Regioselective Synthesis of N-Substituted 4-Methylene-2-oxazolidinones and 4-Oxazolin-2-ones. Study of Reactivity in Thermal Michael Conjugate Additions

✍ Scribed by Rafael Martı́nez; Hugo A. Jiménez-Vázquez; Joaquı́n Tamariz

• Publisher: Elsevier Science
• Year: 2000
• Tongue: French
• Weight: 172 KB
• Volume: 56
• Category: Article
• ISSN: 0040-4020
• DOI: 10.1016/s0040-4020(00)00311-2

✦ Synopsis

AbstractÐN-Substituted 4-methylene-2-isoxazolidinones 9a±9e have been prepared from the tandem condensation of isocyanates 3 with a-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 provided the C-5 adduct 15. When the reaction was carried out with the captodative ole®n 17, the unexpected aniline 18 was isolated. The regiochemistry of the Michael addition was rationalized in terms of FMO theory by ab initio calculations.