Enantiomerically Pure α,β-Unsaturated Five-Membered-Ring Aldehydes by Ring Contraction of Epoxyhexopyranosides

Article abstract of DOI:10.1021/jo970666k

A series of epoxyhexopyranosides, variously substituted in the 6-position, were each transformed by ring contraction into a single, enantiomerically pure, α,β-unsaturated furanosidic aldehyde. Similar ring contraction of a C-propylglycosidic analog of one of the epoxyhexopyranosides gave a mixture of two diastereomeric aldehydes. This finding supports the previously suggested mechanism of the reaction and indicates that O-glycosidic epoxypyranosides also rearrange into two aldehydes, one of which is unstable.

Full text of DOI:10.1021/jo970666k

7972
J . Org. Chem. 1997, 62, 7972-7977
En a n tiom er ica lly P u r e r,â-Un sa tu r a ted F ive-Mem ber ed -Rin g
Ald eh yd es by Rin g Con tr a ction of Ep oxyh exop yr a n osid es
Fritiof Ponte´n and Go¨ran Magnusson*
Organic Chemistry 2, Center for Chemistry and Chemical Engineering, Lund University, P.O. Box 124,
S-221 00 Lund, Sweden
Received April 14, 1997X
A series of epoxyhexopyranosides, variously substituted in the 6-position, were each transformed
by ring contraction into a single, enantiomerically pure, R,â-unsaturated furanosidic aldehyde.
Similar ring contraction of a C-propylglycosidic analog of one of the epoxyhexopyranosides gave a
mixture of two diastereomeric aldehydes. This finding supports the previously suggested mechanism
of the reaction and indicates that O-glycosidic epoxypyranosides also rearrange into two aldehydes,
one of which is unstable.
Sch em e 1
In tr od u ction
Ring contraction of epoxycyclohexanes and epoxycy-
clohexanols provides cyclopentane- and cyclopentenecar-
boxaldehydes, respectively.1-4 The latter have been used
as starting materials for the syntheses of a number of
terpenes.5 Similarly, epoxypyranosides give R,â-unsatur-
ated furanosidic aldehydes,6,7 which were used for the
synthesis of enantiomerically pure tetrahydrofuran-based
natural products, including several lignans.8 The mech-
anism of the ring contraction has been investigated using
deuterium-labeled epoxy alcohols.4,6,7
Epoxycyclohexanols3,4 normally give high yields (>80%)
of the ring-contracted aldehydes as isomeric mixtures
that are difficult to separate into the individual alde-
hydes. In contrast, epoxypyranosides give only a single
aldehyde that is easily purified, but the yields are modest
(∼25-60%).6,7 However, different stereo- and regioiso-
mers of the epoxypyranosides provide the same aldehyde
(cf. Scheme 1), which makes it possible to use readily
available mixtures of sugar epoxides for the ring contrac-
tion. It should also be noted that the methyl O-glycosidic
aldehydes can undergo a 1,4-elimination of methanol,
thus providing a route to substituted furan-3-alde-
hydes.6,7 Ring contractions have also been performed
with pyranosidic sulfonyl esters, which gave some fura-
nosidic saturated and R,â-unsaturated aldehydes.9,10
tion (Scheme 2). A C-glycoside analog of one of the
O-glycosidic epoxypyranosides was also synthesized and
ring-contracted, which gave a mixture of two isomeric
aldehydes (Scheme 4). This experiment provided an
explanation for the fortuitous formation of a single
aldehyde in most ring contractions of O-glycosidic ep-
oxypyranosides.
Resu lts a n d Discu ssion
I. Rin g Con tr a ction of Meth yl Ep oxyh exop yr a -
n osid es. Treatment of the epoxy alcohols11,12 1-6 with
LiBr and tetramethylurea (TMU) in refluxing toluene for
10 min resulted in ring contraction and dehydration,
which produced the R,â-unsaturated aldehydes 10-15 in
57-38% yield (Scheme 2). Only one aldehyde could be
isolated from each reaction mixture, except for 15, which
contained approximately 3% of an isomeric aldehyde
(15a ). The latter was not obtained in pure form, but its
1H NMR spectrum (mixture of 15 and 15a ) was consistent
with a structure corresponding to the unstable aldehyde
depicted in Scheme 3. The chromatographic isolation of
10-15 on silica gel was simple since they all had a higher
Rf value than the byproducts.
Sulfone epoxide 7 gave the aldehyde 16 in only 9%
yield, and the sulfone epoxides 8 and 9 gave no aldehyde
product at all. Compound 8 was recovered (75%) after
standard treatment with LiBr/TMU, and compound 9
was only consumed after prolonged reaction in the
presence of additional LiBr. It seems as if the sulfone
group competes with the epoxide oxygen for lithium ion,
thus interfering with bromide ion attack on the epoxide
carbon and consequently reducing the amount of the
bromohydrin intermediate available for ring contraction.
A simplified reaction mechanism is depicted in Scheme
3; for a full discussion, see refs 4, 6, and 7.
In order to investigate the generality of the formation
of a single stable aldehyde from epoxypyranosides, we
submitted a number of these compounds to ring contrac-
X Abstract published in Advance ACS Abstracts, October 1, 1997.
(1) Rickborn, B.; Gerkin, R. M. J . Am. Chem. Soc. 1971, 93, 1693.
(2) Magnusson, G. Org. Prep. Proc. Int. 1990, 22, 547.
(3) Magnusson, G.; Thore´n, S. J . Org. Chem. 1973, 38, 1380.
(4) Bergman, R.; Magnusson, G. J . Org. Chem. 1986, 51, 212.
(5) Lactaral: Froborg, J .; Magnusson, G.; Thore´n, S. Acta Chem.
Scand. Ser. B 1974, 28, 265. Tanis, S. P.; Head, D. B. Tetrahedron
Lett. 1982, 23, 5509. Marasmic acid: Greenlee, W. J .; Woodward, R.
B. Tetrahedron 1980, 36, 3367, 3361. Hirsutene: Hudlicky, T.;
Kutchan, T. M.; Wilson, S. R.; Mao, D. T. J . Am. Chem. Soc. 1980,
102, 6351. Capnellene: Stevens, K. E.; Paquette, L. A. Tetrahedron
Lett. 1981, 22, 4393. Silphinene: Paquette, L. A.; Leone-Bay, A. J .
Am. Chem. Soc. 1983, 105, 7352. (+)-Isovelleral: Bergman, R.;
Hansson, T.; Sterner, O.; Wickberg, B. J . Chem. Soc., Chem. Commun.
1990, 865.
(6) Sundin, A.; Frejd, T.; Magnusson, G. J . Org. Chem. 1986, 51,
3927.
