ABSTRACT: A modern method for the preparation of some new
N-arylthiophene-2-carboxamidines via amidinyl radicals generated
using UV−vis-light promoting the reduction of N-arylthiophene-2-
carboxamidoximes without any catalyst in a short amount of time,
highly straight forward, and in an efficient manner is described.
This method defeats the flaws of the conventional methods for the
reduction of amidoxime derivatives to amidine derivatives, which
require harsh conditions such as using a strong acid, high
temperature, and expensive catalysts. Benzo[d]imidazoles, benzo-
[d]oxazoles, and amides can also be synthesized by applying this
method. The photoproducts were analyzed by various spectroscopic
and analytical techniques, including thin-layer chromatography,
column chromatography, high-performance liquid chromatography, gas chromatography/mass spectrometry, IR, 1H NMR,
13C NMR, and MS. Notably, the chromatographic analyses proved that the best time for the production of N-arylthiophene-2-
carboxamidines is 20 min. The reaction mechanism comprising pathways and intermediates was also suggested via the homolysis of
N−O and C−N bonds.