Differential crystallisation With racemisation

Resolution of amino acids by differential crystallisation with racemisation Differential crystallisation and racemisation when enolisation is impossible Kinetic resolution with racemisation... 

Resolution of amino acids by differential crystallisation with racemisation... 

Sometimes these differential crystallisations with racemisations are very easy to do. Racemic /V-butyrovl proline 91 gives a good yield of one enantiomer in moderate ee just by melting the racemic compound with catalytic acetic anhydride and seeding with one enantiomer. Further crystallisations improve the ee. The yield is 6.3 from 10.5 g or 60% of the total material. This process is clearly a great improvement on simple differential crystallisation both in simplicity of operation and because it is no longer necessary to alternate the isolation of enantiomers. 

Resolution of compounds made as diastereoisomeric mixtures The synthesis of Jacobsen s Mn(III) epoxidation catalyst by resolution Resolution with half an equivalent of resolving agent Physical Separation of Enantiomers Chromatography on chiral columns Resolution of triazole fungicides by HPLC A commercial drug separation by chiral HPLC Differential Crystallisation or Entrainment of Racemates Conglomerates and racemic compounds Typical procedure for differential crystallisation (entrainment) Conventional resolution ofL-methyl DOPA Resolution ofL-methyl DOPA by differential crystallisation Finding a differential crystallisation approach to fenfluramine Resolution with Racemisation... 

When the /V-acctyl derivative of the intermediate 94 was crystallised from isopropanol with seeding a good yield of enantiomerically pure l-DOPA could be crystallised out. Treatment of the residue from the mother liquor with NaCN in DMSO led to complete racemisation and the differential crystallisation could be repeated.23... 

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