ISSN:
0947-3440
Keywords:
Cyclooctatetraene-bicyclooctatriene valence tautomerism
;
[4+2] Cycloadditions, inverse
;
Cycloocta[d]pyridazine ⇛ barreleno[d]pyridazine rearrangement
;
[1, 3]-Carbon migration
;
Catalysis, 1,3-tautomerization with 2-hydroxypyridine
;
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
As part of the valence tautomeric system cyclooctatetraene (2) bicyclo[4.2.0]octa-2,4,7-triene (3), the monocyclic polyene (2) reacts as a dienophile with the diazadiene 3,6-bis(trifluoromethyl)-1,2,4,5-tetrazine (1) to form after N2-elimination two products: The 1 : 1-adduct 6, a cycloocta[d]pyridazine, and the tetracyclic bis-Diels-Alder cycloadduct 9. Depending on solvent polarity and temperature, compound 6 displays interesting novel rearrangements. On refluxing in nonpolar solvents like toluene, compound 6 yields the barreleno[d]pyridazine 13 in high yield. Compound 13 can be oxidized with 4-phenyltriazolinedione 14 to the barreleno[d]pyridazine 15. When the more polar nitromethane is used as a solvent, heating of 6 at 90° 2°C surprisingly leads to the dihydrocycloocta[d]pyridazine 18 in a multistep reaction including proton-shift tautomerism and [1, 5]-sigmatropic rearrangement. The structures of the compounds 15 and 18 were assigned by the spectral data and verified by X-ray crystallography.
Additional Material:
2 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jlac.199519950493
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