The electrophilic addition of bromine to dimethyl 7-oxabicyclo[2.2.1]hepta-2,5-diene-2,3-dicarboxylate 10 at 0 and -60 degreesC led in high yield to the formation of dibromide 11. However, high-temperature bromination of 10 in carbon tetrachloride at 77 degreesC gave four products 12-15, three of them with nonrearranged skeleton. Similarly, bromination of the dibromides 14 and 15 at 77 degreesC yielded the nonrearranged tetrabromides 13 and 16, respectively. The structure of the tetrabromide 13 was solved by single-crystal X-ray analysis. The formation mechanism is discussed and supported by calculations.