Synthesis of 2-Alkylbenzoic Acids: Alkyllithium Additions to 2-Vinylbenzoic Acid

Recently there has been an increasing interest in the chemistry of nucleophilic additions to styrene and its derivatives {1-6}. Although there were some early reports on the addition of nucleophiles to styrene without leading to polymerization, the synthetic application of this reaction was not exploited until our group started new studies on its chemistry{1}. Now that the synthetic viability of these additions has been established, it is of great interest to study the scope of the reaction. Here we present our studies on the addition of alkyllithiums to 2-vinylbenzoic acid (1). In an earlier report {4} of the reaction of 1 with BuLi, the expected product was obtained only in a 19% yield. As the authors did not mention any reason for the low yield we decided to study this addition to see if there was any incompatibility between the carboxylic acid group and the alkyllithium. There could be a competition between the reaction of addition to carboxylate to give a ketone and the addition to the exocyclic double bond.