PREPARATION OF NITRAMINE-NITRATES BY RING-OPENING NITRATION OF AZETIDINES BY DINITROGEN PENTOXIDE (N2O5)

Eleven azetidines, bearing various types of substituents on the ring n itrogen, were treated with N2O5 in chlorinated solvents at sub-ambient temperature and in certain cases formed 1,3-nitramine-nitrate product s by a novel ring-opening nitration reaction analogous to that establi shed for aziridines. Yields of the nitramine-nitrates, where ring-open ing took place, were generally moderate to high (41-88%), but azetidin es bearing N-acyl substituents (acetyl, butyryl or carbamyl) instead u nderwent nitrolysis of the exocyclic substituent to form N-nitroazetid ine. Also, azetidines bearing strongly electron-withdrawing groups suc h as picryl were inert to attack by N2O5. The different reactivity of azetidines compared with aziridines is rationalised in terms of the re duced ring strain of the four-membered ring compounds.