2,43,6 -Pyrimidine tetrone

Alloxan [2,4,5,6(l//,3//]pyrimidine, tetrone] [50-71-5] M 142.0, m 170 (dec), pK 6.64. Crystn from water gives the tetrahydrate. Anhydrous crystals are obtained by crystn from acetone, glacial acetic acid or by sublimation in vacuo. 

Alloxan or N,N-Mesoxalyl Urea (Pyrimidine-tetrone or Erythric Acid of Brugnatelli, OC-NH-CO... 

AI3-15282 Alloxan Alloxan 7169 Alloxane Barbituric acid, 5-oxo- EINECS 200-062-0 Mesoxalylcarbamide Mesoxalylurea NSC 7169 2,4,5,6-Pyrimidintetron 2,4,5,6(1H,3H)-Pyrimidine-tetrone 2,4,5,6-Tetraoxohexa-hydropyrimidine Urea, mesoxalyl-. Used in nutrition experiments. Causes diabetes in experimental animals. Crystals dec 256° soluble in H2O. Wako Pure Chem. Ind. 

Pyrimido[5,4-d]pyrimidine-2,4,6,8-tetrone X-ray, 3, 339 (66JCS(A)639> Pyrimido[4,5-d]pyrimidine-4-thione pK 3, 339 (58JOC1451) Pyrimido[4,5-d]pyrimidine-2,4,7-triamine,... 

Pyrimido[ 1,2-a]pyrimidine-1,4,6,9-tetrones rearrangement, 3, 341 Pyrimido[4,5-d]pyrimidine-2,4,5,7-tetrones synthesis, 3, 364... 

In contrast with the Schiff base salen, salicylaldehyde oxime (79) (salox) complexes of Co have received comparatively little attention, but a series of bis-bidentate divalent complexes of the form iraiis-Co(sa 1 ox)2( D M SO)2 have been reported.343 The heterocyclic bidentate oxime violurate (lH,3H-pyrimidine-2,4,5,6-tetrone 5-oximate, Hvi) (80) and its /V-methyl (mvi) and /V,/V -dimethyl (dmvi) derivatives form high-spin divalent [Co(vi)]+ and Co(vi)2 complexes, whereas [Co(vi)3] is low spin.344 The mixed-ligand Co(dmvi)2(phen) complex is also low spin. The crystal structure of m-Co(pxo)2Br2 (pxo = 2-acetylpyridine-l-oxide oxime) is isostructural with the Ni11 relative.345 The dichloro complex also adopts a cis configuration. The tridentate dioximes 2,6-diformyl-4-methylphenol dioxime and 2,6-diacetyl-4-methylphenol dioxime (Hdampo) form binuclear complexes of the type (81a) and (81b) respectively.346 Cobalt oxide nanoparticles were prepared by... 

The pyrimidinylhydrazine (53) is transformed into the 2,4,7,9-tetramethyl-l,2,3,4,7,8,9,10-octahydropyrimido[4,5-c]pyridazino[3,4-fif]pyrimidine-l,3,8,10-tetrone (54) under diazo transfer conditions. The azopyrimidines (55) can also be obtained from 53 and they cyclise to triazolo[4,5-tf pyrimidines (56) on heating in DMF [94MC208],... 

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