Electronic excited states of small ring compounds. IV. Bicyclo[2.1.0]pentanes by the photocycloaddition of cyclopropenes to olefins

1977 ◽  
Vol 55 (3) ◽  
pp. 393-406 ◽  
Author(s):  
D. R. Arnold ◽  
R. M. Morchat
Keyword(s):  
Excited States ◽  
Nuclear Overhauser Effect ◽  
Dimethyl Fumarate ◽  
Small Ring ◽  
H Nmr ◽  
Ring Compounds ◽  
Overhauser Effect ◽  
Direct Irradiation ◽  
Nuclear Overhauser ◽  
Thermal Stability Of

Direct irradiation of the charge-transfer complex between the cyclopropenes 3,3-dimethyl-1,2-diphenylcyclopropene (3) and 1,2,3-triphenylcyclopropene (7), and the electron deficient olefins dimethyl fumarate (5) and maleic anhydride (11) resulted in formation of the cycloadducts 6, 12–15 which are the bicyclo[2.1.0]pentane derivatives. These products were also formed when the reaction was photosensitized by triplet–triplet transfer. The structure of the adducts rests largely upon the interpretation of 13C and 1H nmr spectra. Nuclear Overhauser effect studies were used to assign stereochemistry. The thermal stability of these new bicyclo[2.1.0]-pentane derivatives has been examined, particularly with regard to the ring-flipping process and the rearrangement to the corresponding cyclopentene derivatives.

Electronic excited states of small ring compounds. VII. Bicyclo[2.1.0]pentanes by the photocycloaddition of 1,2,3-triphenylcyclopropene to fumaro- and maleonitrile

1979 ◽  
Vol 57 (9) ◽  
pp. 1037-1049 ◽  
Author(s):  
P. C. Wong ◽  
D. R. Arnold
Keyword(s):  
Excited States ◽  
Charge Transfer Complex ◽  
Nuclear Overhauser Effect ◽  
Small Ring ◽  
Triplet Energy ◽  
Ring Compounds ◽  
Overhauser Effect ◽  
Ca 50 ◽  
Nuclear Overhauser ◽  
Thermal Stability Of

Irradiation of the charge-transfer complex between 1,2,3-triphenylcyclopropene (1) and fumaronitrile (7) and maleonitrile (8) leads to formation of bicyclo[2.1.0]pentane cycloaddition products (9, 10, 11) and the photoene product (12). These products were also formed when the reaction was photosensitized (triplet–triplet transfer). The structure of the adducts was established by analysis of 13C and 1Hmr spectra. Nuclear Overhauser effect studies were also useful. The triplet energies of 7 and 8 (ET ca. 50 kcal mol−1) were determined by studying the photosensitized isomerization as a function of sensitizer triplet energy. The thermal stability of the new bicyclo [2.1.0]pentanes has been studied, particularly with regard to the isomerization resulting from cleavage of the central [0] bond in these strained systems. The mechanism of the photocycloaddition reactions is discussed.

Synthesis, stereochemistry, and transformations of (E)-1,2-bis(benzenesulfonyl)ethylene cycloadducts to 2-oxa substituted 1,3-dienes

1984 ◽  
Vol 62 (11) ◽  
pp. 2487-2497 ◽  
Author(s):  
Ottorino De Lucchi ◽  
Vittorio Lucchini ◽  
Moreno Zamai ◽  
Giorgio Modena ◽  
Giovanni Valle
Keyword(s):  
Nuclear Overhauser Effect ◽  
H Nmr ◽  
Overhauser Effect ◽  
Nuclear Overhauser ◽  
High Yields ◽  
Structure Assignment

The cycloaddition of (E)-1,2-bis(benzenesulfonyl)ethylene (2) to 2-acetoxy- and 2-silyloxy-1,3-cyclodienes occurs in high yields and with high steroselectivity. Structure assignment has been based largely on 1H nmr nuclear Overhauser effect (nOe) experiments on the isolated products. The cycloadducts 4a and 4b derived from the 2-oxa substituted cyclopentadienes have been further elaborated to the parent norbornenone, to the respective unsaturated sulfones 5, and to the β-hydroxy substituted sulfone 6. The vinyl sulfones 5 have also been independently synthesized via cycloaddition of benzenesulfonyl acetylene. The sulfones obtained are potentially important starting molecules for the preparation of more complex targets.

