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
作者:Alessandra Giardinà、Tiziana Mecozzi、Marino Petrini
DOI:10.1021/jo001003x
日期:2000.12.1
configuration that favors the attack of the nucleophile from the si-si face. Disappointing results are obtained using silyl ketene acetals; 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
光学活性的N- [1-(苯磺酰基)烷基]咪唑烷基-2-酮在低温下在四氯化锡的存在下反应,生成无环的N-酰亚胺离子。这些亲电子底物在与π-亲核试剂反应后产生加成产物。烯丙基三甲基硅烷以高收率和高非对映选择性提供相应的烯丙基化产物。可以通过考虑中间N-酰基亚胺离子对E结构的偏爱来合理化此过程的立体化学结果,该E结构有利于亲核试剂从si-si面进攻。使用甲硅烷基乙烯酮缩醛可获得令人失望的结果。相反,苯乙酮的三甲基甲硅烷基烯醇醚以非对映体高选择性得到相应的加合物。