Unexpected B(C₆F₅)₃ Catalyzed Cleavage of Alkenyl Group from Alkenyl Alkyl Ethers by Hydrosilanes

In contrast to the well known cleavage of the C(sp³)−O bond, the activation of C(sp²)−O is more challenging and way more rare, especially by metal-free approaches. Unexpectedly, C(sp²)−O bond was cleaved with high selectivity when alkenyl alkyl ethers were reacted with Et₃SiH in the presence of catalytic amount of B(C₆F₅)₃, leading to alkoxysilanes and alkenes. Supposedly, this reaction is a result of a B(C₆F₅)₃ catalyzed tandem hydrosilylation reaction of C=C double bond of the alkenyl group, followed by previously unprecedented Peterson type olefination. This reactivity was probed with different alkenyl alkyl ethers and its limitations are presented. The mechanism of this cleavage reaction is proposed based on both experiments and density functional theory (DFT) calculations.