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4,6‐Barbaralanedicarboxy‐2,8‐dicarboxylic anhydride and 1,5‐dimethyl‐4,6‐semibullvalenedicarboxy‐2,8‐dicarboxylic anhydride: examples of unusual barbaralanes and semibullvalenes that do not undergo the Cope rearrangement. They are locked as the closed tautomers
Author(s) -
Williams Richard Vaughan,
Aring Andrew J.,
Bonifacio Margel C.,
Blumenfeld Alexander
Publication year - 2017
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.3622
Subject(s) - tautomer , chemistry , cope rearrangement , dicarboxylic acid , stereochemistry , polymer chemistry
Barbaralanes and semibullvalenes are generally fluxional molecules renowned for their exceedingly low Cope rearrangement activation barriers and their close approach to homoaromaticity. The title compounds are unusual in that they do not undergo the Cope rearrangement and are locked as a single tautomer with no evidence whatsoever for the existence of the other “open” tautomer. This total lack of the Cope rearrangement was demonstrated through variable‐temperature 13 C NMR spectroscopy and computational studies. Copyright © 2016 John Wiley & Sons, Ltd.