Thiazole Synthesis by Cyclocondensation of l-Alkynyl(phenyl)-lambda~3 -iodanes with Thioureas and Thioamides

摘要

In 1996,Wipf and Venkatraman reported an efficient method for the synthesis of thiazoles,which involved the cyclo-condensation of hypervalent l-alkynyl(phenyl)-lambda~3-iodanes with thioureas or thioamides.For instance,the reaction of phenylethynyl(phenyl)(mesylato)-lambda~3-iodane (la) (X = OMs,Ms = methanesulfonyl) with thiourea in methanol in the presence of triethylamine at 0 deg C directly afforded 2-amino-4-phenylthiazole (2;R = Ph,R'=NH_2) in a good yield (Scheme 1).