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 γ‐aminonorbornan‐2‐ols |
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Authors: | Antonio García Martínez Enrique Teso Vilar Amelia García Fraile Santiago de la Moya Cerero Paloma Martínez Ruiz Cristina Díaz Morillo |
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Institution: | 1. Departamento de Química Orgánica I, Facultad de Ciencias, Ciudad Universitaria s/n, Madrid 28040, Spain;2. Facultad de Ciencias, UNED, Madrid 28040, Spain |
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Abstract: | A new set of optically active 2,3,3‐ and 2,7,7‐trimethyl‐substituted γ‐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 γ‐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. Chirality 2010. © 2010 Wiley‐Liss, Inc. |
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Keywords: | bridgehead γ – aminonorbornan‐2‐ols C(2) configuration chiral ligands enantioselective addition diethylzinc |
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