Nuclear magnetic resonance studies. V. The tautomerism of tasmanone and related β-triketones

1965 ◽  
Vol 18 (9) ◽  
pp. 1405 ◽  
Author(s):  
IRC Bick ◽  
DHS Horn
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Usnic Acid ◽  
Nuclear Magnetic Resonance Study ◽  
Magnetic Resonance Study ◽  
Magnetic Resonance Studies ◽  
Nuclear Magnetic

From a nuclear magnetic resonance study of the tautomerism of tasmanone and 1,1,3,3-tetramethylphloroglucinol (syncarpic acid), it is deduced that tasmanone consists of a mixture of tautomers (I) and (II) with the tautomer (I) present in the larger proportion. Similarly it is deduced that the tautomers of agglomerone (XI; R = CHMe2), 3-acetyl-O-methylfilicinic acid (XI R; = Me), ceroptene (XI; R = CH=CHPh), and usnic acid (XIII) with the extended conjugation are the more stable and populated ones.

Nuclear magnetic resonance studies. XXXI. Rearrangement and deuterium exchange through β-enolization in bicyclooctanones. An 2H nuclear magnetic resonance study.

1977 ◽  
Vol 55 (3) ◽  
pp. 447-453 ◽  
Author(s):  
A. K. Cheng ◽  
J. B. Stothers ◽  
C. T. Tan
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Nuclear Magnetic Resonance Study ◽  
Magnetic Resonance Study ◽  
Deuterium Incorporation ◽  
Proton Abstraction ◽  
Magnetic Resonance Studies ◽  
H Nmr ◽  
Derivatives Of ◽  
Nuclear Magnetic

The bicyclo[2.2.2]octan-2-one and -[3.2.1]octan-6-one skeletons are interconvertible under strongly basic conditions. Their α,α-dimethyl derivatives in tert-Buo−/tert-BuOH at 185 °C undergo very slow interconversion by β-proton abstraction. Using 2H nmr the stereoselectivity of deuterium incorporation at the β-methylene sites was established. The relative reactivities of β-methyl exchange in the [3.2.1] system were also determined. As models for this process, exchange in the α,α,α′,α′-tetramethyl derivatives of the monocyclic ketones, C5–C8, was also studied.

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