Aryl Azide Thermolysis A Series of Rather Involved Rearrangement

Aryl Azide Thermolysis A Series of Rather Involved Rearrangement Reactions  

In 1996, Indian workers reported the formation of a most unusual product from the thermolysis of a highly substituted aryl azide (S.V. Eswaran, H.Y. Neela, S. Ramakumar and M.A. Viswamitra, J. Heterocyclic Chem., 33,1333-1337 (1996)). Thus, heating of the azide 1 in chlorobenzene for 4 hours at 130°C followed by removal of the solvent by distillation under reduced pressure and chromatography of the residue on silica gel gave the product 2 in 19% yield. The structure of 2 was established by X-ray analysis, but no mechanism was suggested for its formation. 

An efficient synthesis of hexakis(trifluoromethyl)cyclopentadiene 1 has been described very recently. Thus, a mixture of 1,1,3,3,3-pentafluoropropene (2 eq.), perfluoro-3,4-dimethylhexa-2,4-diene (1 eq.) and dried cesium fluoride (4 eq.) in anhydrous acetonitrile was sealed in a Carius tube which was rotated, using a mechanical arm, at room temperature for 48 hours. This gave 1 in 74% yield. 

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