PAPER
A Simple and Efficient Total Synthesis of a Styryllactone, 7-epi-Goniodiol
387
(10 mL) was then added and the resulting mixture was stirred vig-
orously at 0 °C for a further 30 min. The resulting mixture was vac-
uum filtered through Celite and the filter cake was washed well with
CH2Cl2. The organic phase was separated and aqueous phase was
extracted with CH2Cl2 (2 × 50 mL); the combined organic phases
were washed with brine and dried (anhyd Na2SO4). Removal of sol-
vent under reduced pressure and purification by chromatography
(silica gel) gave the epoxide 7 as a viscous liquid; yield: 2.7 g
(87%).
[a]D25 –64.12 (c 1.2, CHCl3).
IR (KBr): 3447, 2987, 1743, 1631, 1455, 1376, 1216, 1055 cm–1.
1H NMR (300 MHz, CDCl3): d = 1.51 (s, 3 H), 1.52 (s, 3 H), 3.08–
3.05 (m, 1 H), 3.18 (dd, J = 2.26, 6.04 Hz, 1 H), 3.69 (dd, J = 5.28,
8.30 Hz, 1 H), 3.92 (dt, J = 2.26, 2.08 Hz, 1 H), 4.91 (d, J = 7.55 Hz,
1 H), 7.40–7.28 (m, 5 H).
nate (1.06 g, 3.2 mmol) in anhyd THF (2 mL) was added dropwise
at 0 °C. The mixture was stirred for 30 min at this temperature and
then cooled to –78 °C and the aldehyde 9 (0.8 g, 3.2 mmol) in THF
(1 mL) was added dropwise over a period of 10 min, and the result-
ing mixture was stirred at –78 °C for 1 h. The mixture was quenched
with sat. NH4Cl and the product was extracted into Et2O (2 × 10
mL). The organic layer was dried (anhyd Na2SO4) and evaporated
in vacuo (water-bath temperature should not exceed more than
30 °C) and the product was purified using column chromatography
(silica gel) to afford Z-alkene ester 10 as light yellow liquid; yield:
0.81 g (84%).
[a]D25 +4.58 (c 1, CHCl3).
IR (KBr): 3415, 2925, 2854, 1701, 1619, 1385, 1081 cm–1.
1H NMR (200 MHz, CDCl3): d = 1.50 (s, 3 H), 1.54 (s, 3 H), 2.84–
2.62 (m, 2 H), 3.69 (s, 3 H), 3.98–3.80 (m, 2 H), 4.99 (d, J = 7.03
Hz, 1 H), 5.83 (dd, J = 1.5, 11.7 Hz, 1 H), 6.32 (dt, J = 7.8, 11.7 Hz,
1 H), 7.52–7.22 (m, 5 H).
13C NMR (75 MHz, CDCl3): d = 26.7, 26.9, 54.6, 56.4, 60.9, 77.1,
81.1, 81.7, 110.3, 126.6, 128.6, 128.5, 128.6, 137.8.
LC-MS (EI): m/z = 273 (M+ + Na).
13C NMR (75 MHz CDCl3): d = 26.6, 26.9, 32.3, 50.8, 71.1, 79.7,
84.9, 108.9, 121.4, 127.0, 127.8, 128.0, 138.3, 145.3, 166.8.
(1R)-1-[(4R,5R)-2,2-Dimethyl-5-phenyl-1,3-dioxolan-4-yl]pro-
pane-1,3-diol (8)
LC-MS (EI): m/z = 329 (M+ + Na).
To stirred soln of epoxide 7 (2 g, 8 mmol) in anhyd THF (10 mL),
Red-Al (4.5 mL, 16 mmol) was added dropwise over a period of 10
min under N2 atmosphere at –15 °C. The mixture was stirred at r.t.
for 3 h. When the reaction was complete (TLC), the mixture was
cooled to 0 °C and quenched with H2O (3 mL) and 15% NaOH soln
(3 mL). The mixture was then diluted with CH2Cl2, filtered through
Celite and washed with CH2Cl2. The organic layer was then washed
with brine, dried (Na2SO4), and evaporated under reduced pressure.
Purification by chromatography (silica gel) gave the diol 8 as a vis-
cous liquid; yield: 1.6 g (80%).
[a]D25 –11.4 (c 0.7, CHCl3).
