S. Kumar Das, S. Kumar Das, G. Panda
FULL PAPER
–101.2 (c = 0.74, CH3OH). Rf = 0.50 (60% EtOAc/hexane). 1H
NMR (300 MHz, CDCl3, 25 °C): δ = 7.50 (d, J = 8.2 Hz, 2 H,
ArH), 7.18 (d, J = 8.0 Hz, 2 H, ArH), 6.42 (s, 2 H, ArH), 5.05 (d,
oil. [α]2D9 = –91.8 (c = 0.12, CH3OH). Rf = 0.35 (50% EtOAc/hex-
ane). H NMR (300 MHz, CDCl3, 25 °C): δ = 6.57 (s, 2 H, ArH),
4.60 (s, 2 H), 4.40 (d, J = 5.4 Hz, 1 H), 3.94 (s, 1 H), 3.86 (s, 6 H),
1
J = 3.8 Hz, 1 H), 4.91 (d, J = 3.9 Hz, 1 H), 4.56–4.50 (m, 2 H), 3.84 (s, 3 H), 3.41 (s, 3 H), 2.05 (s, 1 H), 1.21 (d, J = 6.3 Hz, 3 H)
4.14 (q, J = 7.1 Hz, 2 H), 3.82 (s, 3 H), 3.75 (s, 6 H), 3.30 (s, 3 H),
ppm. 13C NMR (75 MHz, CDCl3, 25 °C): δ = 153.1, 137.4, 133.7,
1.20 (t, J = 7.1 Hz, 3 H) ppm. 13C NMR (75 MHz, CDCl3, 25 °C): 104.4, 94.5, 82.3, 70.6, 60.7, 56.0, 55.7, 18.4 ppm. IR (neat): ν =
˜
δ = 166.7, 152.9, 144.9, 137.7, 132.5, 130.3, 129.3, 127.5, 103.9,
3444, 1637, 1128, 770 cm–1. ESI-MS: m/z (%) = 287.2 (46) [M +
H]+, 268.3 (100) [M – H2O]+. C14H22O6 (286.32): calcd. C 58.73,
H 7.74; found C 58.81, H 7.64.
93.9, 80.7, 76.2, 62.0, 60.5, 55.7, 21.4, 13.7 ppm. IR (neat): ν =
˜
2941, 2363, 1771, 1596, 1368, 1192, 1124, 1036, 841, 553 cm–1. ESI-
MS: m/z (%) = 499.6 (100) [M + H]+. C23H30O10S (498.54): calcd.
C 55.41, H 6.07; found C 55.32, H 6.17.
Mesylate 13: To an ice-cooled solution of compound 12 (0.2 g,
0.7 mmol) in dry CH2Cl2 (5 mL), Et3N (0.3 mL, 2.1 mmol) was
added followed by methanesulfonyl chloride (0.08 mL, 1.0 mmol)
and the reaction mixture was stirred at 0 °C for 1.5 h. After com-
pletion of the reaction, water was added, organic layer was sepa-
rated and the aqueous layer was extracted thrice with CH2Cl2
(3ϫ25 mL). The combined organic layer was washed with brine
(25 mL), dried with anhydrous Na2SO4, filtered and concentrated
under reduced pressure to a yellow coloured crude product. This
crude product was purified over silica gel column (25% EtOAc/
hexane) to furnish 13 (0.24 mg, 95%) as colourless oil. [α]2D2 = –46.4
(c = 0.87, CH3OH). Rf = 0.35 (40% EtOAc/hexane). 1H NMR
(300 MHz, CDCl3, 25 °C): δ = 6.58 (s, 2 H), 4.87–4.83 (m, 1 H),
4.67 (d, J = 4.9 Hz, 1 H), 4.61 (s, 2 H), 3.86 (s, 6 H), 3.83 (s, 3 H),
3.41 (s, 3 H), 2.74 (s, 3 H), 1.44 (d, J = 5.9 4 Hz, 3 H) ppm. 13C
NMR (75 MHz, CDCl3, 25 °C): δ = 153.2, 138.0, 132.6, 104.6,
Alcohol 10: To an ice-cooled solution of compound 9 (1.0 g,
2.0 mmol) in dry THF (20 mL) in a 100 mL round-bottomed flask
fitted with a CaCl2 guard tube, 2 LiBH4 in THF (1.5 mL,
3.0 mmol) was added. The reaction mixture was allowed to stir at
the same temperature for 30 min. After completion of the reaction,
water was added to it, organic phase was separated and the aque-
