Terephthalic acid reacts with alkyl halides under Birch conditions to substituted 1,4-cyclohexadienes in high yields and good stereoselectivities. Electrophiles containing ester or nitrile groups undergo a surprising fragmentation under the reaction conditions. Subsequent treatment with chlorosulfonic acid proceeds by an interesting tandem decarbonylation/decarboxylation, affording 1,4-dialkylbenzenes in excellent regioselectivity. Thus our new method is superior to classical Friedel-Crafts alkylations.

A strategy for the regioselective alkylation of arenes was developed, starting from commercially available and inexpensive terephthalic acid or naphthalene‐1,4‐dicarboxylic acid. The method entails a formal ipso‐substitution of the carboxylate groups by a sequence of reductive alkylation under Birch conditions and subsequent acid‐mediated rearomatization with loss of carbon monoxide and carbon dioxide. More than 20 different arenes with various side‐chains were synthesized. With naphthalene‐1,4‐dicarboxylic acid as starting material, we were able to control the degree of alkylation by choosing the appropriate electrophile in the Birch reduction. Thus, bisalkylated naphthalenes and naphthoic acids became available chemoselectively. All reactions afforded a single regioisomer exclusively in high yields. Overall, aromatic dicarboxylic acids are suitable substrates for a two‐step ipso‐substitution that allows the selective synthesis of alkylated benzenes and naphthalenes.

Regioselective Synthesis of Alkylarenes by Two-Step ipso-Substitution of Aromatic Dicarboxylic Acids. -The reaction sequence consists of a Birch reduction/substitution followed by a rearomatization. Depending on the starting material the substitution yields either mono-or disubstituted products or a mixture of both. -(BRAMBORG, A.; LINKER*, T.; Eur.

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