Asymmetric Dipolar Cycloaddition of Nitrile Oxides to the α,β-Unsaturated Esters Bearing an Imidazolidine Chiral Controller at the β-Position
作者:Shuji Kanemasa、Takashi Hayashi、Hidetoshi Yamamoto、Eiji Wada、Tosio Sakurai
DOI:10.1246/bcsj.64.3274
日期:1991.11
Some α,β-unsaturated esters bearing an imidazolidine chiral controller at the β-position were employed in the asymmetric cycloaddition to nitrile oxides. Regio- and diastereoselectivities were both poor when the chiral controller was a perhydropyrrolo[1,2-c]imidazol-3-yl auxiliary, while the reaction of the esters bearing a C2-symmetric imidazolidine chiral controller was exclusively regioselective or diastereoselective depending upon the nature of N-substituent. The transition state was briefly discussed.
一些在 β 位带有咪唑烷手性控制剂的 α,β-不饱和酯被用于与腈氧化物的不对称环加成反应。当手性控制剂是全氢吡咯并[1,2-c]咪唑-3-基助剂时,区域选择性和非对映选择性都很差,而带有C2对称咪唑烷手性控制剂的酯的反应完全是区域选择性或非对映选择性,具体取决于N-取代基的性质。简要讨论了过渡状态。