Direct Deaminative Alkynylation of Aliphatic Primary Amines.

Alkyl-substituted internal alkynes are useful motifs in organic synthesis and medicinal chemistry, but their preparation from common amine precursors remains challenging. Aliphatic primary amines are widespread functional groups, yet their direct use as alkylating reagents is limited by the strength of the C(sp3)─N bond. Herein, we describe a direct deaminative alkynylation of aliphatic primary amines using alkynyl bromides as coupling partners. The transformation proceeds under metal-free conditions with an N-anomeric amide as a nitrogen-deletion reagent, enabling formation of C(sp3)─C(sp) bonds without prior amine prefunctionalization. The reaction shows good functional-group tolerance and accommodates a range of aliphatic amines, including substrates derived from pharmaceuticals and natural products. This study demonstrates the feasibility of converting aliphatic primary amines into internal alkynes and expands the scope of deaminative C─C bond-forming reactions.