Atom‐Efficient Synthesis of Alkynylfluoroborates Using BF3‐Based Frustrated Lewis Pairs

A sterically demanding amine, 1,2,2,6,6‐pentamethylpiperidine (PMP), forms a highly reactive Lewis acid–base pair with boron trifluoride. This pair reacts with terminal acetylenes to give the products of C(sp)?H borylation, previously unknown tri‐ and tetraalkynylboron compounds. Trialkynylfluoroborates can serve as surrogates of alkynyltrifluoroborates for C?C coupling reactions. Using aqueous NaOH, PMP can be recovered from its tetrafluoroborate salt, which is formed as a C?H borylation byproduct. Combining the discovered borylation reactivity with the PMP recovery provides a straightforward and atom‐efficient approach to synthetically useful alkynylfluoroborates.