2618
D. K. Mohapatra et al. / Tetrahedron 63 (2007) 2613–2621
was purified by column chromatography on silica gel by
eluting with ethyl acetate and light petroleum (1:19) to
afford 23 (1.2 g, 90%) as a light yellow coloured liquid. Rf
(10% ethyl acetate/light petroleum) 0.57; nmax (liquid film,
a Celite pad and concentrated. The residue was chromato-
graphed on silica gel using ethyl acetate and light petroleum
(1:13) to give 16 (0.4 g, 82%) as a colourless oil. Rf (15%
ethyl acetate/light petroleum) 0.55; [a]2D5 +48.6 (c 1.8,
1
CHCl3) 3019, 2975, 1452, 1275 cmꢁ1; H NMR (CDCl3,
CHCl3); IR (CHCl3): 1781, 1602, 1584, 1496, 1454 cmꢁ1
;
500 MHz) d: 2.44–2.50 (1H, m, CHCH2OBn), 3.33 (3H, s,
OMe), 3.44 (1H, dd, J 5.5, 9.2 Hz, CHaHbOBn), 3.78 (1H,
t, J 9.2 Hz, CHaHbOBn), 3.97 (1H, d, J 4.6 Hz, CHOBn),
4.24 (1H, t, J 8.6 Hz, CHCH]CH2), 4.45 (1H, d, J
11.9 Hz, CHaHbPh), 4.48 (1H, d, J 11.9 Hz, CHaHbPh),
4.51 (1H, d, J 11.9 Hz, CHaHbPh), 4.62 (1H, d, J 11.9 Hz,
CHaHbPh), 4.87 (1H, s, CHOMe), 5.11 (1H, d, J 9.6 Hz,
CH]CHaHb), 5.19 (1H, d, J 17.4 Hz, CH]CHaHb), 5.79–
5.85 (1H, m, CH]CH2), 7.20–7.30 (10H, m, Ph); 13C
NMR (CDCl3, 125 MHz) d: 47.3/45.2, 54.4/55.0, 65.9,
72.3/72.4, 72.8/73.1, 82.0/82.7, 106.1/106.4, 115.3/116.4,
127.4, 127.5, 127.6, 127.7/127.8, 128.2, 128.3, 137.8/
138.0, 137.9/138.3, 139.4; MS: m/z 354. Anal. Calcd for
C22H26O4: C, 74.55; H, 7.39. Found: C, 74.46; H, 7.49%.
1H NMR (CDCl3, 500 MHz) d: 2.52 (1H, quintet, J
6.0 Hz, CHCH2OBn), 3.50 (1H, dd, J 6.9, 9.2 Hz,
CHaHbOBn), 3.76 (1H, dd, J 6.9, 9.2 Hz, CHaHbOBn),
4.15 (1H, d, J 6.9 Hz, CHCH]CH2), 4.47 (1H, d, J
11.9 Hz, CHaHbPh), 4.50 (1H, d, J 11.9 Hz, CHaHbPh),
4.65 (1H, d, J 11.9 Hz, CHaHbPh), 4.84 (1H, t, J 5.8 Hz,
CHOBn), 4.90 (1H, d, J 11.9 Hz, CHaHbPh), 5.24 (1H, d,
J 10.6 Hz, CH]CHaHb), 5.33 (1H, d, J 17.0 Hz, CH]
CHaHb), 5.83 (1H, m, CH]CH2), 7.22–7.35 (10H, m,
Ph); 13C NMR (CDCl3, 125 MHz) d: 45.8, 65.5, 72.3,
73.0, 73.4, 80.5, 117.9, 127.5, 127.7, 127.9, 128.0, 128.3,
128.4, 134.7, 136.9, 137.7, 173.4; MS: m/z 338. Anal. Calcd
for C21H22O4: C, 74.54; H, 6.55. Found: C, 74.64; H, 6.56%.
4.9. 3-Benzyloxy-4-benzyloxymethyl-2-methyl-hept-
6-ene-2,5-diol (25)
4.7. 3-Benzyloxy-4-benzyloxymethyl-5-vinyl-tetra-
hydrofuran-2-ol (24)
A solution of 16 (0.80 g, 2.4 mmol) in dry ether (20 mL) was
added drop-wise to a freshly prepared methyl magnesium
iodide obtained from magnesium (0.2 g, 8.4 mmol) and
methyl iodide (0.5 mL, 7.2 mmol) in Et2O. The temperature
was maintained below 40 ꢀC throughout the addition. After
stirring the reaction mixture for another 4 h, the reaction
mixture was quenched with an ice-cooled saturated solution
of ammonium chloride (20 mL). The aqueous reaction mix-
ture was extracted with ether (3ꢂ40 mL). The combined
ether extracts were dried over anhydrous sodium sulfate
and concentrated. The residue was purified by column chro-
matography on silica gel eluting with ethyl acetate and light
petroleum (1:4) to afford 25 (0.69 g, 79%) as a colourless
liquid. Rf (40% ethyl acetate/light petroleum) 0.43; [a]D25
+44.0 (c 1.5, CHCl3); nmax (liquid film, CHCl3) 3393,
Compound 23 (1.4 g, 4.0 mmol) was dissolved in 20% aque-
ous acetic acid (35 mL) and concd H2SO4 (0.4 mL), and
refluxed for 12 h. The reaction mixture was diluted with
ethyl acetate and neutralized with NaHCO3. It was then par-
titioned between ethyl acetate (50 mL) and water (20 mL).
