Ring-opening of cyclic ethers by aluminum hydridotriphenylborate

Abstract

Molecular aluminum hydride [(L)AlH₂] (L = Me₃TACD) reacted with 2 equiv. of BPh₃ in THF or THP to give the cationic alkoxides [(L)Al(OR)][HBPh₃] (R = nBu, nPent) by facile ring-opening of the cyclic ethers. The C_α–O bond cleavage which involves the isolable intermediate [(L)AlH][HBPh₃] is a result of hydride transfer to C_α from [HBPh₃]⁻.