scholarly journals Nucleoside macrocycles formed by intramolecular click reaction: efficient cyclization of pyrimidine nucleosides decorated with 5'-azido residues and 5-octadiynyl side chains

2018 ◽  
Vol 14 ◽  
pp. 2404-2410 ◽  
Author(s):  
Jiang Liu ◽  
Peter Leonard ◽  
Sebastian L Müller ◽  
Constantin Daniliuc ◽  
Frank Seela
Keyword(s):  
Click Reaction ◽  
Coupling Constants ◽  
Protecting Groups ◽  
Side Chains ◽  
X Ray ◽  
Pyrimidine Nucleosides ◽  
H Nmr ◽  
High Yields ◽  
Very High ◽  
Sugar Conformation

Copper(I)-promoted "click" cyclization in the presence of TBTA afforded nucleoside macrocycles in very high yields (≈70%) without using protecting groups. To this end, dU and dC derivatives functionalized at the 5-position of the nucleobase with octadiynyl side chains and with azido groups at the 5’-position of the sugar moieties were synthesized. The macrocycles display freely accessible Watson–Crick recognition sites. The conformation of the 16-membered macrocycle was deduced from X-ray analysis and 1H,1H-NMR coupling constants. The sugar conformation (N vs S) was different in solution as compared to the solid state.

Propargyl-, Allenyl- und Alkinyl-Phosphane; Synthese, Reaktivität, Isomerisierung/ Propargyl-, Allenyl- and Alkynyl-Phosphanes; Synthesis, Reactivity, Isomerization

1993 ◽  
Vol 48 (1) ◽  
pp. 27-36 ◽  
Author(s):  
Heinrich Lang ◽  
Uwe Lay ◽  
Michael Leise ◽  
Laszlo Zsolnai
Keyword(s):  
Spectroscopic Data ◽  
X Ray ◽  
H Nmr ◽  
High Yields

The synthesis and reactivity of non-coordinated and coordinated propargyl phosphanes are discussed. The isomerization of the propargyl unit in (R)P(Cl)(CH2C ≡ CH ) (3) (R = 2,4,6-tBu3-C6H2O) in the presence of NEt3 yields the allenyl substituted p roduct (R)P(Cl)(CH = C = CH2) (4). However, in the presence of HNEt2 the dimethylenecyclobutane 7 is formed.Different synthetic pathways for the preparation of LnMP(Ph)m(CH2C ≡ CH)3-m complexes (m = 2: LnM = (η5-C5H5)(CO)2Mn: 10a; LnM = (CO)5Cr: 10b; m = 1: LnM = (η5-C5H5)(CO)2Mn: 13a; LnM = (η5-C 5H4Me)(CO)2Mn: 13b) are described. The synthesis o f the alkynyl substituted phosphane compounds LnMP(Ph)m(C ≡ CR )3-m (m = 2: R = Ph, LnM = (η5-C5H5)(C O )2Mn: 20a; LnM = (CO )5 Cr: 20b; R nBu, LnM = (CO)5 Cr: 20c; m = 1: R = Ph, LnM = (η5-C5H5)(CO)2Mn: 22) was also possible. The reaction of (η5-C5H4Me)(CO)2,MnPPh (CH2C ≡CH)2 (13 b) with Co2(CO)8 affords in high yields (η5-C5H4Me)(CO)2MnPPh[(η2 -CH2C ≡ CH )Co2(CO )6]2 (15).All new com pounds have been characterized by analytical and spectroscopic data (IR , 1H -, 13C {1H }-, 31P { 1H } -NMR , MS) and (η5-C5H5)(CO)2MnP(Ph)(CH2C ≡ CH)2 (13a) by X -ray analysis.

