p-Terphenyl- and Phenanthraquinone Derivatives: An NMR Study

Abstract

(1)H- and (13)C-NMR spectral data are presented for six p-terphenylquinone derivatives (and for two monosubstituted quinones 1 and 2, used as model compounds) and for 9,10-phenanthraquinone and retenequinone. The chemical shifts were confirmed through correlation spectroscopy and NOE measurements.

Cytotoxic Terphenyl Neolignans from Fungus Terana coerulea: New Natural Corticins D and E, and Revised Structure for Corticin A

“…Thus, the column chromatography (CC) of the EtOAc extract on silica gel led to the isolation of the compound 8 and some fractions where it was accompanied with its analogues 9 and 10. [11] but in its p-quinol or leuco-form as occurs with corticin A described by Briggs et al [6]. This structure was confirmed by two-dimensional NMR experiments performed in the present work and also by comparison with other natural products described in the literature as candidusins [12].…”

Terphenylquinone Inhibitors of the Src Protein Tyrosine Kinase fromStilbellasp.

“…According to the information obtained from HRESIMS and from 1 H and 13 C NMR spectroscopy, compound 1 was identified as the already known 2,5-dihydroxy-3,6-diphenyl-1,4-benzoquinone. , Similarly, the identity of compound 2 with the previously described 2,5-dihydroxy-3-(4-hydroxyphenyl)-6-phenyl-1,4-benzoquinone (= ascocorynin) , was verified by NMR spectroscopic analysis. Interestingly, the 13 C NMR spectra of 1 and 2 showed at 303 K in DMSO- d 6 a broadened resonance at δ 168.…”

“…Compound 1 exhibited spectral data (UV, IR, 1 H NMR, 13 C NMR, and EIMS) comparable to published values. 11,12 2,5-Dihydroxy-3-(4-hydroxyphenyl)-6-phenyl-1,4-benzoquinone (2): green solid; HPLC (analytical system 1) tR 12.8 min; 13 6). An excess of o-phenylenediamine (45 mg) was added to a solution of 3 (33 mg, 0.10 mmol) in HOAc (9 mL).…”

Elucidation of the Biosynthesis and Degradation of Allantofuranone by Isotopic Labelling and Fermentation of Modified Precursors

“…This tautomerization occurs very rapidly, with the four oxygenated carbons in the quinone coalescing in the 13 C NMR spectrum and forming a single broad signal. [9] The postulated oxidative ring cleavage of polyporic acid (6) yields a product similar to the seco-precursor of 6 existing in the form of two different isotopomers and ultimately leads to allantofuranone with the observed labelling pattern.…”