Process for Preparing Enantiopure E-(2S)-Alkyl-5-Halopent-4-Enoic Acids and Esters

A process for preparing enantiopure E-(2S)-alkyl-5-halopent-4-enoic acids and their esters of the formula (I), in which R is a C1-C6-alkyl radical, R1 is H or C1-C4-alkyl and X is chlorine, bromine or iodine, in which the corresponding racemic 2-alkyl-5-halopent-4-enoic acid a) is reacted in a suita...

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Bibliographic Details
Main Authors STEINBAUER GERHARD, POJARLIEV PETER, ROSSLER MARKUS
Format Patent
LanguageEnglish
Published 13.11.2008
Subjects
ACYCLIC OR CARBOCYCLIC COMPOUNDS
CHEMISTRY
METALLURGY
ORGANIC CHEMISTRY
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Summary:A process for preparing enantiopure E-(2S)-alkyl-5-halopent-4-enoic acids and their esters of the formula (I), in which R is a C1-C6-alkyl radical, R1 is H or C1-C4-alkyl and X is chlorine, bromine or iodine, in which the corresponding racemic 2-alkyl-5-halopent-4-enoic acid a) is reacted in a suitable solvent first with (S)-3-Methyl-2-phenylbutylamine, quinine or with N-methyl-D-glucamine, after which b) the corresponding (S)-3-Methyl-2-phenylbutylamine salt, quinine or glucamine salt of the (R)-pentenoic acid is precipitated and removed, and c) the remaining filtrate is mixed with a second chiral base or an inorganic salt, after which the corresponding salt of the (S)-pentenoic acid is precipitated and d) is then converted into the corresponding E-(2S)-alkyl-5-halo-4-pentenoic acid and subsequently where appropriate into the corresponding ester of the formula (I) in which R1 is C1-C4-alkyl.
Bibliography:Application Number: US20060885740