Asymmetric cyclopropanation of 2,5-dimethyl-2,4-hexadiene by copper catalysts bearing new bisoxazoline ligands.
Some new bisoxazoline ligands with an aryl group at the 4-position and gem-dimethyl groups at the 5-position on the oxazoline ring were prepared from arylglycines. Remarkable enhancement of the trans-selectivity (trans/cis = 87/13) and the enantioselectivity (96% ee for the trans product) was demonstrated for the asymmetric cyclopropanation of 2,5-dimethyl-2,4-hexadiene with tert-butyl diazoacetate catalyzed by the new copper-bisoxazoline complex.
Itagaki
Makoto
M
Organic Synthesis Research Laboratory, Sumitomo Chemical Co., Ltd., 1-98 Kasugade-naka, 3-chome, Konohana-ku, Osaka 554-8558, Japan. itagakim@sc.sumitomo-chem.co.jp
Masumoto
Katsuhisa
K
Yamamoto
Yohsuke
Y