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

Abstract

<jats:title>Abstract</jats:title><jats:p>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<jats:italic>H</jats:italic>, 10<jats:italic>H</jats:italic>‐indolo[3,2‐<jats:italic>b</jats:italic>]quinolin‐11‐one), from the West African plant <jats:italic>Cryptolepis sanguinolenta.</jats:italic> All nmr data for this minor, preparative hplc‐isolated alkaloid, including <jats:sup>1</jats:sup>H‐<jats:sup>15</jats:sup>N onebond heteronuclear shift correlation (HMQC) data, were recorded on an 800 μg sample of the alkaloid dissolved in 140 μl of 100% d<jats:sub>6</jats:sub>‐DMSO using a 400 MHz spectrometer.