2.6- Dioxo-1-hydroxy

N-heterocyclic azafluoranthenes N,N-carbonyldi(azoles) cyano-N-heterocyclics dioxo-hydroxy-imines, cyclic o-imino-N-heterocyclics... 

H-Cyclopenta[7,8]naphtho[2,3-6]furan-7-yl glyoxylate, 2,3,6,10-tetrahydro-6-hydroxy-6-methyl-3,10-dioxo-, methyl ester H NMR. 4, 560 (66JCS(C)743) Cyclopenta[6]quinoline, 6,7,8,9-tetrahydro- C NMR, 2, 122 (77JOC300, 77JOC2742)... 

Hydroxy-6-methyl-10 (5 6) abeo-cholestan-5-one acetate, 391 3 a-Hydroxy-16a-methyl-11,20-dioxo-5/3-pregnane-21-glyoxylic acid, 191 17 -Hydroxy-l-niethyl-A-homo-5a-androst-l-en-3-one acetate, 362 17 /3-Hy droxy-5a, 1 Oa-methy lene-A-norestran-3-one, 429 17 3-Hydroxy-17 a-methyl-10 ( 5 4) -fl( < o-estrane-3,5-dione, 314 3a-Hydroxy-16a-methyl-5/3-pregnane-11,20-dione, lyl... 

A/-o-(Benzoyloxymethyl)benzoyl, 562 A/-(2-Acetoxymethyl)benzoyl, 562 A/-2-[(t-Butyldiphenylsiloxy)methyl]benzoyl, 562 A/-3-(3, 6 -Dioxo-2, 4, 5 -trimethylcyclohexa-1, 4 -diene)-3,3-dimethylpropionyl, 562 AZ-o-Hydroxy-frans-cinnamoyl, 562... 

Hydroxy-l,l-dioxo-l,2-dihydro-lX -benzo [e] [1,2] thiazine-3-carboxylic acid isopropyl ester (55)... 

Trihydroxypteridine exists predominantly in the dioxo-mono-hydroxy form 191(R = H), its ultraviolet spectrum closely resembling those of both the 1- and the 3-methyl derivatives and that of l,3-dimethyl-7-methoxypteridine-2,4-dione (191, R = Me). These spectra are quite different from those of 8-methyl- (192, R = H) and l,3,8-trimethyl-pteridine-2,4,7-trione (192, R = Me), which are similar to each other and to those of other 8-substituted pteridine-2,4,7-triones. However, the ultraviolet spectrum of 2,4,7-trihydroxypteri-dine does, indeed, show that a small proportion of the trioxo form is present at equilibrium. A somewhat larger proportion of the 6-methyl derivative exists in the trioxo form, although structure 193 predominates. The trioxo form (194) of 2,4,7 trihydroxy-l,3,6-trimethyl-pteridine is the most important tautomer, but the corresponding 6-carboxylic acid exists entirely in the monohydroxy-dioxo form 195. 

Reaction of 2,4-dichloro-l,5-naphthyridine with ammonia (170°, 20 hr), hydrazine (100°, 16 hr), or aqueous hydrochloric acid (100°, 3 hr) was shown to yield the 2-amino- (47% yield) and 2-hydroxy-4-chloro derivatives (66% yield), but 2-hydrazino substitution (68% yield) was assumed. Disubstitution with ammonia (190°, 4 hr), hydrazine (100°, 48 hr), and ammonia-phenol (180°, 6 hr) occurred in high yield. Displacement of the 4-oxo group in 2,4-dioxo-l,5-naphthyridine occurs with aniline plus its hydrochloride (180°, 12 hr, 88% yield) to yield 429. Oxo groups in the 2- or 4-positions were... 

Uracil, thymine, and cytosine have been studied using this technique (89JA2308 and references therein). For uracil and thymine, the dioxo tautomer predominates in the case of cytosine (70), three tautomers were detected, 70a, 70b, and 70c, the last one being the least abundant. The gas-phase tautomeric equilibrium of 2-pyridone 15a and 2-hydroxypyridine 15b has been studied by MW spectroscopy (93JPC46) using both a conventional spectrometer and a jet-cooled millimeter-wave spectrometer. The relative abundances are 3 1 in favor of the hydroxy form 15b, which exists in the Z conformation shown (Scheme 23). 

