4784 J . Org. Chem., Vol. 62, No. 14, 1997
Zeng et al.
mmol) and hexanoyl Meldrum’s acid (7, 480.8 mg, 1.99 mmol)
was refluxed in 15 mL of toluene overnight, and then the
solvent was removed and the residue was purified by vacuum
flash chromatography using 20% ethyl acetate in hexane as
1.53 (3H, s), 1.47 (3H, s), 1.37 (3H, s), 1.33 (3H, s), 1.29 (4H,
m), 0.88 (3H, t, J ) 7.1 Hz); 13C NMR (CDCl3) δ 202.4, 166.6,
109.1, 108.8, 101.3, 70.7, 70.5, 70.0, 66.0, 61.3, 49.1, 42.9, 31.1,
26.5, 25.9, 25.2, 24.1, 23.1, 22.4, 13.9; DCIMS (NH3) m/ z
(intensity, %), 418 (M + NH4+, 100), 401 (M + H+, 13.8), 385
(31.8), 360 (8.6), 343 (26.4), 278 (10.4); HRMS calcd for
C20H33O8 401.2175, found 401.2185.
eluant to give ester 13 (505.6 mg, 78.9%). [R]25 ) -47.1 (c
D
1.22, CHCl3); IR(KBr) νmax 3100, 2900, 1760, 1720, 1490, 1080
cm-1; 1H NMR (CDCl3) δ 7.37-7.28 (5H, m), 4.87 (1H, dd, J )
3.8, 5.5Hz), 4.75 (1H, d, J ) 11.9 Hz), 4.53 (3H, m), 4.25 (1H,
d, J ) 11.9 Hz), 4.02 (1H, d, J ) 10.3 Hz), 3.88 (1H, dd, J )
3.8, 10.3 Hz), 3.48 (2H, s), 2.53 (2H, t, J ) 7.4 Hz), 1.57 (2H,
m), 1.50 (3H, s), 1.33 (3H, s), 1.27 (4H, m), 0.88 (3H, t, J ) 7.1
Hz); 13C NMR (CDCl3) δ 202.5, 166.8, 137.7, 128.4, 127.8,
127.7, 112.7, 107.6, 84.6, 80.3, 71.9, 63.5, 60.1, 49.1, 42.8, 31.2,
26.3, 24.9, 23.1, 22.4, 13.9; DCIMS (NH3) m/ z (intensity, %),
438 (M + NH4+, 32.6), 313 (100), 271 (13.8), 91 (20.5); HRMS
calcd for C23H36NO7 438.2492, found 438.2500.
1-(3-Oxo-7-oct en oyl)-2,3-O-isop r op ylid en e-â-D-th r eo-
p en tu lofu r a n ose (20). To a solution of 1 (219.0 mg, 1.15
mmol), 3-oxooctenoic acid (152.2 mg, 0.98 mmol),14 and DMAP
(31.5 mg, 0.26 mmol) in 50 mL of anhyd CH2Cl2 was added
DCC (305.2 mg, 1.48 mmol) at 0 °C. The reaction mixture
was stirred at 0 °C for 3 h. Precipitated urea was filtered off,
and the filtrate was evaporated to dryness. The residue was
taken up in ethyl acetate and filtered free of any further
precipitated urea. The solvent was removed by evaporation,
and the residue was purified by vacuum flash chromatography
using 5% acetone in chloroform to yield the desired primary
monoester 20 (104.2 mg , 47.9%), secondary monoester (35.0
mg, 16.1%), diester (66.7 mg, 21.6%), and recovered 1 (93.0
1-(3-Oxoocta n oyl)-3,4-isop r op ylid en e-D-er yth r o-p en tu -
lofu r a n ose (14). To a solution of 13 (111.9 mg) in 5 mL of
ethyl acetate was added 10% Pd/C catalyst (40.3 mg). The
mixture was stirred under H2 atmosphere at rt overnight.
