One-Pot Synthesis of 3-Difluoromethyl Benzoxazole-2-thiones.

A one-pot strategy for the diversified synthesis of 3-difluoromethyl benzoxazole-2-thiones is reported. The reaction of 2-aminophenol, sodium chlorodifluoroacetate, and elemental sulfur in the presence of NaO t-Bu gives exclusively 3-difluoromethyl benzoxazole-2-thiones in good yield (up to 98%). The mechanism of this reaction presumably involves first cyclization of 2-aminophenols with thiocarbonyl fluoride, followed by N-difluoromethylation with difluorocarbene. The developed synthetic procedures are versatile, robust, and easily scalable for the synthesis of 3-difluoromethyl benzoxazole-2-thione derivatives, some of which have shown insecticidal activities.