1-Amino-2-phthalimido-diazene-1-oxides: Formation, Properties and Fragmentation Reactions into Imido- and Amino-nitrenes

Article abstract of DOI:10.1002/hlca.19810640326

Oxidatively generated phthalimido-nitrene (1) reacts with the nitrosoamines 2a-d (see Scheme 1) to give the corresponding (Z)-1-amino-2-phthalimido-diazene-1-oxides 3a-d in good yields.With the O-nitroso compound 2e, no addition of the nitrene 1 took place.The constitution of the adducts 3 (R = NR2') is deduced from their spectroscopic properties (UV., IR., 1H-NMR. and MS.) as compared to those of (Z)-1-aryl- and (Z)-1-alkyl-2-phthalimido-diazene-1-oxides 3 (R = aryl and alkyl, resp.).The (Z)-configuration of 3 (R = NR2') follows from an X-ray analysis wich is reported separately.Compounds 3 (R = NR2') are cleaved photolytically as well as by acid to the corresponding nitrosoamines 2 (R = NR2') and the nitrene 1, which could be trapped by cyclohexene to give 40percent of 7-phthalimido-7-azabicyclo<4.1.0>heptane (8) and by dimethylsulfoxide to yield 96percent of S,S-dimethyl-N-phthalimido-sulfoximide (13).Nucleophilic attack leads to fragmentation of 3 (R = NR2') into derivatives of phthalic acid and degradation products of intermediate aminonitrenes 24 corresponding to the respective nitrosoamines 2 (R = NR2') with loss of oxygen.A general rationalization for the formation of 24 includes as a key step a N-to C-migration of the O-atom (see Scheme 6).The final fate of 24 is depending of the type of the nucleophile used.Thus, hydrazinolysis of 3b and of 3c generates besides N,N'-phthalohydrazine (15), morpholine (14) from 3b and 1,3-dihydroisoindole (16) together with 6'-methylidene-1,2,3,4-tetrahydronaphthalene-2-spiro-1'-cyclohexa-2',4'-diene (17) from 3c (see Scheme 5).Treatment of 3b and of 3c with sodium methylate leads in both reactions to monomethyl phthalate (33) and, with 3b, to1,2-dimorpholinodiazene (31) and, with 3c, to 17 (see Scheme 7).Finally, the reaction of 3b with diethylamine generates N,N-diethylphthalamic acid (36), morpholine (14), 1,1,4,4-tetraethyl-2-tetrazene (34) and 1,1-diethyl-4,4-(3-oxapentamethylene)-2-tetrazene (35) (see Scheme 8).