(7) Rehnberg, N.; Magnusson, G. J . Org. Chem. 1990, 55, 5467.
(8) Botryodiplodin: Rehnberg, N.; Magnusson, G. Acta Chem. Scand.
1990, 44, 377. Lignans: Rehnberg, N.; Magnusson, G. J . Org. Chem.
1990, 55, 4340.
(9) Binkley, R. W. J . Org. Chem. 1992, 57, 2353.
(10) Kassou, M.; Castillo´n, S. J . Org. Chem. 1995, 60, 4353.
(11) Ponte´n, F.; Magnusson, G. Acta Chem. Scand. 1994, 48, 566.
(12) Ponte´n, F.; Magnusson, G. J . Org. Chem. 1996, 61, 7463.
S0022-3263(97)00666-X CCC: $14.00 © 1997 American Chemical Society

R,â-Unsaturaated Five-Membered-Ring Aldehydes
J . Org. Chem., Vol. 62, No. 23, 1997 7973
Sch em e 2a
Sch em e 3a
a
Simplified mechanistic scheme; for a full account, see refs 4,
6, and 7.
byproducts, the C-epoxyglycoside analogs 24 and 25 were
prepared and submitted to ring contraction (Scheme 4).
Allyl C-glycoside 1714 was hydrogenated to give the
C-propyl analog 18 (95%). Deacetylation of 18 with
methanolic MeONa, followed by acetalization with R,R-
dimethoxytoluene gave the 4,6-O-benzylidene acetal 19
(88%). Treatment of 19 with p-TsCl-K2CO3-NaOH-
DMSO in toluene15 gave the corresponding ditosylate,
which was treated, without purification, with the two-
phase system H2O-toluene-NaOH-Bu4NHSO4-MeO-
CH2CH2OH-DMSO to give the epoxide 20 (18%). In an
attempt to raise the yield, 19 was tosylated in pyridine,
which gave a mixture of the two corresponding monoto-
sylates. Treatment of the mixture with methanolic
MeONa gave the epoxides 21 (65%) and 20 (25%). The
benzylidene group of 20 and 21 was removed by hydro-
genolysis over several days, which gave 22 (74%) and 23
(75%), respectively. Silylation of 22 with dimethylhexyl-
chlorosilane gave the epoxy alcohol 24 (16%) after 3 days.
The low yield was probably due to migration of the silyl
group from O-6 to O-4, followed by silylation of O-6, since
a significant amount of disilylated material was also
obtained. Silylation of 23 under the same conditions
gave, after 18 h, epoxy alcohol 25 (61%), as well as some
disilylated material. The sluggishness of the epoxidation,
hydrogenolysis, and silylation reactions was unexpected,
since the O-glycoside analogs reacted readily under the
same conditions.7,15
a
(a) LiBr, TMU, toluene, reflux, 10 min; (b) 3% of the isomer
15a (see Experimental Section) was also formed; (c) no aldehyde
was obtained.
The ease of preparation and the purity of the aldehydes
shown in Scheme 2 makes the ring contraction a useful
preparative procedure. However, it is disturbing not
knowing the reasons for the modest yields obtained. On
the basis of mechanistic investigations with deuterated
epoxycyclohexanols4 and epoxypyranosides,6,7 we expect
that not only the isolated aldehyde is formed in the ring
contraction but also its isomer (cf. the unstable aldehyde
of Scheme 3). A very limited number of R,â-unsaturated
aldehydes carrying an (RO)2CH group in the R-position
is known. They are generally difficult to prepare, and
more importantly, they are prone to undergo elimination
of alcohol from the acetal moiety, as well as polymeriza-
tion.13 Such side reactions would explain the limited
yield of isolated aldehydes (Scheme 2), as well as the
absence of isomers (except for 15a ).
Ring contraction (LiBr, TMU) of the epoxy alcohols 24
and 25 gave mixtures of the two aldehydes 26 and 27,
together with the ketone 28. No other products could
be identified. The ketone was probably formed via a 1,2-
hydride shift followed by loss of water. Such hydride
shifts were observed in the rearrangement of epoxycy-
clohexanols described previously.4 The total product
yield in the rearrangement of 24 and 25 was lower than
expected from the TLC analysis. It might in part be due
II. Syn th esis a n d Rin g Con tr a ction of C-Glyco-
sid ic Ep oxy Alcoh ols. In order to investigate the
importance of the methoxy group for the formation of
(13) (a) Nishino, T.; Miichi, Y.; Tokyuama, K. Bull. Chem. Soc. J pn.
1973, 46, 580. (b) Tanaka, M.; Abe, Y.; Tokuama, K. Chem. Pharm.
Bull. 1978, 26, 1558. (c) Depezay, J . C.; Merrer, Y. L.; Saniere, M.
Synthesis 1985, 8, 766. (d) Boussoufi, A.; Parrain, J .-L.; Hudhomme,
P.; Daguay, G. Tetrahedron 1994, 50, 12609.
(14) (a) Bennek, J .; Gray, G. J . Org. Chem. 1987, 52, 892. (b) Horton,
D.; Miyake, T. Carbohydr. Res. 1988, 184, 221.
(15) Szeja, W. Carbohydr. Res. 1988, 183, 135.

7974 J . Org. Chem., Vol. 62, No. 23, 1997
Ponte´n and Magnusson
Sch em e 4a
H-1′′, Me2Si, and Me2CH, but not with H-2 and H-1′ (for
numbering, see Scheme 4). In addition, the long-range
HETCOR experiment showed couplings between C-2 and
CHO, and between C-4 and H-1′′. The NMR spectra of
27 (in a mixture with 26) were fully consistent with the
given structure. The observation that aldehyde 26 was
formed from the C-glycosidic epoxy alcohol 24 indicates
that an isomer of 10 was probably also formed in the
reaction of the analogous O-glycosidic epoxy alcohol 1,
but it was destroyed during the reaction, thus greatly
simplifying the isolation of 10.
Exp er im en ta l Section
1H NMR spectra were recorded (23 °C) at 400 or 300 MHz
proton frequency, using CDCl3 or C6D6 as solvent and CHCl3
(δ 7.26 ppm) or C6D5H (δ 7.30 ppm) as internal standards. 13
C
NMR spectra were recorded at 100 or 75 MHz carbon fre-
quency, using the same solvents and internal standards (δ 77.0
and 128.0 ppm, respectively) as above. The compounds
described below with signal assignments were investigated by
2D NMR experiments. LiBr was dried under reduced pressure
(0.1 mmHg) at 120 °C for 2-12 h. Tetramethylurea (TMU)
was distilled and kept over 4 Å molecular sieves. TLC
analyses were performed with Merck SiO2 60 F254 precoated
aluminum sheets with visualization by UV light, by I2, or by
charring with anisaldehyde in ethanolic sulfuric acid.16 Pre-
parative column chromatography was performed with Matrex
SiO2 60 (35-70 mm) unless otherwise stated. Compounds 1,7
3,12 4,11 5,12 6,12 7,11 8,11 9,11 10,7 and 1714 have been described.
