To optimize these fluorescent probes, the electron-donating p-dimethylamino group and electron-accepting
cyano group were introduced to construct a compound with a donor-[pi]-acceptor structure (Figure 1).
The IR spectrum showed a strong absorption band at 1732 [cm.sup.-1] corresponding to lactonic carbonyl group and the disappearance of the
cyano group. Also the structure was confirmed by elemental analysis; 1H-NMR spectrum showed a singlet at [delta] 12.52 ppm of NH, a doublet at [delta] 7.162-7.136 ppm and [delta] 6.84-6.81 ppm of aromatic protons, a singlet at [delta] 4.7 ppm of benzylic proton, and a singlet at [delta] 3.68 ppm of three protons for OC[H.sub.3] group.
The desired transformations were investigated using the conditions reported by Konig [26], by coupling the substrates 1 and 1a with the inorganic
cyano group using CuCN surprisingly, contrary to the results revealed by Konig, a marked improvement in the isolated yields (90 and 85 %) were observed following the 18 and 20 h of irradiation under 7 W fluorescent bulb (Table 2, entries 2, 4).
(23.) Yan, H, Wang, H, Cheng, J, Fang, Z, Wang, H, "Effect of Iron Acetylacetonate on the Crosslink Structure, Thermal and Flammability Properties of Novel Aromatic Diamine-Based Benzoxazines Containing
Cyano Group." RSC Adv., 5 (24) 18538-18545 (2015)
2 showed several characteristic absorption peaks at 2233 and 1651 [cm.sup.-1] attributed to the stretching vibration of
cyano group (C [equivalent to] N) and carbonyl (C=O), respectively, which correlated well with the chemical structure of m-PAEK-CN shown in Fig.
The peak of
Cyano group is visible at [delta] = 119.5.
It has been found that all the compounds were found to be more active against all bacterial strains than ampicillin whereas compounds 6d and 6e substituted with chloro and
cyano group were found to most potent.
Although direct introduction of the methyl group at C24 by opening the 23,24-epoxide was not successful, a
cyano group was introduced specifically at C24 to give 22R,23R-diol (54).
Bromoxynil-degrading enzymes degrade the
cyano group of bromoxynil into a carboxyl group.