11-cryptolepinyl moieties

Long-range H- C connectivity information in the phase-sensitive HMBC spectrum (Figure 5.7) allowed the assembly of the structural fragment shown by 14. The wavy lines denote the point beyond which long-range correlations could not reach. Structural fragment 14 and an 11-cryptolepinyl moiety derived from 13 account for 31 of 32 carbons in the empirical formula of the molecule. A sole... 

Cursory examination of the NMR sample, when dissolved in DMSO, allowed the deduction that an 11-cryptolepinyl moiety was contained in the structure based on the intense purple color, which is characteristic of the extended conjugation of cryptolepine. Because of the relatively small size of the sample, 100 pg, all of the NMR spectral data were recorded using a sealed sample of the degradant isolate in 150 pi of d -DMSO in a sealed 3 mm NMR tube using a 5 mm 500 MHz gradient inverse-detection triple resonance cryogenic NMR probe. 

From the start of data interpretation to the completion of the strucmre elucidation, including the quantum leap provided by the recognition that the structure contained an 11-cryptolepinyl moiety based on the observed color and then confirmed by the data assignment, a highly competent spectroscopist required 72 h to assemble the structure. Using the same data, including the CIGAR-HMBC data, which afforded correlations to... 

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