Novel metabolites from the roots of Cadaba natalensis

•An extract of the roots of Cadaba natalensis Sond. was investigated.•A novel macrocyclic dibenzo-diazacyclododecanedione was characterized.•The absolute configuration of 2-ethyl-2-methyloxazolidin-5-one is 2S.•5-Ethyl-5-methyloxazolidin-2-one is reported as a natural product.

From an extract of the roots of Cadaba natalensis Sond. the novel macrocyclic dibenzo-diazacyclododecanedione 1 was isolated together with (S)-2-ethyl-2-methyloxazolidin-5-one (2a). In addition, the five known compounds were obtained. Of these, (R)-5-ethyl-5-methyloxazolidin-2-one (3) is reported as a natural product for the first time. The structures of the isolated compounds were elucidated by analysis of the spectral data, 1D NMR (1H, 13C, and DEPT), 2D NMR (COSY, HMQC, HMBC, and NOESY), and HRESIMS, as well as by the comparison with previously reported data.

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