School of Pharmacy, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, China.
J Am Chem Soc. 2010 Dec 1;132(47):17041-4. doi: 10.1021/ja108238a. Epub 2010 Nov 8.
Novel planar chiral ferrocene nucleophilic catalysts (Fc-PIP) containing both central and planar chiral elements were designed and synthesized for catalytic enantioselective acyl transfer of secondary alcohols. A remarkably efficient catalyst with high selectivity factors (up to S = 1892) was identified. Comparing the combination of central and planar chirality revealed a strong requirement for the "matched" chiral elements, indicating that the stereogenic center of the imidazole rings should present itself on the same face as the ferrocenyl fragment; otherwise, the catalyst is completely inactive. An exclusively stacked transition state that accounts for the high selectivity of the kinetic resolution of secondary alcohols is proposed. Notably, this newly designed catalyst family is suitable for the catalytic kinetic resolution of bulky arylalkyl carbinols, producing esters with extremely high ee (>99%).
新型平面手性二茂铁亲核催化剂 (Fc-PIP) 同时含有中心和平面手性元素，被设计并合成用于催化仲醇的对映选择性酰基转移。鉴定出一种具有高选择性因子 (高达 S = 1892) 的非常有效的催化剂。比较中心和平面手性的组合表明，“匹配”手性元素的要求很强，表明咪唑环的手性中心应出现在与二茂铁片段相同的面上；否则，催化剂完全没有活性。提出了一种仅堆叠的过渡态，该过渡态解释了仲醇动力学拆分的高选择性。值得注意的是，这个新设计的催化剂家族适用于大位阻芳基烷基仲醇的催化动力学拆分，生成的酯具有极高的对映体过量 (>99%)。