1H NMR (300 MHz, CDCl3): d = 1.50–1.58 (m, 2 H), 1.48 (s, 3 H),
1.53 (s, 3 H), 3.67–3.81 (m, 2 H), 3.86 (dd, J = 7.9, 4.5 Hz, 1 H),
4.01–4.10 (m, 1 H), 4.95 (d, J = 8.12 Hz, 1 H), 7.27–7.47 (m, 5 H).
(6R)-6-[(1S,2R)-1,2-Dihydroxy-2-phenylethyl]-5,6-dihydro-2H-
pyran-2-one (1)
To a stirred soln of 10 (0.5 g, 1.6 mmol) in anhyd benzene (15 mL)
was added a catalytic amount of PTSA (14 mg, 0.08 mmol) under
an N2 atmosphere. The mixture was stirred at r.t. for 6 h and then the
reaction was quenched by addition of solid NaHCO3, the mixture
was filtered and the solvent was removed from the filtrate under re-
duced pressure. The residue was purified by column chromatogra-
phy to afford 1 as viscous liquid; yield: 0.27 g (73%).
[a]D25 +84.2 (c 0.4, MeOH).
IR (neat): 3451, 2986, 1719, 1645, 1440, 1375, 1210, 1058 cm–1.
1H NMR (200 MHz, CDCl3): d = 2.58 (m, 1 H), 2.54 (m, 1 H), 3.88
(dd, J = 5.28, 3.82 Hz, 1 H), 4.41 (dt, J = 11.33, 6.04 Hz, 1 H),
4.80–5.80 (br s, 1 H), 4.93 (d, J = 3.77 Hz, 1 H), 5.96 (ddd, J = 9.33,
2.34, 1.51 Hz, 1 H), 6.83 (ddd, J = 9.33, 5.93, 2.54 Hz, 1 H), 7.60–
7.16 (m, 5 H).
LC-MS (EI): m/z = 275 (M+ + Na).
(3R)-3-[(4R,5R)-2,2-Dimethyl-5-phenyl-1,3-dioxolan-4-yl]-3-
hydroxypropanal (9)
13C NMR (75 MHz CDCl3): d = 29.6, 76.1, 77.4, 120.8, 126.4,
128.1, 128.7, 140.3, 145.8, 164.0.
To an ice-cooled soln of 2-iodoxybenzoic acid (IBX, 1.2 g, 4.6
mmol) in DMSO (1 mL, 15.6 mmol) was added a 0 °C soln of alco-
hol 8 (1 g, 3.9 mmol) in anhyd CH2Cl2 (10 mL). The mixture was
stirred at r.t. for 2 h and then filtered through a Celite pad and
washed with Et2O. The combined organic filtrates were washed
with H2O and brine, dried (anhyd Na2SO4), and concentrated in vac-
uo. The crude product was purified by column chromatography (sil-
ica gel, petroleum ether–EtOAc, 8:2) to afford aldehyde 9 as a
viscous liquid; yield: 0.59 g (60%).
LC-MS (EI): m/z = 257 (M+ + Na).
Acknowledgment
K.S. thanks UGC, New Delhi for the award of a fellowship.
References
[a]D25 –18.2 (c 0.4, CHCl3).
(1) IICT Communication No: 060820.
1H NMR (200 MHz, CDCl3): d = 1.45 (s, 3 H), 1.51 (s, 3 H), 2.24–
2.35 (m, 1 H), 2.52–2.60 (m, 1 H), 4.08–4.37 (m, 1 H), 4.74–4.98
(m, 1 H), 5.34 (d, J = 8.78 Hz, 1 H), 7.17–7.50 (m, 5 H), 9.72 (s,
1 H).
(2) (a) Wu, Y. C.; Duh, C. Y.; Chang, F. R.; Wang, S. K.; Chang,
J. J.; McPhail, D. R.; McPhail, A. T.; Lee, K. H. J. Nat. Prod.
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LC-MS: m/z = 273 (M+ + Na).
Methyl (Z,5R)-5-[(4R,5R)-2,2-Dimethyl-5-phenyl-1,3-dioxolan-
4-yl]-5-hydroxypent-2-enoate (10)
In a 50-mL round-bottomed flask containing NaH (0.12 g, 4.8
mmol) was added under N2 anhyd THF (4 mL). After 5 min,
bis(2,2,2-trifluoromethyl) [(methoxycarbonyl) methyl]phospho-
Synthesis 2007, No. 3, 385–388 © Thieme Stuttgart · New York