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

Here, we describe simple B(C6F5)(3)-catalyzed mono- and dihydrosilylation reactions of terminal alkynes by using a silane-tuned chemoselectivity strategy, affording vinylsilanes and unsymmetrical geminal bis(silanes). This strategy is applicable to the dihydrosilylation of both aliphatic and aryl terminal alkynes with different silane combinations. Gram-scale synthesis and conducting the reaction without the exclusion of air and moisture demonstrate the practicality of this methodology. The synthetic utility of the resulting products was further highlighted by the structural diversification of geminal bis(silanes) through transforming the secondary silane into other silyl groups. Comprehensive theoretical calculations combined with kinetical isotope labeling studies have shown that a prominent kinetic differentiation between the hydrosilylation of alkynes and vinylsilane is responsible for the chemoselective construction of unsymmetrical 1,1-bis(silanes).

Automated summary

The simple B(C6F5)(3)-catalyzed mono- and dihydrosilylation reactions of terminal alkynes are achieved by using a silane-tuned chemoselectivity strategy, producing vinylsilanes and unsymmetrical geminal bis(silanes). This methodology is applicable to both aliphatic and aryl terminal alkynes with different silane combinations. The chemoselective construction of unsymmetrical 1,1-bis(silanes) is attributed to a prominent kinetic differentiation between the hydrosilylation of alkynes and vinylsilane, as evidenced by comprehensive theoretical calculations and kinetical isotope labeling studies.