Tetrahydro-pyrimidines

Dimethyl sulfoxide 1 -Dimethyl-1,4,5,6-tetrahydro-pyrimidine Pyrantel pamoate 3,5-Dinitrobenzoic acid Diatrizoate sodium Dioctyl sodium sulfosuccinate Docusate calcium... 

Acyl-thioharnstoffe vom Typ des 4-Oxo-2-thiono-imidazolidins bzw. -hexahydro- oder tetrahydro-pyrimidins werden von komplexen Hydriden in der Regel an den Acyl-Grup-pen reduziert (s. S. 252f.). 

Bei der Reduktion von Purinen wird zumeist der Funfring aufgespalten. Die galvano-statische Elektrolyse (3—4 A/8 V fur mehrere Stdn.) von 2,8-Diamino-purin in 25,8 n Schwefelsaure an Blei-Kathoden liefert neben 2,8-Diamino-1,2,3,4,5,6-hexahydro-9H-purin 2-Amino-5-guanidino-6-oxo-3,4,5,6-tetrahydro- und 2-Amino-5-guanidino-3,4-dihydro-pyrimidin (nur das Tetrahydro-pyrimidin-Derivat ist abtrennbar (Totalausbeute -45% d.Th.)3. 

In addition to the dihydro compounds discussed above, the triethylsilane/trifluoroacetic acid reduction system can also be used to prepare tetrahydro pyrimidine derivatives, especially when dichloromethane is used as the solvent <2004TL2107>. Thus, treatment of 2-amino-5-phenylpyrimidine 398 with 2.5 equiv of triethylsilane and 5 equiv of TEA in dichloromethane at room temperature gave a quantitative yield of the tetrahydro derivative 399, whereas only a dihydro derivative was obtained with 10 equiv of the silane in the absence of dichloromethane <2004TL2107>. 

The one-step synthesis of further tri- and tetracyclic pteridine derivatives from 2-aminopyrazine 153 has also been described <2001JHC1173>. Cyclic analogues of A -[bis(methylthio)methylene]amino reagents such as 2-(methylthio)-2-thiazoline, 5,6-dihydro-2-(methylthio)-4//-l,3-thiazine, 2-(methylthio)-2-imidazoline, 2-(methylthio)-l,4,5,6-tetrahydro-pyrimidine, 2-(methylthio)-2-pyrazine, and 2-chloropyrimidine reacted with aminopyrazine 153 to afford thiazolo/thia-zino[2,3-3]- 159 ( = 1 (53%), n = 2 (42%)), imidazo/pyrimidino[2,l-/ ]- 160 ( = 1 (53%), = 2 (57%)), pyrazino[2,l-/ ]-161 (21%), and pyrimido[2,l-/ ]-pteridine 162 (42%) derivatives, respectively. 

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". 

Disubstituierte 5-Brom-6-methyl-2,4-dioxo-l, 2,3,4-tetrahydro-pyrimidine rcagieren mit aliphatischen Aminen in Dimethylformamid unter Ersatz des Brom-Atoms durch eine Amino-Gruppe4. Dagegen erfolgt bei Reaktion mit aromatischen Aminen allylische Substitution durch eine Arylamino-Gruppe, und man erhalt z.B. 6-Anilino-1,3-dimethyl-... 

QinTOuraci and Derivatives 5-Diazouracil 5-Diazo-2,4-pyrimidinediol or 5-Diazo-4-hydroxy-2(1 H)-pyrimidinone (called 5-Diazo-uracil 5-Diazo-2.4-dioxo-tetrahydro-pyrimidin or 5"Diazo-2.4-dioxy-pyriinidin in Ger),... 

Acyclic ureas have been obtained in moderate yield (up to 66%, after 20 h) by the thermal decomposition of carbamate salts (RNH3)02CNHR at high temperature (453 K), without the use of a catalyst [127a, b]. At high temperatures and pressures, diamines can also react with C02, in the absence of a catalyst, to afford cyclic ureas (imidazolidin-2-ones, tetrahydro-pyrimidin-2-ones) in moderate to good yield and selectivity [69c, 127c]. 

Methyl-2-oxo-4-phenyl-l,2,3,4-tetrahydro-pyrimidine-5-carboxylic acid ethyl ester... 

