Synthesis, X-ray crystal structure and fluorescent spectra of novel pyrazolo[1,5-a]pyrazin-4(5H)-one derivatives

Crystal structure of ethyl 3-(4-methoxyphenyl)-1-(2-(4-methoxyphenyl)-2-oxoethyl)-1H-pyrazole-5-carboxylate, C22H22N2O5

C22H22N2O5, triclinic, P1̅ (no. 2), a = 7.592(2) Å, b = 9.835(3) Å, c = 13.579(4) Å, α = 86.600(3)°, β = 83.755(3)°, γ = 89.549(3)°, V = 1006.1(5) Å3, Z = 2, R gt(F 2) = 0.0495, wR ref(F 2) = 0.1441, T = 273 K.

Synthesis, Crystal Structure, and DFT Study of Ethyl 1-(2-(Hydroxyimino)-2-phenylethyl)-3-phenyl-1H-pyrazole-5-carboxylate

The crystal structure of ethyl 1-(2-(hydroxyimino)-2-phenylethyl)-3-phenyl-1H-pyrazole-5-carboxylate has been determined by X-ray single crystal diffraction. The crystal of the title compound is the monoclinic space group P2/c with unit cell parameters of a=8.634(2) Å, b=9.616(2) Å, c=22.190(3) Å, β=99.2652°, V=1818.3(4) Å3, and Z=4. The dihedral angles formed by the planes of the central pyrazole ring and the adjacent benzene rings are 73.60(7)° and 3.55(7)°, respectively. The combination of the weak intermolecular C-H⋯O and N-H⋯O hydrogen-bonding interactions stabilizes the crystal packing. The geometries of its Z and E isomers and the corresponding transition state (TS), as well as the dimer of its Z isomer, are optimized using the B3LYP hybrid functional coupled with def-TZVP triple-zeta polarized basis set. The bond angles and bond lengths of the optimized structure of Z dimer are very consistent with those of its single crystal parameters. Double-hybrid functional PWPB95-D3 in combination with very highly accurate basis set def2-QZVP is employed to evaluate accurate energy of each isomer and TS. The calculated equilibrium constant between Z and E isomers corresponds to the [Z]/[E] ratio of 4.29. Mulliken atomic charges and electrostatic potential (ESP) on molecular van der Waals (vdW) surface are calculated in order to study and predict the intermolecular interactions. The molecular total energies and frontier orbital analysis are also discussed.

Progress of the synthesis of condensed pyrazole derivatives (from 2010 to mid-2013)

Condensed pyrazole derivatives are important heterocyclic compounds due to their excellent biological activities and have been widely applied in pharmaceutical and agromedical fields. In recent years, numerous condensed pyrazole derivatives have been synthesized and advanced to clinic studies with various biological activities. In this review, we summarized the reported synthesis methods of condensed pyrazole derivatives from 2010 until now. All compounds are divided into three parts according to the rings connected to pyrazole-ring, i.e. [5, 5], [5,F 6], and [5, 7]-condensed pyrazole derivatives. The biological activities and applications in pharmaceutical fields are briefly introduced to offer an orientation for the design and synthesis of condensed pyrazole derivatives with good biological activities.