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

Vladimir Iashin; Konstantin Chernichenko; Imre Pápai; Timo Repo

doi:10.1002/anie.201608520

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

Angew Chem Int Ed Engl. 2016 Nov 2;55(45):14146-14150. doi: 10.1002/anie.201608520. Epub 2016 Oct 6.

Authors

Vladimir Iashin¹, Konstantin Chernichenko², Imre Pápai³, Timo Repo⁴

Affiliations

¹ Department of Chemistry, University of Helsinki, A. I. Virtasen aukio 1, FI-, 00014, Helsinki, Finland.
² Department of Chemistry, University of Helsinki, A. I. Virtasen aukio 1, FI-, 00014, Helsinki, Finland. kochern@gmail.com.
³ Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar tudósok körútja 2, H-, 1117, Budapest, Hungary.
⁴ Department of Chemistry, University of Helsinki, A. I. Virtasen aukio 1, FI-, 00014, Helsinki, Finland. timo.repo@helsinki.fi.

PMID: 27709758
DOI: 10.1002/anie.201608520

Abstract

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.

Keywords: C−H activation; alkynes; amines; boron trifluoride; frustrated Lewis pairs.

Publication types

Research Support, Non-U.S. Gov't