| 摘要 |
<p>A process for the preparation of a compound of formula (I) or a salt thereof or a carboxylic acid ester derivative thereof, wherein L represents a leaving group, which comprises (a) treating a compound of formula (II) wherein R represents COOH or a salt thereof or a derivative thereof and L and L1 represent leaving groups with a base such that L1 is eliminated and the oxazole ring is formed; and (b) if necessary converting the R moiety to COOH or a salt thereof or a carboxylic acid ester derivative thereof. A further aspect of this invention is the preparation of the potassium salt of a pyrrolidinyl derivative of compound of formula (I) and coupling of the said salt to an amine.</p> |
