Regiodivergent Rhodium(I)-Catalyzed Azide-Alkyne Cycloaddition (RhAAC) To Access Either Fully Substituted Sulfonyl-1,2,3-triazoles under Mild Conditions.

A regiodivergent Rh(I)-catalyzed azide-alkyne cycloaddition (RhAAC) was developed for the synthesis of both fully substituted 4-sulfonyl-1,2,3-triazoles and 5-sulfonyl-1,2,3-triazoles in high regioselectivities and yields under mild conditions in one step. Nonmetallic sulfur(II) or sulfur(VI) could efficiently control the regioselectivity of RhAAC reactions by chelation or nonchelation mechanisms to give excellent 1,4- or 1,5-regioselectivities. The utility of this method is further highlighted by its compatibility with water and air, broad substrate scope, good functional group tolerance, gram-scale preparation, applicability to carbohydrates, and the tandem CuAAC-RhAAC reaction.