Process for preparing isomers of salbutamol

  • US RE43,984 E1
  • Filed: 12/10/2001
  • Issued: 02/05/2013
  • Est. Priority Date: 12/11/2000
  • Status: Active Grant
First Claim
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1. A process for making optically pure (R) salbutamol or pharmaceutically acceptable salts thereof having a value of 95% enantiomeric excess or more, which process comprises obtaining the (R) isomer of either salbutamol or a salbutamol precursor, wherein the salbutamol precursor is 4-benzyl albuterol or methyl-5-[2-[(1,1-dimethylethyl)amino]-1-hydroxyethyl]-2-(phenylmethoxy)-benzoate in optically pure form by:

  • a) dissolving a mixture of salbutamol, 4-benzyl albuterol or methyl-5-[2-[(1,1-dimethylethyl)amino]-1-hydroxyethyl]-2-(phenylmethoxy)-benzoate enantiomers and a molar excess (with respect to said salbutamol or said precursors) of (L) tartaric acid in a solvent;

    b) allowing the solution to cool to crystalize a salt of one enantiomer;

    c) separating the salt from the solution;

    d) liberating the enantiomer from the salt;

    e) when the enantiomer is 4-benzyl albuterol or methyl-5-[2-[(1,1-dimethylethyl)amino]-1-hydroxyethyl]-2-(phenylmethoxy)-benzoate, reducing the enantiomer; and

    f) except when salbutamol is used in step a), debenzylating the enantiomer and recoVering the (R) enantiomer of salbuamol;

    then optionally converting said optically pure (R) salbutamol into a pharmeucedically acceptable salt.

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