Relative sign determination of phosphorus-carbon coupling constants by 2D carbon-13 NMR spectroscopy

1989 ◽  
Vol 8 (2) ◽  
pp. 568-571 ◽  
Author(s):  
Leslie H. Randall ◽  
Andrew A. Cherkas ◽  
Arthur J. Carty
Keyword(s):  
Nmr Spectroscopy ◽  
Coupling Constants ◽  
Relative Sign ◽  
Sign Determination

Convenient Sign Determination of Various Coupling Constants in Alkynylplatinum(II) Phosphine Complexes

1991 ◽  
Vol 46 (1) ◽  
pp. 35-38 ◽  
Author(s):  
Bernd Wrackmeyer
Keyword(s):  
Coupling Constants ◽  
Two Dimensional ◽  
Model Compounds ◽  
Standard Equipment ◽  
Phosphine Complexes ◽  
Sign Determination

(1)The utilization of two-dimensional (2 D) 13C /1H , 31P/1H and 195Pt/1H heteronuclear shift correlations for the sign determination of various coupling constants [e.g., 2J(31PPt13C) > 0 (trans), 2J(31PPt13C) < 0 (cis), 3J( 31PPtC13C) > 0 (cis, trans), 4J(31PPtCC1H ) > 0 (trans), 4J(31PCC1H ) < 0 (cis), 3J(195PtCC1H ) > 0, 2J(31PC1H ) < 0, etc.] is demonstrated, using standard equipment. The complexes [trans-(Bu3P)2Pt(C ≡ C -H)2] and [cis-(Et2PCH2CH2PEt2)Pt(C ≡ C - H)2] (2) serve as model compounds.

scholarly journals Long-range proton–carbon coupling constants for the determination of the stereochemical structure of organic compounds.

2021 ◽  
pp. 125-131
Author(s):  
Anwar, E. M. Noreljaleel
Keyword(s):  
Nmr Spectroscopy ◽  
Organic Compounds ◽  
Long Range ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Spectroscopy Method ◽  
Stereochemical Structure ◽  
New Methods ◽  
Spin Coupling Constants

A new methods for elucidating stereochemistry of organic compounds was developed on the basis of long-range proton–carbon coupling constants (2,3JC,H) and interpreting spin-coupling constants (3JH,H). Reaction of compound containing pyrin ring with nucleophile reagent was done to open the ring. HSQC-TOCSY experiments one of the new NMR spectroscopy method used to measure this values of spin-coupling constants and elucidating the stereochemistry of the product.

Ecuadorin, a novel tetranortriterpenoid of Guareakunthiana: structure elucidation by 2-D NMR spectroscopy

1992 ◽  
Vol 70 (5) ◽  
pp. 1260-1264 ◽  
Author(s):  
Baldwin S. Mootoo ◽  
Cumandá Játiva ◽  
Winston F. Tinto ◽  
William F. Reynolds ◽  
Stewart McLean
Keyword(s):  
Nmr Spectroscopy ◽  
Structure Elucidation ◽  
Pulse Sequence ◽  
Coupling Constants ◽  
Spectroscopic Methods

Ecuadorin (1), C29H34O10, a novel tetranortriterpenoid, has been isolated from Guareakunthiana (Meliaceae) collected in Ecuador. Its structure has been established by spectroscopic methods, mainly 2-D NMR spectroscopy; the value of the FLOCK pulse sequence in the determination of 2- and 3-bond 13C–1H connectivities is illustrated. Ecuadorin has been reduced to the dihydro and tetrahydro derivatives (2 and 3), and these have provided information regarding the stereochemistry of ecuadorin. Stereochemical arguments have been based on observed vicinal 1H–1H coupling constants and NOE measurements, as well as on biosynthetic hypothesis.

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