ASYMMETRIC CATALYST DERIVED FROM POLYMER IMOBILIZED CHIRAL 1,2-DIAMINES

从苯并苯甲酸酯衍生物出发，合成了具有两个酚羟基的新型手性1,2-二胺。这种手性1,2-二胺与氯甲基化聚苯乙烯相连。还制备了具有1,2-二胺结构的手性单体，并与苯乙烯和其他非手性单体聚合得到聚合物负载的手性1,2-二胺。我们已经合成了各种手性1,2-二胺单体。具有两个对乙烯基苯基作为可聚合基团的1,2-二胺单体得到交联聚合物。具有一个对乙烯基苯基的1,2-二胺单体与苯乙烯聚合得到线性可溶聚合物。在交联剂存在下，得到了具有手性1,2-二胺悬垂的不溶性聚合物。枝状单体结构也被引入并聚合。为了评价聚合物手性1,2-二胺配体的性能，我们选择酮的不对称加氢反应作为模型反应。Noyori等人开发的1,2-二胺- binap - ru…More Cl_2手性配合物是获得高对映选择性光学活性仲醇的有力工具。我们已经用上述聚合物支持的手性1,2-二胺制备了相同的配合物。通常在2-丙醇中进行不对称加氢反应，使醇在定量转化中具有较高的对映选择性。遗憾的是，由于其在溶剂中的收缩，聚苯乙烯基聚合物手性1,2-二胺配体没有发生反应。我们发现DMF和2-丙醇的混合溶剂允许用聚合手性配体加氢得到醇。1,2-二胺悬垂交联聚合物衍生的聚合物催化剂在酮类加氢反应中表现出最好的性能。这种聚合物催化剂的对映选择性与低分子量催化剂在均相溶液体系中的对映选择性几乎相同。不溶性聚合物催化剂可以很容易地从反应混合物中分离出来，并且在不损失催化活性的情况下可以多次回收。少

Starting from benzoin derivative we have synthesized new chiral 1,2-diamine having two phenolic hydroxyl groups. This chiral 1,2-diamine was attached to chloromethylated polystyrene. Chiral monomers having 1,2-diamine structure were also prepared and polymerized with styrene and other achiral monomers to give the polymer-supported chiral 1,2-diamine. We have synthesized various kinds of chiral 1,2-diamine monomers. A 1,2-diamine monomer having two p-vinylbenzyl groups as polymerizable group gave the crosslinked polymer. A 1,2-diamine monomer having one p-vinylbenzyl group was polymerized with styrene to give a linear soluble polymer. In the presence of cross-linking agent the insoluble polymer having chiral 1,2-diamine pendant was obtained. Dendritic monomer structure was also introduced and polymerized.In order to evaluate the performance of the polymeric chiral 1,2-diamine ligands, we chose asymmetric hydrogenation of ketone as a model reaction. Chiral complex of 1,2-diamine-BINAP-Ru … More Cl_2 developed by Noyori et al is a powerful tool to obtain optically active secondary alcohols in high level of enantioselectivity. We have prepared the same complex using polymer-supported chiral 1,2-diamine mentioned above. The asymmetric hydrogenation is usually performed in 2-propanol to give the alcohol in quantitative conversion with high enantioselectivity. Unfortunately, no reaction occurred with the polystyrene based polymeric chiral 1,2-diamine ligand mainly due to its shrinkage in the solvent. We found that the mixed solvent of DMF and 2-propanol allowed the hydrogenation using polymeric chiral ligand to give the alcohol. Polymeric catalyst derived from cross-linked polymer having 1,2-diamine pendant showed the best performance in the hydrogenation of ketones. Enantioselectivities attained with this type of polymeric catalyst are almost same as those from the low-molecular-weight catalyst in homogeneous solution system. The insoluble polymeric catalysts could be easily separated from the reaction mixture and recycled many times without loss of catalytic activity. Less