Oxidation of the title compounds 8, 9 with lead tetraacetate at room temperature gives a variety of products depending on the substituents on the carbonyl carbon atom. Thus, on oxidation of the aldehyde derivatives 8 1,3,4‐oxadiazolo derivatives 10 are obtained in good yields. However in some cases formation of N‐acetyl‐N‐arylacetyl‐N′‐benzoylhydrazines 11 is also observed, whereas oxidation of the ketone hydrazones 9 gives in good yields the 2H,5H‐1,3,4‐oxadiazoles 15 or substituted monoacetoxy‐ 17 and diacetoxyalkanes 18. The reaction mechanisms are also discussed.

Die symm. bzw. unsymm. Trisarylhydrazone (I) bzw. (VI) werden nach Literaturmethoden hergestellt (55‐80%) und der Oxidationsreaktion A) unterworfen.

The mass spectra upon electron impact at 70 eV of the title compounds are examined. The fragmentation pattern of the tetrahydro‐benzotriazoles with unsymmetrically substituted the aryl groups in 2‐position and in hydrazone group cannot support the aspect for a mononuclear heterocyclic rearrangement.

182. Heterocyclic Rearrangement of 4,5,6,7-Tetrahydro-6,6-dimethylbenzo[c] [ 1,2,5]oxadiazol-4-one (Z)-Arylhydrazones into Corresponding 2-Aryl-4,5,6,7-tetrahydro-2H-benzo[d] [ 1,2,3]triazo1-4-one Oximes The thermal base-catalysed and photochemical transformation (Boulton-Kutritzky rearrangement) of the title tetrahydrobenzo[c][l,2,5]oxadiazoles to tetrahydro-2H-benzo[d] [1,2,3]triazoles is studied. Attempts to induce analogous rearrangement in tetrahydro-2H-benzo[d] [ 1,2,3]triazol-4-one arylhydrazones or oximes failed. Some CND0/2 calculations are also carried out.We have reported previously [ 13 [2] that attempts to induce thermal or photochemical mononuclear heterocyclic rearrangement in 2-aryl-4,5,6,7-tetrahydro-6,6-dimethyl-2Hbenzo[d] [ 1,2,3]triazo1-4-one (Z)-arylhydrazones were unsuccessful. This prompted us to a more systematic study in order to examine whether this unsuccessful rearrangement [3] i Z; either due to the thermodynamical stability of the triazole ring [4] [5] or to an unfavored geometry of the condensed ring system.The present study is concerned with Boulton-Katritzky-type rearrangements [6] [7] of 4,5,6,7-tetrahydro-6,6-dimethylbenzo[c] [ 1,2,5]oxadiazo1-4-one (Z)-arylhydrazones (2) to the corresponding 2-aryl-4,5,6,7-tetrahydro-2H-benzo[d] [ 1,2,3]triazo1-4-one oximes (3). Comparatively few examples of ring transformations of 1,2,5-0xadiazoles to 1,2,3-Scheme I

Die Z‐isomeren Arylhydrazone (II), neben ihren E‐Isomeren (III) [thermische Isomerisierung zu (II)] aus den Ketonen (I) erhältlich, gehen eine thermische basenkatalysierte Umlagerungsreaktion unter Bildung der Tetrahydrobenzotriazolonoxime (IV) ein; die (E)‐Isomeren (III) liefern unter gleichen Bedingungen ebenfalls quantitativ (IV), jedoch geht dieser Reaktion wahrscheinlich eine Isomerisierung von (III) zu (II) voraus.