A diels–alder reaction of 2,5-dimethylfuran and maleic anhydride gives a compound a that undergoes acid-catalyzed dehydration to give 3,6-dimethylphthalic anhydride.
The reaction above is illustrated in details in the file attached, where I used CHEMDRAW program to draw the compounds included compound (A), and illustrate the reaction, Please find the attachment.