Then the catalyst was removed by filtration, and the solvent
was evaporated to give 14 in almost quantative yield. IR(KBr)
mg). 20: [R]25 ) +2.2 (c 1.11, CH2Cl2); IR(film) νmax 3500,
D
2950, 1780, 1730, 1200, 1070 cm-1; H NMR (CDCl3) δ 5.74
1
νmax 3500, 2950, 1760, 1720, 1080 cm-1 1H NMR (CDCl3) δ
;
(1H, m), 5.01 (2H, m), 4.46 (1H, s), 4.46 (1H, d, J ) 11.8 Hz),
4.41 (1H, d, J ) 11.8 Hz), 4.26 (1H, d, J ) 2.7 Hz), 4.19 (1H,
dd, J ) 9.4, 2.7 Hz), 3.98 (1H, d, J ) 9.4 Hz), 3.55 (1H, d, J )
15.6 Hz), 3.49 (1H, d, J ) 15.6 Hz), 2.56 (2H, t, J ) 7.3 Hz),
2.07 (2H, bq, J ) 7.0 Hz), 1.71 (2H, m), 1.51 (3H, s), 1.36 (3H,
s); 13C NMR (CDCl3) δ 203.2, 166.5, 137.6, 115.5, 112.4, 112.1,
85.4, 75.1, 74.0, 64.6, 48.9, 42.3, 32.7, 27.2, 26.3, 22.3; DCIMS
(NH3) m/ z (intensity, %), 346 (M + NH4+, 100), 329 (M + H+,
12.9), 313 (14.0), 288 (8.0), 271 (70.3), 208 (27.0); HRMS calcd
for C16H28NO7 346.1866, found 346.1871.
4.86 (1H, dd, J ) 3.6, 5.9 Hz), 4.59 (1H, d, J ) 11.6 Hz), 4.50
(1H, d, J ) 5.9 Hz), 4.28 (1H, d, J ) 11.6 Hz), 4.05 (1H, dd, J
) 3.6, 10.6 Hz), 3.96 (1H, d, J ) 10.6 Hz), 3.54 (2H, s), 2.50
(2H, t, J ) 7.4 Hz), 1.54 (2H, m), 1.43 (3H, s), 1.28 (3H, s),
1.26 (4H, m), 0.85 (3H, t, J ) 7.0 Hz); 13C NMR (CDCl3) δ
204.3, 166.9, 112.8, 104.2, 84.9, 80.6, 71.6, 65.8, 49.1, 43.1, 31.1,
26.2, 24.8, 23.1, 22.4, 13.9; DCIMS (NH3) m/ z (intensity, %),
348 (M + NH4+, 47.6), 330 (M + NH4+ - H2O, 3.7), 313 (100),
190 (12.4); HRMS calcd for C16H30NO7 348.2022, found
348.2025.
(-)-∆7-Syr in golid e 1 (21). Primary ester 20 (56.6 mg, 0.17
mmol) was stirred with 2 mL of TFA-H2O (9:1) at rt for 2 h.
Then the reaction mixture was neutralized with saturated
aqueous NaHCO3 and extracted with ethyl acetate (3 × 15
mL). The extracts were combined, dried over Na2SO4, filtered,
and evaporated. After prechromatography on a silica Sep-Pak
using ethyl acetate as eluant, the residues were purified by
HPLC with 40% ethyl acetate in hexanes on a Maxsil 5 silica
(1R ,7S ,8R )-7-H y d r o x y -4,10,11-t r io x a -1-p e n t y lt r i-
cyclo[6.2.1.02,6]u n dec-2(6)-en -3-on e (16). The ester 14 (115.2
mg, 0.35 mmol) was treated with 1 mL of TFA-H2O (9:1) for
15 min to deacetonize. Then the mixture was neutralized with
saturated aqueous NaHCO3 and extracted with ethyl acetate.
