1326
P. Phukan et al.
PAPER
gram Sil G/UV254. Solvents were distilled prior to use; petroleum
ether with a boiling range of 40–60 °C was used.
HRMS (FT-ICR-ES): m/z calcd for C25H29NO6Na [M + Na]+,
462.18871; found, 462.18816.
The alcohol 6 was prepared as described in Scheme 210–12 and the
alcohols 7 and 8 have been reported by us previously.13 The general
procedure followed for the preparation of tosylates listed in Table 1
is the same as the one given below for 9.
(4S)-4-Benzyl-3-((2S)-2-{(1R)-1-{[tert-butyl(dimethyl)silyl]-
oxy}-3-[(4-methoxybenzyl)oxy] propyl}but-3-enoyl)-1,3-oxa-
zolidin-2-one (15)
To a solution of 14 (0.5 g, 1.15 mmol) and 2,6-lutidine (0.31 g, 2.87
mmol) in CH2Cl2 (10 mL) was added tert-butylsilyltrifluo-
romethane sulfonate (0.394 g, 0.34 mL, 1.49 mmol) and the solution
was stirred overnight. The mixture was treated with H2O (20 mL),
stirred for 30 min, and then the mixture was extracted with CH2Cl2
(3 × 20 mL). The organic phase was washed with 1 N HCl (20 mL),
sat. aq NaHCO3 (20 mL), brine (20 mL), dried (Na2SO4), filtered,
and concentrated. Flash chromatography of the residue (10%
EtOAc in petroleum ether) yielded 605 mg (95%) of the TBS-ether
15 as a gum; Rf 0.42 (petroleum ether–EtOAc, 4:1); [ ]D24 +42.3
(c = 0.52, CH2Cl2).
5-[(Triisopropylsilyl)oxy]pentyl 4-Methylbenzenesulfonate (9);
Typical Procedure
A solution of 5-[(triisopropylsilyl)oxy]pentan-1-ol14 (0.42 g, 1.61
mmol) in pyridine (5 mL) was treated with p-toluenesulfonyl chlo-
ride (0.37 g, 1.94 mmol) at 0 °C. The resulting mixture was stirred
for 2 h at r.t., followed by addition of H2O (40 mL) and Et2O (60
mL). After separation of the layers, the Et2O layer was washed with
1 N HCl (20 mL), sat. aq NaHCO3 solution (20 mL), and brine. The
organic layer was dried (MgSO4), filtered, and concentrated. Flash
chromatography (petroleum ether–EtOAc, 9:1) of the residue pro-
vided the tosylate 9 as a colorless oil (0.55 g, 82%); Rf 0.50 (petro-
leum ether–EtOAc, 9:1).
IR (film): 2954, 2930, 2856, 1782, 1696, 1612, 1513, 1383, 1353
cm–1.
IR (film): 2942, 2866, 1462, 1361, 1189, 1177 cm–1.
1H NMR (400 MHz, CDCl3): = 7.39–7.24 (m, 5 H), 7.21 (d,
J = 7.8 Hz, 2 H), 6.87 (d, J = 8.6 Hz, 2 H), 6.10–5.94 (m, 1 H),
5.34–5.22 (m, 2 H), 4.67–4.51 (m, 2 H), 4.43 (d, J = 11.6 Hz, 1 H),
4.39 (d, J = 11.6 Hz, 1 H), 4.25 (dd, J = 11.4, 5.1 Hz, 1 H), 4.07 (dd,
J = 9.1, 2.0 Hz, 1 H), 3.89 (t, J = 8.3 Hz, 1 H), 3.80 (s, 3 H), 3.67–
3.56 (m, 1 H), 3.55–3.43 (m, 1 H), 3.26 (dd, J = 13.4, 2.8, 1 H), 2.73
(dd, J = 13.4, 9.6, 1 H), 1.93 (m, 2 H), 0.89 (s, 9 H), 0.05 (s, 3 H),
0.04 (s, 3 H).
1H NMR (400 MHz, CDCl3): = 7.77 (d, J = 8.3 Hz, 2 H), 7.33 (d,
J = 8.1 Hz, 2 H), 4.01 (t, J = 6.6 Hz, 2 H), 3.61 (t, J = 6.3 Hz, 2 H),
2.43 (s, 3 H), 1.73–1.58 (m, 2 H), 1.54–1.41 (m, 2 H), 1.40–1.29 (m,
2 H), 1.12–0.90 (m, 21 H).
13C NMR (100 MHz, CDCl3): = 144.56, 133.24, 129.74, 127.82,
70.56, 62.90, 32.15, 28.62, 21.77, 21.55, 17.95, 17.65, 11.92.
13C NMR (100 MHz, CDCl3): = 127.37, 159.04, 152.77, 135.35,
134.05, 130.65, 129.43, 129.22, 128.85, 127.23, 119.43, 113.64,
72.51, 71.07, 65.78, 65.69, 55.38, 55.22, 53.15, 37.49, 35.24, 25.77,
17.96, –4.49, –4.63.
MS (EI): m/z (%) = 285 (100), 257 (6), 243 (3), 155 (3), 115 (3), 91
(7).
HRMS (FT-ICR-ES): m/z calcd for C21H38O4SSiNa [M + Na]+,
437.21523; found, 437.21526.
MS (EI): m/z (%) = 359 (3), 309 (4), 302 (13), 251 (2), 234 (3), 211
(2), 173 (6), 137 (3), 121 (100), 91 (5).
