Synthesis of Enantiopure 1,5-Enynes and 1,5-Diynes with Propargylic Quaternary Centers

Diastereoselective quaternization of ortho‐sulfinylbenzyl‐methylpropargylic carbanions has been carried out with various allylic, propargylic, and benzylic halides. The stereoselectivity is efficiently controlled by the sulfinyl group, acting as a remote chiral auxiliary. Desulfinylation of the resulting compounds with tBuLi provides access to enantiopure 1,5‐enynes, 1,5‐diynes, and 4‐arylalkynes bearing all‐carbon quaternary propargylic centers. Diastereoselective quaternization of o‐sulfinylbenzyl‐methylpropargylic carbanions has been achieved with allylic, propargylic, and benzylic halides. The stereoselectivity is efficiently controlled by the sulfinyl group, acting as a remote chiral auxiliary. This method provides access to enantiopure 1,5‐enynes, 1,5‐diynes, and 4‐arylalkynes bearing quaternary propargylic centers.