Synthese von 2,2a,3,4-Tetrahydro[1,2-d]benz[b]-1,4-oxazin-2,4-dionen, 2. Mitt.

Synthesis of 2,2a,3,4,-Tetrahydro[1,2d]benz[b]-1,4-oxazine-2,4-diones, II The diasteromeric 3-amino-β-lactams 7 and 8 were obtained from the azides 5 and 6 and the phthalimido derivatives 9 and 12 . Compound 9 was synthesized directly from 2 by means of phthalimidoacetyl chloride/triethylamine, whereas 12 is accessible from 11 only by the Mitsunobu reaction. Acylation of 7 or 8 (to 13 or 14 ) is followed by hydrolysis of the ester function (to 15 or 16 ) and debenzylation to yield 17 or 18 which are lactonized to 19 or 20 by the action of DCC.