Comparison between Conventional and Nonconventional Methods for the Synthesis of Some 2-Oxazolidinone Derivatives and Preliminary Investigation of Their Inhibitory Activity Against Certain Protein Kinases

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A series of propargyl and allyl carbamates were prepared directly from propargyl and allyl alcohols and phenyl or cyclohexyl isocyanate or indirectly by generating the isocyanates in situ from the corresponding Cbz-protected amines. The obtained carbamates underwent intramolecular nucleophilic cyclization in presence of cesium hydroxide monohydrate as a base catalyst under conventional and ultrasonic irradiation conditions to give the corresponding substituted 4-(benzylidene)methylidene-2-oxazolidinones in good to excellent yields. The use of ultrasonic irradiation provided remarkably improved yield of the cyclization products and significant shortening of the reaction time. In some cases the reaction was highly stereoselective, and (Z)-4-benzylideneoxazolidinones were formed as a single stereoisomer. A series of biological tests were performed to evaluate the inhibitory potential of all synthesized compounds against some protein kinases.