¹³C NMR of lapachol and some related naphthoquinones

Abstract

13C NMR chemical shift assignments for lapachol and nine related naphthoquinones have been measured and interpreted. Data, based on the results of a number of 1D and 2D experiments performed at 9.4 T, correct several previously reported assignments for some of these compounds.

Growth Inhibitory Activity of Extracted Material and Isolated Compounds from the Fruits ofKigelia pinnata

“…The 1 H-NMR spectra of the identified compounds (1-6, l " Fig. 2) were consistent with those previously reported [17][18][19][20][21][22][23][24][25][26][27][28].…”

“…Concentration of the appropriate fractions gave 2-(1-hydroxyethyl)-naphtho[2,3-b]furan-4,9-dione (16); yield: 109 mg, yellow solid. The 1 H-NMR spectrum was consistent with previously reported data[23][24][25][26][27][28].…”

A Pimarane Diterpene and Cytotoxic Angucyclines from a Marine-Derived Micromonospora sp. in Vietnam’s East Sea

“…An HMBC correlation observed between aromatic hydrogen H-11 and the carbonyl C-12 was critical to establishment of the phenol position relative to the central quinone ring. The positions of the C-7 and C-12 relative to the oxygenated carbon at C-6a were based on comparison to previously reported 13 C chemical shift values of similarly substituted paraquinones [ 16 , 17 ]. The 1-OH peri-proton showed HMBC correlations to C-1, C-12b, and C-2, providing evidence for connectivity of the hydroxy group to C-1.…”

Antitumour activity of 3-chlorodeoxylapachol, a naphthoquinone from Avicennia germinans collected from an experimental plot in southern Florida

“…The 1 H and 13 C NMR resonances of 3-chlorodeoxylapachol were consistent with those of deoxylapachol (Perry et al 1991), with the exception of those associated with C-3, which in 3-chlorodeoxylapachol was a quaternary carbon at C ¼ 142.82, compared with C ¼ 134.66 for the olefinic methine C-3 in deoxylapachol. In contrast, the chemical shift for a hydroxy substituent in this position is C ¼ 152.67 (Dawson et al 1989). EIMS gave ions at m/z ¼ 260 (molecular ion), 262 (M þ 2 isotope peak) and 225 (M À 35, base peak), consistent with the presence of chlorine in the molecule, and the molecular formula C 15 H 13 ClO 2 was confirmed by HRCIMS (m/z ¼ 260.0612, calculated for C 15 H 13 ClO 2 , 260.0604).…”