نتایج جستجو برای: tautomer
تعداد نتایج: 566 فیلتر نتایج به سال:
We have measured the IR and UV spectra of cytosine in a low-temperature argon matrix. An attempt was made to determine the tautomeric ratios existing in the matrix, making use of the matrix-isolation IR spectrum and computed IR intensities of the tautomers in a least squares fitting procedure. The mole fractions are about 0.22 for oxo(-amino) form, 0.26 and 0.44 for the two rotamers, respective...
The mol-ecule of the title compound, C(4)H(7)N(3)S, exists as the thione tautomer in the solid state. The asymmetric unit consits of one mol-ecule in which all atoms are located on a crystallographic mirror plane. In the crystal, adjacent mol-ecules are linked by N-H⋯N and N-H⋯S hydrogen bonds into chains running along the a axis. π-π stacking inter-actions between the triazole rings [centroid-...
Simultaneous control of the kinetics and thermodynamics of two different types of covalent chemistry allows pathway selectivity in the formation of hydrogelating molecules from a complex reaction network. This can lead to a range of hydrogel materials with vastly different properties, starting from a set of simple starting compounds and reaction conditions. Chemical reaction between a trialdehy...
The tautomerism of 2'-deoxy-7-deaza-isoguanosine (2) was studied and compared to that of 2'-deoxyisoguanosine (1). The fixed (1)N-methyl (8) and O-methyl (4) derivatives were synthesized to represent the pure extremes of each tautomer. The replacement of the imidazole ring in 1 with a pyrrole ring in 2 makes the keto form in the latter more favored by 2 orders of magnitude (K(TAUT) for 2 approx...
In the title compound, C(21)H(21)N(3)O(2), an intra-molecular N-H⋯O inter-action generates an S(6) ring, which stablizes the enamine-keto tautomer. The S(6) ring makes dihedral angles of 33.07 (7), 56.50 (8) and 38.59 (8)°, respectively, with the benzoyl-acetone benzene ring and the anti-pyrine pyrazole and benzene rings.
The density functionals B3LYP, B3PW91, M062X, and CAM-B3LYP with the 6-311+G(d,p) basis set predict the cysteine sulfenic acid O-sulfenylation of the s-cis-ketoenol tautomer of 1,3-cyclohexanedione proceeds through a cyclic 14-membered transition state structure containing three water molecules.
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...
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