EFFECT OF THE SUBSTITUTION PATTERN ON THE OXIDATION OF THE ISOXAZOLIDINE MOIETY IN BICYCLIC AND TRICYCLIC COMPOUNDS

The N-benzylated bicyclic compounds 5 were converted to C-phenyl nitro nes 6 by highly regioselective oxidative opening of the isoxazolidine ring with MCPBA. One or both of the isoxazolidine rings of compound 8 were opened in the same way affording a mixture of compounds 9 and 10. Compounds 13a and b were formed by oxidation of N-methylated bicyclic compounds 11a and 4 respectively, with MCPBA, while Ile was decompose d under these conditions. A mixture of 15 and 16 was isolated after ox idation of the tricyclic compound 14, whereas oxidation of the diaster omeric 17 provided the oxime 19 as the single product. The reason for the different course of the oxidation is discussed. (C) 1998 Elsevier Science Ltd. All rights reserved.