Shizheng Zhu

Single-crystal-to-single-crystal transformation in a one-dimensional Ag-Eu helical system.

Single-crystal-to-single-crystal transformation of one-dimensional 4d-4f coordination polymers has been investigated for the first time. More importantly, we observed the transformation of a meso-helical chain to a rac-helical chain as a function of the temperature.

Novel and Efficient Synthesis of Water‐Soluble [60]Fullerenol by Solvent‐Free Reaction

Abstract Water‐soluble fullerenol was conveniently synthesized via the direct solvent‐free reaction of fullerene with a mixture of H2O2 and NaOH under grinding conditions in air at room temperature. This practical method provides a novel and efficient access to water‐soluble fullerenol in excellent yield.

Efficient synthesis of 5-fluoroalkylated 1H-1,2,3-triazoles and application of the bromodifluoromethylated triazole to the synthesis of novel bicyclic gem-difluorinated 1H-pyrano[3,4-d][1,2,3]-triazol-4-one compounds

Abstract A series of 5-fluoroalkylated 1 H -1,2,3-triazoles were synthesized in good yield by the regiospecific 1,3-dipolar cycloaddition reaction of ( Z )-ethyl 3-fluoroalkyl-3-pyrrolidino-acrylates with aryl or benzyl azides. In the cases of benzyl azides, addition of Na 2 CO 3 was crucial for a high yield of the triazoles. Tetrakis(dimethylamino)ethylene (TDAE) promoted reaction of bromodifluoro-methylated triazole with aldehydes affording a new class of β,β-difluoro-β-triazolyl alcohol derivatives, which were lactonized with catalytic amount of p -toluenesulfonic acid in toluene at 80–90°C to give a series of novel bicyclic gem -difluorinated 1 H -pyrano[3,4- d ][1,2,3]-triazol-4-one compounds in good yield.

Enantioselective synthesis of functionalized fluorinated cyclohexenones via robinson annulation catalyzed by primary-secondary diamines.

Primary-secondary diamine catalysts were used to catalyze the asymmetric Robinson annulation to synthesize multiply substituted fluorinated chiral cyclohexenones with two contiguous stereogenic centers, one of which is a fluorinated quaternary chiral center, with excellent enantioselectivities and diastereoselectivities in moderate to good yields.

Regioselective synthesis of fluorinated pyrazole derivatives from trifluoromethyl-1,3-diketone

Abstract 1,1,1-Trifluoropentane-2,4-dione (1a) and 1-(thien-2-yl)-4,4,4-trifluorobutane-1,3-dione (1b) reacted readily with per(poly)fluorophenylhydrazines ArfNHNH2 (Arf: C6F5, HC6F4, ClC6F4) to give N-per(poly)fluorophenyl-5-methyl(or thien-2-yl)-3-trifluoromethylpyrazoles 3 and 3-methyl (or thien-2-yl)-5-hydroxy-5-trifluoromethyl-4,5-dihydropyrazoles 4, respectively. Treatment of 4 with P2O5 yielded the dehydrated product N-per(poly)fluorophenyl-3-methyl(or thien-2-yl)-5-trifluoromethyl-pyrazole in good yield.

Synthesis of fluorinated pyrazole derivatives from β-alkoxyvinyl trifluoroketones

Abstract 1,1,1-Trifluoro-4-ethoxy-3-butene-2-one, 3-trifluoroacetyl-3, 4-dihydro-2H-pyran or furan reacted readily with pentafluorophenylhydrazine or per(poly)fluoroacectylhydrazine R f CONHNH 2 (R f : BrCF 2 , C 3 F 7 ) to give N -substituted-5-hydroxy-5-trifluoromethyl heterocycles Y  N  N  CH  CH ( R ) C ( OH ) CF 3 (Y: H, Ar f or R f CO), which were dehydrated by treatment with P 2 O 5 or SOCl 2 to form N -substituted 5-trifluoromethyl pyrazoles Y  N  N  CH  C ( R ) C CF 3 (Y: H, Ar f or R f CO) in good yields. Download full-size image

Temperature- and solvent-controlled dimensionality in a zinc 6-(1H-benzoimidazol-2-yl)pyridinecarboxylate system

