AMINOCYCLOPENTITOLS FROM N-ALKYLPYRIDINIUM SALTS - A PHOTOCHEMICAL APPROACH

The photolysis of N-alkylpyridinium halides 9a-e in alkaline H2O gave 6-azabicyclo[3.1.0]hexenol derivatives 10a-e. N-Substituents bearing e ther, acetal, and alcohol functions were found to do nor adversely inf luence the photochemical reaction course. The free OH groups of the N- (3-hydroxypropyl) derivative 10 d were protected by benzoylation. The ensuing dibenzoate 14 underwent stereocontrolled opening of the azirid ine ring on reaction with MeSH/BF3 to give a thioether 15. With benzoi c acid in CHCl3, 10 d gave the 4-hydroxy-5-aminocyclopent-2-enyl benzo ate 11. The meso-2-aminocyclopent-4-ene-1,3-diol 12 was obtained by hy drolysis of 11. On reaction with Boc(2)O and NaI, the aziridine ring o f 14 was converted to a bicyclic compound 17. Hydrolysis of 17 provide d the trans-1,3-diol 18, the epimer of 12. Face-selective dihydroxylat ion of Boc-protected 12 gave a meso-aminocyclopentanetetrol 23 which w as characterized upon peracetylation. Dihydroxylation of 15 provided a racemic analogue of epi-mannostatin A (26).