A new type of ferrocene-based phosphine-oxazoline ligand has been prepared over a few simple steps. An iridium complex of this ligand is air stable and exhibits excellent performance for the asymmetric hydrogenation of simple ketones (up to 98% yield, up to 99% ee, and 20 000 S/C). Exo-α,β-unsaturated cyclic ketones could be regiospecifically hydrogenated to give chiral allylic alcohols with good results
通过几个简单的步骤即可制备出新型的二茂铁基膦-恶唑啉配体。该配体的铱络合物是空气稳定的,并且对于简单的酮的不对称氢化表现出出色的性能(最高98%的收率,最高99%的ee和20000 S / C)。Exo -α,β-不饱和环状酮可被区域特异性氢化,得到手性烯丙基醇,效果良好。这项研究表明,P,N-配体也可以有效地促进Ir催化的不对称氢化反应,而无需NH-氢键辅助。
RuPHOX-Ru-Catalyzed Selective Asymmetric Hydrogenation of Exocyclic α,β-Unsaturated Pentanones
A RuPHOX-Ru catalyzed selective asymmetrichydrogenation of exocyclic α,β-unsaturated ketones has been developed, furnishing the corresponding chiral exocyclic allylic alcohols in high yields and with up to >99.5% ee. The reaction could be performed on a gram scale with a relatively low catalyst loading (up to 10000 S/C) without any loss in reaction activity and enantioselectivity. The resulting hydrogenated
已开发出RuPHOX-Ru催化的环外α,β-不饱和酮的选择性不对称氢化,可提供高收率和最高> 99.5%ee的相应手性环外烯丙基醇。该反应可以以克级进行,具有相对较低的催化剂负载量(最高10000 S / C),而没有任何反应活性和对映选择性的损失。所得的氢化产物可以容易地转化为具有高不对称性能的几种生物活性化合物。不对称方案为合成手性环外烯丙基醇提供了一种有效的方法。
Highly enantioselective biomimetic intramolecular dehydration: kinetic resolution of β-hydroxy ketones catalyzed by β-turn tetrapeptides
作者:Zhi-Xue Du、Li-Yuan Zhang、Xin-Yuan Fan、Feng-Chun Wu、Chao-Shan Da
DOI:10.1016/j.tetlet.2013.03.087
日期:2013.5
Racemic beta-hydroxy ketones were kinetically resoluted into the enantiopure isomers and (E)-alpha,beta-unsaturated ketones using catalytic asymmetric intramolecular dehydration for the first time. Synthetic tetrapeptides were used to imitate fatty acid dehydratases to efficiently discriminate racemic beta-hydroxy ketones, enantioselectively catalyze the intramolecular dehydration, and result in highly enantioenriched beta-hydroxy and (E)-alpha,beta-unsaturated ketones in the environmentally benign process. Mechanistically, the high discrimination of the racemic substrates and successive enantioselective dehydration are highly dependent on the cooperative catalysis of the NH2 and COOH groups of the peptide. (C) 2013 Elsevier Ltd. All rights reserved.