The reaction between 1,2,3-triazole (I) and 3,4-difluoronitrobenzene (II) afforded a mixture of two regioisomeric substituted triazoles (III) and (IV), from which the required 1-substituted isomer (III) was isolated by column chromatography. Reduction of the nitro group of (III) by hydrogenation over Raney-Ni gave aniline (V), which was converted to carbamate (VI) upon treatment with benzyl chloroformate. Subsequent condensation of (VI) with (R)-(-)-glycidyl butyrate (VII) in the presence of lithium bis(trimethylsilyl)amide produced the chiral oxazolidinone (VIII). Mesylation of the alcohol group of (VIII), followed by displacement with NaN3 yielded azide (IX). This was reduced by hydrogenation over Raney-Ni to give amine (X), which was finally acetylated using Ac2O and pyridine.
The reaction between pyrrole (I) and 3,4-difluoronitrobenzene (II) afforded the N-aryl pyrrole (III). Selective reduction of the nitro group of (III) by hydrogenation over sulfided platinum on carbon gave aniline (IV), which was converted to carbamate (V) upon treatment with benzyl chloroformate. Subsequent condensation of (V) with (R)-(-)-glycidyl butyrate (VI) in the presence of lithium bis(trimethylsilyl)amide produced the chiral oxazolidinone (VII). Mesylation of the alcohol group of (VII), followed by displacement with NaN3 yielded azide (VIII). This was reduced by hydrogenation over Pt/C/S to give amine (IX), which was finally acetylated using Ac2O and pyridine.