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

以苯偶姻衍生物为原料，合成了一种新的含两个酚羟基的手性1，2-二胺。将该手性1，2-二胺连接至氯甲基化聚苯乙烯。合成了具有1，2-二胺结构的手性单体，并与苯乙烯等非手性单体聚合得到聚合物负载的手性1，2-二胺。我们合成了多种手性1，2-二胺单体。具有两个对乙烯基苄基作为可聚合基团的1，2-二胺单体得到交联聚合物。将具有一个对乙烯基苄基的1，2-二胺单体与苯乙烯聚合，得到线性可溶性聚合物。在交联剂的存在下，得到了不溶性的具有手性1，2-二胺侧基的聚合物。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氢化反应作为模型反应。1，2-二胺-BINAP-Ru手性配合物 ...更多信息 Noyori等人开发的Cl_2是一种高效的手性合成工具，可以高选择性地合成光学活性的仲醇。我们使用上述聚合物负载的手性1，2-二胺制备了相同的配合物。不对称氢化通常在异丙醇中进行，以定量转化得到醇，具有高的对映选择性。不幸的是，没有与基于聚苯乙烯的聚合物手性1，2-二胺配体发生反应，主要是由于其在溶剂中收缩。我们发现，DMF和异丙醇的混合溶剂允许使用聚合物手性配体氢化得到醇。衍生自具有1，2-二胺侧基的交联聚合物的聚合物催化剂在酮的氢化中显示出最好的性能。在均相溶液体系中，这种高分子催化剂的对映选择性与低分子催化剂的对映选择性几乎相同。不溶性高分子催化剂可以很容易地从反应混合物中分离出来，并可以多次循环使用而不损失催化活性。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