Unusually Stable Isoxazolidinyl Epoxides: Synthesis and Reactivity in Nucleophilic Substitutions

摘要

The synthesis of new N-carbamoyl-substituted isoxazolidine-4,5-diols and their 4,5-anhydro analogues, isoxazolidinyl epoxides, is described. The 4,5-unsubstituted 2,3-dihydroisoxazole starting materials reacted directly with potassium osmate/4-methylmorpholine N-oxide and 3,3-dimethyldioxirane, respectively. All addition reactions proceeded with excellent anti selectivity with respect to the substituent at C-3. The obtained isoxazolidinyl epoxides as well as benzoylated isoxazolidine-4,5-diols were subjected to nucleophilic substitution reactions with various nucleophiles. 4-Hydroxyisoxazolidines with chlorine, methoxy, and azide substituents bound to C-5 were prepared in moderate to good yields. In terms of chemical stability, the discussed isoxazolidinyl epoxides can be isolated and stored for a long time.