10- -dione, structure

Cholestane, pregnan-20-one, and androstan-17-one derivatives with the 5,10-seco-19-nor-5-yne-3,10-dione structure (506) have been prepared via cleavage (tosylhydrazide) of the 5j8,10jS-epoxy-6-ketones (505). The required 5(10)-en-6-ones (504) were obtained in one step by oxidation of the respective 19-hydroxy-A -derivatives (503) with chromium trioxide-pyridine. 

Pteridine-6,7-dione, 4-amino-2-chloro-chlorination, 3, 296 Pteridine-6,7-dione, 2,4-dichloro-synthesis, 3, 291 Pteridine-6,7-dione, 5-hydroxy-synthesis, 3, 316 Pteridine-6,7-dione, 8-methyl-reduction, 3, 298 Pteridine-2,6-diones structure, 3, 272 Pteridine-4,6-diones structure, 3, 272 synthesis, 3, 310 Pteridine-6,7-diones reduction, 3, 298 synthesis, 3, 316... 

One-component syntheses, in which a pyran ring (type B,l) or a 1,5-dione structure (type B,2) is already present. 

The piperidine dione structure can be generated by acylation of Meldrum s acid with N-protected /3-amino acids followed by thermolysis of the resulting N-protected fi-amino-/3-ketoacid (Equation 166 Table 6) <2004JOC130>. 

The heterocyclic ring in l,2,4-triazine-3,5-dione (12) and its 6-methyl derivative (13) is planar. The data clearly show that in the crystal only the dione structure is present no indication of any other tautomeric structure was found. The methyl group in the 6-position of (13) has an influence on the bond lengths of the two carbonyl groups. While in (12) the two carbonyl groups are equal (1.224 A), in (13) two different distances were found C(3)=0 = 1.213 A and C(5)=0 = 1.242 A. In the ribosides (14) and (15) both carbonyl groups are nearly the same length. 

Thus far there is only one report describing such a system. A naphtho [2,3-d]-l,2-diazetin-4,9-dione structure has been proposed for the product I from the reaction between 2,3-dichloro-1,4-naphthoquinone and diphenyl-hydrazine (85MI1). 

Westphal and Stroh originally thought that the product obtained in the reaction of anthranilic acid and levulinic acid was the linearly annelated compound 84. The pyrrolo[l,2-fl]quinazoline-l,5-dione structure 85 was later elucidated by Yamato and Takeuchi. ... 

Oxadiazine-3,5-diones are acidic the parent compound has pKa 7.6.5 These compounds arc included in this section because of formal tautomerism with unsaturatcd dihydroxy forms such as 5. However, there is no evidence for the existence of such tautomers. The oxadiazinediones exhibit two NH absorptions in the region 3200 3100 and two carbonyl bands, one at ca. 1750 and the other at 1710-1670 cm 1. The, 3C NMR spectra of oxadiazine-dione and its 2-substituted derivatives are informative C3 resonates at ca. 5 = 150, C5 at ca. 5 = 169 and C6 at ca. <5 = 70 ppm. An X-ray analysis of the parent compound confirmed its dione structure the structure shown gives bond lengths (pm) and angles of 2//-l,2,4-oxadi-azine-3,5(4/7,6//)-dione.6... 

Only a few 1,2,4-triazines have been isolated from natural sources. Most are fused examples, such as the pyrimido[5,4-c]-l,2,4-triazine fervenulin (6). In 1988 the very surprising monocyclic 4,5-dihydro-1,2,4-triazine-3,6-dione structure (7) was reported to be isolated from the seeds of Butea... 

Quinones - Compounds having a fuUy conjugated cyclic dione structure, such as that of benzoquinones, derived from aromatic compounds by conversion of an even number of -CH= groups into -C(=0)- groups with any necessary rearrangement of double bonds. [5]... 

Pterin (2-amino-4-hydroxypteridine, which occurs in the lactam form 8) and lumazin (2,4-dihy-droxypteridine, which exists as the l,2,3,4-tetrahydropteridine-2,4-dione structure 9) are the basic structures of the naturally occurring pteridine derivatives ... 

---