1,3-Dimethyl-4,8-dioxo-5,7-diphenyl

The following alkoxypyrazines have been prepared from the corresponding dichloropyrazines and alkoxide ions 2,3-dimethoxy-5,6-dimethyl(and diphenyl) (797) 2,3-dibenzyloxy (sodium benzyl oxide in benzyl alcohol at reflux for 24 hours (883)] [but 23-dichloropyrazine with sodium hydride and benzyl alcohol in xylene gave l,4-dibenzyl-2,3-dioxo-l,2,3,4-tetrahydropyrazine)(988)] 2-chloro-5-methoxy (838) 2,5-diethoxy-3,6-dimethyl (872) 2methanolic sodium methoxide refluxed for 2 h) 2,5-dimethoxy-3-phenyl (817) 2-chloro-5-methoxy(and ethoxy)-3,6-diphenyl (817) 2,5-dimethoxy-3,6-dimethyl (and diisopropyl) (844) 2,5-dimethoxy-3-isopropyl-6-methyl (methanolic potassium methoxide at reflux for 6 days) (844) 2(5)-s-butyl-3-chloro-6-ethoxy-5(2)-isobutyl (93) 2-chloro-6-methoxy (838, 883) 2,6-dimethoxy (reflux for 8h) (832) 2,6-diethoxy (reflux for 14 h) (883) 2-benzyloxy-6-chloro (1 equiv. of sodium hydride and benzyl alcohol in benzene at reflux) (832) 2,6-dibenzyloxy (5 equiv. of sodium benzyloxide in benzene at reflux gave 70%) (832) and 3,5-dimethoxy-2-methyl (535). 

Nur eine Carbonyl-Gruppe wird bei der Hydrodimerisierung von 1,3-Dioxo- 1,3-diphenyl-propan an Quecksilber reduziert [90% d.Th. 1,6-Dioxo-l,6-diphenyl-hexandiol-(3,4)]9-, analog verhalt sich 3,5-Dioxo-l,l-dimethyl-cyclohexan (Dimedon)10 ... 

In einer Photoreaktion reagiert 2,5-Diphenyl-l,3,4-oxadiazol mit l,3-Dimethyl-2,4-dioxo-1,2,3,4-tetrahydro-pyrimidin unter Ringspaltung. Das gebildete 5-(a.-Benzoylhydrazono-ben-zyl)-1,3-dimethyl-2.4-dioxo-1.2,3,4-teirahydro-pyrimidm (4 44%) kann zu anderen Folgepro-dukten wciterreagieren78". 

Diphenyl-4-ethoxy-l-tellurinium fluorosulfate reacted with 2,2-dimethyl-4,6-dioxo-1,3-dioxane (Meldrum s acid) to give 4-(2,2-dimethyl-4,6-dioxo-l, 3-dioxane-5-ylidene)-... 

Dimethyl-4,6-dioxo-1,3-dioxane-5-ylidene)-2,6-diphenyl-4/7-tellurin4 1.44 g (10 mmol) of Meldrum s acid are dissolved in 25 ml of pyridine, 5.0 g (10 mmol) of powdered 2,6-diphenyl-4-ethoxytellurinium fluorosulfate are added, and the dark red solution is immediately concentrated under vacuum. The residue is chromatographed on 100/200 mesh Florisil with dichloromethane as the mobile phase yield 4.0 g (80%) m.p. 199-201°. 

DipheDyl-4-methyltellurinium Tetrafloroborate1 12.0 g (24.7mmol) of 4-(2,2-dimethyl-4,6-dioxo-l,3-dioxane-5-ylidene)-2,6-diphenyl-4f/-tellurin are dissolved in 240 ml of 88% formic acid and the mixture is stirred on a steam bath until evolution of carbon dioxide ceases. 5.30 g (29.6 mmol) of tetrafluoroboric acid are then added and the resultant mixture is concentrated under reduced pressure. The residue is dissolved in 40 ml of acetonitrile, the solution is filtered through a sintered glass funnel into 400 ml of diethyl ether, and the yellow precipitate is filtered off yield 9.6 g (87%) m.p. 187-192". 

Dimethyl-6,8-dioxo-2,4.7-triphenyl- 1108 6,8-Dioxo-7-phenyl-2,3,3,4-tetramethyl- 1108 4,7-Diphenyl-6,8-dioxo-2,3.3-trimethyl-1108... 

Dibeiizoyl-2-methylamino-l,3-thiazol (R =R3 = CH3 R2 = CO—C6H5)904 Eine Ldsung von l,07g (4,58 mmol) l,4-Dioxo-l,4-diphenyl-2-butin in 5 ml Tetrahydrofuran wird zu einer Losung von 0,495 g (3,83 mmol) 3,4-Dimethyl-5-imino-4,5-dihydro-l,2,4-thiadiazol in 10 ml Tetrahydrofuran getropft. Man lafit die Mischung 12 h stehen. Das Reaktionsprodukt wird abgesaugt und aus Ethanol umkristallisiert Ausbeute 1,2 g (96%) Schmp. 197-198,5°. 

Dioxo-3,4-diphenyl-cydopenten-(3)-yliden-amino"]-l,5-dimethyl- 748 4-Fluor-l-diathylamino- 1156 l -luor-dichloi-si)yl)-pentafluor- 1392 4-Fluor-l-methoxy- 1156... 

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