1.5- dioxo-3,3-diphenyl

H-Pyrazino[l,2-a][l,3,5]triazine, 2-amino-8-methyl-4,9-dioxo-cis-6,7-diphenyl-6,7,8,9-tetrahydro-... 

The primary dihydro product can be obtained by reduction of the quinonoid dyestuff. Thus for example 4,4 -diphenyl-2,2 -dioxo-A -biselenazol-5,5 -inylidene bis-benzylidenehydrazone could be reduced to 4,4 -diphenyl-2,2 -benzylidene hydrazino-5,5 -biselenazoie (13). This... 

Chemical Name 1,2-Diphenyl(3,5-dioxo-4-(3 -methyl-2 -butenyl)-pyrazolidine Common Name Phenylprenazone, prenazone Structural Formula ... 

The reaction mixture is refluxed for 1 hour, then the solvent Is slowly distilled off, the distillation being completed in vacuo. The solid residue so obtained is dissolved in 400 ml of water and washed with ether. The solution is acidified with 10% HCI and the 1,2-diphenyl-3,5-dioxo-4-(3 -methyl-2 -butenyl)-pyrazolidlne which separates is purified by crystallization from ethanol (MP 155°Cto 156°C). 

Chemical Name 4-butyl-1,2-diphenyl-3,5-pyrazolidinedione Common Name 3,5-dioxo-l, 2-diphenyl-4-n-butylpyrazolidine Structural Formula ... 

The product is dissolved in water, clarified with a little animal charcoal and 15% hydrochloric acid is slowly added until an acid reaction to Congo red paper is produced. 1,2-Diphenyl-3,5-dioxo-4-n-butyl-pyrazolidine separates as an oil, which rapidly become crystalline. It crystallizes from alcohol as colorless needles with a MP of 105°C. 

After being left in the refrigerator overnight the mixture, which has set solid, is triturated with 50 ml of isopropyl alcohol and the solid product filtered off and dried in vacuo over phosphorus pentoxide. 63 g (60% yield) of 1,2-diphenyl-3,5-dioxo-4-n-butyl-4-(N -methylpiper-azinomethyl)pyrazolidine are obtained, melting at 1 29°C after recrystallization from 150 ml of isopropyl alcohol. 

Y2 receptors are characterised by an order of potency of NPY PYY > C-terminal fragment [Pro34]-substituted analogue > PP. BIIE 0246 ((S -iV2- 1 -[2-[4-[(i ,5)-5,11 -dihydro-6(6h)-oxodibenz[b,e]azepin-l 1 -yl]-l-piperazinyl]-2-oxoethyl]cyclopentyl]acetyl]-iV -[2-[l, 2-di-hydro-3,5-(4H)-dioxo-l, 2-diphenyl-3H-l, 2,4-ttiazol-4-yl]ethyl]-argininamide) is a Y2-selective antagonist with an affinity of 3 nM. 

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 ... 

DieKeto- undEnol-Formen von l,3-Dioxo-2-methyl- 1,3-diphenyl-propan liefern ver-schiedene Reduktionsprodukte4 ... 

Eine wichtige Anwendung dieser Reaktion ist die Entschwefelung von Brennstoffen. Zur reduktiven Dimerisierung von oo-Brom-acetophenon zu 1,4-Dioxo-l,4-diphenyl-butan kann auch Pentacarbonyleisen eingesetzt werden (s. ds. Handb., Bd. VII/2b, S. 1877), obwohl in der Regel Zink/Kupfer verwendet wird. 

Tetraphenyl-4,4 -bi-4H-pyranyliden wird in einfacher Weise durch Elektro-reduktion und nachfolgende Dehydrierung von 2,6-Diphenyl-pyrylium-perchlorat in Acetonitril/Tetrabutylammoniumperchlorat zu 48% d.Th. erhalten (als Nebenprodukt fallt 15% d.Th. 1,5-Dioxo-l,5-diphenyl-pentan an)8 ... 

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 AcetonitrilundTctraathylammoniumperchlorat als Leitsalz erhalt manbei —2 V an Quecksilber aus l,5-Dioxo-l,5-diphenyl-pentan 1,2-Dihydroxy-1,2-diphenyl-cyclopen-tan (76% d.Th.)2, vgI"3 und aus l,6-Dioxo-l,6-bis-[4-hydroxy-phenyl]-hexan /,2-Dihydroxy- 1,2-bis- 4-hydroxy-phenyl]-cyclohexan3 ... 

Azobenzol liefert in Gegenwart von Bernsteinsaure-dichlorid in guter Ausbeute 3,6-Dioxo-1,2-diphenyl-hexahydro-pyrazin (49% d. Th.)s ... 

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