Borane-catalyzed selective dihydrosilylation of terminal alkynes: reaction development and mechanistic insight

Abstract

A B(C6F5)3/silane-based system enables the chemoselective dihydrosilylation of terminal alkynes. Using a combination of different types of hydrosilanes, a series of unsymmetrical or symmetrical 1,1-bis(silanes) could be constructed.

Activation of Si–H and B–H bonds by Lewis acidic transition metals and p-block elements: same, but different

“…Nevertheless, Li and co-workers have recently addressed this problem, and found that terminal alkynes can undergo a double hydrosilylation reaction in a highly efficient process leading to geminal bis(silanes) (Scheme 32) using a particular set of combinations of hydrosilanes. 81 In this work, the authors noticed that hydrosilylation reactions proceed more efficiently at low temperatures (typically at −20 °C). After a cautious inspection of the process, they observed that B(C 6 F 5 ) 3 degrades through an irreversible 1,1-carboboration reaction as depicted in Scheme 33, a process that, according to DFT calculations, might take place at moderate temperatures (with a highest activation barrier of 21.6 kcal mol −1 ).…”

Recent Advances in the Functionalization of Terminal and Internal Alkynes

“…Very recently, Li and co‐workers developed boron catalyzed selective mono‐ and dihydrosilylation of terminal alkynes for the synthesis of vinylsilanes and unsymmetrical geminal bis(silanes) by using a silane‐tuned chemoselective strategy (Scheme 36). [35] This methodology was suitable for dihydrosilylation of both aliphatic and aryl terminal alkynes with different silane combinations. Mechanistic investigations show that tertiary silanes (like EtMe 2 SiH) prefer hydrosilylation of alkynes (1 st hydrosilylation), while primary hydrosilanes (like PhSiH 3 and BuSiH 3 ) prefer hydrosilylation of vinylsilane (2 nd hydrosilylation).…”

Cobalt‐Catalyzed Regiodivergent Double Hydrosilylation of Arylacetylenes

“…However, due to the high sensitivity of the trichlorosilyl group towards air and moisture, the vicinal bis‐silyl products were converted to diols via one‐pot oxidation. To obtain stable and easily modifiable bis‐silyl compounds, our group, [13d, e] Zhu group, [11e] and Li group [13a] have independently and systematically developed efficient 1,1‐dihydrosilylation of terminal alkynes by using different catalysts, giving Si−H bonds‐containing geminal bis(silane)s as the final products (Scheme 1a). However, until now, the synthesis of vicinal bis(silane)s containing Si−H bonds remains elusive.…”