Reaction of Selenoamide Dianions with Thio- and Selenoformamides Leading to the Formation of 5‑Aminoselenazoles: Photophysical and Electrochemical Properties

5-Amino-2-selenazolines
were synthesized by reacting selenoamide
dianions generated from secondary selenoamides and BuLi with tertiary
thio- and selenoformamides followed by treatment with iodine. The
resulting 5-amino-2-selenazolines were further oxidized with iodine
to give 5-aminoselenazoles in moderate to good yields. The general
tendencies in the 77Se NMR spectra of the starting selenoamides,
5-amino-2-selenazolines, and 5-aminoselenazoles were determined. The
chemical shifts of these compounds were highly influenced by the skeletons
involving the selenium atom as well as the substituents on the carbon
atoms of each skeleton. The molecular structures of 5-aminoselenazoles
were clarified by X-ray analyses, and their electronic structures
were elucidated by DFT calculations. Finally, UV–vis and fluorescence
spectroscopy and cyclic voltammetry (CV) of 5-aminoselenazoles were
performed, and their properties are discussed in relation to the substituents
on the selenazole rings.