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2004
Urea derivatives
Q 0640
Efficient Synthesis of Ureas by Direct Palladium-Catalyzed Oxidative Carbonylaof Amines. — A general synthetic approach towards di- and trisubstituted urea de45- 101 tion
rivatives is presented, involving the direct reaction of amines with a CO—air mixture
in the presence of PdI2—KI catalytic system. Thus, reaction of primary aliphatic (I) or
aromatic amines (VI) with CO—air mixture provides access to symmetrical disubstituted ureas (III) and (VII). The use of CO2 as promoter is beneficial to the more basic
amines while detrimental effect is observed for less basic amines. No reaction is observed with secondary amines, which points to the formation of a reactive isocyanate
intermediate from the primary amines. This isocyanate, however, can be quenched by
reaction with a primary or a secondary amine, opening a pathway to trisubstituted ureas
(V) or (VIII). The method is successfully applied to α-amino acid esters (XIII), (XV)
as amine component. — (GABRIELE*, B.; SALERNO, G.; MANCUSO, R.; COSTA,
M.; J. Org. Chem. 69 (2004) 14, 4741-4750; Dip. Sci. Farm., Univ. Calabria, I-87030
Arcavacata di Rende, Cosenza, Italy; Eng.) — Mischke
2004
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