Polymer-supported O-alkylisoureas: useful reagents for the O-alkylation of carboxylic acids.
Polymer-supported O-alkylisoureas were prepared by reaction of an alcohol with a polymer-supported carbodiimide under copper(II) catalysis. These reagents were used to transform carboxylic acids into the corresponding methyl, benzyl, allyl, and p-nitrobenzyl esters in a highly chemoselective manner in high yields and in very high purity after simple resin filtration and solvent evaporation. The reactions could be carried out using both conventional or microwave heating, with reaction times as short as 3-5 min in the latter case, without compromising yield, purity, or chemoselectivity. Unfortunately, the corresponding solid-supported tert-butyl isoureas could not be prepared.
Crosignani
Stefano
S
Combinatorial Centre of Excellence, School of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, United Kingdom.
White
Peter D
PD
Linclau
Bruno
B