Unequivocal 13C NMR assignment of cyclohexadienyl rings in bromotyrosine-derived metabolites from marine sponges

John A. Kalaitzis, Rohan A. Davis, Ronald J. Quinn*

*Corresponding author for this work

Research output: Contribution to journalLetter

6 Citations (Scopus)

Abstract

Bromotyrosine-derived compounds are commonly isolated from Verongida sponges and are a major class of marine natural products. Here we report on the unequivocal 13C NMR assignment of the brominated carbons at positions C-2 and C-4 of the cyclohexadiene ring, two carbons whose resonances are often incorrectly assigned. Interpretation of HMBC data acquired for a series of known bromotyrosine analogues, which included ianthesine E (1), aerothionin (2), 11-hydroxyaerothionin (3), and 11,19-dideoxyfistularin-3 (4), allowed us to unequivocally assign the carbons in question, C-2 and C-4, through the observance of unique HMBC correlations from the C-1 hydroxyl proton. Here we present the complete 2D NMR data sets recorded in DMSO-d 6 for 2-4 that were used to confirm the assignment and establish the working model. Using this model, a survey of the literature revealed that many members of this structure class had been wrongly assigned. This paper serves to reassign those compounds whose 13C NMR assignment at positions C-2 and C-4 of the cyclohexadiene ring should be reversed.

Original languageEnglish
Pages (from-to)749-754
Number of pages6
JournalMagnetic Resonance in Chemistry
Volume50
Issue number11
DOIs
Publication statusPublished - Nov 2012
Externally publishedYes

Keywords

  • NMR
  • ¹H
  • ¹³C
  • HMBC
  • bromotyrosine-derived sponge metabolites
  • ¹³C NMR assignment of cyclohexadienyl rings
  • Verongida natural products

Fingerprint Dive into the research topics of 'Unequivocal <sup>13</sup>C NMR assignment of cyclohexadienyl rings in bromotyrosine-derived metabolites from marine sponges'. Together they form a unique fingerprint.

  • Cite this