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Effect of oxime substituents on 9‐fluorenyl carbocations
Author(s) -
Creary Xavier,
Wolf Allison
Publication year - 2000
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 - 10.1002/1099-1395(200006)13:6<337::aid-poc249>3.0.co;2-t
Subject(s) - chemistry , carbocation , oxime , computational chemistry , medicinal chemistry , stereochemistry
9‐Fluorenyl carbocations substituted with the oxime functional groups CHNOCH 3 , CH 3 CNOCH 3 , and i ‐PrCNOCH 3 were generated by solvolyses of the corresponding chlorides in methanol. These cations form at rates which greatly exceed those of formation of the parent 9‐fluorenyl cation. Relative rate data suggest that stabilization of 9‐fluorenyl cations by CHNOCH 3 is greater than stabilization by CH 3 CNOCH 3 , which is in turn greater than that by i ‐PrCNOCH 3 . Computational studies on these cations show that the oxime group is progressively rotated out of conjugation with the cationic center as the oxime group becomes larger. These rate and computational studies also suggest that 9‐fluorenyl cations are not antiaromatic. They are essentially delocalized ‘nonatetraenyl’ cations, where formally antiaromatic resonance forms contribute little to the overall structure. Copyright © 2000 John Wiley & Sons, Ltd.