Science of Synthesis

Matsumoto, M., Science of Synthesis, (2004) 16, 28.

As described in the introduction to the chapter, dibenzo[b,e][1,4]dioxins are aromatic and are, therefore, capable of undergoing various electrophilic substitutions. A representative substitution is direct chlorination and bromination of the aromatic ring.[‌35‌,‌71‌] For dibenzo[b,e][1,4]dioxin (‌3‌), chlorination occurs initially at C2, and then the second chlorination takes place at C7 or C8 since the chlorinated ring becomes less reactive to electrophiles. Further chlorination occurs, in general, at the 2-, 3-, 7-, and 8-positions before functionalization of the remaining carbons. These reactions, however, usually lack selectivity and lead to many products, which are difficult to separate. They have been used to prepare a wide variety of polychlorinated dibenzo[b,e][1,4]dioxins and various modifications have been made to improve the selectivity of products.

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References

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• 8.Meeeee-Meee, (8888) M 8e, 88.