Cyclobutanetetracarboxylate compound and preparation method thereof

A process for the preparation of a cyclobutanetetracarboxylate compound of formula I

• in which:
• R can be the same or R is different from each other and independently represents hydrogen or a halogen or a monovalent organic radical;
• and R1 is a C1-C4 alkyl,
• comprising:
• conducting a cyclization reaction by irradiating a precursor compound of general formula (IV)
• with an energy ray in a solvent in which the compound of formula (IV) is insoluble or difficult to be dissolved, to obtain the cyclobutanetetracarboxylate compound of general formula (I).