Ormula was determined as C13H18O4 via HRESIMS, establishing an index of hydrogen deficiency of 5. The NMR information suggested structural similarity with compound 1. On the other hand, compound two lacked the olefinic proton at H 6.90, which was replaced by three aliphatic protons (H 1.79, two.43, and two.91). These data suggested a difference involving 1 and 2 of a double bond, as supported by a two amu distinction within the HRMS data. The 1H NMR information of 2 revealed the presence of four olefinic protons, corresponding to two trans-disubstituted olefins (H five.52, ddq, J = 15.5, 8.0, 1.7; 5.55, ddq, J = 15.5, five.two, 1.7; 5.91, dqd, J = 15.five, six.9, 1.7; and 5.99, dq, J = 15.five, 6.9, for H-1, H-1, H-2, and H-2, respectively), 4 oxymethines (H 3.48, dd, J = 12.0, 8.6; 3.84, bq, J = two.9; 4.03, ddd, J = 5.two, 2.9, 1.7; and four.67, dd, J = eight.six, eight.0, for H-7a, H-3, H-2, and H-7, respectively), one methine (H 2.91, ddd, J = 12.six, 12.0, three.four, for H-4a), one methylene (H 1.79, ddd, J = 13.two, 12.6, two.9; and 2.43, ddd, J = 13.2, 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 1 exchangeable proton (H 1.84, for 3-OH). The 13C NMR data revealed 13 carbons, consistent using the HRMS data and indicative of one particular carbonyl (C 173.5 for C-5), 4 olefinic carbons (C 125.7, 126.4, 130.six, and 134.3, for C-1, C-1, C-2, and C-2, respectively), five methines (C 39.0, 66.3, 81.2, 82.1, and 82.four for C-4a, C-3, C-2, C-7a, and C-7, respectively), one 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 as well as the carbonyl group accounted for three degrees of unsaturations, leaving the remaining two Caspase 12 Purity & Documentation accommodated by the bicyclic ring system. COSY information identified 1 spin method 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 crucial HMBC correlations have been observed: H3-3C-1, H3-3C-1, H-2C-2, H-7C-2, H-3C-4a, H-7aC-4, 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 had been all on the same face. Alternatively, NOESY correlations observed from H-4a to H-7 indicated that these two protons have been on the similar side of the BACE1 Gene ID molecule but opposite towards the preceding set (Figure 2b). Comparing all of these data with those for 1 yielded the structure of two (Figure 1), which was ascribed the trivial name transdihydrowaol A. The absolute configuration of 2 was assigned by way of a modified Mosher’s ester technique,17 establishing the configuration as 2R, 3R, 4aR, 7S, and 7aR (Figure three).18 Compound three (1.45 mg) was obtained as a colorless oil.19 The molecular formula was determined as C13H18O4 by means of HRESIMS, and was exactly the same as compound two. The NMR information (Table S1 and Figures S5 and S6) recommended structural similarity with 2. Key differences have been a coupling continual of 0.6 Hz in between H-4a (H 2.58, ddd, J = 7.five, 2.3, 0.six) and H-7a (H 4.17, dd, J = 4.six, 0.6) in three vs 12 Hz in two, plus 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 those protons were on the identical face (FigureTetrahedron Lett. Author manuscript; offered in PMC 2014 August 07.NIH-PA Author Manuscript NIH-PA Author Manuscript NIH-P.
