Synthesis and DFT-NMR-guided structure revision of cremenolide.

The structure of an anti-plant pathogenic and plant growth-promoting nonenolide, namely cremenolide, was revised by an efficient combination of DFT-based theoretical NMR calculations and synthesis of a target diastereomer. Initially, the planar structure of cremenolide was reconsidered by an individual analysis of the reported NMR spectra. Subsequently, the relative configuration was predicted using NMR calculations of all possible diastereomers based on the ωB97X-D functional. Finally, the relative configuration of cremenolide was unambiguously confirmed by preparation of the proposed structure.