Elucidation of the structure of quindolinone, a minor alkaloid of cryptolepis sanguinolenta: Submilligram ¹H‐¹³c and ¹H‐¹⁵N heteronuclear shift correlation experiments using micro inverse‐detection

Elucidation of minor natural product structures has been significantly augmented by inverse‐detection; further improvement has been afforded by the development of micro inverse‐detection probes. We report here the elucidation of the structure of a new alkaloid, quindolinone (5H, 10H‐indolo[3,2‐b]quinolin‐11‐one), from the West African plant Cryptolepis sanguinolenta. All nmr data for this minor, preparative hplc‐isolated alkaloid, including 1H‐15N onebond heteronuclear shift correlation (HMQC) data, were recorded on an 800 μg sample of the alkaloid dissolved in 140 μl of 100% d6‐DMSO using a 400 MHz spectrometer. Copyright © 1995 Journal of Heterocyclic Chemistry