Synergistic formal ring contraction for the enantioselective synthesis of spiropyrazolones

We report the first ring contraction/formal [6 + 2] cycloaddition using synergistic Pd(0)/secondary amine catalysis, obtaining [5,5]-spiropyrazolone derivatives in excellent yields and stereoselectivities. We detected the key palladium activated intermediate in its protonated form by mass spectrometry and characterized its structure by infrared spectroscopy and DFT calculations, allowing us to propose a conceivable mechanistic pathway for this reaction.

Download Full-text

Synergistic catalysis: enantioselective cyclopropanation of alkylidene benzoxazoles by Pd(ii) and secondary amine catalysis. Scope, limitations and mechanistic insight

Organic Chemistry Frontiers ◽

10.1039/c7qo00858a ◽

2018 ◽

Vol 5 (5) ◽

pp. 806-812 ◽

Cited By ~ 6

Author(s):

Marta Meazza ◽

Victor Polo ◽

Pedro Merino ◽

Ramon Rios

Keyword(s):

Dft Calculations ◽

Secondary Amine ◽

Ring Opening ◽

Synergistic Catalysis ◽

Mechanistic Insight ◽

Amine Catalysis

An enantioselective synergistic cascade cyclopropanation/NHC catalyzed ring opening has been reported. DFT calculations have been performed to confirm the mechanism.

Download Full-text

Synergetic Effect of Co-pyrolysis of Cellulose and Polypropylene over an All-Silica Mesoporous Catalyst MCM-41 Using Thermogravimetry–Fourier Transform Infrared Spectroscopy and Pyrolysis–Gas Chromatography–Mass Spectrometry

Energy & Fuels ◽

10.1021/acs.energyfuels.7b01651 ◽

2017 ◽

Vol 31 (9) ◽

pp. 9576-9584 ◽

Cited By ~ 10

Author(s):

Junjie Xue ◽

Jiankun Zhuo ◽

Mi Liu ◽

Yongchao Chi ◽

Dahu Zhang ◽

...

Keyword(s):

Mass Spectrometry ◽

Gas Chromatography ◽

Fourier Transform ◽

Infrared Spectroscopy ◽

Synergetic Effect ◽

Gas Chromatography Mass Spectrometry ◽

Mesoporous Catalyst ◽

Pyrolysis Gas ◽

Pyrolysis Gas Chromatography ◽

Mcm 41

Download Full-text

DFT calculations on the structural stability and infrared spectroscopy of endohedral metallofullerenes

Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy ◽

10.1016/j.saa.2009.06.051 ◽

2009 ◽

Vol 74 (2) ◽

pp. 553-557 ◽

Cited By ~ 12

Author(s):

Sheng Peng ◽

Yan Zhang ◽

Xiao Jun Li ◽

Yan Ren ◽

Deng Xin Zhang

Keyword(s):

Infrared Spectroscopy ◽

Dft Calculations ◽

Structural Stability ◽

Endohedral Metallofullerenes

Download Full-text

New Volatile Perfluorinated Amidine–Carboxylate Copper(II) Complexes as Promising Precursors in CVD and FEBID Methods

Materials ◽

10.3390/ma14123145 ◽

2021 ◽

Vol 14 (12) ◽

pp. 3145

Author(s):

Katarzyna Madajska ◽

Iwona Barbara Szymańska

Keyword(s):

