The title compound, (C(6)H(9)N(2))(2)[CuCl(4)], contains a distorted tetra-hedral [CuCl(4)](2-) anion and two protonated amino-pyridinium cations. The geometries of the protonated amino-pyridinium cations reveal amine-imine tautomerism. The crystal packing is influenced by N-H⋯Cl and C-H⋯Cl hydrogen bonds and π-π stacking inter-actions [centroid-centroid distances = 3.635 (4) and 3.642 (4)°].

androstane skeleton with a keto-enol tautomerism at the cyclopentane ring. Wecarried out further isolation for PFTase inhibitors from the cultured broth of strain FO-3929 and found andrastin D (4, Fig. 1). In this paper, fermentation, isolation, structure elucidation, and biological properties of 4 are described. A stock culture of strain FO-3929 was inoculated into six 500-ml Erlenmeyer flasks...

Biologically and pharmaceutically active core structures containing a new class of 4-hydroxy-α-carbolines, dihydropyrido[2,3-b]indoles, pyrimido[4,5-b] and [5,4-b]indoles have been synthesized in good yields via Pd-catalyzed amidation and cyclizations. The keto-enol tautomerism in 4-hydroxy-α-carbolines has been investigated by DFT calculations and spectroscopic techniques. The fluorescence stu...

In this laboratory exercise we will measure the Equilibrium Constant Kc for the keto-enol tautomerism of two -diketones and two -diketoesters. This will be accomplished by measuring the signal strength of key protons in the Nuclear Magnetic Resonance (NMR) spectrum of the equilibrium system. The influence of the solvent on the equilibrium position will be examined by considering the measured ...