Synthesis and Diversification of Macrocyclic Alkynediyl Sulfide Peptides.

The synthesis of rare macrocyclic alkynediyl sulfides by a Cu-catalyzed Csp -S cross-coupling is presented. The catalytic protocol (Cu(MeCN)4 PF6 /dtbbpy) promotes macrocyclization of peptides, dipeptides and tripeptides at ambient temperature (14 examples, 23→73 % yields) via thiols and bromoalkynes, and is chemoselective with regards to terminal alkynes. Importantly, the underexplored alkynediyl sulfide functionality incorporates a rigidifying structural element and opens new opportunities for diversification of macrocyclic frameworks through S oxidation, halide addition and azide-alkyne cycloaddition chemistries to integrate sulfones, halides or valuable fluorophores (7 examples, 37→92 % yields).