Fig. 1: Synthesis of internal alkynes.

a Sonogashira coupling of unactivated alkyl halides with terminal alkynes (Fu3); b Cu-catalyzed alkynylation of C(sp3)-H adjacent to a nitrogen atom (Li7); c terminal alkynes as radical acceptors (Chen and Xiao19, Leonori28); d alkynylation of C-radicals with Waser’s EBX reagent25; e reaction design: working hypothesis; f Cu-catalyzed C(sp3)–C(sp) coupling of oxime esters with terminal alkynes. NHC N-heterocyclic carbene, dtbbp 4,4′-di-tert-butyl-2,2′-dipyridyl.