In addition, the reaction was extended to the 4-unsubstituted tetrahydro-pyrimidines 60. Here the same reaction pattern as before was observed The 1-unsubstituted derivative led to the 6-cyanopyrimidine 61, whereas the 1-methyl derivative afforded the geminal diazide 62 [90LA505],... 

Three different dynamic processes were detected in N-aryl-2-phenyl-tetrahydro-pyrimidine (cf. Scheme 60) by dynamic NMR spectroscopy enantiomerization of stereolabile atropisomers, restricted rotation about the Ph-C bond and, presumably, ring inversion of the tetrahydropyrimidine... 

Perhydro derivatives (270) are prepared from 1-substituted 1,4,5,6-tetrahydro-pyrimidines which form cycloadducts with epoxides (70LA(742)128). 4H-5,6-Dihydro-l,3-oxazines and -thiazines react in the same way to form products of type (270) (66AG(E)875). 

Azine approach. Substituted 6,7,8,8a-tetrahydro-5H-[l,2,4]oxadiazolo[4,5-a]-pyrimidines (613) have been prepared by cycloaddition of nitrile oxides or their chloro-oxime equivalents to a tetrahydro pyrimidine (73GEP2155753). 

The trend in the few examples where an NHC is functionalised with a sulfur-containing group does not necessarily reflect the choice of scaffold seen above, but the S functionalised NHC ligands do, in part, follow the general development of an S/P exchange in conventional functionalised phosphanes. The other major source for S functionalised NHC complexes of transition metals is the replacement of sulfur by a transition metal in certain Ji-sulfurane compounds. The NHC ligand, a tetrahydro-pyrimidine derivative, is only liberated during the reaction of the sulfurane with the transition metal precursor. 

Chikhale RV, Bhole RP, Khedekar PB, Bhusari KP (2009) Synthesis and pharmacological investigation of 3-(substituted l-phenylethanone)-4-(substitutedphenyl)- , 2, 3,4-tetrahydro-pyrimidine-5-carboxylates. Eur J Med Chem 44 3645-3653... 

In a series of cyclic guanidines, (2-amino-tetrahydro-pyrimidines, 171a-e), all mem-... 

Chlor-phenyl)-2-hydroxy-l,3-thiazol (R1—R = 0 R2 = 4-C l—C HJ972 Eine Suspension von 1,41 g (0,01 mol) 6-Methyl-4-oxo-2-thiono-l,2,3,4-tetrahydro-pyrimidin und 2,33 g (0,01 mol) w-Brom-4-chlor-acetophenon in 50 ml Ethanol wird mit 5 ml konz. Salzsaure versetzt und 7 h unter RiickfluB erhitzt. Nach 12 h Stehen saugt man das Produktab und kristallisiertum. Das Filtrat wird mit Natriumhydrogcncarbonat neutralisiert und mit Chloroform extrahicrt. Nach Trockncn fiber Natriumsulfat wird das Losungsmittel abdcstilliert und der Rfickstand umkristallisiert Ausbeute 1,9 g (90%) Schmp. 220°. 

Nitroso-3(5)-[l,2-oxazol-3(5)-yl]- 674 4-Nitro-5-[(3,4,5,6-tetrahydro-pyrimidin-2-yl)-amino]- 560... 

Bci 2,4-Dioxo-5-methyl-l - car boxy methyl -1,2,3,4-tetrahydro-pyrimidin (V) konkurriort die Decarboxylierung zu 2,4-Dioxo-l,5-dimethyl-pyrimidin (VI) mit der Photodimerisierung 3 ... 

AusschlieBlieh Wasser-Addition ertolgt bei UV-Bestrahlung einer 0,07 m Losung von 2.4-Dioxo-l,3-dimethyl-l,2,3,4-tetrahydro-pyrimidin in Wasser zu 6-Hydroxy-2,4-dioxo-], >-dimethyl-hexahydropyrimidin (60-75% d.Th. F 105-106°)3. 

H3c N R R = H 2 -Methyl-5 -aminomethyl-1,4,5,6-tetrahydro-pyrimidin 70 292-294 (Bis-hydro-chlorid )... 

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