A Universal Organocatalyst for Selective Mono-, Di- and Tri-Boration of Terminal Alkynes

Abstract

Multiboronate compounds are valuable synthetic building blocks for the construction of complex organic architectures via cross-coupling chemistry at C-B bonds. Hence, there has been a tremendous amount of work in the past decades to develop practical multiboration reactions. Many of developed methods start from alkynes, the most versatile synthetic precursors for multiboronates, and use transition-metal complexes as catalysts. However, several drawbacks such as low efficiency, poor selectivity and narrow substrate and catalyst scopes remain major challenges to be ad-dressed in this research area. Herein, we report the development of a universal organocatalytic system to promote the mono-, di- and tri-boration of terminal alkynes in highly efficient and selective manner. The reaction outcomes can be manipulated at will by varying catalyst loading, reagent stoichiometry and reaction time.

Conversion of Carbon Dioxide into a Series of CBxOy– Compounds Mediated by LaB3,4O2– Anions: Synergy of the Electron Transfer and Lewis Pair Mechanisms to Construct B–C Bonds

“…In the condensed phase, the construction of multiple B−C bonds is usually limited by the narrow substrates and catalyst scopes around 40−150 °C. 25 Under room temperature, we experimentally observe a series of novel CB x O y − (x = 2−3, y = 2 or 3) ions by applying CO 2 molecules as the carbon source (Figures 1 and S1 − /CO 2 system have been investigated theoretically. On the one hand, the synergy of electron transfer and boron− boron Lewis pair mechanisms promotes the complete C�O double bond breaking; on the other hand, the boron sites can capture the newly formed CO unit, which facilitates the formation of products with B−C bonds.…”

“…Organoboron species with multiple B−C bonds enable novel chemical transformations, resulting in complex organic molecules with C−C or C− heteroatom bonds. 25,26 Poor selectivity, low efficiency, limited substrates, and fewer valuable catalysts are common drawbacks of this kind of reaction. 27 Therefore, how to utilize CO 2 to build multiple B−C bonds in an effective, selective, and green manner at room temperature is appealing and urgently required.…”