New azabenzoquinones by ring‐expansion reactions

Abstract

Ozonolysis of the pyrrolidinediones 4 afforded the pyrrolidinetriones 5, which in the presence of Lewis acids were converted into maleimide 6. Analogously, ozonolysis of the pyrrolidinones 7 gave the pyrrolidinediones 8, which were converted into the pyridinetriones 11a, b via Lewis acid catalyzed isomerization to yield the trihydroxypyridones 10 and ensuing air oxidation. In solution two tautomeric forms of the pyridinetriones 11 may exist both of which represent hydroxy-azabenzoquinones. In two steps compounds 11 were transformed into the azaquinone derivatives 19. Representatives of another type of azaquinones are compounds 28a, b. These were generated in two steps from the pyridones 25. The azaquinone 28a reacted easily with acidic compounds yielding the adducts 26, 27 and 29 or with 2-butenal forming the cycloadduct 30.

The Solid-State Structures of Cyclic NH Carboximides

“…Four of these structures, compounds 166 [143], 167 [144], 168 [145] and 169 [146] (Figure 51) exist as simple R 2 2 (8) dimers of category A, with 166 and 168 displaying an additional intramolecular S(6) interaction. Compound 170 [147] exists as a simple linear C( 5) chain with the imide NH bonded to a remote oxygen on the next molecule in a type F pattern. The remaining structure, compound 171 [148] (Figure 52) exhibits a more complex pattern similar to 31 and 66, with imide NH to imide CO dimers forming R…”

Functionalized Imides by Regioselective Ozonation

“…Apparently, we have at hand a useful method for the preparation of variably substituted alkylidenepyrrolidine-2,3,5-triones. Such substances are interesting because they can be converted into persubstituted pyridinones in a few steps, as already shown by the conversion of the benzylidene compound 14a into the pyridine derivative 15 [24]. In addition, compounds of type 14 have been used for the preparation of different types of heterocycles by cycloaddition or cyclocondensation reactions [25].…”