Meth yl 2,3-An h yd r o-6-d eoxy-6-p r op yl-r-D-a llop yr a n o-
sid e (2). Methyl 2,3-anhydro-4-benzoyl-6-deoxy-6-(prop-2-en-
1-yl)-R-D-allopyranoside17 (378 mg, 1.24 mmol) was dissolved
in EtOAc (30 mL), and the mixture was hydrogenated (H2, 1
atm, Pd/C, 74 mg) for 15 h. The catalyst was filtered off
(Celite), and the solvent was removed. The crude product was
dissolved in MeOH (10 mL) and debenzoylated by treatment
with methanolic NaOMe (0.25 mL, 0.5 M) for 20 h. The
mixture was neutralized with SiO2 and concentrated. The
residue was chromatographed (heptane/EtOAc, 1:1) to give 2
1
(198 mg, 79%) as an oil: [R]23 +167 (c 0.9, CHCl3); H NMR
D
data (C6D6) δ 4.57 (d, 1 H, J ) 2.7 Hz), 3.79 (dt, 1 H, J ) 2.3,
9.1 Hz), 3.49 (br dd, 1 H, J ) 8.6, 9.1 Hz), 3.35 (s, 3 H), 3.14
(dd, 1 H, J ) 2.8, 4.1 Hz), 3.12 (dd, 1 H, J ) 1.5, 4.1 Hz), 2.01
(m, 1 H), 1.94 (br d, 1 H, J ) 8.9 Hz), 1.70 (m, 1 H), 1.34-1.60
(m, 4 H), 1.04 (t, 3 H, J ) 7.1 Hz); 13C NMR data (CDCl3) δ
94.5, 69.9, 68.7, 56.0, 55.7, 54.1, 31.1, 27.9, 22.5, 14.0; HRMS
calcd for C10H22O4N (M + NH4) 220.1549, found 220.1552.
Gen er a l P r oced u r e for Rin g Con tr a ction of th e Ep oxy
Alcoh ols 1-9, 24, a n d 25. The epoxy alcohol was dissolved
in dry toluene, and dry LiBr and dry TMU were added under
stirring (magnet). The mixture was refluxed for 10 min and
then cooled to room temperature. TLC analysis showed a UV-
active aldehyde spot with an Rf value 2-3 times greater than
the Rf values of the byproducts (the TLC plates were developed
by the anisaldehyde/H2SO4 reagent16). The mixture was added
to a short (10-15 cm) SiO2 column and chromatographed to
give pure 10-16 and 26 + 27. The eluent was chosen to give
an Rf value of approximately 0.3 for the aldehyde product. The
ring contractions that produced aldehydes in less than 20%
yield generally appeared as brown-black mixtures, whereas
reaction mixtures giving more than 20% yield were less
colored; mixtures giving 10-13 and 26 + 27 had a weak yellow
color.
a
(a) H2, Pd/C, EtOAc/toluene 1:1, 5 h, 22 °C; (b) MeONa/MeOH,
3 h, 22 °C, then (MeO)2CHC6H5, p-TsOH, MeCN, 24 h, 22 °C; (c)
p-TsCl, K2CO3, NaOH, toluene/DMSO, 22:1, 22 h, 22 f 55 °C, then
MeOCH2CH2OH, Bu4NHSO4, 28 h, 22 °C (f ditosylate), then 50%
aqueous NaOH, Bu4NHSO4, DMSO, MeOCH2CH2OH, toluene, 8.7
d, 22 °C f reflux; (d) p-TsCl, pyridine, 24 h, 60 °C, then MeONa/
MeOH, 96 h, 22 °C; (e) H2, Pd/C, EtOAc/THF 1:3, 6 d (20) and 10
d (23), 22 °C; (f) Me2CHMe2CMe2SiCl, pyridine, 72 h (24) and 18
h (25), 22 °C; (g) LiBr, TMU, toluene, reflux, 10 min.
to losses in the workup, since the products are quite
volatile.
The aldehydes 26 and 27 could not be separated by
preparative column chromatography. Attempted separa-
tion with HPLC, both on SiO2 and C8 columns, was
equally unsuccessful. Similar difficulties would probably
have arisen with the O-glycosidic aldehydes of Scheme
2, if the unstable isomeric aldehyde (cf. Scheme 3) had
not been destroyed in the rearrangement reaction. This
was corroborated by unsuccessful attempts to separate
15 from its isomer 15a .
(-)-(2S ,5S )-2-[[[D im e t h y l(1,1,2-t r im e t h y lp r o p y l)-
silyl]oxy]m eth yl]-5-m eth oxy-2,5-d ih yd r ofu r a n -3-ca r ba l-
d eh yd e (10). Epoxy alcohol 17 (145 mg, 0.45 mmol), toluene
(4 mL), LiBr (69 mg, 0.79 mmol), and TMU (0.128 mL, 1.07
mmol) were treated according to the general procedure. The
Aldehyde 26 was obtained, by preparative GC, in
acceptable purity (90-95%) for structure determination
(16) Casey, M.; Leonard, J .; Lygo, B.; Procter, G. Advanced Practical
Organic Chemistry, 1st ed.; Chapman & Hall: New York, 1990.
(17) (a) Keck, G.; Enholm, E.; Yates, J .; Wiley, M. Tetrahedron 1985,
41, 4079. (b) Keck, G.; Yates, J . J . Am. Chem. Soc. 1982, 104, 5829.
