Formation of lanthanide complexes with bipyridine-functionalized amide compounds and their unusually high amide reactivity

Article abstract of DOI:10.1246/bcsj.72.2729

The amide of 6-benzoylamino-6'-L-phenylalanyl-amino-2,2'-bipyridine (1a) was efficiently cleaved at 30°C to generate L-phenylalanine ester in methanol almost quantitatively. The reaction followed the Michaelis-Menten type via the 1:1 1a-Ln³⁺ complex. The half-life time of the scissile amide bond of the complex was as short as 2 min for the complex. The reactions depended on the structure of the substrates, which require 2,2'-bipyridine with two acylamino side chains at the 6,6'-positions and an amino group at the α-position of the scissile carbonyl. The less reactive 6-6'bis(benzoylamino)-2,2'-bipyridine with lanthanide cations formed 1:1 complexes. The formation constants were on the order of 10³-10⁵ cu dm/mole in methanol at 30°C. Coordination of the bipyridine nitrogens and the carbonyl oxygens was demonstrated in chloroform although coordination of the carbonyl oxygens was not seen in methanol.