Depending on the character of the starting substances, one or other of the processes described may in particular give only low yields of an intended benzenesulfonyl urea, or be unsuitable for the synthesis of this compound.
In continuation of our work in this area we developed an improved one-potprocedure for the synthesis of 5-acyl-1,2,3,4-tetrahydropyrimidine-2-thiones/onesstarting from -tosyl substituted thioureasand ureas without isolation of the intermediate 4-hydroxyhexahydropyrimidine-2-thiones/ones.
Microwave-Assisted Synthesis of N-Monosubstituted …
Under mild microwave irradiation conditions a variety of symmetrical and unsymmetrical N,N′-disubstituted thioureas and ureas were prepared via the reaction of N-monosubstituted hydroxylamines with isocyanate and isothiocyanate derivatives over MgO under solvent-free conditions. This new method afforded satisfactory results with good yields, short reaction time, and simplicity in the experimental procedure.
ChemInform Abstract: Microwave-Assisted Synthesis …
The synthesis of (±)-thalictroidine , is the first reportedsynthesis of the natural product, and spectroscopic and crystallographic data are in agreementwith the structure proposed by Kennelly et al.125The synthesis of several 5-monosubstituted indolizidines, used in model studies in order toestablish fundamental skeletal and functional group transformations for 5,8-disubstitutedindolizidines are then shown.
1 Mahmoud Nasrollahzadeh, Mehdi Maham, S
Thus the present work demonstrates that 5-acyl-1,2,3,4-tetrahydropyrimidine-2-thiones/ones("Biginelli compounds") can be efficiently prepared by one-pot reactionof readily available -tosyl substituted thioureasor ureas with enolates of -oxoesters or 1,3-dicarbonylcompounds followed by acid treatment of reaction mixtures. The applicationof this method provides a simple powerful tool for the synthesis of a largenumber of multifunctional pyrimidine-2-thiones/ones.
A New Synthesis of Biginelli Compounds
A detailed example for such a reaction is disclosed in OrganicSynthesis, volume 31 (1951), pages 9 to 11, where the reaction of p-bromoaniline with sodium isocyanate in glacial acetic acid/water to give p-bromophenylurea is described.
A New Synthesis of Biginelli Compounds ..
The benzenesulfonylureas which are possible starting substances for the process can be unsubstituted, monosubstituted or, in particular, disubstituted on the side of the urea molecule opposite the sulfonyl group.
Mohammad Sajadi - Faculty of Science - Google Sites
The described approach was also applied to the one-pot synthesis ofthe 4-alkyl substituted 1,2,3,4-tetrahydropyrimidine-2-thiones 7e-nand 4-aryl substituted 1,2,3,4-tetrahydropyrimidine-2-thiones 7o-s byreaction of the corresponding thioureas 4a-f with the potassiumenolates of 5a-f in ethanol (r.t., 4.5-6 h) followed by acidificationand refluxing of the reaction mixtures.