No abstract

Solid‒state NMR spectra were recorded for 1,3-imidazolidine-2-thione, 1,3-imidazolidine-2-selenone and some of their N-substituted derivatives. Spinning side-bands of thione and selenone carbons were analysed to yield chemical shift anisotropies for these carbons. The NMR spectrum of imidazolidine-2-thione (Imt) showed some evidence for the presence of thiol tautomer. Molecular computations were carried out for Imt and its N-methyl derivative to yield relative energies of various tautomers.

Proton-transfer reactions from the excited state of 1-naphthylamine (RNH 2 ) have been investigated in aqueous solutions of various HClO 4 concentrations. The system is found to contain three species rather than simply the acidic and the neutral form of RNH 2 as previously believed. The new species X, can be clearly detected at [HClO 4 ] g 5 M, in both absorption and emission. X is proposed to be an adduct of RNH 2 and an unhydrated HClO 4 , i.e., X ≡ RNH 2 ---H + ---ClO 4 -. Absorption and fluorescence spectra of X are shown. Quantum yields of the three excited species RNH 2 *, RNH 3 + *, and X* have been found to be 0.49, 0.327, and 0.065, respectively. A kinetic scheme is presented indicating that the proton transfer from RNH 3 + * depends on the availability of free water, i.e., water that can accept protons. All rate constants have been determined. A theoretical model for the hydration of protons shows that as long as there is excess free water an average of 9 water molecules are used for the hydration of one proton.

No abstract

N‐(Anisyl)‐5‐(2‐chloroacetamido)‐4‐cyano‐3‐methylthiophene‐2‐carboxamide (3) was synthesized and reacted with several nucleophilic reagents. The reactions with sulfur nucleophiles (namely, mercaptoacetic acid, ethyl 2‐mercaptoacetate, 5‐(phenylamino)‐1,3,4‐thiadiazole‐2‐thiol, 2‐mercapto‐4,6‐dimethyl‐nicotinonitrile, 4‐anilino‐3‐arylazo‐4‐mercapto‐butenones, ethyl 3‐anilino‐2‐arylazo‐3‐mercapto‐acrylates, and ammonium thiocyanate) yielded the corresponding sulfide, thiophene, or thiazolin‐4‐one derivatives, respectively. The reaction with salicylaldehyde (an example of oxygen nucleophile) furnished the targeting benzofuran compound 21. The reactions with nitrogen nucleophiles (namely, piperidine and aniline) yielded the corresponding thiophene‐carboxamide derivatives 23 and 25, respectively. IR, 1H NMR, and 13C NMR were used to deduce the structures of the target thiophene containing compounds. The effect of the synthesized thiophenes on the viability of HepG2, A2780, and A2780CP was determined. The most effective drug was shown by the thienopyridine‐carboxamide compound 11, against liver cancer cell lines (HepG2) and ovarian cancer cell lines (A2780CP and A2780), whose IC50 values were remarkably near those of Sorafenib, the antitumor drug.