Pyrimidine-2-thiol

An efficient method has been developed for the conversion of pyrimidine-2-thiol into the sulfonyl chloride 75, which was reacted in situ with amines. A modified method gave the rather more stable (and storable) sulfonyl fluoride 74 <06JOC1081>. 

A method for extraction and spectrophotometric determination of traces of Te(IV) from hydrochloric acid media with l-(4-bromophenyl)-4,6,6-trimethyl-l,4-dihydro-pyrimidine-2-thiol (4-bromoPTPT) in CHCI3 has been described [1]. Tellurium in alloys and in synthetic mixtures with Se(lV) was determined. 

Aminopyrido[2,3-d]pyrimidine-2-thiol is converted into 2-sulfanylpyrido[2,3-rf]pyrimidin-4(3//)-one by refluxing in 2 M aqueous sodium hydroxide.79... 

In a general annulation method, 4-aminonicotinonitriles are treated with ethyl orthoformate to give the corresponding (ethoxymethylene)amino compounds. The nitrile group is then converted with sodium hydrogen sulfide into a thioamide function which cyclizes to yield the 2-sulfanylpyrimidine moiety. An application of this method is the synthesis of 6-benzyl-5,6,7,8-tetrahydropyrido[4,3-t/]pyrimidine-2-thiol (3) from l-benzyl-4-[(ethoxymethylene)amino]-l,2,5,6-tetrahydropyridine-3-carbonitrile (2).491 492... 

In a sodium ethoxide catalyzed condensation of 3,5-bis(arylmethylene)-4-piperidones 22 with ureas or thioureas, one of the exo-methylene functions is used to build up the pyrimidine part of a 8-methylene-l,4,5,6,7,8-hexahydropyrido[4,3-ethanolic solution of 1-methyl-3,5-bis(ferrocenylmethylene)-4-piperidone with an excess of thiourea in the presence of sodium ethoxide, the corresponding pyrido[4,3-r/]pyrimidine-2-thiol is obtained.512 The use of guanidine in this reaction affords the corresponding 2-amino compounds.513... 

A partial aromatization of hexahydropyrido[4,3-potassium hexacyanoferrate(III).531 Starting from the hydrochloride of8-benzylidene-6-methyl-4-phenyI-3,4,5,6,7,8-hexahydropyrido[4,3-d]pyrimidine-2-thiol, after methylation of the sulfanyl group, the oxidation gives 8-benzylidene-2-(methylsuIfanyI)-6-methyl-4-phenyl-5,6,7,8-tetrahydropy-rido[4,3-d]pyrimidine. In a similar way, several 4-aryl-8-arylidene-6-methyl-3,4,5,6,7,8-hexahy-dropyrido[4,3-rf]pyrimidin-2-amines have been partially aromatized.513... 

Treatment of 5-acetyl-4-chloro-6-methyl-2-phenylpyrimidine (38, R1 = Ph R2 = Me) with urea leads to the corresponding pyrimido[4,5-d]pyrimidine 39 (R1 = Ph, R2 = Me). On the other hand, the reaction with thiourea affords not the expected 4,5-dimethyl-7-phenylpyrimido[4,5-t/]pyrimidine-2-thiol, but instead 5-acetyl-6-methyl-2-phenylpyrimidine-4-thiol.116... 

Scheme 3 Structures of pyrimidine-2-thiol (7), 2,3-pyrazinedithiol (8), quinoxaline-6,7-dithiol (9), and 2,5-dimercaptobenzene dicar-boxylic acid (10). Like molecules 5 and 6, the thiol donor are conjoined with electron-withdrawing groups (e.g., the pyrimidine unit in 7) to temper its interaction with metal ions, and to promote the formation of ordered networks...

Thiazolo[3,2-a]pyrimidines [C3NS-C4N2].—Condensation of 6-amino-4-hydroxy-pyrimidine-2-thiol with ethyl a-chloroacetoacetate yields a sulphide, which cyclizes on crystallization from ethanol to give a bicyclic product which is cither compound (82) or its isomer formed by ring-closure at the other nitrogen. Dehydration and acetylation of the amino-group occur with acetic anhydride. 

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