Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)We disclose herein a new strategy for the diastereoselective preparation of 4- and 4,5-substituted oxazolidinones from Morita-Baylis-Hillman adducts. The strategy is based on an intramolecular cyclization involving a nucleophilic attack of an alkoxide ion to the carbonyl group of a carbamate. The latter is prepared from a Curtius rearrangement having Morita-Baylis-Hillman adduct as substrate. The oxazolidinones were prepared in six steps with an overall yield of 18% and 49%.412227242Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)