Copper-Catalyzed Geminal Difunctionalization of Terminal Alkynes by Splitting Sulfonyl Hydrazones into Two Parts.

A copper(I)-catalyzed geminal difunctionalization of terminal alkynes was developed via a carbene migratory insertion and an addition of a sulfonyl anion to the triple bond at the same time under mild reaction conditions, providing a variety of vinyl sulfones with good yields and excellent stereoselectivities.