ous phase was extracted thrice with EtOAc (3ϫ100 mL). The com-
bined organic layer was washed with brine (50 mL), dried with an-
hydrous Na2SO4, filtered and concentrated under vacuo to afford
white crude product. This crude product was chromatographed
over silca gel, 50% EtOAc/hexane as an eluent, to furnish the
alcohol 10 (0.85 g, 91%) as colourless oil. [α]2D9 = –81.2 (c = 1.24,
CH3OH). Rf = 0.31 (60% EtOAc/hexane). 1H NMR (300 MHz,
CDCl3, 25 °C): δ = 7.64 (d, J = 8.1 Hz, 2 H, ArH), 7.25 (d, J =
8.1 Hz, 2 H, ArH), 6.43 (s, 2 H, ArH), 4.88–4.45 (m, 5 H), 3.83 (s,
3 H), 3.78 (s, 6 H), 3.73–3.64 (m, 1 H), 3.42–3.34 (m, 1 H), 3.27 (s,
94.3, 81.4, 78.8, 60.7, 56.1, 55.8, 38.0, 16.9 ppm. IR (neat): ν =
˜
2369, 1636, 1461, 1349, 1126, 770 cm–1. ESI-MS: m/z (%) = 365.2
(100) [M + H]+. C15H24O8S (364.41): calcd. C 49.44, H 6.64; found
C 49.54, H 6.58.
3 H), 2.43 (s, 3 H) ppm. IR (neat): ν = 3661, 3633, 3449, 2926,
˜
2361, 1679, 1208, 1107, 760, 671 cm–1. ESI-MS: m/z (%) = 457.6
(100) [M + H]+. C21H28O9S (456.51): calcd. C 55.25, H 6.18; found
C 55.39, H 6.02.
Alcohol 14: To an ice-cooled solution of compound 13 (100.0 mg,
0.2 mmol) in CH3OH (2 mL), concd. HCl (0.5 mL) was added drop
by drop. The reaction mixture was heated at 50 °C for 30 min and
then it was neutralized by saturated NaHCO3 solution. The organic
layer was extracted thrice with EtOAc (3ϫ10 mL), dried with an-
hydrous Na2SO4, filtered and concentrated under reduced pressure.
The crude product was then purified (30% EtOAc/hexane) over
silica gel column to furnish 14 (74.0 mg, 85%) as colourless oil.
[α]2D2 = –8.8 (c = 0.56, CH3OH). Rf = 0.35 (50% EtOAc/hexane).
1H NMR (300 MHz, CDCl3, 25 °C): δ = 6.60 (s, 2 H), 4.92–4.88
(m, 2 H), 3.86 (s, 6 H), 3.83 (s, 3 H), 2.90 (s, 3 H), 2.33 (br., 1 H),
1.35 (d, J = 6.1 Hz, 3 H) ppm. 13C NMR (75 MHz, CDCl3, 25 °C):
δ = 153.2, 137.7, 134.6, 103.5, 83.3, 75.4, 60.8, 56.1, 38.4, 15.3 ppm.
Epoxide 11: To an ice-cooled solution of the previously prepared
alcohol 10 (1.0 g, 2.1 mmol) in dry methanol (30 mL) in a 100 mL
round-bottomed flask fitted with a CaCl2-guard tube, anhydrous
K2CO3 (580.1 mg, 4.2 mmol) was added and allowed to stir at
room temperature for 2 h. After completion of the reaction, meth-
anol was removed under reduced pressure, water was added and
aqueous part was extracted thrice with EtOAc (3ϫ100 mL). The
combined organic layer was washed with brine (50 mL), dried with
anhydrous Na2SO4, filtered and concentrated under reduced pres-
sure to a colourless residue. The crude product was purified over
silica gel column chromatography (30% EtOAc/hexane) to furnish
11 (0.56 g, 90%) as colourless oil. [α]2D9 = –44.5 (c = 0.88, CH3OH).
