LITHIUM MIGRATION IN THE PYRIDINE SERIES - DOUBLE CATALYSIS AND REFORMING - SYNTHESIS OF DERIVATIVES OF 2-BROMO-3-LITHIO-PYRIDINE AND 4-BROMO-2-HALOGENO-3-LITHIO-PYRIDINES

The lithium of an organolithio-pyridinic derivative can be moved from one position to an other by an intermolecular reaction. Two new reactions are possible for pyridinic organic synthesis: the isomerisation of any lithio derivative to a more stable one, and a reaction that transforms a mixture of various bromo-lithio derivatives into a single one. The processes involved and the experimental tools used are described in terms of the 2-bromo-3-lithio- and 4-bromo-2-halogeno-3-lithio-pyridines derivatives synthesis. © 1990.