14-hydroxy structure

Coumarin, 7-amino-7-(diethylamino)-, I, 333 Coumarin, 7-amino-4-methyl-fluorescence spectra, 3, 601 Coumarin, 7-amino-3-phenyl-brightening agents, I, 339 Coumarin, 4-aryl-occurrence, 3, 677 synthesis, 3, 810 Coumarin, 3-arylazo-4-hydroxy-structure, 3, 643 Coumarin, 3-bromo-reactions... 

Lumazine, 6,7-diphenyl-5,6-dihydro-properties, 3, 306 UV spectrum, 3, 279 Lumazine, 6,7-diphenyl-2-thio-glycosidation, 3, 297 reactions, 3, 300 Lumazine, 6,7-diphenyl-4-thio-reactions, 3, 300 Lumazine, 2,4-dithio-methylation, 3, 299 Lumazine, l-/3-D-glucopyranosyl-NMR, 3, 282 Lumazine, 1-hydroxy-structure, 3, 282... 

Pteridin-4-one, 7-chloro-2-methylthio-synthesis, 3, 296 Pteridin-4-one, 5,6-dihydro-structure, 3, 279 Pteridin-4-one, 7,8-dihydro-structure, 3, 279 Pteridin-4-one, 3-hydroxy-structure, 3, 282 synthesis, 3, 318... 

Pteridin-7-one, 2,4-diamino-8-hydroxy-structure, 3, 282 Pteridin-7-one, 5,6-dihydro-oxidation, 3, 307 structure, 3, 279 Pteridin-7-one, 8-hydroxy-synthesis, 3, 319 Pteridin-7-one, 8-methyl-synthesis, 3, 297... 

The parent indolo[2,3-fl]carbazole (1) has also been the subject of a study probing its reactivity toward oxidizing agents. One of the substrates involved, namely 85 (prepared from 1 and 2,5-dimethoxytetrahydrofuran in the presence of acid), was subjected to treatment with m-chloroperbenzoic acid, to give the dione 86 as the major product and a sensitive compound assigned the hydroxy structure 87. A cleaner reaction took place when 85 underwent oxidation with tert-butyl hydroperoxide assisted by VO(acac)2, to produce 86 exclusively in 86% yield. Likewise, A,N -dimethylindolo[2,3-fl]carbazole furnished the dione 88 on treatment with this combination of reagents (96J(X 413). 

In 1883, the hydroxy structure 82 was assigned to indoxyl on the basis of chemical evidence. More recently, however, the infrared spectra of 1-acetyl- and 1-methyl-indoxyl measured in chloroform indicated that the oxo form 83 (R = Ac, Me) greatly predominates, " ... 

Daniels352 has shown that the excitation spectra for triplet state formation and fluorescence emission from uracil and thymine in neutral aqueous solution at room temperature were anomalous when compared with the UV absorption spectra of these pyrimidines. These experimental facts have been critically examined with respect to three molecular models, of which the model based on tautomerism of uracil in aqueous solution is, in the opinion of Daniels, the best. The data suggested that the fluorescing tautomer contained an enol group, and the UV data favored the 4-hydroxy structure, i.e., form 28. The second tautomer, from which the triplet originated, was expected to be the predominant diketo form (32). 

The N-hydroxy structure (26) was preferred123 to an iV-oxide representation on account of the amphoteric nature of the product and because the derived acetate formed a well-defined hydrochloride salt. Hydrogenation of these N-hydroxyimidazoles over Raney nickel gives imidazoles in 60-94% yields.122 The reaction has been adapted for the preparation of 4-mercaptoimidazoles, using an a-ketothionamide (27) with an aldimine.124... 

The precise location of the new hydroxyl group in hydroxycodeine remains uncertain against the 9-hydroxy structure [xxix] may be cited the fact that it does not show the properties of a caorbinolamine [306]. 3 4 9-trimethoxyphenanthrene has been prepared by synthesis [311], but [xxxn] has not been converted to a trimethoxyphenanthrene for comparison. 

Similarly 8-hydroxy rather than 11-hydroxy structures have been demonstrated for alangicine and alangimarckine (417) by synthesis from the ester prepared as an intermediate in the synthesis of ankorine, by conversion into amides of 3-benzyl-oxy-4-methoxypheny1ethyl amine and tryptamine respectively, followed by Bischer-Napieralski ring closures (T. Fujii et al.. Tetrahedron Letters, 1976, 2553 1977, 3477 1978, 3111). 

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