Notes

Four-Component Activity of Polysubstituted Pyrazin-2(1H)-ones through a Ugi/Staudinger/Aza-Wittig/Isomerization Series.
The new heterometallic complex, aqua-1κO-bis-(μ2-2-imino-methyl-6-meth-oxy-phenolato-1κ2 O 1,O 62κ2 O 1,N)bis-(thio-cyanato-1κN)calcium(II)copper(II), [CaCu(C8H8NO2)2(NCS)2(H2O)], has been synthesized using a one-pot reaction of copper powder, calcium oxide, o-vanillin and ammonium thio-cyanate in methanol under ambient conditions. The Schiff base ligand (C8H9NO2) is generated in situ from the condensation of o-vanillin and ammonia, which is released from the initial NH4SCN. The title compound consists of a discrete binuclear mol-ecule with a Cu(μ-O)2Ca core, in which the Cu⋯Ca distance is 3.4275 (6) Å. The coordination geometries of the four-coordinate copper atom in the [CuN2O2] chromophore and the seven-coordinate calcium atom in the [CaO5N2] chromophore can be described as distorted square planar and penta-gonal bipyramidal, respectively. In the crystal, O-H⋯S hydrogen bonds between the coordinating water mol-ecules and thio-cyanate groups form a supra-molecular chain with a zigzag-shaped calcium skeleton. © Plyuta et al. 2020.In the crystal of the title Schiff base compound, C13H9ClN2O2, [CNBA; systematic name (E)-N-(4-chloro-phen-yl)-1-(4-nitro-phen-yl)methanimine], the CNBA mol-ecule shows whole-mol-ecule disorder (occupancy ratio 0.650.35), with the disorder components related by a twofold rotation about the shorter axis of the mol-ecule. The aromatic rings are inclined to each other by 39.3 (5)° in the major component and by 35.7 (9)° in the minor component. In the crystal, C-H⋯O hydrogen bonds predominate in linking the major components, while weak C-H⋯Cl inter-actions predominate in linking the minor components. The result is the formation of corrugated layers lying parallel to the ac plane. The crystal packing was analysed using Hirshfeld surface analysis and compared with related structures. © Leela et al. 2020.The whole mol-ecule of the cadmium(II) complex, di-iodido-N,N',N'',N'''-[pyrazine-2,3,5,6-tetra-yltetra-kis-(methyl-ene)]tetra-kis-(N-methyl-aniline)-κ3 N 2,N 1,N 6cadmium(II), [CdI2(C36H40N6)], (I), of the ligand N,N',N'',N'''-[pyrazine-2,3,5,6-tetra-yltetra-kis-(methyl-ene)]tetra-kis-(N-methyl-aniline) (L), is generated by a twofold rotation symmetry; the twofold axis bis-ects the cadmium atom and the nitro-gen atoms of the pyrazine ring. The ligand coordinates in a mono-tridentate manner and the cadmium atom has a fivefold CdN3I2 coordination environment with a distorted shape. In the zinc(II) complex, dichloridoN,N',N'',N'''-[pyrazine-2,3,5,6-tetra-yltetra-kis-(methyl-ene)]tetra-kis-(N-methyl-aniline)-κ3 N 2,N 1,N 6zinc(II) di-chloro-methane 0.6-solvate, [ZnCl2(C36H40N6)]·0.6CH2Cl2, (II), ligand L also coordinates in a mono-tridentate manner and the zinc atom has a fivefold ZnN3Cl2 coordination environment with a distorted shape. It crystallized as a partial di-chloro-methane solvate. In the crystal of I, the complex mol-ecules are linked by weak C-H⋯I contacts, forming ribbons propagating along [100]. In the crystal of II, the complex mol-ecules are linked by a series of C-H⋯π inter-actions, forming layers lying parallel to the (11) plane. In the crystals of both compounds there are metal-halide⋯π(pyrazine) contacts present. The Hirshfeld analyses confirm the importance of the C-H⋯halide contacts in the crystal packing of both compounds. © Tesouro Vallina and