1
by NMR (1H-1H NOESY and H-13C long-range HET-
COR). Thus, H-4 showed a strong NOE with CHO, H-5,

R,â-Unsaturaated Five-Membered-Ring Aldehydes
J . Org. Chem., Vol. 62, No. 23, 1997 7975
mixture was chromatographed (heptane/EtOAc, 4:1) to give
10 (78 mg, 57%); [R]D and NMR data were as reported.7
(-)-(2R,5S)-2-Bu tyl-5-m eth oxy-2,5-d ih yd r ofu r a n -3-ca r -
ba ld eh yd e (11). Epoxy alcohol 2 (171 mg, 0.84 mmol),
toluene (8 mL), LiBr (124 mg, 1.43 mmol), and TMU (0.240
mL, 2.00 mmol) were treated according to the general proce-
1.77 (m, 1 H), 1.31 (t, 3 H, J ) 7.1 Hz); 13C NMR data (CDCl3)
δ 187.2, 167.1, 147.7, 142.1, 140.1, 124.7, 107.4, 82.6, 60.7, 54.9,
31.9, 26.9, 14.2; HRMS calcd for C13H19O5 (M + H) 255.1232,
found 255.1216. Compound 15a : 1H NMR data (CDCl3) δ 9.90
(d, 1 H, J ) <1 Hz), 6.67 (dd, 1 H, J ) 1.5, 3.0 Hz), 6.18 (d, 1
H, J ) 1.5 Hz), 5.87 (dd, 1 H, J ) 1.2, 4.2 Hz), 5.49 (m, 1 H),
5.14 (m, 1 H), 4.18 (q, 2 H, J ) 7.1 Hz), 1.30 (t, 3 H, J ) 7.1
Hz).
dure. The mixture was chromatographed (heptane/EtOAc, 4:1)
1
to give 11 (87 mg, 56%): [R]23 -19 (c 2.3, CHCl3); H NMR
D
data (CDCl3) δ 9.90 (s, 1 H), 6.66 (dd, 1 H, J ) 1.6, 1.8 Hz),
5.88 (dd, 1 H, J ) 1.3, 4.2 Hz), 5.14 (m, 1 H), 3.43 (s, 3 H),
1.92 (dddd, 1 H, J ) 3.2, 4.8, 10.9, 13.8 Hz), 1.59 (m, 1 H),
1.38-1.21 (m, 4 H), 0.89 (t, 3 H, J ) 7.1 Hz); 13C NMR data
(CDCl3) δ 187.7, 148.6, 142.3, 107.7, 83.8, 55.2, 33.5, 27.2, 23.0,
14.4; HRMS calcd for C10H17O3 (M + H) 185.1178, found
185.1178.
(-)-(2R,5S)-2-(Bu t-3-en -1-yl)-5-m eth oxy-2,5-d ih yd r ofu -
r a n -3-ca r ba ld eh yd e (12). Epoxy alcohol 312 (180 mg, 0.90
mmol), toluene (8 mL), LiBr (132 mg, 1.51 mmol), and TMU
(0.250 mL, 2.08 mmol) were treated according to the general
procedure. The mixture was chromatographed (heptane/
EtOAc, 4:1) to give 12 (75 mg, 46%): [R]23D -26 (c 2.0, CHCl3);
1H NMR data (CDCl3) δ 9.90 (s, 1 H, CHO), 6.67 (dd, 1 H, J )
1.4, 2.0 Hz, H-4), 5.89 (dd, 1 H, J ) 1.3, 4.2 Hz, H-5), 5.81
(dddd, 1 H, J ) 5.9, 6.7, 10.4, 17.1 Hz, H-3′), 5.16 (dddd, 1 H,
J ) 2.2, 4.3, 6.6, 9.2 Hz, H-2), 5.02 (ddd, 1 H, J ) 1.6, 3.3,
17.1 Hz, H-4′), 4.96 (dddd, 1 H, J ) 1.2, 1.8, 3.3, 10.2 Hz, H-4′),
3.43 (s, 3 H, OMe), 2.18-2.00 (m, 3 H, H-1′ and 2′), 1.72-1.61
(m, 1 H, H-1′); 13C NMR data (CDCl3): δ 187.7 (CHO), 148.4
(C-3), 142.4 (C-4), 138.3 (C-3′), 115.4 (C-4′), 107.7 (C-5), 83.2
(C-2), 55.2 (OMe), 32.9 (C-1′), 29.3 (C-2′); HRMS calcd for
C10H15O3 (M + H) 183.1021, found 183.0985.
(+)-(2S,5S)-2-[(Decylsu lfon yl)m et h yl]-5-m et h oxy-2,5-
d ih yd r ofu r a n -3-ca r ba ld eh yd e (16). Epoxy alcohol 711 (272
mg, 0.75 mmol), toluene (6 mL), LiBr (110 mg, 1.26 mmol),
and TMU (0.215 mL, 1.79 mmol) were treated according to
the general procedure. The mixture was chromatographed
(heptane/EtOAc, 1:1 f 0:1) to give 16 (23 mg, 9%), which
crystallized upon standing: mp 54-56 °C; [R]23 +46 (c 1.4,
D
CHCl3); 1H NMR data (CDCl3): δ 9.92 (d, 1 H, J ) 0.4 Hz,
CHO), 6.79 (dd, 1 H, J ) 1.3, 2.3 Hz, H-4), 5.96 (dd, 1 H, J )
1.3, 4.0 Hz, H-5), 5.53 (dddt, 1 H, J ) 0.4, 2.3, 4.0, 8.7 Hz,
H-2), 3.66 (dd, 1 H, J ) 2.3, 14.9 Hz, H-1′), 3.46 (s, 3 H, OMe),
3.16 (dd, 1 H, J ) 8.7, 14.9 Hz, H-1′), 3.12 (dd, 2 H, J ) 7.9,
8.3 Hz, H-3′), 1.94-1.76 (m, 2 H, H-4′), 1.48-1.41 (m, 2 H,
H-5′), 1.35-1.27 (m, 12 H), 0.89 (t, 3 H, J ) 6.7 Hz, H-12′);
13C NMR data (CDCl3) δ 186.6, 145.1, 142.1, 108.1, 78.2, 55.4,
55.1, 31.8, 29.5, 29.3, 29.1, 28.5, 22.7, 21.9, 14.1; HRMS calcd
for C17H30O5S (M+) 346.1814, found 346.1800.
