Asymmetric Hydrogenation of Ketones and Olefins

均相不对称催化为制备重要生物物质和先进材料的手性构件提供了基础工具。聚合物结合催化剂具有固有的操作和经济优势：固定在固体基质上有利于从反应混合物中分离，回收和再利用昂贵的手性化合物。此外，固相反应为面向多样性的组合合成提供了技术基础。许多树脂支撑（预）催化剂沿着这条路线发展，尽管它们的实际应用仅限于少数情况。其中许多催化剂的反应性比均相催化剂体系低得多，而且它们的立体选择性经常降低，阻碍了实际应用。我们发现RuCl_2（膦）_2（1,2-二胺）配合物在2-丙醇中与碱性碱偶联，比共存的共轭或非共轭的C=C键更能使C=0官能团氢化…更多的s，卤素原子，各种杂环和许多其他官能团。适当的手性二膦和二胺的使用，可使一系列的非手性和手性酮迅速而高效地进行不对称氢化反应。他们的高效率促使我们和其他团队固定化BINAP/二胺RuCl_2配合物。该反应显示周转率（TON）高达12300 /批次或重复使用总计33000。聚合物结合催化剂的对映选择性、产率和加氢速率与均相条件下的催化剂相当。手性RuCl_2（二膦）（1,2-二胺）配合物与NaBH_4反应，定量生成反式ruh (η^1- bh_4)（二膦）（1,2-二胺）。通过单晶x射线分析、核磁共振和红外光谱对TolBINAP/DPEN Ru配合物进行了表征。新的Ru配合物允许简单酮在2-丙醇中不对称加氢，而不需要额外的强碱。在温和的条件下，各种碱敏感酮以高对映体纯度转化为手性醇，底物/催化剂比高达10万。构型不稳定的2-异丙基和2-甲氧基环己酮具有较高的对映体分辨能力。该方法克服了先前使用RuCl_2（二膦）（二胺）和碱性碱的方法的缺点，这种方法有时会引起不希望的反应，如酯交换、环氧环开环、β消除和酮底物的聚合。少

Homogeneous asymmetric catalysis provides a fundamental tool for the preparation of chiral building blocks for biologically important substances and advanced materials. Polymer-bound catalysts have inherent operational and economical advantages : immobilization on solid matrices facilitates the separation from reaction mixtures, recovery, and reuse of the expensive chiral compounds. Further, the solid-phase reaction offers a technical basis for diversity-oriented combinatorial synthesis. Numerous resin-supported (pre)catalysts have been developed along this line, though their practical application application is limited to only a few cases. Many of these are much less reactive than the homogeneous catalyst systems, and their stereoselectivity is often reduced, impeding practical use. We have found that RuCl_2(phosphine)_2(1,2-diamine) complexes, coupled with an alkaline base in 2-propanol, hydrogenate a C=0 function preferentially over coexisting conjugated or nonconjugated C=C linkage … More s, halogen atoms, various hetrocycles, and many other functional groups. The use of appropriate chiral diphosphines and diamines results in rapid and productive asymmetric hydrogenation of a range of achiral and chiral ketones. Their high efficiency prompted us and other groups to immobilize the BINAP/diamine RuCl_2 complexes. This reaction exhibits a turnover number (TON) as high as 12,300/batch or a total of 33,000 by repeated use. The enantioselectivity, productivity, and rate of hydrogenation using the polymer-bound catalysts are comparable to those attained under homogeneous conditions.Reaction of a chiral RuCl_2(diphosphine)(1,2-diamine) complex and NaBH_4 forms trans-RuH(η^1-BH_4)(diphosphine)(1,2-diamine)quantitatively. The TolBINAP/DPEN Ru complex has been characterized by single crystal X-ray analysis as well as NMR and IR spectra. The new Ru complexes allows for asymmetric hydrogenation of simple ketones in 2-propanol without an additional strong base. Various base-sensitive ketones are convertible to chiral alcohols in a high enantiomeric purity with a substrate/catalyst ratio of up to 100 000 under mild conditions. Configurationally unstable 2-isopropyl- and 2-methoxycyclohexanone can be kinetically resolved with a high enantiomer discrimination. This procedure overcomes the drawback of an earlier method using RuCl_2(diphosphine)(diamine) and an alkaline base, which sometimes causes undesired reactions such as ester exchange, epoxy-ring opening, (β-elimination, and polymerization of ketonic substrates. Less