A rational synthesis of trans-2-(3-phenylprop-1-yl)cyclohexylamino-2-oxazoline enantiomers

A novel method has been developed for the synthesis of the optical antipodes of trans-2-(3-phenylprop-1-yl)cyclohexylamino-2-oxazoline 1 from racemic cis-octahydrocoumarin 4 instead of cyclohexene oxide 2, because the synthesis of 1 from compound 2 was unsuccessful. Compound 4 was resolved with 1-phenylethylamine enantiomers. Although the preparation of this oxazoline from cyclohexene oxide is known, the resolution and the enantiomeric enrichment step have not been described.

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cis-OctahydrocoumarineC9H14O2Ee >99.5% by chiral HPLC[α]D20=-40.3 (c 1, CHCl3)Absolute configuration: (S,S)

2-(3-Phenylprop-1-yl)cyclohexylamino-2-oxazolineC18H26N2OEe >99.5% by chiral HPLC[α]D20=+30.5 (c 1, CHCl3)Prepared from optically active materialAbsolute configuration: (R,S)