A rapid and efficient route to benzazole heterocycles
Richard D Carpenter1, Mark J Kurth
1Department of Chemistry, University of California, Davis, California, USA. rcarpenter@ucdavis.edu
Abstract:
This protocol describes a rapid, high-yielding, microwave-mediated route that affords benzazole heterocycles in high crude purity and represents a significant advancement toward an environmentally friendly reaction. The reaction of aryl isothiocyanates with o-nucleophilic anilines produces thiourea intermediates that, in the presence of a carbodiimide-functionalized resin, cyclize to benzazoles with the safe removal of one equivalent of hydrogen sulfide. This procedure takes ∼ 8.5 h to complete: 1-3 h for setup, 4.5 h for benzazole formation and 2 h for workup and purification.
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