Pyrimidines , hydrazino

Pyrimidine, 2,6-dimethyl-4-hydrazino-hydrogenation, 3, 87 Pyrimidine, 4,5-dimethyl-2-(methylthio)-synthesis, 3, 112... 

Cyclization of the 5-(A -arylcarboxamido)-4-hydrazino-6methylpyrim-idin-2-ones 104 with two molar equivalents of formaldehyde in the presence of pyridine caused the concomittant triazole and pyrimidine ring formation to yield the 4-aryl-l,3,4,10-tetrahydro-6-methyl-l,2,4-tria-zolo-[2,3,4-c,d]pyrimido[4,5-d]pyrimidine-5,8-diones 105 (89AP599)... 

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). 

The 4-hydrazino-pyrazolo[3,4-rf]pyrimidine derivative 80 yields pyrazolo[4,3-e]-[l,2,4]triazolo[4,3-c]pyrimidinones 82 through hydrazone derivatives 81 <00JCS(P1)33>, these compounds being a new class of potential xanthine oxidase inhibitors. 

This degenerate transformation of 30 into 30 can be explained when the incorporation of the label into the pyrimidine ring occurs by ring closure of the open-chain species, which is formed by ring opening of the covalent hydrazino adduct, probably at position 6 (Scheme III.18). 

A hydrazine or substituted hydrazine in lieu of the amino group on the pyrimidine precursor is also an effective species. In what may be described as a Fischer indole-type reaction, 2-amino-6-hydrazino-4(3//)-oxopyrimidine 129 undergoes thermolytic cyclization when heated with compounds 130 (Scheme 12). The resultant product 131 is obtained in modest yield <1996H(43)323, B-2002MI439>. 

Dicyano-l,3-dimethyluracil (156) undergoes substitution reactions with amines or sodium methoxide to yield 157 (R = NHR or OCH3). Compounds 157 reacted with hydrazines to yield the hydrazino derivative 158, which readily cyclized to the pyrazolo[3,4-[Pg.343]

Reaction of 160 with hydrazine affords the hydrazino derivative 161, which reacts further with hydrazine to yield the pyrazolo [3,4-d] pyrimidine derivative 162. Reaction with hydrazine hydrochloride afforded 163, which was converted into 162 upon treatment with hydrazine (79JHC1109). 

Amino-2-hydrazino-4(3//)-pyrimidinone (397) and orthoesters in hot acetic acid or BuOH gave l,2,4-triazolo[4,3-a]pyrimidin-7(8//)-ones 398. When the heating in acetic acid was continued overnight, the acetamido derivative 399 was obtained. In acetic acid at room temperature, the re-... 

Another way to prepare 2-amino derivatives is by the reaction of 2-methylthio-4-oxo-4// derivatives with amines.268,288 The 2-methylthio-4-imino derivative reacted differently (see Section III,C,8). 2-Ainino-4-oxo-4//-pyrido[l,2-a]pyrimidine could have also been prepared by reducing the 2-hydrazino derivative with hydrogen sulfide.289... 

Hydrolysis of the 2-acetylthioxy derivative (103 X = S) in aqueous methanol gave the 2-mercapto derivative, which was then desulfurized to 4-oxo-4H-pyrido[l,2- ]pyrimidine in 3"0 aqueous ammonia in the presence of Raney nickel.167 The same product was obtained in poor yield when 2-hydrazino-4-oxo-4f/-pyrido[l,2-u]pyrimidine was treated with a 15"/ solution of copper(ll) sulfate in aqueous acetic acid.255... 

The hydrazino group of 2-hydrazino-4-oxo-4ff-pyrido[l,2-u]pyrimidine was alkylated at N-2 with 6-chloronebularine,281 formylated at N-2 by heating in formic acid,166 and transformed to a SchifT s base by reaction with benzaldehyde.166... 

As part of their study on aza-transfer reactions, Tisler and co-work-ers289 290 reacted 2-hydrazino-4-oxo-4//-pyrido[l,2-u]pyrimidine with various diazo derivatives and obtained 2-azido- and 2-amino-4-oxo-4/f-pyrido[l,2-u]pyrimidines. From 2-azido-4-oxo-4/f-pyrido[l,2-u]pyrimi-dines various derivatives of 2-(l,2,3-triazol-l-yl)-4-oxo-4//-pyrido[1.2- ]-pyrimidine (221) were prepared by reaction with acetylene,287 1,3-dioxo compounds,166 ordiethylamine.291 For further ring transformation reactions of the 2-azido-4-oxo-4//-pyrido[l,2- ]pyrimidine (102), see Section lll.C.lO. 

Condensation of 2-hydrazino-4-oxo-4//-pyrido[l,2- ]pyrimidines with benzaldehyde, followed by treatment with bromine in acetic acid, afforded the pyridyltriazole (271).166... 

The tetracyclic systems, triazolothienopyrimidines, tetrazolothienopyrimidines, and related tetrazepino derivatives, were obtained from 2,3,5,6,7,8-hexahydro-3-amino-2-hydrazino-l-benzothieno[2,3-<7]pyrimidine-4(37/)-one <1995PS85>. 

Indolin-2-on-3yl)hydrazino-5,6,7,8-tetrahydrobenzo[fe]thieno[2,3-d]-pyrimidine 185 showed 10-20% herbicidal activity against pigweed, velvet leaf, red millet, green foxtail, and soya bean (81JHC1277). 

Reaction of 2-hydrazino-4-piperazinothiopyrano[3,2- ]pyrimidine with either RC(OEt)3 or NaN02 gave the corresponding triazolo or tetrazolo derivatives <90JHC1159>. 

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