Ozonolysis of ethyl vinyl ether (7a) in the presence of the O-methylat
ed oxime of cyclohexanone (8) afforded N-methoxy-1,2-dioxa-4-azaspiro[
4.5]decane (9a), and ozonolyses of the O-methylated dioximes of 1,4- a
nd 1,5-dicarbonyl compounds (10a-e) afforded N-methoxylated bicyclic 1
,2,4-dioxazolidines (12a-e).