C1-symmetric versus C2-symmetric ligands in enantioselective copper-bis(oxazoline)-catalyzed cyclopropanation reactions.
A thorough experimental and theoretical study of the enantioselective cyclopropanation of alkenes catalyzed by chiral bis(oxazoline)- and azabis(oxazoline)-copper complexes, which comprise a new family of ligands that lack C2 symmetry, has been conducted. Surprisingly high enantioselectivities were observed with some of these ligands, which were rationalized on the basis of molecular modeling studies. The course of the asymmetric induction in connection with ligand symmetry and the implications for supported enantioselective catalysts are discussed.
Departamento de Química Orgánica, ICMA, CSIC-Universidad de Zaragoza and IUCH, Universidad de Zaragoza, Pedro Cerbuna 12, 50009 Zaragoza, Spain.
José M
JM
Fraile
José I
JI
García
Anja
A
Gissibl
José A
JA
Mayoral
Elísabet
E
Pires
Oliver
O
Reiser
Marta
M
Roldán
Isabel
I
Villalba