Transition-Metal-Free Superbase-Catalyzed C–H Vinylation of Aldimines with Acetylenes to 1‑Azadienes

Aldimines react with aryl- and hetarylacetylenes in the presence of KOBut/dimethyl sulfoxide (DMSO) or NaOBut/DMSO systems under exceptionally mild conditions (14 °C, 1 h) to afford C–H-vinylated products, 1-azadienes of E configuration relative to the C–C bond, in up to 72% yield. Vinylation involves the unprecedentedly fast multiposition proton transfer in the intermediate adducts of acetylene to the CN bond. This new Csp2–Csp2 bond-forming reaction opens a straightforward pot-, atom-, step-, and energy-economic access to synthetically valuable 1-azadienes.