Regioselective Synthesis of N-Substituted 4-Methylene-2-oxazolidinones and 4-Oxazolin-2-ones. Study of Reactivity in Thermal Michael Conjugate Additions
作者:Rafael Martı́nez、Hugo A. Jiménez-Vázquez、Joaquı́n Tamariz
DOI:10.1016/s0040-4020(00)00311-2
日期:2000.6
N-Substituted 4-methylene-2-isoxazolidinones 9a–9e have been prepared from the tandem condensation of isocyanates 3 with α-ketol 7. In a more polar solvent (DMF) the same reaction led to stereoisomeric alcohols 11 and 12, which could be transformed to the thermodynamically more stable isomers 4-oxazolin-2-ones 10 in good yield. Thermal conjugate additions of both heterocycles 9a and 10a to enone 13