scholarly journals The DP5 Probability, Quantification and Visualisation of Structural Uncertainty in Single Molecules

2021 ◽  
Author(s):  
Alexander Howarth ◽  
Jonathan Goodman
Keyword(s):  
Drug Development ◽  
Chemical Synthesis ◽  
13C Nmr ◽  
Nmr Spectra ◽  
Single Molecules ◽  
Step Change ◽  
Structural Uncertainty ◽  
13C Nmr Spectra ◽  
Candidate Structure

Whenever a new molecule is made, a chemist will justify the proposed structure by analysing the NMR spectra. The widely-used DP4 algorithm will choose the best match from a series of possibilities, but draws no conclusions from a single candidate structure. Here we present the DP5 probability, a step-change in the quantification of molecular uncertainty: given one structure and one 13C NMR spectra, DP5 gives the probability of the structure being correct. We show the DP5 probability can rapidly differentiate between structure proposals indistinguishable by NMR to an expert chemist. We also show in a number of challenging examples the DP5 probability may prevent incorrect structures being published and later reassigned. DP5 will prove extremely valuable in fields such as discovery-driven automated chemical synthesis and drug development. Alongside the DP4-AI package, DP5 can help guide synthetic chemists when resolving the most subtle structural uncertainty. The DP5 system is available at https://github.com/Goodman-lab/DP5.

scholarly journals The DP5 Probability, Quantification and Visualisation of Structural Uncertainty in Single Molecules

2021 ◽  
Author(s):  
Alexander Howarth ◽  
Jonathan Goodman
Keyword(s):  
Drug Development ◽  
Chemical Synthesis ◽  
13C Nmr ◽  
Nmr Spectra ◽  
Single Molecules ◽  
Step Change ◽  
Structural Uncertainty ◽  
13C Nmr Spectra ◽  
Candidate Structure

Whenever a new molecule is made, a chemist will justify the proposed structure by analysing the NMR spectra. The widely-used DP4 algorithm will choose the best match from a series of possibilities, but draws no conclusions from a single candidate structure. Here we present the DP5 probability, a step-change in the quantification of molecular uncertainty: given one structure and one 13C NMR spectra, DP5 gives the probability of the structure being correct. We show the DP5 probability can rapidly differentiate between structure proposals indistinguishable by NMR to an expert chemist. We also show in a number of challenging examples the DP5 probability may prevent incorrect structures being published and later reassigned. DP5 will prove extremely valuable in fields such as discovery-driven automated chemical synthesis and drug development. Alongside the DP4-AI package, DP5 can help guide synthetic chemists when resolving the most subtle structural uncertainty. The DP5 system is available at https://github.com/Goodman-lab/DP5.

Some Considerations Regarding the 1H and 13C Spectra of 4-(1-azulenyl)-2,6-bis(2-heteroaryl-vinyl)- pyrylium and Pyridinium and their Corresponding Pyridines

2018 ◽  
Vol 69 (1) ◽  
pp. 64-69
Author(s):  
Liviu Birzan ◽  
Mihaela Cristea ◽  
Constantin C. Draghici ◽  
Alexandru C. Razus
Keyword(s):  
Double Bond ◽  
13C Nmr ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Pyridinium Salts ◽  
13C Nmr Spectra ◽  
1H And 13C Nmr ◽  
Pyrylium Salts

The 1H and 13C NMR spectra of several 2,6-diheteroarylvinyl heterocycles containing 4-azulenyl moiety were recorded and their proton and carbon chemical shifts were compared with those of the compounds without double bond between the heterocycles. The influence of the nature of central and side heterocycles, molecule polarization and anisotropic effects were revealed. The highest chemical shifts were recorded for the pyrylium salts and the lowest at pyridines, but in the case of the pyridinium salts, the protons chemical shifts at the central heterocycle are more shielded due to a peculiar anisotropy of the attached vinyl groups.

