Collect. Czech. Chem. Commun. 1982, 47, 676-688

Synthesis of methyl 3-(N'-alkylureido)-2-methyl-2-propenoates and their cyclization to 3-alkyl-5-methyluracils

Miroslav Ledvina and Jiří Farkaš

Institute of Organic Chemistry and Biochemistry, Czechoslovak Academy of Sciences, 166 10 Prague 6


Stereoisomeric methyl 3-(N' -alkylureido)-2-methyl-2-propenoates (Ia-Id) were prepared by acid-catalyzed reaction of N-alkylureas (R = methyl, benzyl, isopropyl and tert-butyl) with methyl 3-methoxy-2-methyl-2-propenoate (III). Reaction of the ester III with N-tert-butyl-thiourea afforded the thioureides (E)-Ie and (Z)-Ie. On treatment with sodium methoxide in methanol, compounds Ia-Ic cyclized to the corresponding 3-alkyl-5-methyluracils IIa-IIc whereas compounds Id and Ie underwent only a base-catalyzed E/Z isomerization with (E)-isomers predominating.