Chiral C-2-symmetric bisferrocenyldiamines as ligands for transition metalcatalyzed asymmetric cyclopropanation and aziridination

A new series of chiral C-2-symmetric bisferrocenyldiimine 1 and bisferrocen yldiamines 2 and 3 proved to be efficient ligands for the copper(I)-catalyz ed asymmetric cyclopropanation, cyclopropenation, and aziridination of alke nes and alkynes to give high diastereo- and enantioselectivity as well as h igh chemical yields. In some instances the enantiomeric excesses of cyclopr opanated products are among the highest (>97% ee) ever reported. Comparativ e studies show that stereoselectivity depends highly on the steric variatio n both in the ligand and the substrate. Other transition metal complexes in corporating some of these ligands such as Ru(3c)Cl-2, [(NBD)Rh(2)]ClO4, [Cu (2)(MeCN)(2)]PF6, and Pd(2)Cl-2 also demonstrated high enantioselectivity i n cyclopropanation reactions. (C) 1999 Elsevier Science Ltd. All rights res erved.