PURPOSE: To easily obtain at low cost a single diastereomer of a oxazolidinone derivative by reaction of a diastereomer mixture of an amino alcohol compound with a specific ester followed by conversion into a fumarate which is then cyclized.
CONSTITUTION: Firstly, a diastereomer mixture of an amino alcohol compound of formula I is reacted with a chloroformic ester of formula ClCOOR (R is a 1-4C alkyl) to form a diastereomer mixture of a urethane compound of formula II. Subsequently, this mixture is reacted with fumaric acid to form a fumarate, which is, in turn, subjected to crystallizing fractionation in an organic solvent to separate fumarate of the diastereomer of the urethane compound with lower solubility followed by cyclizing the remaining fumarate, thus obtaining a single diastereomer of the aimed derivative of formula III or a fumarate thereof.
TAKAHASHI TOSHIHIRO
NOMURA YUTAKA
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