In a preferred form of the invention, the formation of the imidic ester is carried out in a high boiling solvent {HEAD ~ whose presence} enables {TAIL ~ the condensation} to be carried out more effectively at a high temperature than with alkanol alone 
enables
In a preferred form of the invention , the formation of the imidic ester is carried out in a high boiling solvent { HEAD ~ whose presence } enables { TAIL ~ the condensation } to be carried out more effectively at a high temperature than with alkanol alone
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