The aqueous layer was again extracted with ethyl acetate
(2ꢂ20 mL) and the combined organic layers were washed
with brine (35 mL), dried and concentrated. The residue
was purified by column chromatography on silica gel eluting
with ethyl acetate and light petroleum (1:9) to afford a yellow
liquid 24 (1.0 g, 75%). Rf (20% ethyl acetate/light petro-
leum) 0.52; nmax (liquid film, CHCl3) 3395, 3019, 2934,
1276 cmꢁ1 1H NMR (CDCl3, 500 MHz) d: 2.21–2.26
;
(0.5H, m, CHCH2OBn), 2.52–2.58 (0.5H, m, CHCH2OBn),
3.16 (0.5H, br d, J 12.8 Hz, OH), 3.46 (0.5H, dd, J 5.5,
9.2 Hz, CH2OBn), 3.54 (0.5H, dd, J 6.0, 9.2 Hz, CH2OBn),
3.59 (0.5H, dd, J 3.7, 9.2 Hz, CH2OBn), 3.79 (0.5H, t, J
9.2 Hz, CH2OBn), 4.00 (0.5H, d, J 4.6 Hz, CHOBn), 4.07
(0.5H, dd, J 4.6, 7.8 Hz, CHOBn), 4.25 (0.5H, dd,
J 7.8, 9.2 Hz, CHCH]CH2), 4.39 (0.5H, t, J 7.0 Hz,
CHCH]CH2), 4.48 (1H, quintet, J 12.0 Hz, CHaHbPh),
4.51–4.57 (2H, m, CH2Ph), 4.64 (1H, dd, J 12.0, 19.7 Hz,
CHaHbPh), 4.75–4.78 (0.5H, m, OH), 5.11 (1H, t, J 11.0 Hz,
CHOH), 5.21 (1H, ddt, J 1.3, 7.3, 17.0 Hz, CH]CHaHb),
5.34–5.37 (1H, m, CH]CHaHb), 5.78 (0.5H, ddd, J 7.0,
10.5, 17.0 Hz, CH]CH2), 5.88 (0.5H, ddd, J 7.0, 10.5,
17.0 Hz, CH]CH2), 7.23–7.33 (10H, m, Ph); 13C NMR
(CDCl3, 125 MHz) d: 46.9/47.0, 65.9/66.0, 72.3, 73.2/73.6,
78.4/79.0, 83.0/83.4, 96.3/100.3, 116.3/116.8, 127.5/127.6,
127.8/127.9, 128.3, 128.5, 137.4/137.7, 138.1/138.3, 138.0/
139.5; MS: m/z 340. Anal. Calcd for C21H24O4: C, 74.09;
H, 7.11. Found: C, 73.94; H, 7.05%.
3018, 2979, 2934, 1751, 1273 cmꢁ1 1H NMR (CDCl3,
;
500 MHz) d: 1.21 (3H, s, Me), 1.25 (3H, s, Me), 2.18 (1H,
m, CHCH2OBn), 3.37 (1H, m, OH), 3.41 (1H, dd, J 4.6,
9.2 Hz, CHaHbOBn), 3.63 (1H, d, J 4.6.0 Hz, CHaHbOBn),
3.75 (2H, br s, CHOH, CHOBn), 4.39 (1H, s, OH), 4.40
(1H, d, J 11.9 Hz, CHaHbPh), 4.47 (1H, d, J 11.9 Hz,
CHaHbPh), 4.57 (1H, d, J 11.5 Hz, CHaHbPh), 4.68 (1H, d,
J 11.5 Hz, CHaHbPh), 5.11 (1H, d, J 10.6 Hz, CH]CHaHb),
5.22 (1H, d, J 17.2 Hz, CH]CHaHb), 5.83 (1H, m,
CH]CH2), 7.22–7.32 (10H, m, Ph); 13C NMR (CDCl3,
125 MHz) d: 26.5, 27.1, 46.0, 70.1, 70.9, 73.1, 73.3, 75.4,
85.2, 115.8, 127.6, 128.3, 137.9, 138.1, 139.0; MS: m/z
370. Anal. Calcd for C23H30O4: C, 74.56; H, 8.16. Found:
C, 74.64; H, 7.98%.
4.10. 3-Benzyloxy-4-benzyloxymethyl-5-methoxy-
2-methyl-hept-6-ene-2-ol (26)
To a suspension of NaH (60% dispersion in oil, 0.048 g,
1.2 mmol) in dry DMF (10 mL) was added a solution of
25 (0.40 g, 1.1 mmol) in DMF (5 mL) and the mixture was
stirred at 0 ꢀC for 30 min. Then methyl iodide (0.08 mL,
1.3 mmol) was added and the stirring was continued at
room temperature for an additional 1 h. The reaction was
quenched with water (10 mL) and the mixture was extracted
with ethyl acetate (3ꢂ25 mL). The ethyl acetate layer was
4.8. 3-Benzyloxy-4-benzyloxymethyl-5-vinyl-
dihydro-furan-2-one (16)
˚
To a mixture of 24 (0.5 g, 1.5 mmol) and 4 A molecular
sieves (750 mg) in dry CH2Cl2 (6.0 ml), PDC (0.9 g,
2.4 mmol) was added at room temperature. The mixture
was stirred for 1 h at room temperature, filtered through