Ever since the idea arose that melatonin might promote sleep and resynchronize
circadian rhythms, many research groups have centered their efforts on obtaining new
melatonin receptor ligands whose pharmacophores include an aliphatic chain of variable
length united to an N-alkylamide and a methoxy group (or a bioisostere), linked to a central
ring. Substitution of the indole ring found in melatonin with a naphthalene or quinoline
ring leads to compounds of similar affinity. The next step in this structural approximation
is to introduce a quinoxaline ring (a bioisostere of the quinoline and naphthalene rings) as
the central nucleus of future melatoninergic ligand
