Holland Darren C, Carroll Anthony R
School of Environment and Science, Griffith University, Nathan, QLD 4111, Australia.
Griffith Institute for Drug Discovery, Griffith University, Nathan, QLD 4111, Australia.
Molecules. 2024 Jan 25;29(3):594. doi: 10.3390/molecules29030594.
NMR fingerprints are valuable tools for analyzing complex natural product mixtures and identifying incorrectly assigned structures in the literature. Our diagnostic NMR fingerprints for formyl phloroglucinol meroterpenoids revealed discrepancies in the structures reported for eucalyprobusal C () and eucalypcamal K (). NMR fingerprinting PCA analyses identified as an oxepine-diformyl phloroglucinol and as an oxepine 3-acyl-1-formyl phloroglucinol, contrary to their initial assignments as pyrano-diformyl and pyrano 3-acyl-1-formyl phloroglucinols, respectively. Extensive reinterpretation of their reported one- and two-dimensional NMR data, coupled with GIAO DFT-calculated H and C NMR chemical shift and DP4+ analyses, supported the unequivocal reassignment of eucalyprobusal C to and eucalypcamal K to . The absolute configurations of the revised oxepine-containing phloroglucinol meroterpenoids were confirmed via the reinterpretation of their reported ROESY and NOESY NMR data, along with comparative TDDFT-calculated and experimental ECD spectra.
核磁共振指纹图谱是分析复杂天然产物混合物以及识别文献中错误归属结构的宝贵工具。我们针对甲酰基间苯三酚半萜类化合物的诊断性核磁共振指纹图谱揭示了文献中报道的桉叶原丁素C（）和桉叶卡马酚K（）结构存在差异。核磁共振指纹图谱主成分分析确定为氧杂环庚三烯二甲酰基间苯三酚，为氧杂环庚三烯3-酰基-1-甲酰基间苯三酚，这与它们最初分别归属为吡喃二甲酰基和吡喃3-酰基-1-甲酰基间苯三酚的归属相反。对其报道的一维和二维核磁共振数据进行广泛的重新解读，结合GIAO DFT计算的氢和碳核磁共振化学位移以及DP4+分析，支持将桉叶原丁素C明确重新归属为，将桉叶卡马酚K重新归属为。通过重新解读其报道的ROESY和NOESY核磁共振数据，以及比较TDDFT计算和实验ECD光谱，确定了修订后的含氧杂环庚三烯间苯三酚半萜类化合物的绝对构型。
