Issue ICHC-20 ARKIVOC 2006 (vii) 439-451 ISSN 1424-6376 Page 439 © ARKAT Synthesis of β-tropolone and fused heterocycles by acid-catalyzed and photoreactions of o-quinones with quinolines and benzimidazoles Vladimir I. Minkin,* Vitaly N. Komissarov, and Yurii A. Sayapin Institute of Physical and Organic Chemistry. Rostov University, 194/2 Stachka St. 344090 Rostov on Don. Russian Federation E-mail: minkin@ipoc.rsu.ru Abstract The condensation of 3,5-di-(tert-butyl)-1,2-benzoquinone 1 with 2-methylquinolines 2 proceeding on refluxing o-xylene solutions of the components in the presence of catalytic amounts of p-toluenesulfonic acid gives rise to previously unknown β-tropolones 3. In the case of quinolines 2 containing amino or nitro groups in position 4, the reaction with quinone 8 also leads to the formation of derivatives of a novel heterocyclic system of 2-azabicyclo[3.3.0]octa- 2,7-dien-4,6-dione-N-oxide 10. β-Tropolones 3, under UV-irradiation, in heptane solution undergo an irreversible rearrangement leading to the formation of derivatives of 3-[(1Н)- quinolinylidene]-1,6-di-(tert-butyl)-bicyclo[3.2.0]hept-6-ene-2,4-dione ring system 14. The reaction of o-quinone 1 with 2-methylbenzimidazole affords the derivatives of a novel condensed heterocyclic system [benzimidazo-(1,2-b)][benzimidazo-(1,2-a)-pyrrolo(3,4,5-j,i]-13,16-dihydro- 16-oxoisoquinoline 17. Keywords: 2-Azabicyclo[3.3.0]octa-2,7-dien-4,6-dione-N-oxides, 3,5-di-(tert-butyl)-1,2-benzo- quinone, 2-methylquinolines, photolysis, 2-quinolyl-β-tropolones, X-ray crystallography Contents 1. Introduction 2. Results and Discussion 3. Acknowledgements 4. References