5.6- Dihydro-6-hydroxy pyrimidines

A trivial terminology for these products is common. The substances are 5,6-dihydro-6-hydroxy pyrimidines (9) they could be properly cited... 

Einige Pyrimidine und 2-Hydroxy-pyrimidine liefem in schwach saurem Medium neben den Tetrahydro-pyrimidinen Dihydro-Dimere. Amino-Substituenten werden als Ammoniak abgespalten (geteilte Zelle, Quecksilber-Kathode)3. 

Partly saturated pyrazino[l,2-r-]pyrimidines were prepared by formation of the pyrazine ring. 2-Substituted-8-hydroxy-3,4-dihydro-177,277-pyrazino[l,2-r-]pyrimidin-l-ones were prepared by a [6+0] synthesis involving cyclization of 6-hydroxy-pyrimidine-4-(fV-hydroxyethyl)carboxamides <2005W02005/087766>. The 2/7-pyra-zino[l,2-c]pyrimidine-3-carboxamide 164 (Y = NH) was formed from [5+1] atom fragments via the uracil derivative 163 (Y = NH) and DMF-dimethyl acetal. Compounds 163 were prepared from 6-chloromethyluracil and glycine methyl ester 162 (Y = NH) (Scheme 20) <2004W02004/014354>. 

The preparation of 9-niethyl and 9-butyl-2-hydroxy-8,9-dihydro-7H-purine-8-thione (XXVa Table 7) is somewhat unusual. Brown [45) has obtained these compounds from carbon disulfide and respectively f-methyl and 1 -butyl-5,6-diamino-1,2-dihydropyrimidin-2-one (XXIVa.). Evidently a shift of the alkyl group from the 3-N to the 9 N atom must occur during the ring closure. The structure of these two purines has been confirmed by their independent synthesis from 4-methylamino and 4-butylamino-5-amino-2-hydroxy pyrimidine. 

Hydrazone of 1 -hydrazino-1 -hydroxy-4-phenyl-1,2-dihydro-3//-pyrido [l,2-c]pyrimidin-3-one was patented as cross-linkers for making physiologically compatible and H2O insoluble hydrazine or hydrazono compounds (97JAP(K)97/59303). 

Other degradation products of the cytosine moiety were isolated and characterized. These include 5-hydroxy-2 -deoxycytidine (5-OHdCyd) (22) and 5-hydroxy-2 -deoxyuridine (5-OHdUrd) (23) that are produced from dehydration reactions of 5,6-dihydroxy-5,6-dihydro-2 -deoxycytidine (20) and 5,6-dihydroxy-5,6-dihydro-2 -deoxyuridine (21), respectively. MQ-photosen-sitized oxidation of dCyd also results in the formation of six minor nucleoside photoproducts, which include the two trans diastereomers of AT-(2-de-oxy-/j-D-eryf/iro-pentofuranosyl)-l-carbamoyl-4 5-dihydroxy-imidazolidin-2-one, h/1-(2-deoxy-J8-D-crythro-pentofuranosyl)-N4-ureidocarboxylic acid and the a and [5 anomers of N-(2-deoxy-D-eryfhro-pentosyl)-biuret [32, 53]. In contrast, formation of the latter compounds predominates in OH radical-mediated oxidation of the pyrimidine ring of dCyd, which involves preferential addition of OH radicals at C-5 followed by intramolecular cyclization of 6-hydroperoxy-5-hydroxy-5,6-dihydro-2 -deoxycytidine and subsequent generation of the 4,6-endoperoxides [53]. 

Photolytic cleavage (at 320nm) of the substituent at position 1 of 9-cyclopropyl-l-[(4,5-dimethoxy-2-nitrophenyl)-methoxycarbonyl-3-fluoro-2,6-dioxo-l,2-dihydro-6//-pyrido[l,2-tf]pyrimidine-7-carboxylate gave 9-cyclopropyl-3-fluoro-2-hydroxy-6-oxo-6//-pyrido[ 1,2-tf]pyrimidin-7-carboxylate <1995WO95/010519, 1996WO96/039407,... 

Some interesting fused 1,2,3-triazole ring systems have been reported. A series of 5-piperidyl-substituted 7-hydroxy-3f/-l,2,3-triazolo[4,5-d]pyrimidines 143 has been synthesized from pipecolinate esters, benzylazides, and cyanoacetamide <06CHE246>. 4-Alkylidene-5,6-dihydro-4//-pyrrolo-[l,2-c][l,2,3]triazoles 144 were prepared from alkylidenecyclopropanes via diiodogenation/Cu(I)-catalyzed 1,3-dipolar cycloaddition/intra-molecular Heck reaction sequence <06SL1446>. 6,6-Dimethyl-2-phenyl-4,5,6,7-tetrahydro-27/-benzotriazol-4-one 145 were prepared from A-(5,5-dimethyl-3-oxocyclohexenyl)-S,S-diphenylsulfilimine and... 

Plant The major degradation products of [2- C]terbacil identified in alfalfa using a mass spectrometer were (% of applied amount) 3-/er/-butyl-5-chloro-6-hydroxymethyluracil (11.9) and 6-chloro-2,3-dihydro-7-(hydroxymethyl)-3,3-dimethyl-5//-oxazolo[3,2-a]pyrimidin-5-one (41.2). Two additional compounds tentatively identified by TLC were 3-/er/-butyl-6-hydroxy-methyluracil and 6-chloro-2,3-dihydro-7-methyl-3,3-dimethyl-5//-oxazolo[3,2-a]pyrimidin-5-one (Rhodes, 1977). 

Our laboratory conducted the most extensive investigation of the 2,4,1-benzodiazaborines reported to date. We focused attention on l-hydroxy-lff-2,4,l-benzoxazaborine (50a), 1,2-dihydro-l-hydroxy-2,4,l-benzodiazaborine (50b), and 3-amino-l,2-dihydro-l-hydroxy-2,4,l-benzodiazaborine (50c) because their peripheries so closely matched the pyrimidine ring ones of the naturally occurring purines adenine, hypoxanthine, and guanine, respectively <94JA7597>. 

A similar effect occurs in the reaction of some pyrimidine nucleoside derivatives with hydroxylamine. Studies of the mechanism of this reaction with uridine derivatives340 shows that the initial point for nucleophilic attack is at C-6, and the resultant 5,6-dihydro-6-(hydroxy-amino)uridine derivative (86) is an intermediate in the conversion of the uridine derivative into the ribosylurea derivative 87 and 2-isoxazolin-5-one (88), as shown in Scheme 8. 

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