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Ormula was determined as C13H18O4 via HRESIMS, establishing an index of hydrogen deficiency of five. The NMR data recommended structural similarity with compound 1. On the other hand, compound two lacked the olefinic proton at H six.90, which was replaced by 3 aliphatic protons (H 1.79, two.43, and two.91). These data suggested a distinction between 1 and 2 of a double bond, as supported by a two amu difference inside the HRMS data. The 1H NMR information of two revealed the presence of 4 olefinic protons, corresponding to two trans-disubstituted olefins (H five.52, ddq, J = 15.5, eight.0, 1.7; five.55, ddq, J = 15.5, five.2, 1.7; 5.91, dqd, J = 15.5, 6.9, 1.7; and five.99, dq, J = 15.five, 6.9, for H-1, H-1, H-2, and H-2, respectively), four oxymethines (H 3.48, dd, J = 12.0, eight.6; 3.84, bq, J = 2.9; four.03, ddd, J = 5.2, two.9, 1.7; and 4.67, dd, J = eight.six, eight.0, for H-7a, H-3, H-2, and H-7, respectively), one particular methine (H two.91, ddd, J = 12.six, 12.0, three.four, for H-4a), 1 methylene (H 1.79, ddd, J = 13.two, 12.six, two.9; and two.43, ddd, J = 13.two, three.4, two.9, for H-4 and H-4, respectively), two equivalent methyls (H 1.77, dd, J = 6.9, 1.7, for H-3 and H-3), and one exchangeable proton (H 1.84, for 3-OH). The 13C NMR data revealed 13 carbons, constant with the HRMS data and indicative of one particular carbonyl (C 173.5 for C-5), four olefinic carbons (C 125.7, 126.four, 130.six, and 134.three, for C-1, C-1, C-2, and C-2, respectively), five methines (C 39.0, 66.three, 81.2, 82.1, and 82.four for C-4a, C-3, C-2, C-7a, and C-7, respectively), one particular methylene (C 30.0 for C-4), and two methyls (C 18.1 and 18.two for C-3 and C-3, respectively) (see Supplementary Figures S3 and S4 for the 1H and 13C NMR spectra and Table S1). The two double bonds plus the carbonyl group accounted for 3 degrees of unsaturations, leaving the remaining two accommodated by the bicyclic ring program. COSY data identified one particular spin technique as H3-3/H-2/H-1/H-2/ H-3/H2-4/H-4a/H-7a/H-7/H-1/H-2/H3-3 (Figure 2a). The following essential HMBC PPAR╬▓/╬┤ review correlations were observed: H3-3C-1, H3-3C-1, H-2C-2, H-7C-2, H-3C-4a, H-7aC-4, Cyclin G-associated Kinase (GAK) Inhibitor web H-4aC-7, and H-4aC-5 (Figure 2a). NOESY correlations from H-1 to H-7a, from H-7a to H-2, and from H-2 to H-3 and H-2 indicated that H-1, H-7a, H-2, H-3, and H-2 were all around the similar face. Alternatively, NOESY correlations observed from H-4a to H-7 indicated that these two protons had been around the identical side with the molecule but opposite for the previous set (Figure 2b). Comparing all of these data with these for 1 yielded the structure of two (Figure 1), which was ascribed the trivial name transdihydrowaol A. The absolute configuration of two was assigned by way of a modified Mosher’s ester strategy,17 establishing the configuration as 2R, 3R, 4aR, 7S, and 7aR (Figure three).18 Compound 3 (1.45 mg) was obtained as a colorless oil.19 The molecular formula was determined as C13H18O4 through HRESIMS, and was precisely the same as compound 2. The NMR data (Table S1 and Figures S5 and S6) suggested structural similarity with 2. Key differences were a coupling continual of 0.6 Hz among H-4a (H two.58, ddd, J = 7.five, 2.3, 0.6) and H-7a (H 4.17, dd, J = four.six, 0.six) in 3 vs 12 Hz in 2, and a NOESY correlation from H-4a to H-7a in three vs H-4a to H-7 in 2 (Figure 2d). These data implied a pseudoaxial/pseudoequatorial cis orientation of H-4a/H-7a. NOESY correlations had been also observed from H-2 to H-7a and H-4a, and from H-4a to H-3, indicating that these protons were on the same face (FigureTetrahedron Lett. Author manuscript; readily available in PMC 2014 August 07.NIH-PA Author Manuscript NIH-PA Author Manuscript NIH-P.

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Author: Potassium channel