A novel, efficient approach for the functionalization of microcrystalline cellulose (MCC) is presented. The as-obtained material allows the immobilization of chiral dirhodium catalysts preserving their enantioselectivity in asymmetric cyclopropanation reactions. As model, microcrystalline cellulose is modified with a polyethylene glycol derived linker, and Rh₂(S-DOSP)₄ is grafted on the material to produce a heterogeneous catalyst. SEM images at different stages of the immobilization show an unchanging uniform morphology, providing constantly good separation characteristics. The modification of the cellulose material with the polyethylene derived linker and the immobilization process are monitored using DNP enhanced ¹H → ¹³C CP MAS NMR, quantitative ¹⁹F MAS NMR, TGA and ICP-OES analysis, confirming the success of the immobilization as well as the stability of bonds between the used linker molecule and the cellulose material. Finally, the evaluation of the produced catalyst is demonstrated in the asymmetric cyclopropanation reaction between styrene and methyl(E)-2-diazo-4-phenylbut-3-enoate showing excellent enantioselectivity with an ee of nearly 90% over a wide temperature range as well as good recyclability characteristics in four consecutive catalysis cycles.

提出了一种新的、有效的微晶纤维素 (MCC) 功能化方法。所获得的材料允许固定手性二铑催化剂，在不对称环丙烷化反应中保持其对映选择性。作为模型，用聚乙二醇衍生的接头对微晶纤维素进行改性，并将Rh ₂ ( S -DOSP) ₄接枝在材料上以产生非均相催化剂。固定化不同阶段的 SEM 图像显示出不变的均匀形态，提供始终良好的分离特性。^{使用 DNP 增强型1} H 监测使用聚乙烯衍生接头对纤维素材料进行的改性和固定化过程→¹³ C CP MAS NMR、定量¹⁹ F MAS NMR、TGA 和 ICP-OES 分析，证实了固定的成功以及所用连接分子和纤维素材料之间键的稳定性。最后，在苯乙烯与甲基 ( E )-2-diazo-4-phenylbut-3-enoate之间的不对称环丙烷化反应中证明了所产生催化剂的评价，在很宽的温度范围内表现出优异的对映选择性，ee 接近 90%在连续四个催化循环中具有良好的可回收性。