Sodium as High‐efficient Catalyst in Hydroboration of Unsaturated Compounds

Abstract

The catalysts used to catalyze the hydroboration of nitriles or carbodiimides usually have some disadvantages such as complex structure, high cost, large pollution of environment and so on. It is an important development direction to use the main group metals instead of the transition metals to reduce the costs and realize green catalysis. In this paper, using NaH or NaOH as a catalyst, an efficient reaction of nitrile or carbodiimide with pinacol borane (HBPin) has been achieved. It was found that 3.5 mol% of NaH participated in the hydroboration reaction in a simple and effective method under slight solvent-free circumstances. In addition, intermolecular chemoselectivity hydroboration of nitrile and substrates with different functional groups was also investigated by employing three different catalysts. This reaction uses the inorganic alkali with simple structure, commercially available and low cost to synthesize organoborane compounds, which provides ideas for industrial development.

Applications of catalysis in hydroboration of imines, nitriles, and carbodiimides

“…53 Following such pioneering works, other metal and non-metal main group complexes were developed in related hydroboration transformations. [53][54][55][56][57][58][59][60][61][62][63][64][65] Catalyst free imine hydroboration was also recently introduced by the Rit group. 66 Nitrile hydroboration, operating through the formation of an imine intermediate, 49 was only introduced less than a decade ago by Nikonov and co-workers who employed an imido-hydrido complex of Mo(IV).…”

“…66 Nitrile hydroboration, operating through the formation of an imine intermediate, 49 was only introduced less than a decade ago by Nikonov and co-workers who employed an imido-hydrido complex of Mo(IV). 67 Significant progress has been made in the development of nitrile hydroboration using main group elements 31,63,[68][69][70][71][72] and transition metals (d-and f-blocks) in recent years. 47,[73][74][75][76] One report in 2019 exploited a thorium amide complex in nitrile hydroboration by Eisen and co-workers featuring a broad substrate scope and high TOF (500 h −1 ).…”

“…80 Almost three decades later, there remains only a handful of reports of carbodiimide hydroboration. 62,63,81,82 Numerous catalysts have been reported to effect the hydroboration of imines, nitriles, and carbodiimides. Notably, the current state-of-the-art still relies mainly upon precious metal elements.…”

“…53 Following such pioneering works, other metal and non-metal main group complexes were developed in related hydroboration transformations. 53–65 Catalyst free imine hydroboration was also recently introduced by the Rit group. 66…”

“…80 Almost three decades later, there remains only a handful of reports of carbodiimide hydroboration. 62,63,81,82…”