Preparation of HA Hydrogel by Click Chemistry

2015 ◽  
Vol 1088 ◽  
pp. 286-289
Author(s):  
Yuan Cui ◽  
Jing Peng Zhang ◽  
Wei Zhang ◽  
Qian Duan
Keyword(s):  
Hyaluronic Acid ◽  
Click Chemistry ◽  
Molecular Design ◽  
Click Reaction ◽  
Side Chains ◽  
H Nmr ◽  
Hydrogel Formation

"Click chemistry" was used in this paper to get a novel hyaluronic acid (HA) hydrogel by modified HA molecules' side chains with azide and alkynyl groups to perform "Click" reaction. The HA hydrogel can be achieved "in situ" injection gel. The properties of the HA hydrogel can be controlled by controlling the amount of alkynyl and azide groups on side chains to achieve controllable HA hydrogel by HA molecular design. The reactant, product and hydrogel were characterized by 1H NMR, FTIR and morphology observation to determine the processes of reaction and can hydrogel formation.

Addition of the nitroxyl radical TEMPO to 1-naphthylketene: formation of an unusual adduct

1999 ◽  
Vol 77 (5-6) ◽  
pp. 806-809 ◽  
Author(s):  
Jennifer Carter ◽  
Michael H Fenwick ◽  
Wen-wei Huang ◽  
Vladimir V Popik ◽  
Thomas T Tidwell
Keyword(s):  
Nitroxyl Radical ◽  
Chemical Shifts ◽  
Wolff Rearrangement ◽  
Nmr Spectrum ◽  
X Ray ◽  
H Nmr ◽  
Naphthyl Ring ◽  
Nmr Signals ◽  
Very High

1-Naphthylketene (2), generated by thermal Wolff-rearrangement, is trapped in situ by 2,2,6,6-tetramethylpiridinyloxy radical (TEMPO, TO·) to form the adduct 1-naphthCH(OT)CO2T (4), whose structure is confirmed by an X-ray determination. The 1H NMR spectrum of 4 displays three CH3 groups with very high field chemical shifts (δ 0.10-0.47), and this is attributed to the location of these groups in the shielding region above the π system of the naphthyl ring. At -40°C, doubling of most of the 1H NMR signals occurs, and this is attributed to a freezing out of two conformations differing by rotation around the naphthyl—CH bond.Key words: ketene, TEMPO, restricted rotation, 1H NMR, conformational analysis, free radicals.

Synthesis and Crystal Structure of (1E,2E)-1,2-Di (-3-Nitrobenzylidene) Hydrazine under Micromave Irradiation

2013 ◽  
Vol 787 ◽  
pp. 205-207
Author(s):  
Hong Yan Zhou
Keyword(s):  
Crystal Structure ◽  
Microwave Irradiation ◽  
Monoclinic Space Group ◽  
Stacking Interactions ◽  
X Ray Diffraction ◽  
Synthesis And Crystal Structure ◽  
X Ray ◽  
H Nmr ◽  
The Stability ◽  
High Yields

A compound of (1E,2E)-1,2-di (-3-nitrobenzylidene) hydrazine was synthesized under microwave irradiation (500 w), giving high yields of products (93%). Its structure was determined IR, 1H NMR, MS, elemental analysis and X-ray diffraction. The crystal of the compound is Monoclinic, space group P2(1)/n with a = 6.9611(18), b = 7.823(2), c = 12.999(3) Å, α = 90, β = 105.215(4), γ = 90o, V= 683.1(3) Å3, Z=4, Dc=1.450g/cm3,μ=0.110 mm-1, F(000)=308, R=0.0401 and wR = 0.1131 for 1273 observed reflection with I>2σ (I). π-π stacking interactions contribute to the stability of the structure.

scholarly journals Synthesis of Novel Azo-Linked 5-Amino-Pyrazole-4-Carbonitrile Derivatives Using Tannic Acid–Functionalized Silica-Coated Fe3O4 Nanoparticles as a Novel, Green, and Magnetically Separable Catalyst