Electron Microscopy ◽

Mass Spectrometry ◽

Electron Beam ◽

Infrared Spectroscopy ◽

Density Functional ◽

Variable Temperature ◽

Chemical Vapour ◽

Thermal Decomposition Mechanism ◽

Transmission Electron Microscopy Analysis ◽

Reduced Pressure

In the present study, we have synthesised and characterised newly copper(II) complexes with the general formula [Cu2(NH2(NH=)CC2F5)2(µ–O2CCRF)4], where RF = CF3, C2F5, C3F7, C4F9. Infrared spectroscopy, mass spectrometry with electron ionisation (EI MS), and density-functional theory (DFT) calculations were used to confirm compounds’ composition and structure. The volatility of the compounds was studied using thermal analysis (TGA), EI MS mass spectrometry, variable temperature infrared spectroscopy (VT IR), and sublimation experiments. Research has revealed that these compounds are the source of metal carriers in the gas phase. The thermal decomposition mechanism over reduced pressure was proposed. TGA studies demonstrated that copper transfer to the gaseous phase occurs even at atmospheric pressure. Two selected complexes [Cu2(NH2(NH=)CC2F5)2(µ–O2CC2F5)4] and [Cu2(NH2(NH=)CC2F5)2(µ–O2CC3F7)4] were successful used as chemical vapour deposition precursors. Copper films were deposited with an evaporation temperature of 393 K and 453 K, respectively, and a decomposition temperature in the range of 573–633 K without the use of hydrogen. The microscopic observations made to investigate the interaction of the [Cu2(NH2(NH=)CC2F5)2(µ–O2CC2F5)4] with the electron beam showed that the ligands are completely lost under transmission electron microscopy analysis conditions (200 keV), and the final product is copper(II) fluoride. In contrast, the beam energy in scanning electron microscopy (28 keV) was insufficient to break all coordination bonds. It was shown that the Cu-O bond is more sensitive to the electron beam than the Cu-N bond.

Download Full-text

Conformation analysis of copper(II) etioporphyrin-II by combined gas electron diffraction/mass-spectrometry methods and DFT calculations

Journal of Molecular Structure ◽

10.1016/j.molstruc.2014.12.089 ◽

2015 ◽

Vol 1085 ◽

pp. 276-285 ◽

Cited By ~ 5

Author(s):

Alexander E. Pogonin ◽

Natalya V. Tverdova ◽

Anatoly A. Ischenko ◽

Valentina D. Rumyantseva ◽

Oscar I. Koifman ◽

...

Keyword(s):

Mass Spectrometry ◽

Electron Diffraction ◽

Dft Calculations ◽

Gas Electron Diffraction ◽

Conformation Analysis

Download Full-text

Break the template boundary: Test of different protein scaffolds by genetic code expansion resulted in NADPH-dependent secondary amine catalysis

10.21203/rs.3.rs-468406/v2 ◽

2021 ◽

Author(s):

Thomas Williams ◽

Yu-Hsuan Tsai ◽

Louis Luk

Keyword(s):

Genetic Code ◽

Secondary Amine ◽

Transfer Hydrogenation ◽

Protein Scaffolds ◽

Artificial Enzyme ◽

Enzyme Design ◽

Catalytically Active ◽

Amine Catalysis ◽

Genetic Code Expansion ◽

Distinctive Role

Abstract Here, incorporation of secondary amine by genetic code expansion was used to expand the potential protein templates for artificial enzyme design. Pyrrolysine analogue containing a D-proline could be stably incorporated into proteins, including the multidrug-binding LmrR and nucleotide-binding dihydrofolate reductase (DHFR). Both modified scaffolds were catalytically active, mediating transfer hydrogenation with a relaxed substrate scope. The protein templates played a distinctive role in that, while the LmrR variants were confined to the biomimetic BNAH as the hydride source, the optimal DHFR variant favorably used the pro-R hydride from NADPH for reactions. Due to the cofactor compatibility, the DHFR secondary amine catalysis could also be coupled to an enzymatic recycling scheme. This work has illustrated the unique advantages of using proteins as hosts, and thus the presented concept is expected to find uses in enabling tailored secondary amine catalysis.

Download Full-text

Sequential microhydration of cationic 5-hydroxyindole (5HI+): infrared photodissociation spectra of 5HI+–Wn clusters (W = H2O, n ≤ 4)

Physical Chemistry Chemical Physics ◽

10.1039/c7cp06132c ◽

2018 ◽

Vol 20 (5) ◽

pp. 3092-3108 ◽

Cited By ~ 13

Author(s):

Johanna Klyne ◽

Mitsuhiko Miyazaki ◽

Masaaki Fujii ◽

Otto Dopfer

Keyword(s):

Hydrogen Bonding ◽

Infrared Spectroscopy ◽

Dft Calculations ◽

Bonding Properties

The hydrogen-bonding properties of the acidic OH and NH groups of the 5-hydroxyindole cation are probed by infrared spectroscopy and DFT calculations of its microhydrated clusters.

Download Full-text