ORTHO-SELECTIVE ALKENE ALKYLATION OF ARYLAMINES VIA ACID CATALYSIS

Acid catalysis provides a general synthesis methodology for introducing alkene alkylating agents selectively to the ortho positions of arylamines. In contrast to aluminum alkyl catalyzed olefin ortho-alkylation of arylamines, this reaction proceeds through a positively charged intermediate and is especially useful for placing branched alkyl groups ortho to amino functionality. Lewis and Brønsted acids both provide high ortho-selectivity with solid acids providing the highest selectivity and ease of use. Reaction rates increase with increasing acid strength. The ortho-selectivity of this technique is enhanced by operating at temperatures and residence times which minimize Nalkylates and para-alkylates. Reaction selectivity is also influenced by substituents on the arylamine and alkene reactants. © 1990.