The impact of LR-HSQMBC very long-range heteronuclear correlation data on computer-assisted structure elucidation

Area of Science:

• Organic Chemistry
• Computational Chemistry
• Structural Biology

Background:

• Structure elucidation of complex natural products is crucial for drug discovery and chemical biology.
• Traditional methods like Heteronuclear Multiple Bond Correlation (HMBC) spectroscopy have limitations in analyzing proton-deficient molecules.
• Computer-assisted structure elucidation (CASE) programs require comprehensive input data for accurate predictions.

Purpose of the Study:

• To evaluate the utility of very long-range (n)JCH heteronuclear shift correlation data (LR-HSQMBC) as supplementary input for the Structure Elucidator(®) CASE program.
• To assess the impact of LR-HSQMBC data on the accuracy and efficiency of structure elucidation for challenging molecules.

Main Methods:

• Acquisition and analysis of LR-HSQMBC and HMBC NMR data for model compounds.
• Inclusion of LR-HSQMBC data as additional input for the Structure Elucidator(®) software.
• Comparison of structure elucidation results obtained with and without LR-HSQMBC data.

Main Results:

• LR-HSQMBC data provided valuable long-range coupling information not observed in standard HMBC spectra.
• The Structure Elucidator(®) program demonstrated improved performance and accuracy when incorporating LR-HSQMBC data.
• Successful elucidation of complex structures, including the proton-deficient xanthone antibiotic cervinomycin A2 and the alkaloid staurosporine, was achieved.

Conclusions:

• Very long-range heteronuclear shift correlation data is a powerful supplement to HMBC for computer-assisted structure elucidation.
• This approach significantly enhances the capability of CASE programs to solve complex molecular structures, particularly those with limited protonation.
• The findings pave the way for more efficient and accurate structural characterization of novel natural products and synthetic compounds.