Several 0D, 1D, and 3D metal–organic hybrid frameworks of ZnII have been synthesized by using the asymmetric ligand 6-(1H-benzoimidazol-2-yl)pyridinecarboxylic acid (HL) with control of the temperature and solvent in a solvothermal synthesis technique. In DMF, the structure at room temperature confirms that the resulting compound Zn(L)2·2(H2O) (1) is the 0D mononuclear structure, above ∼80 °C, C–N bond cleavage of partial DMF molecules induces the formation of the 1D chain-like compound {[Zn(L)(HCOO)]·2(H2O)}n (2), but on warming up to 120 and 160 °C, due to the decomposition of a large number of DMF molecules, the same reaction, respectively, gives two 3D metal–organic coordination polymers with 3D channels reported previously {[Zn(HCOO)3]−·[H2N(CH3)2]+}n (3) and [Zn(HCOO)2]n (4), in which the 3D channels of 3 contain guest [H2N(CH3)2]+ motifs, while at high temperature the 3D channels of 4 are an open stable system without any guest molecules. Replacing DMF in the above reaction by ethanol or acetonitrile, only 0D compound 1 is obtained in the range from room temperature to 160 °C. However, the same reaction in DMSO provides a 1D wave-like compound {[Zn(L)(DMSO)]·(ClO4)·H2O}n (5), in which the solvent DMSO molecule coordinates to the central metal ZnII ion. Furthermore, in three new complexes 1, 2 and 5, through π⋯π stacking and hydrogen bonding interactions, 3D supramolecular networks are assembled. It is worth noting that the existence of the twelve-membered cyclic water–perchlorate dimers [(ClO4)⋯(H2O)]22− with chair-conformation in the solid state of 5 not only increases the stability of the supramolecular structure, but also results in a stronger fluorescence signal compared with ligand HL, 1 and 2.

Highly enantio- and diastereoselective synthesis of α-trifluoromethyldihydropyrans using a novel bifunctional piperazine-thiourea catalyst

The first enantioselective Michael addition of alpha-cyanoketones to alpha,beta-unsaturated trifluoromethyl ketones using a novel piperazine-thiourea catalyst was described. The resulting alpha-trifluoromethyldihydropyrans were obtained in high yields and with up to 95% ee within a short reaction time. A useful transformation of the chiral adduct was also illustrated.

Fluorine-containing donor-acceptor complexes: crystallographic study of the interactions between electronegative atoms (N, O, S) and halogen atoms (I, Br)

On the basis of our results, which concern sp3N⋯Br–Rf [Rf=per(poly)fluoroalkyl], sp3O⋯I–Rf, sp2O⋯I–Rf, sp3N⋯I–Rf, sp2N⋯I–Rf and interactions of sp2N⋯I–Rf with different substituents, a brief profile of the interactions between electronegative atoms (N, O, S) and halogen atoms (I, Br) of fluorine-containing alkylates is determined. The first example of an aliphatic fluorine-containing donor-acceptor supramolecule that is based on the N⋯Br–Rf interaction is reported in this paper. Our X-ray structure shows that 1,2-dibromotetrafluoroethane and 1,4-dimethylpiperazine alternately form endless chains depending on the N⋯Br–Rf interactions. The distance between Br and N is 2.864(3) A, which is considerably longer than the average covalent bond between N and Br, but it is also definitively shorter than the sum of the corresponding van der Waals radii of N and Br. From two other crystals, we successfully obtained precise data on the sp3O⋯X–Rf and sp2O⋯X–Rf interactions. Furthermore, an investigation of the substituent group effect is presented. We also report a valuable method to recrystallize and collect X-ray data of co-crystals that are easily disordered.

1,3-Dipolar cycloaddition of β-alkoxyvinyl trifluoromethylketones with aryl (or benzyl) azides: Synthesis of 4-trifluoroacetylated 1H-1,2,3-triazoles

The 1,3-dipolar cycloaddition of aryl (or benzyl)azides with 1,1,1-trifluoro-4-ethoxy-3-butene-2-one proceeded smoothly by heating without solvent. 1-Aryl(or benzyl)-4-trifluoroacetyl-1H-1,2,3-triazoles were formed regiospecifically in good yield. These compounds were readily hydrated when exposed to air. In contrast, the reaction of benzyl azide with 4-trifluoroacety-2,3-dihydrofuran only gave minor amounts of 4-trifluroacetyl-5-benzylamino-2,3-dihydrofuran in addition to an inseparable mixture of other products. 5-Trifluoroacetyl-3, 4-dihydro-2H-pyran was inert towards benzyl azide under the same conditions.Abstract The 1,3-dipolar cycloaddition of aryl (or benzyl) azides with 1,1,1-trifluoro-4-ethoxy-3-butene-2-one proceeded smoothly by heating without solvent. 1-Aryl (or benzyl)-4-trifluoroacetyl-1 H -1,2,3-triazoles were formed regiospecifically in good yield. These compounds were readily hydrated when exposed to air. In contrast, the reaction of benzyl azide with 4-trifluoroacetyl-2,3-dihydrofuran only gave minor amounts of 4-trifluoroacetyl-5-benzylamino-2,3-dihydrofuran in addition to an inseparable mixture of other products. 5-Trifluoroacetyl-3,4-dihydro-2 H -pyran was inert towards benzyl azide under the same conditions.