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The Journal of Organic Chemistry
1.78 – 1.62 (m, 3H), 1.48 – 1.36 (m, 2H), 1.23 (dd, J = 12.5, 2.8 Hz, 1H), 0.87 (s, 6H), 0.85 (s, 3H); 13C{1H}
NMR (100 MHz, CDCl3) δ 171.1, 168.9, 160.9, 158.8, 149.4, 148.1, 122.8, 109.6, 107.3, 103.8, 80.8, 68.4,
62.7, 55.2, 54.8, 40.2, 38.2, 38.1, 36.2, 28.2, 24.3, 24.0, 21.3, 19.2, 16.5, 14.2; IR νmax (neat) 3295, 1730, 1605,
1429, 1235, 1077, 1027 cm-1; HRMS (ESI) m/z: [M + H]+ Calcd for C26H35O6 443.2434; Found 443.2434.
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((3S,4aR,6aS,13aR,13bS)-12-Methoxy-4,4,13b-trimethyl-11-oxo-6a-((phenylselanyl)methyl)-
1,3,4,4a,5,6,6a,9,11,13,13a,13b-dodecahydro-2H-benzo[a]furo[3,4-i]xanthen-3-yl acetate (29). Phenol 15
(100 mg, 0.226 mmol) in CH2Cl2 (10 mL) was added dropwise with stirring to N-(phenylseleno)phthalimide
(410 mg, 1.36 mmol) and SnCl4 (1 M in CH2Cl2; 1.13 mL, 1.13 mmol) in CH2Cl2 (20 mL) at -78 oC. After 7
h, NaOH (2 M; 1 mL) was added and the reaction mixture was filtered through Celite®. NaOH (2 M; 10 mL)
was added and the two phases were separated and the aqueous layer was extracted with CH2Cl2 (3 × 10 mL).
The combined organic layers were dried (MgSO4), filtered, concentrated and chromatographed (pentane :
Et2O 1 : 1) to provide phenylselenide 29 (79 mg, 0.132 mmol, 58%) as a colorless oil: Rf 0.26 (pentane : Et2O
1 : 1); 1H NMR (400 MHz, CDCl3) δ δ 7.45 – 7.40 (m, 2H), 7.23 – 7.16 (m, 3H), 6.39 (s, 1H), 5.09 (s, 2H),
4.53 (dd, J = 11.8, 4.6 Hz, 1H), 4.08 (s, 3H), 3.12 (d, J = 12.6 Hz, 1H), 2.95 (d, J = 12.6 Hz, 1H), 2.77 (d, J =
18.9 Hz, 1H), 2.44 (dd, J = 18.9, 8.4 Hz, 1H), 2.30 (dt, J = 14.0, 3.0 Hz, 1H), 2.05 (s, 3H), 1.94 – 1.57 (m,
7H), 1.19 (td, J = 13.2, 3.9 Hz, 1H), 1.03 (dd, J = 11.3, 2.7 Hz, 1H), 0.92 (s, 3H), 0.85 (s, 3H), 0.66 (s, 3H);
13C{1H} NMR (100 MHz, CDCl3) δ 171.0, 168.8, 160.7, 157.3, 147.4, 133.3 (2C), 130.2, 129.1 (2C), 127.3,
116.0, 108.2, 105.3, 80.4, 79.1, 68.6, 62.1, 53.9, 45.5, 38.03, 37.97, 37.8, 37.7, 37.3, 28.4, 23.4, 21.3, 17.5,
17.4, 16.8, 14.4; IR νmax (neat) 1751, 1734, 1613, 1592, 1429, 1366, 1238, 1131, 1027, 1078, 733 cm-1;HRMS
(ESI) m/z: [M + H]+ Calcd for C32H38O6Se 599.1912; Found 599.1913.
