ISSN:
0941-1216
Keywords:
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
3,6-Bis(trifluoromethyl)-1,2,4,5-tetrazine (1) characterized by a highly reactive, electron deficient diazdiene system reacted with several cyclic and acyclic bis-dienophiles to yield the cage compounds 11, 19a, b, 31a, b and 41 in a pericyclic homo-domino reaction in good yields. The first step of the domino reactions is an inverse electron demand inter-molecular Diels-Alder addition followed by elimination of nitrogen to give 4,5-dihydropyridazines which then undergo a terminal ring closure to yield the cage compounds. The solvent employed and the reaction temperature is of crucial importance. Whereas in nitromethane and at elevated temperatures the main products are the cage compounds, at lower temperature and in dichloromethane as solvent the initially formed 4,5-dihydropyridazines are frequently converted to 1,4-dihydropyridazines by a 1,3-H-shift. Treatment of the tetrazine 1 with cyclooctatriene 23 did not lead to a cage compound in any case; instead via valence tautomeric species octa-1,3,5,7-tetraene 23a and bicyclo[4.2.0]octa-2,4-diene 23b the twofold pyridazine-substituted butadienes 24 and 26 together with the tricyclic cyclobuta[f]phthalazine 25 were formed.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/prac.199733901111
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