A practical amine-free synthesis of symmetric ureas and thioureas by self-condensation if isothiocyanatesReportar como inadecuado




A practical amine-free synthesis of symmetric ureas and thioureas by self-condensation if isothiocyanates - Descarga este documento en PDF. Documentación en PDF para descargar gratis. Disponible también para leer online.

Resumen

Isocianates and isothiocyanates are readily transformed into the corresponding symmetric N,N-disubstituted ureas and thioureas upon treatment with pyridine-water with no formation of side products. Evidence is shown for an amine-free mechanistic pathway, probably involving thiocarbamic anhydrides as reaction intermediates. The methodology is compatible with in situ generation of the isocyanate precursor from and acyl azide via Curtius rearrangement and with the presence of ester and amide functional groups in the molecule. Examples given include alkyl, aryl and carbohydrate substrates. This procedure allows the high yielding preparation of thioureas in those cases where the related amine is not accessible.



Autor: Jiménez Blanco, José L.; - Benito, Juan M.; - Ortíz Mellet, Carmen; - Saitz Barría, Claudio; - Fuentes, José; - Santoyo Gonz

Fuente: http://repositorio.uchile.cl/



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