Synthesis of 1,2-oxazaheterocycles containing an isoindolone moiety from N-hydroxyphthalimide

Syntheses of the isoindolobenzoxazinone 1a and thienoxazinoisoindolones 1b, c was developed from N-hydroxyphthalimide 3 and halogenomethylaryl derivati ves. The resulting aryloxy phthalimides 4a-c were reduced to hydroxylactams 5a-c which cyclized in acidic conditions. A Wittig reaction on 5a using ca rbethoxymethylidenetriphenylphosphorane gave the corresponding acid 6 which treated in Friedel and Crafts conditions led to the isoxazolinone 8 by cle avage of the benzyl C-O bond.