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Effect of Torsional Strain and Electrostatic Interactions on the Stereochemistry of Nucleophilic Additions to Cyclohexanone and Related Systems
Author(s) -
Wu YunDong,
Houk Kendall N.,
PaddonRow Michael N.
Publication year - 1992
Publication title -
angewandte chemie international edition in english
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 0570-0833
DOI - 10.1002/anie.199210191
Subject(s) - cyclohexanone , nucleophile , chemistry , stereoselectivity , strain (injury) , ab initio , electrostatics , solvent , computational chemistry , solvent effects , transition state , gaussian orbital , crystallography , stereochemistry , organic chemistry , catalysis , medicine
The equatorial attack of a nucleophile on the cyclic ketones 1–3 was compared at the ab initio level with the axial attack. The more stable transition structure was provided by the equatorial attack of LiH in the case of 2 and 3 (Δ E = 1.5 and 7.9 kcalmol −1 , respectively) but the axial attack in 1 (Δ E = 1.4 kcalmol −1 ). This change in the stereoselectivity can be explained by the different torsional strains and electrostatic interactions. The fact that in experiments the axial attack is preferred for 2 is rationalized by the solvent effects which were not considered in the calculations.