Rhodium(I)-Catalyzed Regioselective Azide-internal Alkynyl Trifluoromethyl Sulfide Cycloaddition and Azide-internal Thioalkyne Cycloaddition under Mild Conditions

A regioselective method to access fully substituted 5-trifluoromethylthio-1,2,3-triazoles and 5-thio-1,2,3-triazoles from the internal alkynyl trifluoromethyl sulfides and internal thioalkynes by a rhodium(I)-catalyzed azide-alkyne cycloaddition (RhAAC) reaction under mild conditions has been developed. This approach features good compatibility with water and air, a broad substrate scope, good functional group tolerance, high yields and excellent regioselectivities. The high 1,5-regioselectivities were controlled by the strong coordination between the sulfur atom and the pi-acidic rhodium. The advantages of this method further include its applicability to gram-scale preparation, the use of solid-phase synthesis technique, and the mutually orthogonal CuAAC-RhAAC reaction.