Applications of a HOUDINI-Based Structure Elucidation System

Schulz, Klaus‐Peter; Korytko, Andrey A.; Munk, Morton E.

doi:10.1021/ci034058j

Cited by 19 publications

(30 citation statements)

References 11 publications

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“…The system has been described in a number of publications. [14][15][16][17][18][19] SESAMI-C input. The molecular formula and the 1D 1 H/ 13 C and 2D NMR data are fed into the SESAMI-C structure generator prior to program execution.…”

Section: Sesami-cmentioning

confidence: 99%

“…Schulz et al 16 described the SESAMI-H system and compared its efficiency with that of SESAMI-C. The following advantages of the HOUDINI generator over the COCOA system were reported: 13,16 1. HOUDINI, in contrast to COCOA, requires only a single representation of the initial problem state, even in the presence of hybridization uncertainties.…”

Section: Sesami-hmentioning

confidence: 99%

“…To compare the results obtained with the two variants of the system, Schulz et al 16 selected seven natural products (Table 6.1), whose identification from 2D NMR spectra had been described in the literature. [19][20][21][22][23][24] The results of testing the program using the compounds listed in Table 6.1 are presented in Table 6.2, in which the unknown structures with k, the number of structures in the output file, and t g , the generation time values Table. Analysis of the results shows that if there are no contradictions in the 2D NMR data, then the SESAMI-H system can successfully determine the structures of quite large molecules (up to 75 skeletal atoms).…”

Section: Houdini Accepts a Set Of Structural Inferences From Interprementioning

confidence: 99%

“…23 Problems 1, 2, and 5 (Table 6.2) can be solved only if these correlations are deleted or corrected. In the case of lacinan-8-ol, Schulz et al 16 extended all connectivities in the COSY spectrum to 3-4 J HH to solve the problem with non-standard correlations. According to our research (see Chapter 10), this approach is applicable only to very modest-sized molecules, such as lacinan-8-ol.…”

Section: Houdini Accepts a Set Of Structural Inferences From Interprementioning

confidence: 99%

“…In this example, the MAX-ERR-LRDC value was set to zero. This did not hinder the identification of a correct result, since the two non-standard COSY correlations (10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21) and (4-9), indicated by arrows in the structure 6.1, had been extended to 3-5 bonds.…”

Section: The Expert System Cisoc-sesmentioning

confidence: 99%

See 4 more Smart Citations

CASE 2D NMR-based Expert Systems

2011

Contemporary Computer-Assisted Approaches to Molecular Structure Elucidation

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Modern expert systems utilize 1D and 2D NMR data. The 2D NMR expert systems described in the literature over the last two decades will be reviewed as these form the foundation of understanding from which modern systems have been developed. These systems include the SESAMI, CISOC-SES, LSD, COCON and LUCY systems. These systems have previously demonstrated the possibility of elucidating structures common to organic chemistry utilizing 1H-1H COSY-connectivities, one-bond and long-range 1H-13C correlations. These systems have paved the way for the development of the most effective strategies for the application of expert systems.

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Section: Sesami-cmentioning

confidence: 99%

Section: Sesami-hmentioning

confidence: 99%

Section: Houdini Accepts a Set Of Structural Inferences From Interprementioning

confidence: 99%

Section: Houdini Accepts a Set Of Structural Inferences From Interprementioning

confidence: 99%

Section: The Expert System Cisoc-sesmentioning

confidence: 99%

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CASE 2D NMR-based Expert Systems

2011

Contemporary Computer-Assisted Approaches to Molecular Structure Elucidation

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A systematic approach for the generation and verification of structural hypotheses

Elyashberg¹,

Blinov²,

Williams³

2009

Magnetic Reson in Chemistry

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During the process of molecular structure elucidation the selection of the most probable structural hypothesis may be based on chemical shift prediction. The prediction is carried out using either empirical or quantum-mechanical (QM) methods. When QM methods are used, NMR prediction commonly utilizes the GIAO option of the DFT approximation. In this approach the structural hypotheses are expected to be investigated by scientist. In this article we hope to show that the most rational manner by which to create structural hypotheses is actually by the application of an expert system capable of deducing all potential structures consistent with the experimental spectral data and specifically using 2D NMR data. When an expert system is used the best structure(s) can be distinguished using chemical shift prediction, which is best performed either by an incremental or neural net algorithm. The time-consuming QM calculations can then be applied, if necessary, to one or more of the 'best' structures to confirm the suggested solution.

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Enhancing computer‐assisted structure elucidation with DFT analysis of J‐couplings

Buevich

Elyashberg²

2020

Magnetic Reson in Chemistry

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Computer-assisted structure elucidation (CASE) is the class of expert systems that derives molecular structures primarily from one-dimensional and twodimensional nuclear magnetic resonance data. Contemporary CASE systems, including Advanced Chemistry Development/Structure Elucidator (ACD/SE), consider cross-peaks in heteronuclear multiple bond coherence (HMBC) and correlation spectroscopy (COSY) spectra as two-or three-bond correlations by default. However, four and more bond correlations (nonstandard correlations [NSCs]) could be present in these spectra too. The indiscriminate addition of NSCs to the CASE computations is prohibitively expensive. To address this problem, the ACD/SE program performs a logical analysis of observed correlations and determines the minimum number of NSCs. Guided by this information, a more efficient fuzzy structure generation (FSG) algorithm is subsequently applied. Until now, the FSG algorithm was utilized without any verification of the reliability of found NSCs. Here, we report a verification method for NSCs based on the relationship between NSCs and J-couplings computed with high accuracy density functional theory (DFT) methods. We used the example of strychnine to show that 41 (32%) of 8-Hz HMBC crosspeaks were NSCs and were consistent with 4-6 J CH couplings greater than 0.3 Hz. This cutoff value was largely confirmed by the analysis of NSCs in 11 realworld natural products elucidated by ACD/SE. Additionally, utilizing the example of the CASE study of cleospinol A, we showed that the DFT-computed J-couplings of NSCs can distinctively differentiate the correct structure among six proposed isomers. The proposed approach of NSC verification should further improve the robustness of CASE analysis and can help reveal potential problems with reported experimental data.

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Applications of a HOUDINI-Based Structure Elucidation System

Cited by 19 publications

References 11 publications

CASE 2D NMR-based Expert Systems

CASE 2D NMR-based Expert Systems

A systematic approach for the generation and verification of structural hypotheses

Enhancing computer‐assisted structure elucidation with DFT analysis of J‐couplings

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