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Organic & Biomolecular Chemistry
3J = 6.8, 7′′-CH3). 13C NMR (75 MHz, acetone-d6): δ 178.1 (4′-C), (6′-C), 116.1 (4a′-C), 110.8 (3′-C), 102.7 (8′-C), 51.6 (1-OCH3),
170.4 (1-C), 167.4 (2′-C), 160.8 (7′-C), 159.4 (8a′-C), 138.0 (5′-C), 40.9 (2-CH2), 34.1, 31.9, 27.1, 23.0, 14.2 (5′′-CH3). ESI-MS: 305
117.6 (6′-C), 115.3 (4a′-C), 109.9 (3′-C), 101.8 (8′-C), 59.6 (1- (10, [M + H]+), 273 (100), 245 (60). HRESI-MS: Found m/z of
OCH2CH3), 40.3 (2-CH2), 33.2 (1′′-CH2), 31.5, 28.7, 26.5, 22.4, 305.1385 (calculated for C17H21O5 [M + H]+ 305.1389). IR
13.7, 13.4. ESI-MS: 347 (20, [M + H]+), 301 (100), 273 (25). (νmax): 3385, 1698, 1572. UV (CH3OH) λmax (log ε): 215 (4.17),
HRESI-MS: Found m/z of 347.1856 (calculated for C20H27O5 [M 242 (4.03), 250 (4.05), 290 (3.87).
+ H]+ 347.1858). IR (νmax): 3334, 1623, 1594. UV (CH3CH2OH)
λmax (log ε): 220 (4.23), 242 (4.19), 250 (4.21), 291 (4.06).
2-(2-Heptyl-7-methoxy-4-oxochroman-5-yl)acetic acid (15)
To a solution of 11 (100 mg, 0.290 mmol) in methanol (20 mL)
was added 1 M NaOH until the solution became slightly
Methyl 2-(2-pentyl-7-methoxy-4-oxochroman-5-yl)acetate (12)
Prepared in an analogous manner to 11 substituting hexanal cloudy. Methanol was then added until the solution returned
for octanal. The title compound was obtained as an amor- to translucency. The reaction was then heated to reflux for
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phous solid (72%). H NMR (300 MHz, CDCl3): δ 6.39 (1H, d, 16 hours, at which time it was cooled to room temperature
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3
4J = 2.5, 6′-H), 6.34 (1H, d, J = 2.5, 8′-H), 4.39 (1H, dddd, J = and diluted with water. The solution was washed with CH2Cl2
2
4.1, 4.7, 7.3, 11.6, 2′-H), 3.96 (1H, d, J = 16.6, 2-HA), 3.88 (1H, and the aqueous layer was then acidified to pH 1 with 5 M
d, J = 16.6, 2-HB), 3.81 (3H, s, 5′-OCH3), 3.70 (3H, s, 1-OCH3), HCl. After extraction with CH2Cl2 the organic layer was dried
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2
3
2
2.62 (1H, dd, J = 16.5, J = 11.6, 3′-HA), 2.54 (1H, dd, J = 16.5, with MgSO4, filtered and concentrated to yield a colourless
3J = 4.1, 3′-HB), 1.81 (1H, m, 1′′-HA), 1.65 (1H, m, 1′′-HB), amorphous solid (96%, 93.0 mg). 1H NMR (300 MHz, CDCl3): δ
1.5–1.1 (6H, m, 2′′-4′′-CH2), 0.90 (3H, t, 3J = 6.6, 5′′-CH3). 13C 6.46 (1H, d, J = 2.3, 6′-H), 6.40 (1H, d, 4J = 2.3, 8′-H), 4.42 (1H,
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NMR (75 MHz, CDCl3): δ 192.5 (4′-C), 171.8 (1-C), 165.1 (7′-C), m, 2′-H), 3.96 (1H, d, 2J = 15.8, 2-HA), 3.90 (1H, d, 2J = 15.8,
164.5 (8a′-C), 138.4 (5′-C), 113.9 (6′-C), 113.4 (4a′-C), 100.4 2-HB), 3.83 (3H, s, 5′-OCH3), 2.76–2.58 (2H, m, 3′-HA & 3′-HB),
(8′-C), 77.6 (2′-C), 55.6 (7′-OCH3), 51.9 (1′-OCH3), 43.6 (2-CH2), 1.83 (1H, m, 1′′-HA), 1.69 (1H, m, 1′′-HB), 1.48 (2H, m, 2′′-CH2),
41.2 (3′-CH2), 34.9, 31.6, 24.6, 22.6, 14.1 (5′′-CH3). ESI-MS: 343 1.4–1.2 (8H, m, 3′′-6′′-CH2), 0.89 (3H, t, 3J = 7.1, 7′′-H). 13C NMR
(100, [M + Na]+), 289 (60). HRESI-MS: Found m/z of 343.1522 (75 MHz, CDCl3): δ 193.5 (4′-C), 175.6 (1-C), 165.3 (7′-C), 164.9
(calculated for C18H24O523Na [M + Na]+ 343.1521). IR (νmax): (8a′-C), 137.8 (5′-C), 114.1 (6′-C), 113.2 (4a′-C), 100.6 (8′-C), 77.7
2933, 1725, 1601.