An evaluation of high resolution nuclear magnetic resonance experiments and protocols in the structure elucidation of organic molecules. I. A relatively simple system, brucine

1985 ◽  
Vol 63 (2) ◽  
pp. 483-490 ◽  
Author(s):  
Michael A. Bernstein ◽  
Laurance D. Hall
Keyword(s):  
High Resolution ◽  
Chemical Shift ◽  
Structural Information ◽  
Nuclear Overhauser Effect ◽  
Proton Spectrum ◽  
Nmr Spectrum ◽  
H Nmr ◽  
Overhauser Effect ◽  
Nuclear Overhauser ◽  
Nmr Methods

Using a combination of one-dimensional (1D) and two-dimensional (2D) high resolution nmr methods, the 1H nmr spectrum of brucine was fully assigned. The 2D J-resolved and homonuclear chemical shift correlated (COSY) experiments provided assignments without full structural information; this was obtained from nuclear Overhauser effect (nOe) enhancement experiments (1D and 2D). With the proton spectrum fully assigned, proton-bearing carbons in the 13C nmr spectrum were easily assigned using the 2D heteronuclear chemical shift correlation map (CSCM) experiment.

scholarly journals Changes in the Physicochemical Properties of Piperine/β-Cyclodextrin due to the Formation of Inclusion Complexes

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Toshinari Ezawa ◽  
Yutaka Inoue ◽  
Sujimon Tunvichien ◽  
Rina Suzuki ◽  
Ikuo Kanamoto
Keyword(s):  
Physicochemical Properties ◽  
Nuclear Overhauser Effect ◽  
Biological Activities ◽  
Black Pepper ◽  
Molar Ratio ◽  
Stoichiometric Ratio ◽  
H Nmr ◽  
Overhauser Effect ◽  
Methylene Groups ◽  
Nuclear Overhauser

Piperine (PP) is a pungent component in black pepper that possesses useful biological activities; however it is practically insoluble in water. The aim of the current study was to prepare a coground mixture (GM) of PP and β-cyclodextrin (βCD) (molar ratio of PP/βCD = 1/1) and subsequently evaluate the solubility of PP and physicochemical properties of the GM. DSC thermal behavior of the GM showed the absence of melting peak of piperine. PXRD profile of the GM exhibited halo pattern and no characteristic peaks due to PP and βCD were observed. Based on Job’s plot, the PP/βCD complex in solution had a stoichiometric ratio of 1/1. Raman spectrum of the GM revealed scattering peaks assigned for the benzene ring (C=C), the methylene groups (CH2), and ether groups (C-O-C) of PP that were broaden and shifted to lower frequencies. SEM micrographs showed that particles in the GM were agglomerated and had rough surface, unlike pure PP and pure βCD particles. At 15 min of dissolution testing, the amount dissolved of PP in the GM was dramatically increased (about 16 times) compared to that of pure PP. Moreover the interaction between PP and βCD cavity was detected by 1H-1H NMR nuclear Overhauser effect spectroscopy NMR spectroscopy.

Beiträge zur Chemie der Pyrrolpigmente, XXIII [1] Die Struktur eines Bilatrien-abc-Derivates im gelösten Zustande / On the Chemistry of Pyrrole Pigments, XXIII [1] The Structure of a Bilatriene-abc Derivative in the State of Solution

1978 ◽  
Vol 33 (8) ◽  
pp. 924-931 ◽  
Author(s):  
Heinz Falk ◽  
Karl Grubmayr ◽  
Klaus Thirring
Keyword(s):  
Nitrogen Atom ◽  
Nuclear Overhauser Effect ◽  
The State ◽  
The Other ◽  
H Nmr ◽  
Overhauser Effect ◽  
Lactim Ether ◽  
Nuclear Overhauser ◽  
Shift Technique ◽  
Single Bonds

Abstract The (Z,Z,Z)-configuration of the mono-lactim-ether of an alkyl substituted bilatriene-abc, Etiobiliverdin-IV-γ, was established for chloroform solutions. Moreover the conformation of this molecule is a helical one (syn-syn-syn) with a twist along the single bonds at the methine groups of approximately 20°. The two tautomeric lactam-forms with a proton on one or the other nitrogen atom of the pyrromethene subsystem are indistin-guishable by the methods used in this investigation: 1H NMR pattern, Lanthanide induced shift technique and Nuclear Overhauser Effect measurements.

