Chiral Mn(salen) complex 3 bearing a 1-ethyl-1-methylpropyl group at C3, C3′, C5, and C5′ was found to induce higher asymmetry in the epoxidation of conjugated Z-olefins, especially less nucleophilic ones, in the presence of 4-phenylpyridine N-oxide than complex 1 bearing a t-butyl group at the same carbons. The higher enantioselectivity was considered to be attributable to Me-in-plane conformation of the 1-ethyl-1-methylpropyl group at C3 and C3′.
研究发现,在 C3、C3′、C5 和 C5′处含有 1-乙基-1-甲基丙基的手性 Mn(salen)络合物 3 在
4-苯基吡啶 N-氧化物存在下诱导共轭 Z-烯烃(尤其是亲核性较弱的 Z-烯烃)发生环氧化反应的不对称性高于在相同碳原子上含有叔丁基的络合物 1。较高的对映体选择性被认为是由于 C3 和 C3′处的 1-乙基-1-甲基丙基在平面内构象所致。