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N ‐Methyl Inversion Barriers in Six‐membered Rings
Author(s) -
Katritzky Alan R.,
Patel Ranjan C.,
Riddell Frank G.
Publication year - 1981
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.198105211
Subject(s) - inversion (geology) , converse , nitrogen , nitrogen inversion , methyl group , chemistry , stereochemistry , crystallography , mathematics , group (periodic table) , organic chemistry , geology , geometry , paleontology , structural basin
Conformational conversions of N ‐methylazacyclohexanes are of particular interest: they can proceed either via ring‐ or nitrogen‐inversion processes. In both procedures an equatorial N ‐methyl group is converted into an axial one, and the converse. It is appropriate to dissociate the energy barriers for N ‐methyl inversion into two “half‐barriers” for the steps, axial form → transition state and equatorial form → transition state, and to report both values separately.—In this article the N ‐methyl inversion barriers of numerous methylated oligoazacyclohexanes, including species with oxygen or nitrogen atoms in the ring, are discussed.