合成路线1

4-Formylbenzonitrile (I) was converted to oxime (II) by treatment with hydroxylamine hydrochloride in pyridine-ethanol. Chlorination of the oxime with NaOCl, followed by dehydrohalogenation of the intermediate imidoyl chloride and dipolar cycloaddition to vinylacetic acid (III) produced the racemic isoxazoline (IV). The cyano group of (IV) was then converted to amidine (V) by formation of the corresponding imidate and subsequent treatment with methanolic ammonia. After protection of the amidine function of (V) as the Boc-derivative, ester hydrolysis employing LiOH yielded carboxylic acid (VI) (1). Coupling of acid (VI) with the racemic ethyl 2-piperidineacetate (VII) in the presence of O-(1H-benzotriazol-1-yl)-N,N,N',N'-tetramethyluronium tetrafluoborate (TBTU) furnished a diastereomeric mixture of amides (VIII). The Boc group of (VIII) was finally cleaved by means of trifluoroacetic acid.