Total assignment of the proton and carbon NMR spectra of the alkaloid quindoline - utilization of HMQC-TOCSY to indirectly establish protonated carbon-protonated carbon connectivities

摘要: The reisolation of the indoloquinoline alkaloid quindoline (also known as norcryptolepine) from Cryptolepis sanguinolenta is reported. structure was unequivocally confirmed by two-dimensional nmr methods; proton and carbon spectra were assigned for first time. Because congestion in spectrum HMQC-TOCSY used an alternative to more familiar COSY experiment. In addition establishing proton-proton connectivities, affords added benefit providing, indirect sense, connectivity information between protonated carbons.