Journal of Natural Products
Article
21), 7.39−7.43 (1H, m, H-19), 7.29−7.34 (2H, m, H-18, H-20), 5.09
(1H, d, J = 11.0 Hz, H-6), 3.14−3.19 (1H, m, H-1), 2.58 (1H, dd, J =
19.9, 2.43 Hz, Hα-2), 2.46 (1H, dd, J = 20.1, 5.3 Hz, Hβ-2), 2.27−2.34
(1H, m, H-7), 2.03−2.11 (2H, m, Hβ-8, H-9), 1.82 (1H, s, H-15),
1.73−1.81 (1H, m, H′-9), 1.56−1.64 (1H, m, H-8α), 1.54 (1H, s, H-
13), 0.89 (1H, s, H-14); 13C NMR (CDCl3, 125 MHz) δ 207.9 (C-3),
174.7 (C-12), 161.6 (C-5), 143.3 (C-4), 138.2 (C-17, C-21), 130.0
(C-19), 129.1 (C-18, C-20), 123.8 (C-16), 79.1 (C-6), 74.1 (C-10),
52.1 (C-7), 50.4 (C-11), 50.3 (C-1), 45.0 (C-9), 37.1 (C-2), 23.5 (C-
8), 21.8 (C-13), 21.0 (C-14), 9.3 (C-15). It was not possible to assign
the orientation of H-9. HRESIMS m/z 443.0715 [M + Na]+ (calcd
for C21H24NaO4Se, 443.0738). According to GP3 (pathway C),
phenylselenosantonin 12 (200 mg, 0.50 mmol) was treated with
glacial HOAc (60 mL) and H2O (30 mL) to give the target product
as a pale yellow solid (85.7 mg, 0.20 mmol) in 58% yield.
ASSOCIATED CONTENT
* Supporting Information
The Supporting Information is available free of charge on the
■
S
NMR spectra of sesquiterpene lactones 10, 15, and 17−
19, crystal structures of 12, and additional bioassay data
X-ray crystallographic data (CIF)
AUTHOR INFORMATION
Corresponding Author
*Tel: +34.956012770. Fax: +34.956 016288. E-mail:
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( 3 a S , 9 b S ) - 6 , 9 - D i m e t h y l - 3 - m e t h y l e n e - 3 , 3 a , 4 , 5 -
tetrahydroazuleno[4,5-b]furan-2,8(7H,9bH)-dione (17). According
to GP4 (pathway B), isophotosantonin derivate 14 (100 mg, 0.38
mmol) was treated with concentrated sulfuric acid (10 mL) to give
conjugated diene 17 (93 mg, 0.38 mmol) as a colorless oil in
ORCID
quantitative yield: [α]20 −0.3 (c 0.5, CH3Cl); IR νmax (thin film)
D
3267, 3193, 2973, 2932, 1770, 1747, 1703, 1699, 1633, 1446, 1381,
́
1
1315, 1221, 1090, 753 cm−1; H NMR (CDCl3, 500 MHz) δ 6.28
(1H, d, J = 3.5 Hz, H-13b), 5.57 (1H, d, J = 3.5 Hz, H-13a), 5.30
(1H, d, J = 10.5 Hz, H-6), 3.01−3.09 (1H, m, H-7), 2.94 (2H, s, H-
2), 2.58−2.67 (1H, m, H-9), 2.35−2.44 (1H, m, H-8), 2.24−2.30
(1H, m, H′-9), 2.03 (1H, s, H-15), 1.89 (1H, s, H-14), 1.82−1.88
(1H, m, H′-8); 13C NMR (CDCl3, 125 MHz) δ 208.0 (C-3), 168.9
(C-12), 161.0 (C-5), 138.9 (C-11), 138.5 (C-4), 132.7 (C-10), 130.1
(C-1), 121.1 (C-13), 79.5 (C-6), 43.8 (C-7), 40.0 (C-2), 31.3 (C-9),
26.2 (C-8), 24.4 (C-14), 9.4 (C-15); HRESIMS m/z 267.0985 [M +
Na]+(calcd for C15H16NaO3, 267.0997).
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
This research was supported by the Ministerio de Ciencia y
Competitividad, Spain (Project No. AGL2017-88083-R).
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■
(3S,3aR,9bS)-3,6,9-Trimethyl-3-(phenylselenyl)-3,3a,4,5-
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D
1
CHCl3); H NMR (CDCl3, 500 MHz) δ 7.63 (2H, dd, J = 8.1, 1.3
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̌
́
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1
mg): [α]20 +26 (c 1, CHCl3); H NMR (CDCl3, 500 MHz) δ 7.65
D
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(3H, s, H-11), 2.01−2.09 (1H, m, H-8), 2.01 (3H, s, H-15), 1.79−
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199.1 (C-3), 198.2 (C-1), 175.0 (C-13), 159.7 (C-5), 151.4 (C-4),
138.3 (C-17, C-21), 130.1 (C-19), 129.3 (C-18, C-20), 124.1 (C-16),
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G
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