Direct synthesis of oxazolidin-2-ones from tert-butyl allylcarbamate via halo-induced cyclisation

A novel synthetic pathway towards the 2-oxazolidinone derivatives involving the halo-induced cyclisation of tert-butyl allyl(phenyl)carbamate was successfully developed. Various halogenating reagents were evaluated under different reaction conditions for the reaction optimisation. Interestingly, the synthetic route to 2-oxazolidinone derivatives containing one halogen atom in the aliphatic site or two halogen atoms including the extra halogen atom substituted in the aryl group at the para position, were thoroughly established for all chloro-, bromo- and iodo compounds. Either halo-unsubstituted-aryl oxazolidinone or p-halo-substituted-aryl oxazolidinone could be selectively produced by selecting the appropriate choices of halogenated reagents and reaction conditions e.g. reaction time and temperature. Toloxatone, a commercial antidepressant, was successfully synthesized by using this developed method.