The mechanism of the title reaction is found to consist of three steps by DFT calculations: (1) N(2) dissociation, (2) intramolecular Ag-carbene addition, and (3) proton transfer. The N(2) dissociation is turnover determining. The product 3-alkylideneoxindole is favored in tautomerization with 3-acetyl-2-hydroxyindole.

An efficient sensor for Zn(2+) and Cu(2+) was designed based on different binding modes. The sensor displays ratiometric signals for Zn(2+), due to the Zn(2+)-triggered amide tautomerization; while dual-mode selective behaviors for Cu(2+) result from the deprotonation of the amide tautomer.

An efficient palladium-catalyzed asymmetric hydrogenation of fluorinated aromatic pyrazol-5-ols has been developed via capture of the active tautomers. A wide variety of 2,5-disubstituted and 2,4,5-trisubstituted pyrazolidinones have been synthesized with up to 96% and 95% ee, respectively. The hydrogenation pathway includes Brønsted acid promoted tautomerization of pyrazol-5-ols and Pd-catalyz...

A detailed procedure for the quantitative determination of metanephrine and normetanephrine is given. Epinephrine and norepinephrine are eliminated by selective adsorption on an alumina column. Metanephrine and normetanephrine are isolated with a cation-exchange resin. Fluorescence is developed by a two-step ferricyanide oxidation at two different pH values followed by tautomerization. The conc...

A novel luminescent Zn(2+) ions chemosensor, a cyclometalated platinum(II) bipyridyl acetylide complex, was designed. Of particular significance is that it shows a high sensitivity towards Zn(2+) ions without interference from other biologically important cations in acetonitrile. The tautomerization of amide favors detecting Zn(2+) ions among other HTM (heavy and transition metal) ions in aqueo...

The copper-catalyzed ketenimine formation reaction of 1-(o-acetamidophenyl)propargyl alcohols with various sulfonyl azides is found to undergo a concomitant intramolecular nucleophile attack to generate 1,2-dihydro-2-iminoquinolines after aromatization (via elimination of acetyl and hydroxy groups) and tautomerization. The reaction produces 4-substituted and 3,4-unsubstituted title compounds in...

Ir(I)-induced tautomerization of a pyridine moiety to a carbene in 2,3-bipyridyls has been successfully achieved where an amide group plays a key role as a hydrogen-bonding acceptor and the carbene tautomer is stabilized by both chelation effect and by hydrogen-bonding.

A novel one-pot strategy for the synthesis of 3-trifluoromethylquinoxalines from N-aryl enamines and nitromethane was developed. The tandem reaction is achieved through nitrosation of alkenes, tautomerization and cyclization, which can be applicable to a wide range of enamines with excellent functional group tolerance and afford quinoxalines in moderate to good yields.

New Schiff bases derived from 2-aminopyridene and 2-aminopyrazine have been synthesized. The UV-Visible spectra of the compounds have been investigated in acetonitrile and toluene. The compounds were in tautomeric equilibrium (enol-imine O- H...N, keto-amine O...H-N forms) in polar and nonpolar solvents. For some derivatives the keto-amine form was observed in both toluene and acetonitrile. 1H-...

The mol-ecular structure of the title compound, C(8)H(12)N(2)O, indicates that 2-isopropyl-6-methyl-pyrimidin-4-ol (the enol-form) undergoes an enol-to-keto tautomerism during the crystallization process. The pyrimidin-4(3H)-one group is essentially planar, with a maximum deviation of 0.081 (1) Å for the O atom. In the crystal structure, symmetry-related mol-ecules are linked into centrosymmeti...