Isolation and computer-based structural determination of madangolide b

Madangolide (1) is a 17-membered cyclic enamide isolated from the marine cyanobacterium Lyngbya bouillonii. Since its discovery in 1999, the relative and absolute configurations of 1 have remained unknown. Here, we report the isolation, structural determination, and biological activity of a new analog of madangolide (1), madangolide B (2), from a marine Moorena sp. cyanobacterium. The planar structure of 2 was established using conventional two-dimensional NMR spectroscopy. The absolute configuration was clarified by comparing the experimental and theoretical data, including the chemical shifts, homonuclear and heteronuclear coupling constants, and ECD spectra. Based on the similarity of the NMR data, we proposed an absolute configuration of madangolide (1) and verified it through degradation and derivatization reactions. This study demonstrates the effectiveness of modern computational chemistry in revealing the stereochemistry of complex natural products with conformational flexibilit..., , All NMR spectral data were recorded on a JEOL JNM-ECX-400 or a JNM-ECS-400 spectrometer., # Spectroscopic data for madangolide and madangolide B

## Description of the data and file structure

NMR data is grouped in appropriately named folders. In each folder, raw NMR data (jdf format), structure file (mol format), and a short description for the NMR device and processing software are provided. The raw NMR data can be processed by various programs, such as DELTA, provided by JEOL.

### Files and variables
File: madangolide1.zip
Description: (1) 1H NMR data for madangolide (jdf format); (2) structure file of madangolide (mol format); (3) Short description for NMR data (txt format).

File: mdaongolideB2.zip 
Description: (1) 1H NMR, 13C NMR, COSY, HMBC, HMQC, NOESY data for madangolide B (jdf format); (2) structure file of madangolide B (mol format); (3) Short description for NMR data (txt format).

Abbreviation

COSY: correlation spectroscopy, HMBC: heteronuclear multiple-bond correlation, HMQC: heteronuclear multiple-quantum correlation, NOESY: nuclear Overhauser effect spec...