Reversing Carbonyl and Ether or Amine Groups

If we reverse the carbonyl and either the ether or amine groups above, we convert the putatively antiaromatic eight-7t phthalic anhydride and phthalimide into the putatively aromatic ten-7t phenylene carbonate (X = Z = O, Y = CO) (XX) and 2-benzimidazolinone (X = Z = NH, Y = CO) (XXI), and interpolating these last species 2-benzoxazolinone (X = O, Y = CO, Z = NH) (XXII). Calorimetric data are absent for phenylene carbonate (benzo-l,3-dioxole-2-one). 

For 2-benzimidazolinone, we take the contemporary results of [37] (noting the earlier studies of solid 2-benzimidazolinone [38]) and those of [39] for Al V -dimethy-lurea, for the reaction  

Benzo-l,3-dioxole (XXIII) is presumably nonaromatic, other than in its benzene ring. That there are ten 7t electrons does not make this species aromatic because the conjugation is interrupted [40, 41], much as the six-7t cycloheptatriene may enjoy homoaromatic stabilization but not aromatic stabilization, per se [42], Accordingly, we are confident that 2-benzimidazolinone (XXI) with its ten n electrons is aromatic. 

This reaction (13) is exothermic by 14 kJ mol-1 and so 2-benzoxazolinone seems to be nonaromatic. The same reaction enthalpy value as for 2-indanone (six n electrons), not far from indane (21 kJ mol-1), suggests that it lacks aromaticity other than found in its benzene ring, much as found for indane and the indanones. Admittedly, the enthalpy of formation of CH3NHCOOCH3(A,0-dimethylcar-bamate) is unknown however, we may estimate the value to be -420 kJ mol1 by assuming thermoneutrality for reaction 14  

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