- Asymmetric Synthesis of Chiral Primary Amines by Ruthenium-Catalyzed Direct Reductive Amination of Alkyl Aryl Ketones with Ammonium Salts and Molecular H2
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A ruthenium/C3-TunePhos catalytic system has been identified for highly efficient direct reductive amination of simple ketones. The strategy makes use of ammonium acetate as the amine source and H2 as the reductant and is a user-friendly and operatively simple access to industrially relevant primary amines. Excellent enantiocontrol (>90% ee for most cases) was achieved with a wide range of alkyl aryl ketones. The practicability of this methodology has been highlighted by scalable synthesis of key intermediates of three drug molecules. Moreover, an improved synthetic route to the optimal diphosphine ligand C3-TunePhos is also presented.
- Tan, Xuefeng,Gao, Shuang,Zeng, Weijun,Xin, Shan,Yin, Qin,Zhang, Xumu
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supporting information
p. 2024 - 2027
(2018/02/19)
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- Furfurylamines from biomass: Transaminase catalysed upgrading of furfurals
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Furfural is recognised as an attractive platform molecule for the production of solvents, plastics, resins and fuel additives. Furfurylamines have many applications as monomers in biopolymer synthesis and for the preparation of pharmacologically active compounds, although preparation via traditional synthetic routes is not straightforward due to by-product formation and sensitivity of the furan ring to reductive conditions. In this work transaminases (TAms) have been investigated as a mild sustainable method for the amination of furfural and derivatives to access furfurylamines. Preliminary screening with a recently reported colorimetric assay highlighted that a range of furfurals were readily accepted by several transaminases and the use of different amine donors was then investigated. Multistep synthetic routes were required to synthesise furfurylamine derivatives for use as analytical standards, highlighting the benefits of using a one step biocatalytic route. To demonstrate the potential of using TAms for the production of furfurals, the amination of selected compounds was then investigated on a preparative scale.
- Dunbabin, Alice,Subrizi, Fabiana,Ward, John M.,Sheppard, Tom D.,Hailes, Helen C.
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p. 397 - 404
(2017/01/29)
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- Candida antarctica lipase-catalyzed doubly enantioselective aminolysis reactions. Chemoenzymatic synthesis of 3-hydroxypyrrolidines and 4-(silyloxy)-2-oxopyrrolidines with two stereogenic centers
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Aminolyses of racemic and prochiral 3-hydroxyesters with racemic amines are effectively catalyzed by Candida antarctica lipase. In these processes, the simultaneous resolution of the ester and the amine, or the corresponding asymmetrization-resolution, takes place. In all cases, the high enantioselectivity shown by the lipase toward all the reactants allows the preparation of enantiopure 3-hydroxyamides with very high diastereomeric ratios. These 3-hydroxyamides are used as starting materials in the synthesis of 3-hydroxy-and 2-oxopyrrolidines, both containing two stereogenic centers in their structures.
- Sanchez, Victor M.,Rebolledo, Francisca,Gotor, Vicente
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p. 1464 - 1470
(2007/10/03)
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- Asymmetric synthesis. XVIII. Stereocontrolled synthesis of α-substituted-2-furfurylamines via chiral intermediates
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The stereocontrolled synthesis of (R)-α-alkyl-2-furfurylamines (5), using (-)-2-hydroxypinan-3-one as a chiral auxiliary, had been studied. The e.e. values of (5) were 91.4->98%, which determined by capillary GC (stationary phase: Chirasil-Val).
- Shikui,Aiqiao,Lanjun,Yaozhong
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p. 2485 - 2488
(2007/10/02)
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