Process for preparing (R) salbutamol
First Claim
1. Process for preparing levosalbutamol or the pharmacologically acceptable salts thereof starting from prochiral salbutamone as educt, characterised in that salbutamone is subjected to asymmetric hydrogenation in the presence of rhodium and a chiral bidentate phosphine ligand as catalyst system, and the levosalbutamol obtained is optionally converted into a salt with an acid.
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Abstract
The present invention relates to an improved process for preparing levosalbutamol or the pharmacologically acceptable salts thereof on an industrial scale, using asymmetric hydrogenation as the key step and optionally a special sequence of subsequent steps, using rhodium as catalyst and a chiral bidentate phosphine ligand such as (2R, 4R)-4-(dicyclohexylphosphino)-2-(diphenyl-phosphino-methyl)-N-methyl-aminocarbonyl-pyrrolidine as catalyst system.
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Citations
20 Claims
- 1. Process for preparing levosalbutamol or the pharmacologically acceptable salts thereof starting from prochiral salbutamone as educt, characterised in that salbutamone is subjected to asymmetric hydrogenation in the presence of rhodium and a chiral bidentate phosphine ligand as catalyst system, and the levosalbutamol obtained is optionally converted into a salt with an acid.
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20. Process for preparing levosalbutamol or the pharmacologically acceptable salts thereof, which comprises the following steps:
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(a) brominating 4-acetyloxy-3-acetyloxymethylbenzophenone, (b) reacting the product obtained with N-tert-butyl-N-benzylamine, (c) hydrogenating the N-benzylsalbutamone obtained in the presence of a palladium catalyst, (d) hydrogenating the salbutamone obtained in the presence of rhodium and a chiral bidentate phosphine ligand, and (e) optionally treating it with an acid.
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Specification