Oxo-2,3,6,7-tetrahydro-5//-pyrido[l,2,3- /e]-l,4-benzoxazine-2-carbox-ylates (291, X = H2) were obtained by hydrogenation of 4-substituted 3, 4-dihydro-2//-1,4-benzoxazine-2-carboxylates (290, X = H2) over 10% Pd/C catalyst, then by the treatment of free acids with (CF3C0)20 (99EUP894796). 5,7-Dioxo-2,3,6,7-tetrahydro derivatives 291 (X = 0) were prepared similarly from 290 (X = O). The products 291 (X = O) exist in 7-hydroxy-5-oxo-2,3-dihydro-5// tautomeric form. 

Chemical Name 4-(dimethylamino)-1,4,4a,5,5a,6,11,12a-octahydro-3,6,10,12,12a-penta-hydroxy-N-[ [4-(2-hydroxyethyl)-1 -piperazinyl] methyl] -6-methyl-1,11-dioxo-2-naphtha-cenecarboxamide... 

Dimethyleneperoxidecarbamide. See Vol 5, D1337-R 7-Hydroxy-1, 2-Dioxo-l, 2-Dihydro-Naphthalene. See this Vol, N20-R... 

Dioxo-3-alkyl-imidazolidine werden mit Lithiumalanat in der Hitze zu 3-A1-kyl-imidazolidinen reduziert z.B. 2,4-Dioxo-3-methyl-5-phenyl-imidazolidin zu 7-Methyl-4-phenyl-imidazolidin (43% d.Th.) bei 23° und inverser Zugabe wird dagegen (vgl. S. 252) 2-Hydroxy-l-methyl-4-phenyl-imidazol (66% d. Th.) erhalten, das sich unter energischen Bedingungen zum 7-Methyl-4-phenyl-imidazol (25 % d. Th.) reduzieren laftt3 ... 

Bei der Photoreduktion von Uridin wird als Nebenprodukt durch Photohydratation 6-Hydroxy-2,4-dioxo-I-(fi-D-ribofuranosyl)-hexahydro-pyrimidin gebildet. Die Photoreduktion von Thymidin mit Natriumboranat ver-lauft langsamer und kann nicht vom zweiten, Licht-unabhangigen Schritt abgegrenzt werden2. 

Die C=C-Doppelbindung der 2,4-Dioxo-5-[2-hydroxy-pyrimidyl-(4)]-l,2,3,4-tetra-hydro-pyrimidine und deren En-amin-Verbindungen wird durch Natriumboranat auch ohne Belichtung reduziert z.B.4 ... 

Dioxo-4,8-diphenyl-l,3,5,7-tetraaza-bicyclof3.3.0]octan laBt sich durch Lithium-alanat in5-Hydroxy-3- phenyl-1,2,4- triazolidin (14% d.Th.), N-Methyl- benzylamin auf-spalten4 ... 

Besonders ausgepragt ist die selektive Reduzierbarkeit von Dioxo-steroiden mit Na-triumboranat7 (weiteres s. S. 329, 331 f.), wahrend symmetrische Diketone nur als Mono-(2-dimethylamino-athoxyimine) selektiv zu Hydroxy-ketonen reduziert werden8. Benzil kann mit Triathyl-siliciumhydrid durch Zinkchlorid katalysiert selektiv zu Benzoin reduziert werden9 ... 

Analog erhalt man ausgehend von 3/3-Hydroxy-16a-acetoxy-20-oxo-pregnen-(5) 7 6u-Acetoxy-3,20-dioxo-pregnen-(4)5. 

Analog wird 17a.-Hydroxy-21 -acetoxy-pregnatrien-(l,4,9")2 aus 9x-Brom-l 1/ ,17a-dihydroxy-21-acetoxy-3,20-dioxo-pregnadien-(l,4) erhalten. 

Behandelt man 9a-Brom-17a-hydroxy-1 l( ,21-diacetoxy-3,20-dioxo-pregnadien-(1,4) mit Chrom(II)-chlorid in Aceton, so wird als einziges Reaktionsprodukt 17a.-Hydr-oxy-1 lp,21-diacetoxy-3,20-dioxo-5,9-cyclo-pregnen-(l) (36% d.Th. F 186-191°) er-halten6 ... 

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