ABSTRACT.give a-cyanodiazoketones 2 . L and, in the case of fi, also the N- We will also discuss the mechanism of decomposition of REACTION PRODUCTS When the aminoisoxazoles &,b were diazotized with sodium nitrite in hydrochloric acid at 0 -5OC, and then treated with sodium azide, the expected azidoisoxazoles 2 , p were obtained in only small amounts (ranging from 0 to 8 % ) .The major products of the reactions were found to be the a-cyanodiazoketones -3a,b and, in the case of 2, also the N-hydroxytriazole 1.In order to optimize the yields of &,a the reaction conditions were varied, including a change of solvent, nitrosation reagent and temperature. The best results were obtained when the diazotization was carried out at a temperature between -15 and -lO°C, yielding 30% of &,k under the conditions described in the Experimental Section (Method B).-229 -