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US 5,326,884 AGranted
Process for optically active 3-(methane-sulfonyloxy)thiolane and analogs
AssigneePfizer Inc.
InventorFrank J. Urban
Life of this patent
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Abstract
Intermediates and a stepwise process for the conversion of D-methionine or certain of its derivatives to optically active compounds of the formula ##STR1## wherein R is (C.sub.1 -C.sub.3)alkyl, phenyl or tolyl. The latter compounds are in turn useful as an intermediate in the preparation of penem antibiotic 5R,6S-6-(1R-hydroxyethyl)-2-(1R-oxo-3S-thiolanylthio)-2-penem-3-carboxylic acid and corresponding pharmaceutically acceptable salts and esters.
Claims9
A process for the preparation of an optically active compound of the formula ##STR12## wherein R is (C.sub.1 -C.sub.3) alkyl, phenyl or tolyl, which comprises the steps of:
- (a) reacting an optically active diol of the formula ##STR13## in a reaction-inert solvent with at least 2 molar equivalents of RSO.sub.2 Cl in the presence of at least 2 equivalents of a tertiary amine to form an optically active disulfonate of the formula ##STR14## (b) with or without isolation, allowing to stand or heating the disulfonate of the formula (III) neat or in the same or another reaction-insert solvent to form an optically active sulfonium salt of the formula ##STR15## wherein X is RSO.sub.3 or halogen;
- and (c) with or without isolation, heating the sulfonium salt of the formula (IV) with up to three molar equivalents of an additional nucleophilic anion in the same or another reaction-inert solvent to form the compound of the formula (I).
Dependencies are inferred from the claim text.