C-P r op yl 2,3,4,6-Tet r a -O-a cet yl-r-D-glu cop yr a n osid e
(18). Compound 1714 (112 mg, 0.30 mmol) was dissolved in
EtOAc/toluene (10 mL, 1:1) and the mixture was hydrogenated
(H2, 1 atm, Pd/C, 10 mg). After 5 h, the catalyst was filtered
off (Celite), and the solvent was removed. The residue was
chromatographed (SiO2, heptane/EtOAc, 3:1), and the crude
material was crystallized from ether by addition of heptane
(+)-(2S,5S)-2-[(Decylth io)m eth yl]-5-m eth oxy-2,5-d ih y-
d r ofu r a n -3-ca r ba ld eh yd e (13). Epoxy alcohol 411 (504 mg,
1.51 mmol), toluene (12 mL), LiBr (215 mg, 2.47 mmol), and
TMU (0.425 mL, 3.54 mmol) were treated according to the
general procedure. The mixture was chromatographed (hep-
to give pure 18 (107 mg, 95%): mp 132-133 °C; [R]23 +70 (c
D
0.8, CHCl3); 1H NMR data (CDCl3) δ 5.33 (t, 1 H, J ) 9.2 Hz,
H-3), 5.08 (dd, 1 H, J ) 5.8, 9.6 Hz, H-2), 4.99 (dd, 1 H, J )
9.0, 9.4 Hz, H-4), 4.25 (dd, 1 H, J ) 5.2, 12.1 Hz, H-6), 4.19
(ddd, 1 H, J ) 3.3, 5.8, 11.5 Hz, H-1), 4.08 (dd, 1 H, J ) 2.6,
12.1 Hz, H-6), 3.82 (ddd, 1 H, J ) 2.6, 5.2, 9.3 Hz, H-5), 2.10,
2.06, 2.043, 2.036 (4s, 3 H each, Ac), 1.78 (m, 1 H, H-1′), 1.51-
1.42 (m, 2 H, H-1′,2′), 1.33 (m, 1 H, H-2′), 0.97 (t, 3 H, J ) 7.2
Hz, H-3′); 13C NMR data (CDCl3) δ 171.1, 170.6, 170.1, 170.0,
72.9, 70.9, 69.4, 68.9, 62.8, 27.7, 21.2, 21.09, 21.06, 18.6, 14.2;
HRMS calcd for C17H27O9 (M + H) 375.1655, found 375.1656.
C-P r op yl 4,6-O-Ben zylid en e-r-D-glu cop yr a n osid e (19).
Compound 18 (59 mg, 0.16 mmol) was dissolved in MeOH (2
mL), and methanolic NaOMe (0.015 mL, 0.5 M) was added.
After 3 h, SiO2 (ca 0.5 g) was added, and the mixture was
filtered (Celite) and concentrated. The residue was suspended
in a mixture of CH3CN (2.0 mL, freshly distilled) and R,R-
dimethoxytoluene (0.10 mL, 0.67 mmol). p-TsOH (catalytic
amount) was added, and the mixture was stirred for 24 h. The
acid was neutralized by passing the reaction mixture through
a short pad of Al2O3 (basic, grade II). The solvent was removed
to give 19 (41 mg, 88%), which crystallized upon standing: mp
tane/EtOAc, 6:1) to give 13 (215 mg, 45%) as an oil: [R]23
D
+4.2 (c 1.3, CHCl3); 1H NMR data (CDCl3) δ 9.91 (d, 1 H, J )
0.3 Hz), 6.77 (ddd, 1 H, J ) 0.3, 1.3, 1.8 Hz), 5.95 (dd, 1 H, J
) 1.3, 4.1 Hz), 5.38 (dddd, 1 H, J ) 2.0, 2.9, 4.1, 5.0 Hz), 3.45
(s, 3 H), 3.13 (ddd, 1 H, J ) 0.4, 3.2, 13.9 Hz), 2.89 (dd, 1 H,
J ) 4.9, 13.9 Hz), 2.53 (t, 2 H, J ) 7.5 Hz), 1.56 (m, 2 H),
1.40-1.24 (m, 14 H), 0.89 (t, 3 H, J ) 6.7 Hz); 13C NMR data
(CDCl3) δ 187.5, 146.7, 143.1, 108.3, 83.5, 55.5, 36.0, 33.9, 32.3,
30.2, 30.0, 29.9, 29.8, 29.7, 29.6, 29.3, 14.5; HRMS calcd for
C17H30O3S (M+) 314.1916, found 314.1906.
(-)-(2R,5S)-2-[3-(Acetoxym eth yl)bu t-3-en -1-yl]-5-m eth -
oxy-2,5-d ih yd r ofu r a n -3-ca r ba ld eh yd e (14). Epoxy alcohol
512 (237 mg, 0.87 mmol), toluene (8 mL), LiBr (123 mg, 1.42
mmol), and TMU (0.250 mL, 2.08 mmol) were treated accord-
ing to the general procedure. The mixture was chromato-
graphed (heptane/EtOAc, 3:1) to give 14 (85 mg, 38%): [R]23
D
1
-18 (c 0.9, CHCl3); H NMR data (CDCl3) δ 9.90 (d, 1 H, J )
0.3 Hz, CHO), 6.68 (dd, 1 H, J ) 1.3, 2.1 Hz, H-4), 5.88 (dd, 1
H, J ) 1.3, 4.2 Hz, H-5), 5.14 (m, 1 H, H-2), 5.04 (dd, 1 H, J
) 0.8, 1.2 Hz, H-4′), 4.96 (t, 1 H, J ) 0.6 Hz, H-4′), 4.53, 4.50
(AB q, 2 H, J ) 14.3 Hz, CH2OAc), 3.42 (s, 3 H, OMe), 2.17-
2.04 (m, 3 H, H-1′ and 2′), 2.09 (s, 3 H, Ac), 1.77-1.65 (m, 1
H, H-1′); 13C NMR data (CDCl3) δ 187.6 (CHO), 171.2 (Ac),
148.2 (C-3), 143.5 (C-3′), 142.5 (C-4), 113.2 (C-4′), 107.7 (C-5),
83.1 (C-2), 67.3 (CH2OAc), 55.2 (OMe), 31.8 (C-1′), 28.7 (C-2′),
21.4 (Ac); HRMS calcd for C13H18O5 (M+) 254.1154, found
254.1153.
195-197 °C; [R]23 +51 (c 0.6, CHCl3); 1H NMR data (CDCl3)
D
δ 7.51 (m, 2 H, Ph), 7.39 (m, 3 H, Ph), 5.55 (s, 1 H, PhCH),
4.28 (dd, 1 H, J ) 4.6, 10.1 Hz, H-6), 4.10 (m, 1 H, H-1), 3.90
(m, 2 H, H-2,3), 3.71 (t, 1 H, J ) 10.1 Hz, H-6), 3.62 (dt, 1 H,
J ) 4.6, 9.7 Hz, H-5), 3.47 (t, 1 H, J ) 9.3 Hz, H-4), 2.65 (d, 1
H, J ) 1.8 Hz, OH), 2.44 (d, 1 H, J ) 2.4 Hz, OH), 1.71 (m, 2
H, H-1′), 1.53 (m, 1 H, H-2′), 1.36 (m, 1 H, H-2′), 0.99 (t, 3 H,
J ) 7.3 Hz, H-3′); 13C NMR data (CDCl3) δ 137.5, 129.8, 128.8,
126.7, 102.4, 82.6, 76.8, 72.8, 72.1, 69.9, 63.7, 27.0, 19.0, 14.3;
HRMS calcd for C16H23O5 (M + H) 295.1545, found 295.1549.
