engleski

Intramolecular 1, 3-dipolar Cycloreversion - the Key Step in Thermal Isomerisations of Cyclobutane Di-(carbomethoxy) Triazolines

Thermal isomerisation of the strained cyclobutane diester triazoline led to the formation of the product possessing a novel 1, 2, 7-triaza-[3.3.0]octa-2-ene ring system incorporated in a norbornane framework. Experimental evidence and quantum chemical calculations (semiempirical and DFT) have been used to support a postulated reaction mechanism involving as the first step, a rare example of intramolecular 1, 3-dipolar cycloreversion. Subsequently, several steps involving 1, 3-dipolar ring closure, [1, 3]hydrogen-shifts and an intramolecular addition are postulated leading to the observed product of this deep-seated isomerization. The influence of changing substituents on the product outcome of this novel reaction cascade was also studied.

triazolines; dipolar cycloadditions

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