THE CHEMISTRY OF 5-OXODIHYDROISOXAZOLES .12. TRAPPING OF DERIVED KETENIMINES WITH LITHIUM AMIDES AND ALKYLLITHIUMS

Isoxazolones unsubstituted at C3 react with lithium amides or alkylrit hiums to give ketenimines. The presence of an ethoxycarbonyl group at C4 allows capture of this species by addition of a second equivalent o f the lithiated species to give enolates which can be alkylated in sit u. The presence of a phenyl group at C4 gives a ketenimine which react s intramolecularly in the presence of lithium amides, whereas alkyllit hiums undergo addition in synthetically useful processes.