Synthesis and Structural Revision of a Brominated Sesquiterpenoid, Aldingenin C

This paper describes a short step synthesis of the proposed structure for aldingenin C from trans-limonene oxide. The tetrahydropyran-fused 2-oxabicyclo[3.2.2]­nonane skeleton as the structural feature was constructed by an intramolecular epoxide-opening reaction and a brominative cyclization. The spectral data of the synthetic compound did not match those of the natural product reported. Re-examination of the reported NMR data using new CAST/CNMR Structure Elucidator suggests that the structure of aldingenin C should be revised to that of known caespitol.