The synthesis of 5'-methyl-2,2'-bipyridine-6-carboxylic acid is described s
tarting from the pivotal 5'-methyl-6-bromo-2,2'-bipyridine building block.
Functionalisation of the latest at the 5'-methyl position gives access to t
he 5'-bromomethyl, 5'-hydroxymethyl and 5'-aminomethyl derivatives. Upon nu
cleophilic substitution, the hydroxy and amino derivatives react with the 5
'-bromomethyl compound to give quasi-linear and podand type intermediates.
Thanks to a carboalkoxylation reaction at the 6-bromo position of the diffe
rent intermediates, followed by a saponification reaction, mono-, bis- and
tris-tridentate ligands are obtained, which are particularly well suited fo
r the complexation of lanthanide(III) cations. (C) 2001 Elsevier Science Lt
d. All rights reserved.