Dj. Cho et al., Chiral C-2-symmetric bisferrocenyldiamines as ligands for transition metalcatalyzed asymmetric cyclopropanation and aziridination, TETRAHEDR-A, 10(19), 1999, pp. 3833-3848
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.