Univerzita PardubiceFakulta chemicko- technologická

Univerzita Pardubice

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Publikace detail

2-Imino-1,3-thiazines or 2-thioxopyrimidines: That is the question

Autoři: Hanusek Jiří | Hladíková Veronika

Rok: 2014

Druh publikace: ostatní - přednáška nebo poster

Strana od-do: nestránkováno

Tituly:

Jazyk	Název	Abstrakt	Klíčová slova
eng	2-Imino-1,3-thiazines or 2-thioxopyrimidines: That is the question	We decided to start our synthesis from original isothiuronium salts (1a-d) prepared from easily available dimethyl (2-chloromethylidene)malonate and substituted thioureas. These isothiuronium salts were submitted to the reaction with various bases (TEA, aqueous ammonia, sodium methoxide, sodium carbonate) in water, methanol or in biphasic system (chloroform/water) and reaction products were investigated. It was found that strong bases in excess (and sometimes also in equimolar ratio) caused complete decomposition of individual salts to many different product. When equimolar amount or slight excess of weaker base (ammonia) was used then the formation of cyclic product was observed (Scheme 2). In the case of unsubstituted isothiuronium salt corresponding methyl-2-imino-4-oxo-3,4-dihydro-2H-1,3-thiazine-5-carboxylate (2a) was isolated whereas N,N’-dimethyl (1b), N-phenyl (1c) and N-phenyl-N’-methyl (1d) isothiuronium salts possessed corresponding 4-oxo-2-thioxo-1,2,3,4-tetrahydropyrimidine-5-carboxylates (3b-d). On the basis of careful NMR measurements it was found that corresponding 2-imino-1,3-thiazines are always formed first which subsequently undergo nucleophile-assisted Dimroth rearrangement to give 2-thioxopyrimidines (3b-d).	2-Imino-1,3-thiazine; 2-thioxopyrimidine;