17O NMR studies on polycyclic quinones, hydroxyquinones and related cyclic ketones: Models for anthracycline intercalators
✍ Scribed by Subramanian Chandrasekaran; W. David Wilson; David W. Boykin
- Publisher
- John Wiley and Sons
- Year
- 1984
- Tongue
- English
- Weight
- 386 KB
- Volume
- 22
- Category
- Article
- ISSN
- 0749-1581
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✦ Synopsis
The "0 chemid shifts for six cyclic ketones which serve as models for quinones, viz. cydohex-2-enone (l), a-tetralone (2), anthrone (3), 4H-pyran-4-one (4), l-benzopyran-4(4H)-one (5), xanth-9-enone (6), and for six qninones, viz. benzoqninone, naphthoquiwne, antluaquinone, 2,5-dihydroxybenzoquinone 5%dihydroxynaphthoquinone and 1,4-dihydroxyantluaq11inone, were measured in toluene at 90 "C. A shielding effect of approximately 5Oppm per fused benzene ring was noted for the quinones and related aubocydic ketones; however, the analogous series of heterocyclic fused ring ketones 4-6 showed only a slight fused-ring effect on the earbonyl &emid shift. A single 1 7 0 resonance was observed for 2,5-dihydroxybenmquinone (358ppm) and 5 ~-d i h y d r o ~p h t h o q ~n e (283ppm), indicating rapid proton exchange between the oxygen atoms of these compounds. However, l,4-dihydroxyanthraquinone gave two discrete 1 7 0 signals at 441 and 87 ppm, indicating that in this. case proton exchange between oxygen atoms is slow.