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(3S,4aR,6aS,13aR,13bS)-12-Methoxy-4,4,6a,13b-tetramethyl-11-oxo-1,3,4,4a,5,6,6a,9,11,13,13a,13b-
dodecahydro-2H-benzo[a]furo[3,4-i]xanthen-3-yl acetate (14). Phenylselenide 29 (46 mg, 0.0770 mmol),
AIBN (13 mg, 0.0770 mmol) and HSnBu3 (62 µL, 0.231 mmol) in PhH (2 mL) were purged with Ar for 5
o
min and heated to 100 C for 5 h. The reaction mixture was directly purified by chromatography (pentane :
Et2O 1 : 1) through a pad of KF to give meroterpenoid 14 (31 mg, 0.0700 mmol, 91%) as a white solid: Rf
0.29 (pentane : Et2O 1 : 1); m.p. 212 – 213 oC; 1H NMR (400 MHz, CDCl3) δ 6.50 (s, 1H), 5.13 (s, 2H), 4.49
(dd, J = 11.7, 4.7 Hz, 1H), 4.13 (s, 3H), 2.88 (d, J = 18.7 Hz, 1H), 2.71 (dd, J = 18.6, 8.0 Hz, 1H), 2.23 – 2.14
(m, 1H), 2.04 (s, 3H), 1.87 (dt, J = 13.3, 3.7 Hz, 1H), 1.74 – 1.50 (m, 5H), 1.40 (d, J = 8.1 Hz, 1H), 1.17 (s,
3H), 1.13 (dd, J = 13.4, 4.0 Hz, 1H), 1.00 (dd, J = 11.3, 2.1 Hz, 1H), 0.89 (s, 3H), 0.84 (s, 3H), 0.66 (s, 3H);
13C{1H} NMR (100 MHz, CDCl3) δ 170.9, 168.9, 161.6, 157.4, 147.4, 116.0, 107.9, 105.2, 80.5, 76.6, 68.6,
62.0, 54.2, 48.1, 40.1, 37.9, 37.8, 37.6, 28.4, 27.0, 23.4, 21.2, 17.7 (2C), 16.8, 14.3; IR νmax (neat) 1730, 1752,
1612, 1592, 1366, 1238, 1130, 1081, 1025, 901, 731 cm-1; HRMS (ES) m/z: [M + H]+ Calcd for C26H34O6
443.2434; Found 443.2419.
(3S,4aR,6aS,13aR,13bS)-8-Bromo-12-methoxy-4,4,6a,13b-tetramethyl-11-oxo-
1,3,4,4a,5,6,6a,9,11,13,13a,13b-dodecahydro-2H-benzo[a]furo[3,4-i]xanthen-3-yl acetate (30). N-
Bromosuccinimide (19 mg, 0.105 mmol) and H2SO4 (13µL,0.244 mmol) were added sequentially with stirring
to meroterpenoid 14 (31 mg, 0.0700 mmol) in THF (0.4 mL). After 17 h, saturated aqueous NaHCO3 (0.4 mL)
and Na2S2O3 (50 mg, 0.316 mmol) were added and the two phases were separated. The aqueous layer was
extracted with CH2Cl2 (3 × 0.5 mL). The combined organic layers were dried (MgSO4), filtered, concentrated
and chromatographed (pentane : Et2O 7 : 3) to provide bromide 30 (34 mg, 0.0652 mmol, 93%) as a white
foam: Rf 0.19 (pentane : Et2O 7 : 3); 1H NMR (400 MHz, CDCl3) δ 5.07 (s, 2H), 4.50 (dd, J = 11.8, 4.5 Hz,
1H), 4.15 (s, 3H), 2.90 (d, J = 18.8 Hz, 1H), 2.75 (dd, J = 18.8, 8.1 Hz, 1H), 2.38 – 2.29 (m, 1H), 2.04 (s, 3H),
1.86 (dd, J = 13.5, 3.7 Hz, 1H), 1.79 – 1.51 (m, 5H), 1.44 (d, J = 8.2 Hz, 1H), 1.19 (s, 3H), 1.17 – 1.08 (m,
1H), 1.01 (d, J = 11.0 Hz, 1H), 0.90 (s, 3H), 0.85 (s, 3H), 0.63 (s, 3H); 13C{1H} NMR (100 MHz, CDCl3) δ
170.9, 168.4, 157.4, 156.4, 146.9, 117.5, 109.2, 98.3, 80.4, 78.1, 69.3, 62.2, 54.1, 48.0, 39.9, 37.9, 37.8, 37.7,
28.4, 27.1, 23.3, 21.3, 18.3, 17.8, 16.8, 14.2; IR νmax (neat) 1759, 1733, 1603, 1465, 1436, 1366, 1246, 1135,
1029, 904, 732 cm-1; HRMS (ES) m/z: [M + H]+ Calcd for C26H34O6Br 521.1539; Found 521.1549.
(3S,4aR,6aS,13aR,13bS)-12-Methoxy-4,4,6a,8,13b-pentamethyl-11-oxo-1,3,4,4a,5,6,6a,9,11,13,13a,13b-
dodecahydro-2H-benzo[a]furo[3,4-i]xanthen-3-yl acetate (31). A degassed solution of bromide 30 (65 mg,
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