Quaternization at the picolinic carbon. Application to the synthesis of pyridylalkanecarboxylic acids

The paper describes two different methodologies for the construction of a q uaternary center at the picolinic site, and their application to the synthe sis of pyridylalkanecarboxylic acids. The first one involves a one-pot acet ylation-Michael addition procedure followed by an alkylative quaternization of the picolinic carbon. The second one is based on the deprotonation at t he picolinic carbon of 2-(alpha,alpha-dialkyl)pyridines using the superbasi c mixture BuLi-diisopropylamine-(BuOK)-O-t ("KDA"). Both routes give very g ood yields.