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Homoallylic interaction of the double bond with substituents
Author(s) -
Xue Liang,
Lambert Joseph B.
Publication year - 1990
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.610030710
Subject(s) - chemistry , substituent , double bond , ab initio , computational chemistry , bond length , crystallography , molecular geometry , ab initio quantum chemistry methods , stereochemistry , molecule , crystal structure , organic chemistry
Ab initio calculations were carried out on systems with a geometrically constrained relationship between a double bond and a homoallylic substituent X, as in YCCCCX. The axial–equatorial equilibria in 3‐substituted methylenecyclohexanes and 4‐substituted cyclohexenes are determined largely by the homoallylic interaction between X and the double bond. The homoallyic substituent was chosen to be OCH 3 , and the nature of the double bond was varied by changing Y (H, CH 3 , F, Cl, CN). NMR experiments previously had found very significant dependences of the axial–equatorial equilibrium on the nature of the X and Y substituents. Electrostatic calculations, based on Mulliken charges, reproduce the experimental (NMR) substituent effects on the axial–equatorial equilibrium and suffice to explain all the observations.