Conformational studies of Angiotensin II and analogues in dimethyl sulfoxide by 1H NMR: Lability and intramolecular interactions of the tyrosine hydroxyl and histidine imidazole NH protons

1991 ◽  
Vol 56 (6) ◽  
pp. 1348-1357 ◽  
Author(s):  
John Matsoukas ◽  
Glen Bigam ◽  
Raghav Yamdagni ◽  
Graham J. Moore
Keyword(s):  
Dimethyl Sulfoxide ◽  
Nuclear Overhauser Effect ◽  
Peptide Bond ◽  
Intramolecular Interactions ◽  
Nmr Studies ◽  
Hydroxyl Proton ◽  
H Nmr ◽  
Overhauser Effect ◽  
Nuclear Overhauser ◽  
Deshielding Effect

1H NMR studies in dimethyl sulfoxide illustrate that the tyrosine hydroxyl proton and the histidine imidazole NH proton in [Sar1]ANGII and analogues are labile at neutral pH but not at acid pH. This is attributable to intramolecular interactions of these groups with negatively charged groups. Methylation or elimination of the Tyr hydroxyl in [Sar1]ANGII and analogues, invokes a small but consistent deshielding effect on the His C-2 and C-4 protons, suggesting an interaction between the Tyr hydroxyl and the His ring. Nuclear Overhauser Effect (NOE) enhancement experiments in {Sar1]ANGII and the Sarmesin analogue [Des1, Tyr(Me)4]ANGII, support the Tyr/His interaction and confirm the presence of a trans His-Pro peptide bond.

Synthesis and spectral evaluation of 5,10,15,20-tetrakis(3,4-dibenzyloxyphenyl)porphyrin

2017 ◽  
Vol 23 (2) ◽  
pp. 79-83
Author(s):  
Cynthia P. Tidwell ◽  
Prakash Bharara ◽  
Kenneth A. Belmore ◽  
Qiaoli Liang ◽  
Gregory W. Dye ◽  
...  
Keyword(s):  
High Resolution Mass Spectrometry ◽  
Nuclear Overhauser Effect ◽  
Soret Band ◽  
Molar Absorptivity ◽  
H Nmr ◽  
Maldi Tof ◽  
Overhauser Effect ◽  
Spectral Evaluation ◽  
Nuclear Overhauser ◽  
C Nmr

AbstractPorphyrins are of interest in many applications that involve electron transfer and absorption of light, such as solar energy and photodynamic cancer therapy. The newly synthesized 5,10,15,20-tetrakis(3,4-dibenzyloxyphenyl)porphyrin, TDBOPP, was characterized using 1H NMR, 13C NMR, UV-vis and fluorescence spectroscopy and MALDI-TOF/TOF high resolution mass spectrometry. Standard 1H NMR and 13C NMR experiments coupled with nuclear Overhauser effect (NOE) experiments confirmed the structure of the compound. The expected M+ and [M+H]+ ions are observed in the MALDI-TOF/TOF mass spectrum. The UV-vis absorption spectrum of TDBOPP shows a Soret band at 424 nm and three Q bands at 519 nm, 556 nm, and 650 nm with molar absorptivity 3.6×105 cm−1m−1, 1.6×104 cm−1m−1, 1.0×104 cm−1m−1 and 5.3×103 cm−1m−1, respectively. Excitation at 424 nm gives emission at 650 nm. The quantum yield of the porphyrin is 0.11.

Synthesis, multinuclear NMR, and solution conformation of (η5-indenyl)CoIRfL complexes (L = CO, P-donor)

1992 ◽  
Vol 70 (10) ◽  
pp. 2544-2551 ◽  
Author(s):  
Chet R. Jablonski ◽  
Zhongxin Zhou
Keyword(s):  
Nuclear Overhauser Effect ◽  
Spectroscopic Characterization ◽  
Solution Conformation ◽  
H Nmr ◽  
Overhauser Effect ◽  
Ring Junction ◽  
Effect Difference ◽  
Perfluoroalkyl Group ◽  
Nuclear Overhauser ◽  
Indenyl Complexes

The preparation, spectroscopic characterization, and conformational analysis of a series of Co(III) indenyl complexes, (C9H7)CoIRfL (Rf = C3F7, C6F13, L = CO, P-donor), 2–8, are described. I3C and 1H NMR parameters are consistent with a slightly distorted -η5-C9H7 coordination. 1H nuclear Overhauser effect difference (nOed) spectra indicate a preferred solution conformation in which the perfluoroalkyl group is trans to the C3a—C7a ring junction.

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