Boron-Catalyzed Double Hydrofunctionalization Reactions of Unactivated Alkynes

Tandem hydroalkoxylation/hydroallylation and hydroalkoxylation/hydrocyanation reactions of alkyl-substituted unactivated alkynes by catalytic systems based on B(C6F5)3·nH2O and silyl nucleophiles were developed. The characteristic high alkynophilicity of B(C6F5)3 enabled the selective activation of the unactivated alkynes in the presence of the reactive alkene of allylsilane. Moreover, the alkynes were electrophilically activated in the presence of cyanide in this catalytic system. Mechanistic studies suggest that the alkynes are activated by the different catalytic species in the two reactions.