The crude reaction extracts were dried over Na2SO4, filtered,
and evaporated to give 95.0 mg of oily product 15 which was
then stirred with 90 mL of water (pH ) 6) for one week. Then
the mixture was extracted with ethyl acetate and purified by
HPLC using 2-propanol/EtOAc/hexanes (9.4:45.3:45.3) on a
Dynamax silica gel column (µ ) 6 mL/min, tR ) 78 min) to
yield 16 (16.5 mg, 18.6%). [R]25D ) +26.3 (c 0.43, CH2Cl2); IR-
(KBr) νmax 3450, 2950, 1750, 1620, 1040 cm-1; 1H NMR (CDCl3)
δ 4.97 (1H, d, J ) 17.7 Hz), 4.82 (1H, d, J ) 17.7 Hz), 4.78
(1H, bs), 4.14 (1H, dd, J ) 8.4, 7.2 Hz), 4.08 (1H, s), 3.41 (1H,
dd, J ) 8.4, 2.4 Hz), 2.27 (1H, m), 2.15 (1H, m), 1.50 (2H, m),
1.37 (4H, m), 0.90 (3H, t, J ) 6.8 Hz); 13C NMR (CDCl3) δ
gel column to isolate 21 (5.6 mg, 12.2%). [R]25 ) -69.4 (c
D
0.50, CHCl3); IR(KBr) νmax 3350, 2950, 1760, 1070 cm-1
;
1H
NMR (acetone-d6) δ 5.79 (1H, m), 5.41 (1H, s), 5.00 (1H, d, J
) 17.1 Hz), 4.92 (1H, d, J ) 10.2 Hz), 4.66 (1H, d, J ) 10.3
Hz), 4.47 (1H, s), 4.35 (bs), 4.31 (1H, d, J ) 10.3 Hz), 4.13
(1H, d, J ) 2.8 Hz), 3.94 (1H, d, J ) 10.0 Hz), 3.81 (1H, dd, J
) 10.0, 2.8 Hz), 3.09 (1H, s), 2.05 (m), 1.89 (2H, t, J ) 8.0 Hz),
1.58-1.70 (2H, m); 13C NMR (acetone-d6) δ 171.8, 138.5, 114.2,
107.8, 98.1, 91.4, 74.7, 74.5, 74.0, 58.9, 38.1, 33.5, 22.9; DCIMS
(NH3) m/ z (intensity, %), 288 (M + NH4+, 11.0), 270 (M+, 12.5),
253 (23.1), 228 (100), 184 (99.2), 167 (73.6); HRMS calcd for
C13H22NO6 288.1447, found 288.1452.
(-)-Syr in golid e 1 (4). To a solution of 21 (2 mg) in ethyl
acetate (2 mL) was added 10% Pd/C catalyst (0.5 mg). This
mixture was stirred at rt for 3 h under hydrogen atmosphere
and then filtered. Evaporation of the solvent from the filtrate
afforded 4 in nearly quantitative yield based on 1H NMR
analysis.
168.9, 158.4, 130.4, 104.1, 77.8, 69.1, 66.3, 64.3, 31.8, 30.9, 22.5,
+
22.4, 13.9; DCIMS (NH3) m/ z (intensity, %), 272 (M + NH4
,
66.5), 255 (M + H+, 100), 207 (15.2); HRMS calcd for C13H19O5
255.1232, found 255.1229.
1-(3-Oxoocta n oyl)-2,3:4,5-d i-O-isop r op ylid en e-â-D-fr u c-
top yr a n ose (18). Diacetonide 17 (322.5 mg, 1.24 mmol),
which was prepared from D-fructose by isomerization in
pyridine followed by acetonization,12 was esterified by stirring
with hexanoyl Meldrum’s acid (7, 374.1 mg, 1.55 mmol) in
refluxing toluene (15 mL) for 3 h. Then the solvent was
removed in vacuo, and the residue was purified by vacuum
flash chromatography with 20% ethyl acetate in hexane to give
18 (463.3 mg, 93.4%). [R]25D ) -23.1 (c 2.11, CHCl3); IR(KBr)
Ack n ow led gm en t. Mass spectra were determined
by Ron New of the U.C. Riverside Analytical Instru-
mentation Facility. We thank the U.S. Department of
Agriculture (grant no. 9501093) for financial support.
We thank Professor R. W. Rickards for sharing informa-
tion and insightful discussions.
Su p p or t in g In for m a t ion Ava ila b le: 1H and 13C NMR
spectra of 2, 5, 6, 8, 10, 12-14, 16, 18, 20, and 21 (25 pages).
This material is contained in libraries on microfiche, im-
mediately follows this article in the microfilm version of the
journal, and can be ordered from the ACS; see any current
masthead page for ordering information.
νmax 2950, 1760, 1720, 1380, 1080 cm-1 1H NMR (CDCl3) δ
;
4.59 (1H, dd, J ) 2.5, 7.9 Hz), 4.42 (1H, d, J ) 11.7 Hz), 4.29
(1H, d, J ) 2.5 Hz), 4.22 (1H, dd, J ) 1.8, 7.9 Hz), 4.13 (1H,
d, J ) 11.7 Hz), 3.88 (1H, dd, J ) 1.8, 13.0 Hz), 3.75 (1H, d, J
) 13.0 Hz), 3.47 (2H, s), 2.53 (2H, t, J ) 7.4 Hz), 1.58 (2H, m),
(14) 3-Oxooctenoic acid was prepared using 5-hexenoyl chloride to
replace hexanoyl chloride.13 The 5-hexenoyl chloride was prepared from
5-hexen-1-ol by oxidation using PDC in DMF followed by chlorination
with SOCl2.
J O970461B