Synthesis, Crystal Structure and Biological Activity of Diethyl 1,4-dihydro-2,6-dimethyl-4-(4-methyl-1,2,3-thiadi azol-5-yl)pyridine-3,5-dicarboxylate

The title compound diethyl 1,4-dihydro-2,6-dimethyl-4-（4-methyl-1,2,3-thiadiazol- 5-yl） pyridine-3,5-dicarboxylate （C16H21N3O4S, Mr = 351.42） was prepared by the Hantszch reaction with 4-methyl-1,2,3-thiadiazole-5-formaldehyde, ethyl acetoacetate and ammonium acetate in the presence of aluminum chloride in alcohol, and its structure was characterized by IR spectra, 1H-NMR, EA, and single-crystal X-ray diffraction. The crystal of the title compound belongs to monoclinic system, space group P21/n with α= 11.300（2）, b = 12.771（3）, c = 12.826（3） ？, β = 96.55（3）o, V = 1839.0（6） ？3, Z = 4, Dc = 1.296 g/cm3, μ（MoKa） = 0.71073 mm-1, F（000） = 744, R = 0.0981 and wR = 0.1994. X-ray diffraction result shows that the torsion angles of N（1）–C（2）– C（3）–C（4） and C（2）–C（3）–C（4）–C（8） are 178.9（3）° and –130.3（3）°, respectively. All rings in the title compound are non-planar. The bioassay results indicate that the title compound has good fungicidal activity, good antivirus activity against tobacco mosaic virus and certain extent of insecticidal activity against Mythimna separata.

Synthesis and Crystal Structure of Tetraethyl syn-1,5,8,8bβ-Tetrahydrocyclobuta[1,2-b:3,4-b']dipydine-3,4aβ,7,8aβ(4H,4bβH)-tetracarboxylate

The synthesis of syn-photodimer from 1,4-dihydropyridine without 4-aryl was studied, and its single crystal was obtained （C22H30N2O8, Mr= 450.48）. It crystallizes in monoclinic, space group P21/c with a = 11.937（2）, b = 20.913（4）, c = 9.763（2） A,β = 108.46（3）°, V= 2311.9（8） ,A^3, Z= 4, Dc = 1.294 g/cm^3,/7（000） = 960,μ = 0.099 mm^- 1, R = 0.0640 and wR = 0.1464 for 4077 unique reflections with 1598 observed ones （I 〉 2σ（I）. It is shown that the whole molecular structure of the title compound is a twist-boat conformation, and the two double bonds have a trend of potential intramolecular reaction under high-energy irradiation.

Crystal Structure and Bovine Serum Albumin Binding Studies of Methyl 4-(2,4-Dichlorophenyl)-2,7,7-trimethyl-5-oxo-1,4,5,6,7,8-hexahydroquinoline-3-carboxylate

The title compound, methyl 4-(2,4-dichlorophenyl)-2,7,7-trimethyl-5-oxo-1,4,5,6,7,8-hexahydroquinoline-3-carboxylate(C_(20) H_(21)Cl_2NO_3, 1) was synthesized and the crystal structure was —determined by single-crystal X-ray diffraction. It crystallizes in tetragonal system, space group P421 c with a = 16.076(3), b = 16.076(3), c = 14.750(2) ?, V = 3811.8(14) ?3, Z = 8, R = 0.0377 and wR = 0.0845. The interactions between compound 1 and bovine serum albumin(BSA) were investigated using fluorescence spectroscopy. The results revealed that compound 1 can effectively quench the intrinsic fluorescence of BSA by static quenching mechanism. The thermodynamic parameters revealed that the action forces between compound 1 and BSA were mainly van der Waals forces and hydrogen bonds. According to F?rster's non-radioactive energy transfer theory, the binding distance between compound 1 and BSA had been determined. Furthermore, the synchronous fluorescence showed that compound 1 has few effects on the microenvironment and conformation of BSA in the binding process.