作者:Dennis Hülsewede、Jan‐Niklas Dohm、Jan von Langermann
DOI:10.1002/adsc.201900217
日期:——
The unfavorable reaction equilibrium of transaminase‐catalyzed reactions is a major challenge for the efficient biocatalytic synthesis of chiral amines. In this study the synthetic utilization of a salt‐based, continuous in situ‐product crystallization is described to overcome the thermodynamic limit in amine transaminase‐reactions using only the commonly used amine donor isopropylamine. The simultaneous
Rhodium-Catalyzed Asymmetric Hydrogenation of Unprotected NH Imines Assisted by a Thiourea
作者:Qingyang Zhao、Jialin Wen、Renchang Tan、Kexuan Huang、Pedro Metola、Rui Wang、Eric V. Anslyn、Xumu Zhang
DOI:10.1002/anie.201404570
日期:2014.8.4
Asymmetrichydrogenation of unprotected NH imines catalyzed by rhodium/bis(phosphine)‐thiourea provided chiral amines with up to 97 % yield and 95 % ee. 1H NMR studies, coupled with control experiments, implied that catalytic chloride‐bound intermediates were involved in the mechanism through a dual hydrogen‐bonding interaction. Deuteration experiments proved that the hydrogenation proceeded through
由铑/双(膦)-硫脲催化的未保护的NH亚胺的不对称氢化提供了手性胺,产率高达97%,ee值高达95% 。1 H NMR 研究与对照实验相结合,表明催化氯化物结合中间体通过双氢键相互作用参与了该机制。氘化实验证明氢化反应是通过与亚胺一致的途径进行的。
Chiral Brønsted Acids Catalyze Asymmetric Additions to Substrates that Are Already Protonated: Highly Enantioselective Disulfonimide-Catalyzed Hantzsch Ester Reductions of NH–Imine Hydrochloride Salts
作者:Benjamin List、Vijay N. Wakchaure、Carla Obradors
DOI:10.1055/s-0040-1706413
日期:2020.10
are frequently used substrates in asymmetric Bronsted acid catalysis, their corresponding salts are generally considered unsuitable reaction partners. Such processes are challenging because they require the successful competition of a catalytic amount of a chiral anion with a stoichiometric amount of an achiral one. We now show that enantiopure disulfonimides enable the asymmetric reduction of N–H imine
Continuous Preparative Application of Amine Transaminase‐Catalyzed Reactions with Integrated Crystallization
作者:Sven Tiedemann、Jan Eric Neuburger、Alina Gazizova、Jan von Langermann
DOI:10.1002/ejoc.202400068
日期:2024.4.2
In situ product crystallization (ISPC) was used to semicontinuously remove chiral amines from amine transaminase catalyzed reactions. The use of a constant mild vacuum facilitated the synthesis of six compounds in this way in a preparative fashion at gram scale with yields of up to 80 %. The process included intermittent removal steps of the product salt and the replenishment of substrates every 24 h