Evidence map›Paper›PMID 24556787›Full record

ArticleNature protocols2014

A guide to small-molecule structure assignment through computation of (¹H and ¹³C) NMR chemical shifts.

Patrick H Willoughby, Matthew J Jansma, Thomas R Hoye

Open access · bronzeAbstract read
PubMed Publisher
In one paragraph

Article in Nature protocols, 2014. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 111 papers.

0numbers the graph read from it
0cells of the map it votes in
111citing papers in PubMed
13.9field-weighted citation impact, top 1% of its field
1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

The trial behind it

Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.

Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.

3 · Its place in the literature

Who cites it

111 citing papers in PubMed, 400 citations in OpenAlex.

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51 more citing papers are in PubMed but not listed here.

4 · The record

Corrections and comments

5 · Who and what money

Authors and funding

3 authors at 1 institution in 1 country.

Patrick H WilloughbyDepartment of Chemistry, University of Minnesota, Minneapolis, Minnesota, USA.
Matthew J JansmaDepartment of Chemistry, University of Minnesota, Minneapolis, Minnesota, USA.
Thomas R HoyeDepartment of Chemistry, University of Minnesota, Minneapolis, Minnesota, USA.
University of Minnesota · US

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

This protocol is intended to provide chemists who discover or make new organic compounds with a valuable tool for validating the structural assignments of those new chemical entities. Experimental ¹H and/or ¹³C NMR spectral data and its proper interpretation for the compound of interest is required as a starting point. The approach involves the following steps: (i) using molecular mechanics calculations (with, e.g., MacroModel) to generate a library of conformers; (ii) using density functional theory (DFT) calculations (with, e.g., Gaussian 09) to determine optimal geometry, free energies and chemical shifts for each conformer; (iii) determining Boltzmann-weighted proton and carbon chemical shifts; and (iv) comparing the computed chemical shifts for two or more candidate structures with experimental data to determine the best fit. For a typical structure assignment of a small organic molecule (e.g., fewer than ∼10 non-H atoms or up to ∼180 a.m.u. and ∼20 conformers), this protocol can be completed in ∼2 h of active effort over a 2-d period; for more complex molecules (e.g., fewer than ∼30 non-H atoms or up to ∼500 a.m.u. and ∼50 conformers), the protocol requires ∼3-6 h of active effort over a 2-week period. To demonstrate the method, we have chosen the analysis of the cis- versus the trans-diastereoisomers of 3-methylcyclohexanol (1-cis versus 1-trans). The protocol is written in a manner that makes the computation of chemical shifts tractable for chemists who may otherwise have only rudimentary computational experience.

Indexed as

Molecular ConformationEpoxy CompoundsMagnetic Resonance SpectroscopyModels, ChemicalMolecular StructureOrganic ChemicalsPolycyclic CompoundsSmall Molecule LibrariesSpiro CompoundsEpoxy CompoundshexacyclinolOrganic ChemicalsPolycyclic CompoundsSmall Molecule LibrariesSpiro Compoundsvannusal B

Identifiers

PMID24556787
OpenAlexW4230413343

What OpenQuestion holds

Textmetadata
Read underepoch 390

Registered trials

None linked

Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.