Acyclic Stereoselection in the Reaction of Nucleophilic Reagents with Chiral <i>N</i>-Acyliminium Ions Generated from <i>N</i>-[1-(Phenylsulfonyl)alkyl]imidazolidin-2-ones
configuration that favors the attack of the nucleophile from the si-si face. Disappointing results are obtained using silyl keteneacetals; conversely trimethylsilyl enol ether of acetophenone gives the corresponding adducts in high diastereoselectivity. The utilization of trimethylsilyl enol ether of 2-acetylfuran is particularly interesting since the corresponding adducts are obtained with good diastereoselectivity