Drug – bio-affecting and body treating compositions – Designated organic active ingredient containing – Having -c- – wherein x is chalcogen – bonded directly to...
Patent
1995-07-14
1999-09-07
Raymond, Richard L.
Drug, bio-affecting and body treating compositions
Designated organic active ingredient containing
Having -c-, wherein x is chalcogen, bonded directly to...
514338, 514393, 514395, 546183, 5462731, 5462737, 5483037, 5483071, A61K 31415, A61K 3144, C07D40112, C07D23528
Patent
active
059487895
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a process for enantioselective synthesis of the single enantiomers of substituted sulphoxides or said compounds in an enantiomerically enriched form. Such substituted sulphoxides that are suitable for being prepared by the novel process are for examples the single enantiomers of omeprazole as well as the single enantiomers of other structurally related sulphoxides. The obtained products may thereafter be converted to pharmaceutically acceptable salts thereof by conventional processes. Further, the invention also relates to some new single enantiomeric compounds which can be prepared by the novel process and their use in medicine.
BACKGROUND OF THE INVENTION AND PRIOR ART
There are a large number of patents and patent applications disclosing different substituted 2-(2-pyridinylmethylsulphinyl)-1H-benzimidazoles. This class of compounds has properties making the compounds useful as inhibitors of gastric acid secretion. For example the compound, nzimidazole) with the generic name omeprazole, described in i.e. EP 5129, is useful as an antiulcer agent. Other compounds of interest are for instance the compounds with the generic names lansoprazole, pantoprazole, pariprazole and leminoprazole.
These compounds as well as structurally related sulphoxides, have a stereogenic centre at the sulphur atom and thus exist as two optical isomers, i.e. enantiomers. If there is another stereogenic centre in the molecule, these compounds can exist as pairs of enantiomers. Corresponding sulphides of such compounds which already contain a stereogenic centre are not pro-chiral compounds, but chiral compounds. However, the sulphur atom in these compounds does not have asymmetry and therefore they are referred to as pro-chiral sulphides in respect of this invention.
Even though this class of chiral sulphoxides has been discussed in the scientific literature since the late seventies, there is not yet any efficient asymmetric process described for the synthesis of the single enantiomers thereof. The single enantiomers of pharmacologically active compounds have met an increased interest in the last years because of improved pharmacokinetic and biological properties. Therefore, there is a demand and need for an enantioselective process that can be used in large scale for the manufacture of the single enantiomers of pharmacologically active compounds, such as for instance optically pure, substituted 2-(2-pyridinylmethylsulphinyl)-1H-benzimidazoles.
There are processes for resolution of different substituted 2-(2-pyridinylmethylsulphinyl)-1H-benzimidazoles disclosed in the prior art. Such resolution processes are for example described in DE 4035455 and WO 94/27988. These processes involve synthetic steps wherein a diastereomeric mixture is synthesised from the racemate of the corresponding substituted 2-(2-pyridinylmethylsulphinyl)-1H-benzimidazoles. The diastereomers are then separated and finally one of the separated diastereomer is converted to the optically pure sulphoxide in a hydrolytic step.
These resolution methods involving diastereomeric intermediates, suffer from at least three fundamental disadvantages namely: racemic intermediate, has to be further processed in a couple of reaction steps before the single enantiomers can be obtained. stereoisomer, in the form of the opposite diastereomer, is separated and discarded.
Further, prior art describes for instance enantioselective synthesis of the single enantiomers of a sulphoxide agent Ro 18-5364, (1987) 453. The described process is based on an enantioselective oxidation of the corresponding prochiral sulphide to said sulphoxide. The experimental conditions used during the oxidation are stated to be in accordance with the asymmetric sulphide oxidation process developed by Kagan and co-workers (Pitchen, P.; Deshmukh, M.; Dunach, E.; Kagan, H. B. J. Am. Chem. Soc. 106 (1984), 8188). The authors report that the obtained crude product of the sulphoxide, showing an enantiomeric excess (e.e.) of about 30%, can be purified to an esse
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Cotton Hanna Kristina
Larsson Magnus Erik
Sorensen Henrik
Stenhede Urban Jan
von Unge Sverker Per Oskar
Astra Aktiebolag
Raymond Richard L.
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