A Diels–Alder reaction of 2,5-dimethylfuran and maleic anhydride gives a compound A that undergoes acidcatalyzed dehydration to give 3,6-dimethyl phthalic anhydride (see Fig. P16.65).

(a) Deduce the structure of compound A.

(b) Give a curved-arrow mechanism for the conversion of A into 3,6-dimethylphthalic anhydride.

Transcribed Image Text:

Figure P16.65 H₂C CH3 + 2,5-dimethylfuran maleic anhydride A H₂SO4 CH3 O + H₂O CH3 3,6-dimethylphthalic anhydride