(2′-C), 55.7 (7′-OCH3), 43.5 (2-CH2), 41.4 (3′-CH2), 34.9, 31.8,
29.4, 29.2, 24.9, 22.7, 14.1 (7′′-CH3). ESI-MS: 357 (100, [M +
Na]+), 335 (20, [M + H]+). HRESI-MS: Found m/z of 335.1859
(calculated for C19H27O5 [M + H]+ 335.1858). IR (νmax): 2917,
Methyl 2-(2-pentyl-7-methoxy-4-oxo-4H-chromen-5-yl)acetate
(14)
Prepared in an analogous manner to 13. The title compound 1698, 1605.
was obtained as an amorphous solid (89%). 1H NMR
(300 MHz): δ 6.77 (1H, d, J = 2.5, 8′-H), 6.68 (1H, d, J = 2.5,
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2-(2-Heptyl-7-methoxy-4-oxo-4H-chromen-5-yl)acetic acid (16)
6′-H), 6.00 (1H, s, 3′-H), 4.14 (2H, s, 2-CH2), 3.87 (3H, s, 7′-OCH3), Prepared in an analogous manner to 13. Purified via reverse
3.71 (3H, s, 1-OCH3), 2.52 (2H, t, 3J = 7.5, 1′′-CH2), 1.69 (2H, m, phase ODS column chromatography using 40% acetonitrile in
2′′-CH2), 1.4–1.1 (6H, m, 2′′-4′′-CH2), 0.90 (3H, t, 3J = 6.6, 5′′- water (Rf = 0.1). The title compound was obtained as an amor-
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CH3). 13C NMR (75 MHz, CDCl3): δ 179.3 (4′-C), 171.9 (1-C), phous solid (73%). H NMR (300 MHz, CDCl3): δ 6.91 (1H, d,
167.9 (2′-C), 162.6 (7′-C), 159.7 (8a′-C), 137.2 (5′-C), 122.0 (6′-C), 4J = 1.9, 8′-H), 6.83 (1H, d, 4J = 1.9, 6′-H), 6.19 (1H, s, 3′-H), 4.12
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117.6 (4a′-C), 110.7 (3′-C), 100.0 (8′-C), 55.7 (7′-OCH3), 51.9 (2H, s, 2-CH2), 3.89 (3H, s, 7′-OCH3), 2.61 (2H, t, J = 7.5, 1′′-
(1-OCH3), 41.0 (2-C), 33.8, 31.2, 26.5, 22.4, 14.0 (5′′-C). ESI-MS: CH2), 1.72 (2H, m, 2′′-CH2), 1.45–1.20 (8H, m, 3′′-6′′-CH2), 0.88
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341 (100, [M + Na]+), 287 (60). HRESI-MS: Found m/z of (3H, t, J = 6.8, 7′′-CH3). 13C NMR (100 MHz, CDCl3): δ 181.2
341.1364 (calculated for C18H22O523Na [M + Na]+ 341.1365). IR (4′-C), 172.1 (1-C), 170.0 (2′-C), 163.5 (7′-C), 160.1 (8a′-C), 136.3
(νmax): 1649, 1607.
(5′-C), 118.2 (6′-C), 115.5 (4a′-C), 110.3 (3′-C), 100.7 (8′-C), 56.0
(7′-OCH3), 42.3 (2-CH2), 34.0 (1′′-CH2), 31.7, 29.0, 29.0, 26.8,
22.7, 14.1 (7′′-CH3). ESI-MS: 333 (100, [M + H]+), 289 (70).
HRESI-MS: Found m/z of 333.1700 (calculated for C19H25O5
Pestalotiopsone F: methyl 2-(2-pentyl-7-hydroxy-4-oxo-4H-
chromen-5-yl)acetate (4)
Prepared in an analogous manner to 1. The title compound [M + H]+ 333.1702). IR (νmax): 2912, 1653, 1606.
was obtained as an amorphous white solid (85%). Purity was
confirmed via HPLC on a phenomenex LUNA 5μ C18 analytical
Pestalotiopsone C: 2-(2-heptyl-7-hydroxy-4-oxo-4H-chromen-5-
yl)acetic acid (3)
column using 70% methanol in water as solvent with a flow
rate of 1.5 mL min−1 resulting in a retention time of 8.34 min. To a solution of 1 (20.0 mg, 60.0 μmol) in THF (1 mL) was
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1H NMR (300 MHz, acetone-d6): δ 6.82 (1H, d, J = 2.4, 8′-H), added water (5 mL) and H2SO4 (3 drops). The solution
6.76 (1H, d, 4J = 2.4, 6′-H), 5.94 (1H, s, 3′-H), 4.11 (2H, s, was heated to reflux and stirred for 16 hours. The reaction was
2-CH2), 3.60 (3H, s, 1-OCH3), 2.59 (2H, t, 1′′-CH2), 1.72 (2H, m, cooled to room temperature and extracted with EtOAc. The
2′′-CH2), 1.4–1.2 (4H, m, 3′′-4′′-CH2), 0.90 (3H, t, 3J = 7.0, 5′′- organic layer was dried with MgSO4, filtered and concentrated
CH3). 13C NMR (75 MHz, acetone-d6): δ 179.1 (4′-C), 171.9 (1- in vacuo to yield the title compound as a colourless amorphous
C), 168.4 (2′-C), 161.7 (7′-C), 160.4 (8a′-C), 138.8 (5′-C), 118.6 solid (99%, 18.9 mg). Purity was confirmed via HPLC on a
1114 | Org. Biomol. Chem., 2013, 11, 1109–1115
This journal is © The Royal Society of Chemistry 2013