Electro-alkynylation: Intramolecular Rearrangement of Trialkynylorganoborates for Chemoselective C(sp²)–C(sp) Bond Formation

Abstract

An alternative and complementary transformation for the synthesis of aryl- and heteroaryl-substituted alkynes is presented that relies on a chemoselective electrocoupling process. Tetraorganoborate substrates were logically designed and simply accessed by transmetalations using readily or commercially available organotrifluoroborate salts.

Electrochemical synthesis and transformation of organoboron compounds

“…In a similar manner, they further developed the electrochemical oxidative intramolecular crosscoupling of alkenyl-triaryl and alkynyl-triaryl borates to give functionalized alkenes and alkynes (Scheme 16b and c). 42,43…”

Recent Progress on the Zweifel Olefination: An Update

“…Although the electro-olefination protocol is still in its infancy, it has proved useful to trigger the rearrangement of tetraorganoborates for the unprecedented creation of C-C double bonds (Scheme 6). 9 Scheme 6 Electro-olefination for the synthesis of enynes Soon after, the same group reported a photocatalyzed oxidative cross-coupling of tetraorganoborates. Similar to electrochemical synthesis, this photochemical condition also allows the Zweifeltype olefination accomplished without stoichiometric iodine.…”

“…Although the electro-olefination protocol is still in its infancy, it has proved useful for triggering the rearrangement of tetraorganoborates for the unprecedented creation of C–C double bonds (Scheme 6 ). 9…”

Forging C–C Bonds through Intramolecular Oxidative Coupling of Organoborates – An Overview

“…This strategy was illustrated on a large range of substrates (Scheme 15 ), although corresponding alkynes 38 were generally obtained in lower yields than alkenes and biaryl derivatives. 46…”