HRMS (FT-ICR-ES): m/z calcd for C31H43NO6SiNa [M + Na]+,
(4S)-4-Benzyl-3-((2S)-2-{(1R)-1-hydroxy-3-[(4-methoxybenz-
yl)oxy]propyl}but-3-enoyl)-1,3-oxazolidin-2-one (14)
To a stirred solution of imide 12 (1.0 g, 4.1 mmol) in CH2Cl2 (15
mL) was added dibutylboron trifluoromethansulfonate (4.5 mL, 1
M in CH2Cl2, 4.5 mmol) at –78 °C. After stirring for 5 min, the mix-
ture was treated with Et3N (0.8 mL, 5.7 mmol), then kept for 1 h at
–78 °C, and 20 min at 0 °C, and recooled to –78 °C. At this point, a
solution of the aldehyde 13 (1.18 g, 6.1 mmol) in CH2Cl2 (5 mL)
was added dropwise. The reaction was kept for 1 h at –78 °C and 1
h at 0 °C, before it was quenched by addition of pH 7 buffer (5 mL)
followed by MeOH (18 mL). After 5 min, 30% H2O2 (5 mL) was
added and the mixture stirred for 1 h at 0 °C. Most of the solvent was
removed in vacuo and the aqueous remainder extracted with EtOAc
(3 × 30 mL). The organic phase was washed with 1 N HCl (20 mL),
5% aq NaHCO3 (20 mL), brine (20 mL), dried (Na2SO4), filtered,
and concentrated. The crude product was purified by flash chroma-
tography (30% EtOAc in petroleum ether) to give 14 (1.54 g, 86%)
as an oil; Rf 0.15 (petroleum ether–EtOAc, 7:3); [ ]D24 +23.3
(c = 1.57, CH2Cl2).
576.27519; found, 576.27557.
(2R)-2-((1R)-1-{[tert-Butyl(dimethyl)silyl]oxy}-3-[(4-methoxy-
benzyl)oxy]propyl)but-3-en-1-ol (16)
To a stirred solution of 15 (144 mg, 0.27 mmol) in THF (10 mL)
was added a solution of NaBH4 (51 mg, 1.3 mmol) in H2O (2 mL)
at 0 °C. The reaction mixture was stirred at 0 °C for 5 min and then
for 3 h at r.t. The reaction was quenched by addition of sat. aq
NH4Cl solution (5 mL) and the mixture stirred for 1 h. The mixture
was extracted with EtOAc (2 × 20 mL), the combined organic lay-
ers were washed with sat. aq NaHCO3 solution (10 mL), brine (10
mL), dried (Na2SO4), filtered, and concentrated in vacuo. The crude
product was purified by flash chromatography (20% EtOAc in pe-
troleum ether) to give 89 mg (87%) of alcohol 16 as a colorless oil;
Rf 0.3 (petroleum ether–EtOAc, 4:1); [ ]D23 +9.1 (c = 0.9, CH2Cl2).
IR (film): 3450, 2954, 2930, 2857, 1613, 1513, 1250 cm–1.
IR (film): 3503, 2930, 2862, 1780, 1694, 1612, 1513, 1386, 1360
cm–1.
1H NMR (400 MHz, CDCl3): = 7.25 (d, J = 8.6 Hz, 2 H), 6.88 (d,
J = 8.5 Hz, 2 H), 5.79–5.64 (m, 1 H), 5.22–5.03 (m, 2 H), 4.40 (d,
J = 11.6 Hz, 1 H), 4.34 (d, J = 11.6 Hz, 1 H), 4.05–3.94 (m, 1 H),
3.80 (s, 3 H), 3.78–3.69 (m, 1 H), 3.66–3.54 (m, 1 H), 3.46 (t,
J = 6.3 Hz, 2 H), 2.48–2.35 (m, 1 H), 2.22 (s, 1 H), 1.88–1.70 (m, 2
H), 0.89 (s, 9 H), 0.09 (s, 3 H), 0.06 (s, 3 H).
13C NMR (100 MHz, CDCl3): = 159.12, 135.46, 130.44, 129.22,
118.44, 113.71, 72.52, 70.78, 66.45, 63.43, 55.22, 51.19, 33.98,
25.79, 17.95, –4.62.
1H NMR (400 MHz, CDCl3): = 7.40–7.11 (m, 7 H), 6.87 (d,
J = 8.6 Hz), 6.15–5.97 (m, 1 H), 5.39 (dd, J = 12.9, 3.0 Hz, 2 H),
4.76–4.64 (m, 1 H), 4.56 (dd, J = 8.8, 4.3 Hz, 1 H), 4.44 (s, 2 H),
4.29–4.20 (m, 1 H), 4.19–4.09 (m 2 H), 3.80 (s, 3 H), 3.72–3.58 (m,
2 H), 3.42 (br s, 1 H), 3.26 (dd, J = 13.4, 2.8 Hz, 1 H), 2.76 (dd,
J = 13.4, 9.6 Hz, 1 H), 1.94–1.82 (m, 1 H), 1.80–1.68 (m, 1 H).
13C NMR (100 MHz, CDCl3): = 173.46, 159.18, 152.93, 135.04,
131.65, 130.12, 129.43, 129.33, 128.92, 127.35, 121.03, 113.03,
72.86, 70.54, 67.74, 65.95. 55.25, 52.53, 37.55, 33.85.
MS (EI): m/z (%) = 309 (5), 251 (1), 173 (11), 137 (9), 121 (100),
91 (6), 77 (8).
MS (EI): m/z (%) = 351 (3), 285 (1), 259 (10), 244 (8), 216 (10), 168
HRMS (FT-ICR-MS): m/z calcd for C21H36O4SiNa [M + Na]+,
(10), 137 (19), 121 (100), 91 (29).
403.22751; found, 403.22770.
Synthesis 2003, No. 9, 1324–1328 ISSN 1234-567-89 © Thieme Stuttgart · New York