Enantioselective Hydrogenation of Ketones

由于现有的均相催化剂缺乏反应性和/或立体选择性，因此开发实用的方法来实现单酮的立体选择性加氢是非常必要的。一种新的Ru(II)配合物，反式-RuCl2[(S)-二甲基联苯][(S)-代品]或R，R对映体是单酮(二甲基二异氰酸酯=2，2‘-双(二-3，5-二甲基膦)-1，1’-联萘)不对称加氢反应的良好预催化剂。DAIPEN=1，1-二苯甲基-2-异丙基-1，2-乙二胺)反应在含碱性的异丙醇中进行，底物/催化剂摩尔比高达100000，常温下氢气气氛为1~80atm(大部分为~lt；10atm)。各种各样的前手性酮被氢化，具有高度的对映选择性。开链α，β-不饱和酮的氢化反应选择性地在C=O键进行，得到了具有高ee的手性烯丙醇，解决了一个长期存在的合成问题。环丙基酮加氢反应生成相应的…在骨骼无改变的情况下，高ee组的ng型甲醇含量较高。不同取代基烷基芳基酮的氢化反应具有一致的高对映体选择性。2，2，2-三氟苯乙酮和环取代的衍生物也可用作底物。该反应对芳香族卤化物和CF3、OCH2、CoOCH(CH3)2、NO2和NH2基团有较强的耐受性。各种邻位取代的二苯甲酮被氢化成具有稳定高ee的手性苯并氢化合物。没有观察到生成二芳基甲烷的过度还原。该催化剂体系对杂芳酮的对映选择性加氢反应非常有效。具有呋喃、噻吩环、吡咯环、噻唑环或吡啶环的底物以相同的不对称意义进行氢化，以得到持续高ee的手性仲醇。杂环的电子性质、Lewis基本倾向性和空间大小对对映体选择性影响不大。由于催化剂的低成本、操作简单和环保意识，该过程对于大规模反应特别有用。较少

The development of practical methods effecting stereoselective hydrogenation of simple ketones is highly desirable, since the existing homogeneous catalysts lack reactivity and/or stereoselectivity. A new Ru (II) complex, trans-RuCl_2 [(S)-xylbinap][(S)-daipen] or the R, R enantiomer acts as an excellent precatalyst for asymmetric hydrogenation of simple ketones (XylBINAP=2, 2'-bis (di-3, 5-xylylphosphino)-1, 1'-binaphthyl. DAIPEN=1, 1-dianisyl-2-isopropyl-1, 2-ethylenediamine). The reaction is conducted with a substrate/catalyst molar ratio of up to 100000 in 2-propanol containing alkaline base under 1-80 atm (mostly <10 atm) of H_2 at room temperature. A wide variety of prochiral ketones are hydrogenated with a high degree of enantioselection. Hydrogenation of open-chain α, β-unsaturated ketones proceeds selectively at the C=O linkage to afford chiral allylic alcohols with a high ee, solving a long-standing synthetic problem. Hydrogenation of cyclopropyl ketones gives the correspondi … More ng carbinols in high ee without skeletal change. Alkyl aryl ketones with various substituents are hydrogenated with a consistently high enantioselectivity. 2, 2, 2-Trifluoroacetophenone and the ring-substituted derivatives are also usable as substrates. The reaction is tolerant of aromatic halides and CF_3, OCH_2, COOCH(CH_3)_2, NO_2, and NH_2 groups. Various ortho-substituted benzophenones are hydrogenated to chiral benzhydrols with consistently high ee. No over-reduction forming to diarylmethanes are observed. The catalyst system is extremely effective for enantioselective hydrogenation of hetero-aromatic ketones. The substrates with furan, thiophene, pyrrole, thiazole, or pyridine rings are hydrogenated with the same asymmetric sense to give chiral secondary alcohols in consistently high ee. The electronic properties, Lewis basic tendency, and steric size of the heterocycles appear to have little effect on the extent of enantioselectivity. This procedure is particularly useful for a large-scale reaction because of the low cost of the catalyst, operational simplicity, and environmental consciousness. Less