1,3-cycloadditions of pyridinium N-arylimides

✍ Scribed by Rolf Huisgen; Robert Temme

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 240 KB
• Volume: 10
• Category: Article
• ISSN: 1042-7163
• DOI: 10.1002/(sici)1098-1071(1999)10:1<79::aid-hc14>3.0.co;2-m

✦ Synopsis

The title compounds (5a: Ar ‫ס‬ C 6 H 5 , 5b: Ar ‫ס‬ 2-pyridyl) are 1,3-dipoles of the azomethine imine type; their 1,3-cycloadditions are accompanied by the loss of the pyridinium resonance energy. As a consequence, the interaction with electron-deficient ethylenes gives rise to cycloaddition/cycloreversion equilibria, in contrast to the cycloadditions of isoquinolinium N-arylimides; enamines do not react with 5. The cycloadducts of 5a to dimethyl maleate, fumaronitrile, and acrylonitrile are N b -dienyl-phenylhydrazines, which undergo a hydrazo rearrangement affording aminals derived from a tetracyclic system. Like enamines, the dienehydrazine system of the cycloadducts reacts with dimethyl acetylenedicarboxylate by [2 ‫ם‬ 2] cycloaddition and electrocyclic ring opening furnishing tetrahydropyrrolo [3,2-a]azocine derivatives.