C-P r op yl 4,6-O-Ben zylid en e-2,3-a n h yd r o-r-D-a llop yr a -
n osid e (20). Compound 19 (243 mg, 0.82 mmol) was dissolved
in toluene (9 mL), and K2CO3 (1.32 g, 9.55 mmol), powdered
NaOH (480 mg, 12.0 mmol), 4-toluenesulfonyl chloride (409
mg, 2.14 mmol), and DMSO (0.40 mL) were added. The
mixture was stirred at room temperature for 12 h and at 55
°C for 10 h and then cooled to room temperature. 2-Methoxy-
ethanol (0.45 mL, 5.70 mmol) and tetrabutylammonium
hydrogen sulfate (76.2 mg, 0.22 mmol) were added, and the
stirring was continued for 28 h at room temperature. The
mixture was poured into water/toluene (50 mL, 1:1), and the
organic phase was washed with water (3 × 10 mL), dried (Na2-
(-)-(2R,5S)-2-[3-(Eth oxycar bon yl)bu t-3-en -1-yl]-5-m eth -
oxy-2,5-dih ydr ofu r an -3-car baldeh yde (15) an d (-)-(2S,5R)-
5-[3-(Eth oxyca r bon yl)bu t-3-en -1-yl]-2-m eth oxy-2,5-d ih y-
d r ofu r a n -3-ca r ba ld eh yd e (15a ). Epoxy alcohol 612 (58 mg,
0.21 mmol), toluene (2.5 mL), LiBr (31 mg, 0.35 mmol), and
TMU (0.060 mL, 0.50 mmol) were treated according to the
general procedure. The mixture was chromatographed (hep-
tane/EtOAc, 1:1) to give 15, containing 3% of its isomer 15a
23
(20 mg, 38%); [R]D -16 (c 2.0, CDCl3). Compound 15: 1H
NMR data (CDCl3) δ 9.91 (s, 1 H), 6.68 (dd, 1 H, J ) 1.3, 2.0
Hz), 6.15 (m, 1 H), 5.89 (dd, 1 H, J ) 1.3, 4.1 Hz), 5.54 (dd, 1
H, J ) 1.4, 2.8 Hz), 5.17 (m, 1 H), 4.20 (q, 2 H, J ) 7.1 Hz),
3.43 (s, 3 H), 2.34 (dd, 2 H, J ) 7.5, 8.0 Hz), 2.13 (m, 1 H),

7976 J . Org. Chem., Vol. 62, No. 23, 1997
Ponte´n and Magnusson
SO4), and concentrated to give a crude ditosylate (497 mg).
Attempts to purify the ditosylate on silica were unsuccessful.
The crude ditosylate (396 mg, approx. 0.66 mmol) was dis-
solved in a mixture of toluene (7 mL), DMSO (0.35 mL) and
2-methoxyethanol (0.15 mL), and aqueous sodium hydroxide
(2 mL, 50%) and tetrabutylammonium hydrogen sulfate (76.2
mg) were added. The reaction mixture was stirred at room
temperature for 8 days, then refluxed for 17 h, and treated as
in the preparation of the mixture of 21 and 20 below. The
crude product was chromatographed (SiO2, heptane/EtOAc,
days, and the catalyst was filtered off (Celite). The solvent
was removed, and the residue was chromatographed (toluene/
EtOAc, 1:1 f 0:1) to give 23 (293 mg, 75%), which crystallized
from an ether/heptane mixture: mp 75-78 °C; [R]23 +5.3 (c
D
1
1.4, CDCl3); H NMR data (CDCl3) δ 4.11 (dd, 1 H, J ) 4.3,
10.0 Hz, H-1), 3.84 (br d, 1 H, J ) 8.8 Hz, H-4), 3.74 (m, 2 H,
H-6), 3.50 (br d, 1 H, J ) 2.3 Hz, OH), 3.31 (d, 1 H, J ) 3.8
Hz, H-2 or 3), 3.21 (ddd, 1 H, J ) 4.3, 4.5, 9.0 Hz, H-5), 3.06
(d, 1 H, J ) 3.8 Hz, H-2 or 3), 2.70 (br s, 1 H, OH), 1.84 (m, 1
H, H-1′), 1.40-1.55 (m, 3 H, H-1′,2′), 0.98 (t, 3 H, J ) 7.2 Hz,
H-3′); 13C NMR data (CDCl3) δ 71.3, 70.2, 63.5, 63.2, 56.1, 53.3,
31.3, 19.4, 14.3; HRMS calcd for C9H17O4 (M + H) 189.1127,
found 189.1123.
4:1) to give 20 (34 mg, 18%): mp 90-92 °C; [R]23 +40 (c 0.9,
D
CHCl3); 1H NMR data (CDCl3) δ 7.53 (m, 2 H, Ph), 7.36-7.40
(m, 3 H, Ph), 5.58 (s, 1 H, PhCH), 4.20 (ddd, 1 H, J ) 0.7, 4.9,
10.2 Hz, H-6), 4.07 (ddd, 1 H, J ) 3.2, 5.8, 8.6 Hz, H-1), 4.01
(dd, 1 H, J ) 1.2, 9.0 Hz, H-4), 3.85 (ddd, 1 H, J ) 4.9, 9.0,
10.2 Hz, H-5), 3.65 (t, 1 H, J ) 10.2 Hz, H-6), 3.58 (br d, 1 H,
J ) 4.6 Hz, H-3), 3.40 (dd, 1 H, J ) 3.2, 4.6 Hz, H-2), 1.83 (m,
1 H, H-1′), 1.70 (m, 1 H, H-1′), 1.40-1.55 (m, 2 H, H-2′), 1.00
(t, 3 H, J ) 7.3 Hz, H-3′); 13C NMR data (CDCl3) δ 137.7, 129.6,
128.8, 126.7, 103.1, 78.8, 71.4, 69.8, 61.4, 56.1, 52.2, 32.3, 19.2,
14.4; HRMS calcd for C16H21O4 (M + H) 277.1440; found
277.1444.
