Asymmetric catalytic hydrogenation method of imine

Abstract

The invention discloses an asymmetric catalytic hydrogenation method of imine. Chiral amine is prepared through asymmetric hydrogenation of the imine through using a complex as a catalyst in the presence of an iodate or iodine under the co-action of an acid, wherein the complex is prepared through an in-situ reaction of {(R)-1-[(S)-2-di-phenyl-phosphino-ferrocene]}-propyl-di-(3,5-dimethyl-phenyl)phosphine and an iridium complex; and the proper molar ratio (s / c) of the raw material imine to the catalyst is 100-500000. The method has the advantages of easily available ligand, convenience of large-scale preparation, simple operation, and realization of continuous operation, is suitable for the large-scale preparation of the chiral amine, enables the e.e value of the chiral amine to be above 70%, completely satisfies requirements of a pesticide intermediate, is especially suitable for preparing chiral intermediates of a pesticide S-metolachlor, and has a very good industrial practicality.

Description

technical field [0001] The invention belongs to the field of organic synthesis and relates to a method for asymmetric catalytic hydrogenation of imines. technical background [0002] The asymmetric hydrogenation of prochiral imines is one of the important methods for the synthesis of chiral amines, and the selection and use of asymmetric catalysts is the key to the success of the reaction. Since the open-chain imine is a mixture of geometric isomerism in the cis and trans forms during synthesis, asymmetric hydrogenation is especially difficult to obtain better product enantioselectivity. Existing a lot of catalyzers are available for selection (Tang W and Zhang X, Chem.Rev., 2003,103,3029.), but these catalyzers only have good product enantioselectivity and low chemical activity and lose practical utilization value, or The chemical activity of the catalyst is good, but the enantioselectivity of the product is low and the use value is also lost. Patent (EP0691949B1) reporte...

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Problems solved by technology

However, the synthesis of ligands used in this reaction has many inconveniences: firstly, it is not easy to obtain high-enantiopure chiral alcohol intermediates, and if chiral alcohols are resolved by biological enzymes, special techniques for screening hydrolytic enzymes are required and it is time-consuming time; after resolution, the other half of alcohols with useless configuration needs to be converted, which is also very laborious; and directly adopting asymmetric synthesis can not obtain qualified enantiopure chiral alcohols (usually only 80% e.e. products can be obtained), which is difficult to meet Subsequent synthesis needs; secondly, racemic alcohol is converted into racemic amine and then resolved. After resolution, half of the amines in useless configuration are discarded due to difficult conversion

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