Stoeckli-Evans 2020.The two new tetra-kis-substituted pyrazines, 1,1',1'',1'''-(pyrazine-2,3,5,6-tetra-yl) tetra-kis-(N,N-di-methyl-methanamine), C16H32N6, (I) and N,N',N'',N'''-[pyrazine-2,3,5,6-tetra-yltetra-kis-(methyl-ene)]tetra-kis-(N-methyl-aniline), C36H40N6, (II), both crystallize with half a mol-ecule in the asymmetric unit; the whole mol-ecules are generated by inversion symmetry. There are weak intra-molecular C-H⋯N hydrogen bonds present in both mol-ecules and in (II) the pendant N-methyl-aniline rings are linked by a C-H⋯π inter-action. The degredation product, N,N'-[(6-phenyl-6,7-di-hydro-5H-pyrrolo-[3,4-b]pyrazine-2,3-di-yl)bis(methyl-ene)]bis-(N-methyl-aniline), C28H29N5, (III), was obtained several times by reacting (II) with different metal salts. Here, the 6-phenyl ring is almost coplanar with the planar pyrrolo-[3,4-b]pyrazine unit (r.m.s. deviation = 0.029 Å), with a dihedral angle of 4.41 (10)° between them. The two N-meth-yl-aniline rings are inclined to the planar pyrrolo-[3,4-b]pyrazine unit by 88.26 (10) and 89.71 (10)°, and to each other by 72.56 (13)°. There are also weak intra-molecular C-H⋯N hydrogen bonds present involving the pyrazine ring and the two N-methyl-aniline groups. In the crystal of (I), there are no significant inter-molecular contacts present, while in (II) mol-ecules are linked by a pair of C-H⋯π inter-actions, forming chains along the c-axis direction. In the crystal of (III), mol-ecules are linked by two pairs of C-H⋯π inter-actions, forming inversion dimers, which in turn are linked by offset π-π inter-actions [inter-centroid distance = 3.8492 (19) Å], forming ribbons along the b-axis direction. © Tesouro Vallina and Stoeckli-Evans 2020.The title compound, C17H18ClNO2, was prepared and isolated as a pure diastereoisomer, using column chromatography followed by a succession of fractional crystallizations. Its exact structure was fully identified via 1H NMR and confirmed by X-ray diffraction. It is built up from a central five-membered di-hydro-isoxazole ring to which a p-chloro-phenyl group and a cyclo-hex-2-enone ring are attached in the 3 and 5 positions. The cyclo-hex-2-one and isoxazoline rings each exhibit an envelope conformation. The crystal packing features C-H⋯O, C-H⋯N and C-H⋯π inter-actions, which generate a three-dimensional network. © Oubella et al. 740 Y-P in vivo 2020.The crystal structures of tris-[9,9-dihexyl-2-(5-meth-oxy-pyridin-2-yl-κN)-9H-fluoren-3-yl-κC 3]iridium pentane monosolvate, [Ir(C31H38NO)3]·C5H12, (I), di-μ2-chlorido-bis-bis-[2-(5-fluoro-pyridin-2-yl)-9,9-dihexyl-9H-fluoren-3-yl]iridium pentane 0.3-solvate, [Ir2(C30H35FN)4Cl2]·0.3C5H12, (II), di-μ2-cyanato-bis-bis-[9,9-dihexyl-2-(5-meth-oxy-pyridin-2-yl)-9H-fluoren-1-yl]iridium pentane monosolvate, [Ir2(C31H38NO)4(NCO)2(NCO)2]·C5H12, (III), and μ-N,N'-bis-[3,5-bis-(tri-fluoro-meth-yl)phen-yl]oxamidatobis(bis2-[4-(2,4,6-trimethylphenyl)pyridin-2-yl]phenyl-κ2 C 1,N'iridium)-chloro-benzene-pentane (1/2.3/0.4), [Ir2(C20H19N)4(C18H6F12N2O2)]·2.3C6H5Cl·0.4C5H12, (IV), synthesized in the quest for organic light-emitting devices, were determined. The bis-μ2-chloro and bis-μ2-cyanato complexes have ΔΔ and ΛΛ configurations of the distorted octa-hedral Ir centres in racemic crystals, whereas the oxamido complex has a centrosymmetric (meso) structure with the ΔΛ configuration. The bridging oxamido moiety has a nearly planar anti geometry.
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