Premium
Selective heteronuclear NOE enhancements in benzoheterocycles. Effect of ring size on indirect three‐spin effects
Author(s) -
Redondo Jordi,
SánchezFerrando Francisco,
Valls Montserrat,
Virgili Albert
Publication year - 1988
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.1260260615
Subject(s) - heteronuclear molecule , chemistry , homonuclear molecule , protonation , ring (chemistry) , nuclear overhauser effect , spin (aerodynamics) , two dimensional nuclear magnetic resonance spectroscopy , nuclear magnetic resonance , stereochemistry , crystallography , nuclear magnetic resonance spectroscopy , molecule , organic chemistry , physics , ion , thermodynamics
The 80 MHz 1 H NMR and 20 MHz 13 C NMR spectra of five 4‐methylcoumarins, six 4‐methyl‐2(1 H )‐quinolones and nine 3‐methylbenzo[ b ]furans, including six new compounds, were fully assigned. Homonuclear 1 H{ 1 H} NOEs and selective heteronuclear 13 C{ 1 H} NOEs were measured after low‐power pre‐saturation of the methyl protons. Indirect, negative heteronuclear NOE enhancements were found in suitable three‐spin systems of the 13 C 1 H{ 1 H} type, and their magnitude was found to be dependent on ring size. The first examples of indirect, heteronuclear NOE enhancements on non‐protonated carbons are described.