Fluorescent ligands are imperative to many facets of
chemical biology
and medicinal chemistry. Herein, we report the syntheses of two fluorescent
melatonin-based derivatives as potential ligands of melatonin receptors.
The two compounds, namely, 4-cyano and 4-formyl melatonin (4CN-MLT
and 4CHO-MLT, respectively), which differ from melatonin by only two/three
atoms that are very compact in size, were prepared using the selective
C3-alkylation of indoles withN-acetyl ethanolamines
involving the “borrowing hydrogen” strategy. These compounds
exhibit absorption/emission spectra that are red-shifted from those
of melatonin. Binding studies on two melatonin receptor subtypes showed
that these derivatives have a modest affinity and selectivity ratio.