C-P r op yl 2,3-An h yd r o-6-O-[d im eth yl(1,1,2-tr im eth yl-
p r op yl)silyl]-r-D-a llop yr a n osid e (24). Compound 22 (67
mg, 0.36 mmol) was dissolved in dry pyridine (5 mL), and
dimethyl(1,1,2-trimethylpropyl)chlorosilane (0.085 mL, 0.43
mmol) was added at room temperature under stirring. After
2 days, a second portion of dimethyl(1,1,2-trimethylpropyl-
)chlorosilane (0.007 mL, 0.03 mmol) was added, and the
mixture was stirred at -18 °C overnight. TLC (toluene/EtOAc,
1:1) showed that 22 had been consumed. MeOH (1 drop) and
toluene (3 × 10 mL) were added, and the solvents were
removed. The syrupy residue was dissolved in ether (75 mL),
and the organic phase was washed with water (3 × 5 mL),
dried (Na2SO4), and concentrated. The residue was chromato-
C-P r opyl 4,6-O-Ben zyliden e-2,3-an h ydr o-r-D-m an n opy-
r a n osid e (21) a n d C-P r op yl 4,6-O-Ben zylid en e-2,3-a n h y-
d r o-r-D-a llop yr a n osid e (20). Compound 19 (769 mg, 2.61
mmol) was dissolved in dry pyridine (75 mL), and 4-toluene-
sulfonyl chloride (1030 mg, 5.40 mmol) was added. The
mixture was left at room temperature for 1 h, then heated at
60 °C for 24 h, and cooled to room temperature. The solvent
was removed by coevaporation with two portions of toluene,
the residue was partitioned between ether and water, and the
aqueous phase was extracted with ether (5 × 50 mL). The
extract was dried (Na2SO4), filtered, and concentrated. The
syrupy residue was chromatographed (SiO2, heptane/EtOAc,
3:1) to give a regioisomeric mixture of monotosylates (971 mg,
83%). Part of the mixture (237 mg, 0.53 mmol) was dissolved
in MeOH (5 mL), and methanolic NaOMe (2 mL, 0.5 M) was
added under stirring. An additional portion of methanolic
NaOMe (0.5 mL) was added after 3 days, and the stirring was
continued for 24 h. CH2Cl2 (25 mL) was added, and the
mixture was washed with water (3 × 5 mL), dried (Na2SO4),
filtered, and concentrated. The residue was chromatographed
(heptane/EtOAc, 3:1) to give 20 (25 mg, 25%) and 21 (95 mg,
graphed (CH2
Cl2/EtOAc, 100:1 f 10:1) to give 24 (19 mg, 16%)
1
as a syrup: [R]23 -3.2 (c 1.6, CHCl3); H NMR data (CDCl3)
D
δ 4.00 (ddd, 1 H, J ) 3.4, 5.8, 8.9 Hz, H-1), 3.93 (ddd, 1 H, J
) 2.1, 5.2, 7.7 Hz, H-4), 3.76 (dd, 1 H, J ) 5.3, 10.2 Hz, H-6),
3.67 (dd, 1 H, J ) 6.3, 10.2 Hz, H-6), 3.51 (dd, 1 H, J ) 2.1,
4.4 Hz, H-3), 3.47 (dt, 1 H, J ) 5.8, 8.2 Hz, H-5), 3.43 (dd, 1
H, J ) 3.4, 4.4 Hz, H-2), 3.00 (br d, 1 H, J ) 5.2 Hz, OH-4),
1.73 (m, 1 H, H-1′), 1.63 (m, 2 H, H-1′ and Me2CH), 1.45 (m,
2 H, H-2′), 0.97 (t, 3 H, J ) 7.3 Hz, H-3′), 0.87 (d, 6 H, J ) 6.9
Hz, Me2
CH), 0.85 (s, 6 H, Me C), 0.13 (s, 6 H, Me Si); 13C NMR
2
2
data (CDCl3) δ 70.2, 69.7, 69.2, 65.5, 57.7, 54.8, 34.5, 31.6, 25.5,
20.7, 20.6, 19.1, 18.9, 18.8, 14.4, -3.1, -3.2; HRMS calcd for
C17H35O4Si (M + H) 331.2305, found 331.2307.
C-P r op yl 2,3-An h yd r o-6-O-[d im eth yl(1,1,2-tr im eth yl-
p r op yl)silyl]-r-D-m a n n op yr a n osid e (25). Compound 23
(266 mg, 1.41 mmol) was dissolved in dry pyridine (20 mL),
and dimethyl(1,1,2-trimethylpropyl)chlorosilane (0.335 mL,
1.70 mmol) was added at room temperature under stirring.
After 18 h, TLC (toluene/EtOAc, 1:1) showed that 23 had been
consumed. MeOH (1 drop) and toluene (3 × 25 mL) were
added, and the solvents were removed. The syrupy residue
was dissolved in ether (200 mL), and the organic phase was
washed with water (3 × 20 mL), dried (Na2SO4), and concen-
trated. The residue was chromatographed (CH2Cl2/EtOAc, 10:
1) to give 25 (285 mg, 61%) as a syrup [chromatography with
heptane/EtOAc, 4:1, gave a mixture of 25 and the isomer
65%). Both 20 and 21 crystallized upon standing. Compound
1
21: mp 113-115 °C; [R]23 +28 (c 0.8, CHCl3); H NMR data
D
(CDCl3) δ 7.52 (m, 2 H, Ph), 7.39 (m, 3 H, Ph), 5.60 (s, 1 H,
PhCH), 4.25 (dd, 1 H, J ) 4.7, 10.4 Hz, H-6), 4.18 (dd, 1 H, J
) 4.4, 10.1 Hz, H-1), 3.72 (d, 1 H, J ) 10.4 Hz, H-6), 3.68 (d,
1 H, J ) 9.6 Hz, H-4), 3.50 (d, 1 H, J ) 3.8 Hz, H-3), 3.35 (dt,
1 H, J ) 4.7, 9.8 Hz, H-5), 3.07 (d, 1 H, J ) 3.8 Hz, H-2), 1.85-
1.94 (m, 1 H, H-1′), 1.44-1.61 (m, 3 H, H-1′,2′), 1.01 (t, 3 H, J
) 7.2 Hz, H-3′); 13C NMR data (CDCl3) δ 137.6, 129.7, 128.8,
126.6, 102.7, 76.2, 72.8, 70.3, 63.3, 54.5, 53.2, 32.2, 19.5, 14.2;
HRMS calcd for C16H21O4 (M + H) 277.1440, found 277.1437.
