Copper-catalyzed 1,1-difunctionalization of terminal alkynes: a three-component reaction for the construction of vinyl sulfones

A copper-catalyzed 1,1-difunctionalization of terminal alkynes was achieved via a three-component reaction, providing a variety of vinyl sulfones with good yields and excellent chemo- and stereoselectivity. Preliminary mechanistic studies indicated that the reaction probably underwent a Cu-catalyzed formal C–H insertion to produce an allene intermediate, which was then trapped by a sulfonyl anion to give the corresponding product.