Magnetic Resonance in Chemistry

doi: 10.1002/mrc.1260291101pmid: N/A

Atta‐ur‐Rahman, ; Pervin, Azra; Feroz, M.; Perveen, Shahnaz; Choudhary, M. I.; Hasan, Naim

doi: 10.1002/mrc.1260291102pmid: N/A

The isolation and structure elucidation of a novel dimeric alkaloid, griffithine, from the leafy shoots of Sophora griffithii Stock (Papilionaceae) is described. The alkaloid possesses a 12‐membered ring system formed by the linking of C‐10 and C‐10′ of the alkaloid with the N‐1 and N‐1′ atoms, respectively. The structure was established on the basis of extensive 1D and 2D NMR studies. The relative stereochemistry at the chiral centres was determined by NOE difference experiments. 10‐Oxosparteine was isolated for the first time from the leafy shoots of Sophora griffithii.

Licoccia, Silvia; Paci, Maurizio; Tagliatesta, Pietro; Paolesse, Roberto; Antonaroli, Simonetta; Boschi, Tristano

doi: 10.1002/mrc.1260291103pmid: N/A

The synthesis of a new chiral porphyrin, meso‐tetra(α, β, α, β‐o‐camphanylamidophenyl)porphyrin, and its Mn(III) and Rh(III) derivatives is reported. Complete resonance assignments of both the 1H and 13C spectra of the ligand has been achieved via homo‐ and hetero‐nuclear 2D NMR. Insertion of metal ions into the porphyrin ring was performed both in order to test the catalytic properties of the resulting complexes and to characterize the effect of of metal coordination on the spatial distribution of the bulky substituents. The Mn complex was then tested in catalytic chiral epoxidation reactions, giving low enantiomeric excesses (20%). The 2D NMR spectra of the Rh derivative indicate the existence of four molecular species generated by the interaction of the metal atom with the peripheral substituents of the porhyrin ring. In fact, a complex combination of axial coordination, together with the chirality of the camphanyl substituents, removed the symmetry of the porphyrin plane.

Yan, Xin; Fan, Jinsong; Xu, Xiaolong; Wang, Dehua; Nie, Guojun; Qian, Baogong

doi: 10.1002/mrc.1260291104pmid: N/A

The two‐dimensional 113Cd1H Overhauser effect spectra of some cadmium compounds are reported. The results show that the two‐dimensional 113Cd1H Overhauser effect experiments can be used to investigate the intramolecular and intermolecular interactions and structures of cadium compounds.

Tsuda, Sakae; Niki, Ryoya; Kuwata, Tamotsu; Tanaka, Isao; Hikichi, Kunio

doi: 10.1002/mrc.1260291105pmid: N/A

The solution conformation of β‐casein phosphopeptide (CPP) was studied by 1H NMR spectroscopy. As a prerequisite to the conformational analysis the spectral assignment was carried out for CPP in the Ca2+‐free and ‐bound states by the use of two‐dimensional NMR spectroscopy. The assigned resonances were used for (1) pH‐titration experiments, (2) elucidation of the temperature dependence of the amide resonance and (3) a nuclear Overhauser enhancement (NOE) experiment. Although the β‐turn conformation is predicted for the sequence – Val8–Pro9–Gly10–Glu11–of CPP, the present NMR results do not provide favourable evidence for its formation.

Cotelle, Nicole; Cotelle, Philippe

doi: 10.1002/mrc.1260291106pmid: N/A

7‐[2‐(4‐morpholinomethyl)butanoyl]‐4‐methyl‐2H‐1, 4‐benzoxazin‐3 (4H)‐one hydrochloride (2a) (a new elevated high density lipoproteins agent) and related compounds have been studied by NMR spectroscopy. Compound 2a exhibits an intramolecular hydrogen bond between the NH+ and CO bonds in solvents with low nucleophilicity. These results are confirmed by IR spectroscopy in solution.

Kolehmainen, Erkki; Laihia, Katri; Mänttäri, Pia

doi: 10.1002/mrc.1260291107pmid: N/A

Trans‐Cinnamaldehydes (CAs) or o‐, m‐ and p‐X‐(E)‐3‐phenylpropenals; (X = Cl or Br) were synthesized and their 1H, 13C and 17O NMR spectra were measured, assigned and analysed. The long‐range benzylic couplings are discussed in terms of the conformational characteristics of the related styrene systems. The 1H, 13C and 17O NMR substituent chemical shifts of the CA derivatives were compared with those of styrene and explained by the π‐electron delocalization in the conjugated CCCO bond system of CA.

Black, David St C.; Strauch, Richard J.

doi: 10.1002/mrc.1260291108pmid: N/A

13C NMR data for forty 1‐pyrroline 1‐oxides, six 2H‐pyrrole 1‐oxides, three 2H‐pyrroles, eight 1‐pyrrolines and four related oxaziridines are reported. Comparisons are made with respect to the five‐membered ring carbons, subdividing them as the central carbons, the nitrone carbon and the gem‐dimethyl‐substituted carbon adjacent to nitrogen. The effects of substituents on the ring are also discussed.

Laurens, T.; Nicole, D.; Rubini, P.; Lauer, J. C.; Matlengiewicz, M.; Henzel, N.

doi: 10.1002/mrc.1260291109pmid: N/A

The assignment of the carbons of different isomers of methylcyclopentadiene monomers (Me‐CPD) and dimers (diMe‐DCPD) has been performed directly in a mixture, without previous separation of these products, by analysing data from quantitative 13C NMR spectra of the mixtures and applying a J‐modulated spin–echo sequence. Semi‐empirical rules for the influence of methyl groups on the chemical shifts of carbons in pentenic and norbornyl ring systems have been formulated and utilized to assign the absorptions. The same method can then be applied to the carbon assignments in cyclopentadiene–methylcyclopentadiene codimers (Me‐CPD), and it is possible to develop additivity rules and predict chemical shifts for diMe‐DCPD based on the chemical shifts for the carbons of these codimers.

Arias‐Pérez, M. S.; Cosme, A.; Gálvez, E.; Florencio, F.; Fonseca, I.; Sanz, J.

doi: 10.1002/mrc.1260291110pmid: N/A

A series of (±)‐3‐aryl‐1‐azabicyclo[2.2.2]octan‐3‐ols were synthesized and studied by 1H, 13C and 2D NMR spectroscopy, and the crystal structure of (±)‐3‐(4‐methylphenyl)‐1‐azabicyclo[2.2.2]octan‐3‐ol was determined by X‐ray diffraction. The combined use of COSY, NOESY and 1H–13C correlation spectra of these compounds helped in the unambiguous and complete assignments of the bicyclic carbon and proton spin system. This study allows the establishment of the proton magnetic parameters for the quinuclidine moiety. Standard values of 1H1H coupling constants are proposed in order to analyse more complex quinuclidine derivatives.