Doubly Stereoconvergent\nPropargylic Alkylation of\nα‑Cyanocarbonyls: Enantioselective Construction of Vicinal\nStereocenters

An asymmetric propargylic alkylation\nof α-cyanocarbonyls\nis developed for the first time under cooperative Cu(I) and organocatalysis.\nWith ethynyl benzoxazinanones as the propargylic electrophile, this\ndecarboxylative doubly stereoconvergent reaction evades alkyne hydroamination\nto furnish acyclic α-propargylic cyanocarbonyls, bearing vicinal\ntertiary and quaternary stereocenters, with high diastereo- and enantioselectivity\n(up to >20:1 dr and 99.5:0.5 er).