Indazole and Benzisoxazole

The aromaticity of benzisoxazole ( -X-Y- = -CH=N-, Z = O) (XXXV) is studied using the reaction  

The endothermicity of this reaction is 40 kJ mol1 and so we deduce benzisoxazole has significant aromaticity. No direct measurements of the enthalpy of formation of any acyclic oxime ethers appear in the literature. However, from the calculational literature [69] we find a value for the enthalpy of formation of CH3CH=NOCH3 of -7 kJ mol1, Unmeasured by combustion calorimetry because of experimental complications, the enthalpy of formation of benzisoxazole was recently suggested [70] to be 139 kJ mol-1. 

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