2021 ◽  
Vol 9 ◽  
Author(s):  
Farhad Sedighi Pashaki ◽  
Mohammad Nikpassand
Keyword(s):  
Electron Microscope ◽  
Tannic Acid ◽  
Reaction Times ◽  
X Ray ◽  
H Nmr ◽  
Transmission Electron ◽  
Magnetically Separable Catalyst ◽  
Elemental Analyses ◽  
Ft Ir ◽  
High Yields

Tannic acid–linked silica-coated Fe3O4 nanoparticles (Fe3O4@SiO2@Tannic acid) were prepared and characterized by transmission electron microscope (TEM), field emission scanning electron microscope (FE-SEM), X-ray powder diffraction (XRD), X-ray spectroscopy (EDX), vibrating sample magnetometry (VSM), and Fourier transform infrared (FT-IR) spectroscopy. Fe3O4@SiO2@Tannic acid supplies an environmentally friendly procedure for the synthesis of some novel 5-amino-pyrazole-4-carbonitriles through the three-component mechanochemical reactions of synthetized azo-linked aldehydes, malononitrile, and phenylhydrazine or p-tolylhydrazine. These compounds were produced in high yields and at short reaction times. The catalyst could be easily recovered and reused for six cycles with almost consistent activity. The structures of the synthesized 5-amino-pyrazole-4-carbonitrile compounds were confirmed by 1H NMR, 13C NMR, and FTIR spectra, and elemental analyses.

Spectroscopic conformational study of PMS 952, a specific imidazoline ligand. Experimental results

1999 ◽  
Vol 77 (12) ◽  
pp. 2015-2024 ◽  
Author(s):  
Marie-Hélène Baron ◽  
Sabine Halut-Desportes ◽  
Hai-Fen Ye ◽  
Jack Huet ◽  
Edith Favre
Keyword(s):  
Hydrogen Bonds ◽  
Tautomeric Form ◽  
Proton Donor ◽  
Coupling Constants ◽  
X Ray ◽  
H Nmr ◽  
Ftir Studies ◽  
Nmr Study ◽  
Imidazoline Ring ◽  
Imidazoline Derivative

X-ray analysis of PMS 952 displays two kinds of very strong hydrogen bonds, an intramolecular one stabilizing the conformer A and an intermolecular one that associates conformers A to form two infinite chains. The 1H NMR study of vicinal coupling constants based on dihedral angle values, evidences that PMS 952 takes up an eclipsed conformation, in CCl4 and CDCl3 solutions, closely related to the conformation in solid state. Deuterium exchange in methanol-d4 points out the presence of a tautomeric form. However, as there is spectral evidence neither from NMR nor from FTIR studies for such a tautomer, this specie cannot be taken into account to explain the complexity of the FTIR spectra. NMR data also reveal that the imidazoline ring freely rotates while FTIR analysis allows characterizing two conformers (A and B), with lifetime shorter than NMR time scale. These two conformers are stabilized by two different intramolecular H-bonds. Taking into account that conformer A could exist in two states (monomer A and (A)n-chains), an equilibrium between A, (A)n, and B entities allowed the assignment of all main bands of the IR spectra, assigned to vNH, vOH, vCH, and vCN modes. The strength of hydrogen bonds is solvent dependent. Polar solvents, either proton donor or acceptor stabilized the conformer A, while CCl4 favors the conformer B.Key words: hydrogen bonds, X-ray, NMR, FTIR, imidazoline derivative.

scholarly journals Lineare Oligophosphaalkane, XX [1]: Alkalimetall-und Trimethylsilylderivate PH-funktioneller Methylenbisphosphane / Linear Oligophosphaalkanes, XX [1]: Alkali Metal and Trimethylsilyl Derivatives of PH-Functional Methylenebisphosphanes

