Introduction of a pseudoaxial substituent at a stereogenic center adjacent to the nitrogen atom in binaphthyl- and biphenyl-derived azepinium salt organocatalysts affords improved enantioselectivities and yields in the epoxidation of unfunctionalized alkenes. In the biphenyl-derived catalysts, the atropoisomerism at the biphenyl axis is controlled by the interaction of this substituent with the chiral
在衍生自双
萘基和
联苯的氮杂
吡啶鎓盐有机催化剂中与氮原子相邻的立体中心处引入假轴取代基,可提高对映选择性,并提高未官能化烯烃的环氧化收率。在
联苯衍生的催化剂中,
联苯轴上的对映异构通过该取代基与氮上的手性取代基的相互作用来控制。