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NMR structural characterization from one‐bond 13 C 13 C couplings: Complete assignment of a hydrogen‐poor depsidone
Author(s) -
Sestile Shan,
Richardson David,
Toomey Ryan,
Cool Laurence G.,
Harper James K.
Publication year - 2021
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.5077
Subject(s) - chemistry , intramolecular force , tautomer , hydrogen bond , conformational isomerism , characterization (materials science) , crystallography , computational chemistry , stereochemistry , molecule , nanotechnology , organic chemistry , materials science
Abstract The connectivity, conformation, tautomeric form, and dynamics of a new depsidone (perisalazinic acid) were characterized using one‐bond 13 C 13 C NMR scalar couplings ( 1 J CC ) obtained from the INADEQUATE experiment. Characterization of perisalazinic acid using more conventional NMR techniques is problematic due to the extremely limited number of CH protons present. In the present study, 81 candidate structures were considered and a best fit structure was selected by comparing computed 1 J CC values for each candidate to 15 experimental values. Of the six flexible moieties in perisalazinic acid, three are adequately represented by a single orientation stabilized by intramolecular hydrogen bonding. The three remaining groups are present as mixtures of conformers with two sites consisting of a pair of conformations and another disordered over six orientations. This study demonstrates the feasibility of complete three‐dimensional structural characterization of an unknown using only theoretical and experimental 1 J CC values.