Elucidation of the structure of quindolinone, a minor alkaloid of cryptolepis sanguinolenta : Submilligram 1 H‐ 13 c and 1 H‐ 15 N 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 (5 H , 10 H ‐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 1 H‐ 15 N onebond heteronuclear shift correlation (HMQC) data, were recorded on an 800 μg sample of the alkaloid dissolved in 140 μl of 100% d 6 ‐DMSO using a 400 MHz spectrometer.