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1. WO2006094468 - METHOD OF RACEMIZATION OF THE R(-) ISOMER OF THE (2-CHLOROPHENYL)-6,7- DIHYDROTHIENO[3,2-c]PYRIDINE-5(4H)-ACETIC ACID METHYL ESTER

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[ EN ]

C L A I M S

1. A method of racemization of the R(-) isomer of the (2-chlorophenyl)-6,7-dihydro- thieno[3,2-c]pyridine-5(4H)-acetic acid methyl ester of formula II


II

by converting a portion thereof to the S(+) isomer of the (2-chlorophenyl)-6,7-dihydro- thieno[3,2-c]pyridine-5(4H)-acetic acid methyl ester of formula I


characterized in that it is performed in an organic solvent selected from alcohols of general formula RaOH, esters of general formula Ra(O)ORb, ketones of general formula Ra(O)Rb or ethers of general formula RaORb, or in a mixture thereof,

wherein Ra and Rb independently represent a C1-C5 aliphatic substituent or a C5-C8 aromatic substituent,

in the presence of a base selected from substances of formula R1R2R3R4N+OH', wherein R1, R2, R3 and R4 are identical or different substituents selected from C1-C5 alkyls or C5, C6 cycloalkyls or aryls, C7-C9 alkyl-cycloalkyls or alkyl-aryls, the molar ratio of the base to the starting substance being 1: 1 to 1: 10.

: 2. The method according to claim 1 characterized in that the ratio of the base of formula R1R2R3R4N+OH to the reacting substance is selected in the ratio of 1:2 to 1: 4, wherein the symbols are as defined above.

3. The method according to claims 1 or 2 characterized in that R1, R2, R3 and R4 are
selected from C1-C5 alkyls.

4. The method according to claim 3 characterized in that R1=R2=R3=R4 and represents methyl or butyl.

5. The method according to any of claims 1 through 4 characterized in that the reaction is performed in a solvent of the type of an alcohol of formula RaOH or an ester of
formula Ra(O)ORb or their mixture, the general symbols being as defined above.

6. The method according to claim 5 characterized in that the solvent is selected from the series including methanol, isopropylacetate or their mixtures.

7. A method of preparation of the S(+) isomer of the (2-chlorophenyl)-6,7-dihydro- thieno[3,2-c]pyridine-5(4H)-acetic acid methyl ester of formula I characterized in that a mixture of substances I and II is dissolved in an ester of formula Ra(O)ORb, wherein the symbols are as defined in claim 1, and a solution of R-camphorsulfonic acid in a solvent of formula RaOH is added to the solution, from the mixed solution the
camphorsulfonic salt of the substance of formula I is crystallized, which is converted to the substance of formula I in the next step; further a base of formula R1R2R3R4N1OH" in a solution in a substance of formula RaOH is added to the mother liquors after crystallization, thus resulting in a mixture of substances I and II, suitable for
preparation of the substance of formula I.

8. The method according to claim 7 characterized in that methanol is selected as the substance of formula RaOH and isopropylacetate is selected as the substance of
formula Ra(O)ORb.