C-P r op yl 2,3-An h yd r o-r-D-a llop yr a n osid e (22). Com-
pound 20 (149 mg, 0.54 mmol) was dissolved in THF/EtOH
(4.5 mL, 3:1), and the mixture was hydrogenated (H2, 1 atm,
Pd/C, 38 mg). The reaction was monitored by TLC (heptane/
EtOAc, 2:1). The starting material was consumed after 6 days,
and the catalyst was filtered off (Celite). The solvent was
removed, and the residue was chromatographed (toluene/
silylated in the 4-position (407 mg, 10:1)]. Compound 25:
1
[R]23 -19 (c 0.9, CHCl3); HNMR data (CDCl3) δ 4.08 (dd, 1
D
H, J ) 4.4, 10.2 Hz, H-1), 3.81 (dd, 1 H, J ) 5.3, 9.5 Hz, H-6),
3.76 (dd, 1 H, J ) 1.3, 8.6 Hz, H-4), 3.57 (dd, 1 H, J ) 9.0, 9.5
Hz, H-6), 3.28 (d, 1 H, J ) 1.7 Hz, OH-4), 3.26 (d, 1 H, J ) 3.9
Hz, H-2 or -3), 3.23 (m, 1 H, H-5), 3.03 (d, 1 H, J ) 3.8 Hz,
H-2 or -3), 1.85 (m, 1 H, H-1′), 1.61 (heptet, 1 H, J ) 6.9 Hz,
Me2CH), 1.39-1.56 (m, 3 H, H-1′,2′), 0.98 (t, 3 H, J ) 7.1 Hz,
H-3′), 0.88 (d, 6 H, J ) 6.8 Hz, Me2CH), 0.86 (s, 6 H, Me2C),
0.14 (s, 6 H, Me2Si); 13C NMR data (CDCl3) δ 71.3, 68.7, 67.6,
66.6, 55.1, 53.0, 34.5, 31.3, 25.6, 20.7, 20.5, 19.4, 18.9, 18.8,
14.2, -3.2, -3.3; HRMS calcd for C17H35O4Si (M + H)
331.2305, found 331.2312.
EtOAc, 1:1 f 0:1) to give 22 (75 mg, 74%) as an oil: [R]23
D
1
+26 (c 1.6, CHCl3); H NMR data (CDCl3) δ 4.03 (ddd, 1 H, J
) 3.5, 6.0, 9.0 Hz, H-1), 3.95 (br t, 1 H, J ) 7.9 Hz, H-4), 3.76,
3.71 (br ABq, 2 H, J ) 11.7 Hz, H-6), 3.52 (dd, 1 H, J ) 1.8,
4.5 Hz, H-3), 3.47 (dd, 1 H, J ) 3.6, 4.5 Hz, H-2), 3.43 (m, 1 H,
H-5), 3.26 (d, 1 H, J ) 8.2 Hz, OH-4), 2.69 (m, 1 H, OH-6),
1.77-1.68 (m, 1 H, H-1′), 1.65-1.56 (m, 1 H, H-1′), 1.51-1.35
(m, 2 H, H-2′), 0.96 (t, 3 H, J ) 7.3 Hz, H-3′); 13C NMR data
(CDCl3) δ 70.5, 70.4, 66.5, 62.9, 58.5, 55.5, 31.5, 19.2, 14.4;
HRMS calcd for C9H17O4 (M + H) 189.1127, found 189.1127.
C-P r opyl 2,3-An h ydr o-r-D-m an n opyr an oside (23). Com-
pound 21 (571 mg, 2.07 mmol) was dissolved in THF/EtOH
(13.5 mL, 3:1), and the mixture was hydrogenated (H2, 1 atm,
Pd/C, 102 mg). The reaction was monitored by TLC (heptane/
EtOAc, 2:1). The starting material was consumed after 10
(2R,5S)-2-P r op yl-5-[[[Dim eth yl(1,1,2-tr im eth ylp r op yl)-
silyl]oxy]m eth yl]-2,5-d ih yd r ofu r a n -3-ca r ba ld eh yd e (26).
(a) Epoxy alcohol 24 (16.3 mg, 0.049 mmol), toluene (0.8 mL),
LiBr (8.1 mg, 0.093 mmol), and TMU (0.015 mL, 0.125 mmol)
were treated according to the general procedure. The mixture
was chromatographed (heptane/EtOAc, 10:1) to give a mixture
(81:18:1 according to 1H-NMR and GC-MS analysis: DB-Wax
30 m capillary column, 100 °C for 3 min, then 3 °C/min) of 26,
27, and 28 (9.3 mg, 61%).
(b) Epoxy alcohol 25 (201 mg, 0.61 mmol), toluene (6 mL),
LiBr (99 mg, 1.14 mmol), and TMU (0.200 mL, 1.67 mmol)

R,â-Unsaturaated Five-Membered-Ring Aldehydes
J . Org. Chem., Vol. 62, No. 23, 1997 7977
were treated according to the general procedure. The mixture
was chromatographed (heptane/EtOAc, 10:1) to give a mixture
(71:17:12 according to H-NMR and GC-MS analysis) of 26,
H, J ) 6.8 Hz, Me2CH), 0.84 (s, 6 H, Me2C), 0.10 (s, 6 H, Me2-
Si); 13C NMR data (CDCl3) δ 187.4 (CHO), 148.5 (C-4), 146.1
(C-3), 86.1 (C-5), 84.5 (C-2), 65.4 (C-1′′), 36.8 (C-1′), 34.6
(Me2CH), 25.5 (Me2C), 20.7, 18.9, 18.6, 14.4 (C-3′), -3.1 (Me2-
Si); HRMS calcd for C17H33O3Si (M + H): 313.2199, found
313.2186.
1
27, and 28 (114 mg, 60%). A sample of 26 (90-95% purity)
was obtained by preparative GC (6 m OV-351 column with
inner diameter 4 mm; column temperature 175 °C; injector
temperature 225 °C; detector temperature 210 °C; injected
volume of 26 dissolved in ether: 0.150 mL, 100 mg/mL; elution
time 225-230 min). Compounds 27 and 28 were not obtained
pure enough for full structural analysis; 1H NMR and HRMS
of the crude material was consistent with the structures given.
Compound 26: 1H NMR data (CDCl3) δ 9.83 (s, 1 H, CHO),
6.90 (t, 1 H, J ) 1.7 Hz, H-4), 5.11 (dddd, 1 H, J ) 1.7, 4.2,
5.7, 6.3 Hz, H-2), 5.01 (dddd, 1 H, J ) 1.7, 3.5, 5.1, 8.8 Hz,
H-5), 3.81 (dd, 1 H, J ) 4.2, 10.2 Hz, CH2OSi), 3.64 (dd, 1 H,
J ) 6.3, 10.2 Hz, CH2OSi), 1.83 (m, 1 H, OCHCH2CH2), 1.66-
1.54 (m, 2 H, OCHCH2CH2, Me2CH), 1.45-1.33 (m, 2 H,
OCHCH2CH2), 0.93 (t, 3 H, J ) 7.3 Hz, CH2CH3), 0.87 (d, 6
Ack n ow led gm en t. This work was supported by the
Swedish Natural Science Research Council.
Su p p or tin g In for m a tion Ava ila ble: 1H NMR spectra for
all title compounds described in the Experimental Section (16
pages). This material is contained in libraries on microfiche,
immediately 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.
J O970666K