Metal ion-mediated diastereoface-selective nitrone cycloadditions. Reaction mechanism for the reversal of regloselectivity observed in the magnesium and zinc ion-mediated nitrone cycloadditions of allylic alcohols
作者:Shuji Kanemasa、Takashi Tsuruoka、Hidetoshi Yamamoto
DOI:10.1016/0040-4039(95)00911-u
日期:1995.7
Magnesium and zinc ion-mediated cycloaddition reactions of a carbonyl-conjugated nitrone, (Z)-N-(benzoylmethylene)aniline N-oxide to the allylic alcohols bearing a chirality at α-position give isoxazolidine-5-alcohol and isoxazolidine-4-alcohol derivatives, respectively, both in highly lk-1,2-inductive manners. α,α-Disubstitution of allylic alcohol dipolarophiles virtually inhibits the zinc ion-catalyzed
镁和锌离子介导的羰基共轭硝酮,(Z)-N-(苯甲酰基亚甲基)苯胺N-氧化物与在α-位具有手性的烯丙基醇的环加成反应生成异恶唑烷-5-醇和异恶唑烷-4-醇衍生物,分别以高度1k -1,2的方式诱导。烯丙醇双亲亲油的α,α-二取代实际上抑制了锌离子催化的反应路径,并且在镁离子催化的反应中使用配位溶剂导致区域选择性的逆转。提出了金属离子催化竞争性环加成反应的反应机理。