NMR and molecular orbital studies of isomerism and tautomerism in oximes of 2-acyl cyclic 1,3-diones.
Molecular orbital calculations and 13C and 15N NMR experiments have been performed on the O-methyl oximes of two types of 2-acyl cyclic 1,3-diones. One (III; X = CH2) was based on cyclohexane, and the other (X = O) on pyran. The data indicate that both the cyclohexane and pyran compounds prefer to exist as the oxime, rather than the enamine isomer. Two equivalent, interconverting, keto-enol tautomers exist in the cyclohexane compound. The pyran compound exists as the lactone-enol tautomer. Our results have implications in the design of herbicidal compounds and drugs containing similar tautomeric systems.
Winkler
D A
DA
CSIRO Division of Chemicals and Polymers, Melbourne, Australia.
Liepa
A J
AJ
Willing
R I
RI
Anderson McKay
J E
JE
Winzenberg
K N
KN
Morton
T C
TC
D003510:Cyclohexanes / Q000138:chemical synthesis*; D003512:Cyclohexanones / Q000138:chemical synthesis*; D006540:Herbicides / Q000032:analysis*; D007536:Isomerism; D009682:Magnetic Resonance Spectroscopy; D008956:Models, Chemical; D011714:Pyrans / Q000138:chemical synthesis*; D011753:Pyrones / Q000138:chemical synthesis*
D003510:Cyclohexanes; D003512:Cyclohexanones; D006540:Herbicides; D011714:Pyrans; D011753:Pyrones; C060864:2-(1-(methoxyimino)ethyl)-5,5-dimethyl-3-hydroxycyclohex-2-en-1-one; C060867:5,6-dihydro-6,6-dimethyl-4-hydroxy-3-(1-(methoxyimino)ethyl)-2H-pyran-2-one