1988 ◽  
Vol 43 (1) ◽  
pp. 31-44 ◽  
Author(s):  
Franjo Gol ◽  
Gerd Hasselkuß ◽  
Peter C. Knüppel ◽  
Othmar Stelzer
Keyword(s):  
Conformational Changes ◽  
Coupling Constants ◽  
Protecting Groups ◽  
Temperature Dependent ◽  
Nmr Spectrum ◽  
H Nmr ◽  
Trimethylsilyl Derivatives ◽  
First Time ◽  
Derivatives Of ◽  
Association Equilibrium

Abstract The synthesis of the trimethylsilyl derivatives of the PH-functional methylenebisphosphanes, R2-n(Me3 Si)nP-CH2 -PR(SiMe3) (R = Me, iPr, tBu, Ph, 2.4.6-Me3C6H2 ; n = 0.1) is reported. In the Li-phosphides R2-nLinP - CH2 - PLiR used as reactive intermediates, a monomer-oligomer association equilibrium causes a rapid Li-exchange as indicated by the solvent and temperature dependent 31P{1H} and 7Li NMR spectrum of (iPr)2 P-CH2 -P(iPr)Li in various solvents (Et2O, THF and MTHF) in the temperature range from 30 to -110 °C. For the syntheses of the Me-and Ph-substituted PH-functional methylenebisphosphanes R2P-CH2 -PRH and RHP-CH2 -PRH (R = Me, Ph) the chlorophosphane CKP -CH2 -PCl2 is used as a starting material. Bifunctional substituents (Ph -N̍-N̍ -Ph and Me -N̍-CO-N̍-Me) are employed for the first time as protecting groups to block one or two PCl-functions in Cl2P-CH2-PCI2,. Cleavage of the PN-bonds in the five membered ring systems (R = Me, Ph) with HCl affords the P-substituted methylenebis-chlorophosphanes RClP-CH2 - PClR in satisfactory yields. The compounds have been characterized by 1H, 13 C{1H} and 31P{1H} NMR spectroscopy. With-in homologous substitution series of methylenebisphosphanes, e.g. R2P-CH2-PR2-nHnthe coupling constants 2J(PP) seem to reflect conformational changes at the PCP-skeleton.

Chemie polyfunktioneller Liganden, 53 [1] Über methyl-substituierte Triarsa-trioxa-, Triarsa-trithiaund Triarsa-triaza-adamantane und über den stark aufgeweiteten Adamantan-Käfig im Schwefel-Derivat / Chemistry of Polyfunctional Ligands, 53 [1] About Methyl-substituted Triarsa-trioxa-, Triarsa-trithia- and Triarsa-triaza-adamantanes and about the Strongly Spread Adamantane Cage in the Sulfur Derivative

1979 ◽  
Vol 34 (7) ◽  
pp. 975-982 ◽  
Author(s):  
Jochen Ellermann ◽  
Martin Lietz ◽  
Peter Merbach ◽  
Gerhard Thiele ◽  
Gerd Zoubek
Keyword(s):  
Adamantane Derivatives ◽  
Pharmacological Properties ◽  
X Ray Diffraction ◽  
Cage Structure ◽  
Methylene Carbon ◽  
Cage Compounds ◽  
X Ray ◽  
H Nmr ◽  
Closest Packing ◽  
High Yields

Abstract The reaction of l,l,l-tris(diiodarsinomethyl)ethane, CH3C(CH2Asl2)3 (1), with H2O, H2S and CH3NH2 in THF gives the adamantane cage compounds CH3C(CH2ASO)3 (4), CH3C(CH2ASS)3 (5) and CH3C(CH2ASNCH3)3 (6) in high yields. The crystal structure of 5 has been determinated by X-ray diffraction. The unit cell (space group P2i/w) contains 4 isolated molecules in a cubic closest packing. The heteroadamantane 5 has an enlarged cage structure with extremely spread C-C(H2)-As bond angles of 124° at the methylene carbon atoms. Some pharmacological properties of the adamantane derivatives 4 and 5 have been studied. All compounds have been characterized by mass spectrometry and infrared, Raman and X H NMR spectroscopy.