13C-NMR spectra of substituted thiophenecarboxylic acids

1977 ◽  
Vol 42 (7) ◽  
pp. 2167-2170 ◽  
Author(s):  
I. Stibor ◽  
L. Radics ◽  
M. Janda ◽  
J. Šrogl ◽  
M. Němec
Keyword(s):  
13C Nmr ◽  
Nmr Spectra ◽  
13C Nmr Spectra

13C NMR spectra of 1-aryl-ferrocenylethylenes

1986 ◽  
Vol 51 (3) ◽  
pp. 670-676 ◽  
Author(s):  
Eva Solčániová ◽  
Štefan Toma ◽  
Tibor Liptaj
Keyword(s):  
13C Nmr ◽  
Nmr Spectra ◽  
Substituent Effects ◽  
13C Nmr Spectra ◽  
Bridge Group ◽  
C Nmr ◽  
Electron Effects

13C NMR spectra of 18 ferrocene analogues of trans stilbenes (1-aryl-2-ferrocenylethylenes) were measured. It was found that bridge group weakens the transfer of the substituent electron effects into ferrocene nucleus, especially distinctly into 3',4'positions of cyclopentadienyl ring. The transfer of substituent effects into β-position of the bridge -CH=CH- is greater in derivatives studied by us than in stilbenes. Synthesis of 1-(4-dimethylaminophenyl)-2-ferrocenylethylene is described.

17O and 13C NMR spectra of some geminal diacetates

1988 ◽  
Vol 53 (3) ◽  
pp. 588-592 ◽  
Author(s):  
Antonín Lyčka ◽  
Josef Jirman ◽  
Jaroslav Holeček
Keyword(s):  
13C Nmr ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
The Other ◽  
13C Nmr Spectra ◽  
Other Hand ◽  
Carboxylic Esters ◽  
C Nmr ◽  
Oxygen Atoms

The 17O and 13C NMR spectra of eight geminal diacetates RCH(O(CO)CH3)2 derived from simple aldehydes have been measured. In contrast to the dicarboxylates R1R2E(O(CO)R3)2, where E = Si, Ge, or Sn, whose 17O NMR spectra only contain a single signal, and, on the other hand, in accordance with organic carboxylic esters, the 17O NMR spectra of the compound group studied always exhibit two well-resolved signals with the chemical shifts δ(17O) in the regions of 183-219 ppm and 369-381 ppm for the oxygen atoms in the groups C-O and C=O, respectively.

Proximity and conformation effects in 29Si and 13C NMR spectra of di-ortho substituted trimethylsiloxybenzenes

1990 ◽  
Vol 55 (8) ◽  
pp. 2027-2032 ◽  
Author(s):  
Jan Schraml ◽  
Robert Brežný ◽  
Jan Čermák
Keyword(s):  
Benzene Ring ◽  
13C Nmr ◽  
Proximity Effect ◽  
Nmr Spectra ◽  
Methoxy Group ◽  
Chemical Shifts ◽  
Proximity Effects ◽  
13C Nmr Spectra ◽  
Methoxy Groups ◽  
C Nmr

29Si and 13C NMR spectra of five 4-substituted 2,6-dimethoxytrimethylsiloxybenzenes were studied with the aim to elucidate the nature of the deshielding proximity effects observed in the spectra of ortho substituted trimethylsiloxybenzenes. The sensitivity of 29Si chemical shifts to para substitution is in the studied compounds essentially the same as in mono ortho methoxytrimethylsiloxybenzenes. The deshielding proximity effect of the ìsecondî methoxy group is somewhat smaller than that of the ìfirstî group. The present results indicate that the two methoxy groups assume coplanar conformations with the benzene ring and are turned away from the trimethylsiloxy group which is not in the benzene plane. It is argued that in mono ortho methoxytrimethylsiloxybenzenes the two substituent groups adopt the same conformations as in the compounds studied here.

scholarly journals Changes in the natural abundance 13C NMR spectra of intact frog muscle upon storage and caffeine contracture.

1982 ◽  
Vol 257 (6) ◽  
pp. 2741-2743
Author(s):  
M Bárány ◽  
D D Doyle ◽  
G Graff ◽  
W M Westler ◽  
J L Markley
Keyword(s):  
13C Nmr ◽  
Nmr Spectra ◽  
Frog Muscle ◽  
Natural Abundance ◽  
13C Nmr Spectra ◽  
Caffeine Contracture
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