduced by Hiemstra et al. 6, 6a, 6b, 6c and 6d Despite their promising activity in asymmetric catalysis, no other reports appeared using these new auxiliaries, which is probably caused by the rather tedious and lengthy synthetic route needed towards them. 7 Nevertheless, the presence of the electron-donating heteroatoms, which allow a more ...
