The role of the C(2) configuration and methyl substitution on the catalytic activity of novel 2,3,3- and 2,7,7-trimethyl-substituted gamma-aminonorbornan-2-ols.
A new set of optically active 2,3,3- and 2,7,7-trimethyl-substituted gamma-aminonorbornan-2-ols have been obtained from 2-methylenenorbornane-1-carbonitriles derived from (+)-camphor and (-)-fenchone and probed as chiral ligands for the enantioselective addition of diethylzinc to benzaldehyde. This has allowed the study of the structural factors influencing the chirality transfer, such as variation of the relative configuration at C(2) and steric hindrance at C(2), C(3), and C(7) positions of norbornane, which result in the observance of the important role played by the gem-dimethyl position in gamma-aminonorbornan-2-exo-ols. An empirical rationalization of the obtained experimental results has been realized on the basis of energetically-favored diastereomeric Noyori-like transition states.
García Martínez
Antonio
A
Departamento de Química Orgánica I, Facultad de Ciencias, Ciudad Universitaria s/n, Madrid 28040, Spain.
Teso Vilar
Enrique
E
García Fraile
Amelia
A
de la Moya Cerero
Santiago
S
Martínez Ruiz
Paloma
P
Díaz Morillo
Cristina
C