Cycloaddition-reduction-hydrolysis sequence intermediates

A related sequence was used by Kozikowski and Park (74) to prepare the ring skeleton of streptazolin (200), a compound that exhibits antibacterial and antifungal effects. In this approach, the tricyclic isoxazoline intermediate 198 was formed in the key cycloaddition step (Scheme 6.86). Thus, the reaction of oxime 197 (obtained from 4-piperidone) with sodium hypochlorite-triethylamine afforded tricyclic isoxazoline 198 in very good yield. This cycloadduct was converted to p-hydroxyketone 199 by reduction/hydrolysis using Raney Ni in the presence of acetic acid. Racemic streptazolin (200) was obtained from 199 in several additional steps (74). 

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