Efficient alkylation of cyclic silyl enol ethers by diarylmethylium salts

Isolated, bench-stable, non-symmetric diarylmethylium salts have been reacted with cyclic silyl enol ethers. Products have been easily obtained in a prevalent diastereoselectivity irrespective of salt counter-anion, aromatic ring substitution and silyl enol ether ring size. X-ray analyses on two purified diastereomers have been performed; the observed diastereoselectivity has been confirmed and rationalised using DFT calculations.