Rf = 0.50 (50% EtOAc/hexane). 1H NMR (300 MHz, CDCl3,
25 °C): δ = 6.60 (s, 2 H, ArH), 4.63 (dd, J1 = 12.2, J2 = 6.6 Hz, 2
H), 3.87 (s, 6 H), 3.84 (s, 3 H), 3.38 (s, 3 H), 3.17 (dd, J1 = 6.45,
J2 = 3.8 Hz, 1 H), 2.83–2.77 (m, 2 H) ppm. 13C NMR (75 MHz,
CDCl3, 25 °C): δ = 153.3, 137.8, 133.7, 104.2, 94.5, 76.6, 60.8, 56.1,
IR (neat): ν = 3434, 2360, 1218, 1127, 769 cm–1. ESI-MS: m/z. (%)
˜
= 321.1 (100) [M + H]+. C13H20O7S (320.36): calcd. C 48.74, H
6.29; found C 48.69, H 6.35.
Acylate 15: To an ice-cooled solution of compound 14 (100.0 mg,
0.3 mmol) in dry pyridine (1.0 mL), acetic anhydride (0.03 mL) was
added and the reaction mixture was stirred for 10 min. After com-
pletion of the reaction was neutralized by cold 5 HCl solution
and the aqueous phase was extracted thrice with CH2Cl2
(3ϫ10 mL). The combined organic layer was dried with anhydrous
Na2SO4, filtered and concentrated under reduced pressure. The
crude product was purified over silica gel column (35% EtOAc/
hexane) to furnish 15 (80.0 mg, 92%) as colourless oil. [α]2D2 = –40.5
(c = 0.8, CHCl3). Rf = 0.40 (50% EtOAc/hexane). 1H NMR
(300 MHz, CDCl3, 25 °C): δ = 6.52 (s, 2 H), 5.72 (d, J = 4.5 Hz, 1
H), 4.94 (qd, J1 = 6.3, J2 = 4.6 Hz, 1 H), 3.80 (s, 6 H), 3.76 (s, 3
H), 2.77 (s, 3 H), 2.09 (s, 3 H), 1.31 (d, J = 6.4 Hz, 3 H) ppm. 13C
NMR (75 MHz, CDCl3, 25 °C): δ = 169.6, 153.2, 138.1, 130.8,
55.5, 54.1, 45.2 ppm. IR (neat): ν = 3661, 3633, 3019, 2930, 2361,
˜
1679, 1214, 1104, 760, 671 cm–1. ESI-MS: m/z (%) = 285.3 (100)
[M]+. C14H20O6 (284.31): calcd. C 59.14, H 7.09; found C 59.21, H
7.02.
Alcohol 12: To an ice-cooled solution of compound 11 (0.5 g,
1.7 mmol) in dry THF (10 mL), LAH (83.6 mg, 2.2 mmol) was
added and allowed to stir at room temperature for 30 min. After
completion of the reaction, it was quenched with drop by drop
addition of cold NH4Cl solution and then the organic layer was
extracted with EtOAc (3ϫ50 mL). The combined organic layer was
washed with brine, dried with anhydrous Na2SO4, filtered and then
concentrated under reduced pressure to obtain colourless crude oil.
This crude product was purified by column chromatography (40%
ethyl acetate/hexane) to furnish 12 (463.5 mg, 92%) as colourless
104.4, 79.3, 76.0, 60.8, 56.1, 38.4, 21.0, 16.8 ppm. IR (neat): ν =
˜
2936, 2364, 1743, 1461, 1351, 1235, 1175, 1126, 927 cm–1. ESI-MS:
m/z (%) = 363.3 (100) [M + H]+. C15H22O8S (362.39): calcd. C
49.71, H 6.12; found C 49.77, H 6.09.
5104
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Eur. J. Org. Chem. 2010, 5100–5107