Fused heterocycles derived from pseudoephedrine and ephedrine

1992 ◽  
Vol 70 (11) ◽  
pp. 2764-2770 ◽  
Author(s):  
Norberto Farfán ◽  
Rosa L. Santillan ◽  
Dolores Castillo ◽  
Reyna Cruz ◽  
Pedro Joseph-Nathan ◽  
...  
Keyword(s):  
Coupling Constants ◽  
X Ray Diffraction ◽  
X Ray ◽  
H Nmr ◽  
Magnetic Resonance Data ◽  
Fused Heterocycles ◽  
Resonance Data ◽  
Crude Reaction Mixture ◽  
New Compounds ◽  
C Nmr

The formation of heterobicycles by condensation of (1R, 2R)-(−)-pseudoephedrine or (1R, 2S)-(−)-ephedrine with glyoxal is reported. In the case of pseudoephedrine, the nuclear magnetic resonance data of the crude reaction mixture indicate the presence of three isomeric compounds (5, 6, and 7), which were separated by fractional crystallization, while ephedrine afforded the oxazino-oxazine 8 and the known (5S*,6R*)-4,5-dimethyl-6-phenyl-1,4-oxazin-2-one (9). Conclusive spectroscopic evidence for the structures of the new compounds having the cis-[1,4]oxazino[3,2-b]-1,4-oxazine (5 and 8) and the 2,2′-bioxazolidine type structures (6 and 7) was obtained by measurement of the 13C satellite coupling constants in the 300 MHz 1H nmr spectra, combined with the evaluation of dihedral angles using a modified Karplus type relationship. Unequivocal 1H and 13C nmr spectral assignments for all new compounds were done using two-dimensional carbon–proton correlation experiments. Syntheses of the known 5a,6,11a,12-tetrahydro[1,4]benzoxazino[3,2-b]benzoxazine (3a) whose crystal structure has been previously determined, as well as of its N,N′-diisopropyl derivative 3b, allowed us to corroborate the above observations for the six-membered ring heterocycles. Moreover, the structures of 3b and 7 were independently verified by single crystal X-ray diffraction studies, thus validating the structural conclusions deduced from nmr satellite multiplicity measurements.

Synthesis of unsymmetrical organic carbonates catalyzed by a sulfonic acid-functionalized zirconium phosphonate

2011 ◽  
Vol 84 (3) ◽  
pp. 675-684 ◽  
Author(s):  
Jinliang Song ◽  
Binbin Zhang ◽  
Suxiang Wu ◽  
Qian Wang ◽  
Honglei Fan ◽  
...  
Keyword(s):  
Sulfonic Acid ◽  
Sulfamic Acid ◽  
X Ray Diffraction ◽  
X Ray ◽  
Organic Carbonates ◽  
Zirconium Phosphonate ◽  
Ft Ir ◽  
Xrd Techniques ◽  
High Yields ◽  
Very High

Synthesis of unsymmetrical organic carbonates by transesterification of various alcohols with diethyl carbonate (DEC) is an interesting topic in green chemistry. In this work, we synthesized a kind of zirconium phosphonate functionalized with pendent N-SO3H group by the reaction of ZrOCl2·8H2O with N,N-bis(phosphonomethyl)-sulfamic acid, which was formed from sulfamic acid through a Mannich-type reaction. The functionalized zirconium phosphonate was characterized by Fourier transform/infrared (FT/IR), N2 adsorption and desorption, scanning electron microscopy (SEM), and powder X-ray diffraction (XRD) techniques, and was used as the heterogeneous catalyst for the synthesis of unsymmetrical organic carbonates by transesterification of various alcohols with DEC. It was demonstrated that the catalyst is very active and selective for the reactions, and very high yields of the desired products could be obtained. In addition, the catalyst could be easily recovered and the decrease in catalytic activity and selectivity was minor after three-fold usage. The mechanism for the transesterification reactions is discussed.

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