Deoxygenation/dimerization of sugar derivatives with BF3· Et2O-Et3SiH: Synthesis of a β-isonucleoside

Article abstract of DOI:10.1016/j.tetlet.2012.06.121

Lewis acid-Et₃SiH induced deoxygenation of anomeric carbon of sugars generates tetrahydrofuran derivatives, accompanied by hitherto unknown dimeric products. If the reagent addition steps are reversed, tetrahydrofuran derivatives are obtained a

Full text of DOI:10.1016/j.tetlet.2012.06.121

Tetrahedron Letters 53 (2012) 4929–4932
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Tetrahedron Letters
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Deoxygenation/dimerization of sugar derivatives with BF3ꢀEt2O–Et3SiH:
synthesis of a b-isonucleoside
⇑
Subhrangshu Mukherjee , Biswajit G. Roy, Soumendra N. Das, Sukhendu B. Mandal
Chemistry Division, CSIR-Indian Institute of Chemical Biology, 4, Raja S.C. Mullick Road, Jadavpur, Kolkata 700 032, India
a r t i c l e i n f o
a b s t r a c t
Article history:
Lewis acid-Et3SiH induced deoxygenation of anomeric carbon of sugars generates tetrahydrofuran deriv-
atives, accompanied by hitherto unknown dimeric products. If the reagent addition steps are reversed,
tetrahydrofuran derivatives are obtained as the sole products, while only the dimeric products are iso-
lated if Et3SiH is excluded. One of the deoxygenated products has been transformed into a b-
isonucleoside.
Received 1 June 2012
Revised 25 June 2012
Accepted 27 June 2012
Available online 3 July 2012
Ó 2012 Elsevier Ltd. All rights reserved.
Keywords:
Boron trifluoride-etherate
Triethylsilane
Deoxygenation
Dimerization
Synthesis
Isonucleosides
Self-glycosylation reaction for the generation of disaccharides is
scarcely reported. Formation of di- -fructose dianhydrides via acid
catalyzed dimerization1 of
-fructose, sucrose or inulin through a
The starting sugar based precursor 5 was derived from 3-O-ben-
zyl xylose,8 whereas 6 and 9 were obtained from the corresponding
dihydroxymethyl derivatives9,10 via benzylation. Compounds 7,11
8,12 10,13 and 1114 were prepared following the literature methods.
For the deoxygenation of the anomeric carbon, the starting syn-
thons (type A, Scheme 1) 5–11 (Table 1) were treated with Et3SiH
in the presence of BF3ꢀEt2O.15,16 Interestingly, treatment of BF3ꢀEt2O
at first followed by Et3SiH (Method I)17 furnished the normal tetra-
hydrofuran derivatives (type B) 12, 14, 16, 18, 20, 22, and 24 (27–
45% yields) along with the hitherto unknown dimeric products
(type C) 13, 15, 17, 19, 21, 23, and 25 (32–38% yields) (Table 1).
However, reversal of the addition schedule to employ Et3SiH first
and then BF3ꢀEt2O ensured exclusive formation of the deoxygen-
ated products in 67–78% yields (Method II).17 On the other hand,
D
D
fructosyl oxocarbenium cation and in situ glycosylation into the
respective disaccharide has been demonstrated by Mellet and Gar-
cía Fernández group.2 Very recently, a report by Uriel et al.3
disclosed the use of self-glycosylation for stereoselective formation
of disaccharides from mannose-derived orthoesters by treatment
with BF3ꢀEt2O. The role of BF3ꢀEt2O for the cleavage of acetonide
protection and as promoter in glycosylation reaction in a tandem
manner has been clearly revealed in these reactions. It appeared
that during the self-glycosylation reaction occurring through
oxocarbenium ion, in situ addition of a hydride donor that could
act in the presence of the Lewis acid to reduce the double bond
would prevent glycosylation and generate solely 3-hydroxytetra-
hydrofuran derivatives (deoxygenated products), which could be
transformed to bioactive isonucleosides4–7 via nucleophilic dis-
placement of 3-OH group by nucleobases (Fig. 1). However, if gly-
cosylation and hydride addition compete with each other, the
reaction could afford both deoxygenated and dimerized products.
This realization has encouraged us to exploit this strategy for the
stereoselective preparation of D-glucose-based chiral 3-hydroxy-
(i) Acetonide
deprotection and
deletion of C-6
OH
O
2/
O
H
6
O
H
O
1
HO
N
N
N
tetrahydrofuran derivatives and di-D
-glucose 1,20:10,2-dianhy-
drides (dimeric products), and the results are described herein.
O
4
N
O
HO
NH2
(ii) Deoxygenation
of C-1 and nucleo-
sidation at C-2
⇑
Corresponding author.
E-mail address: bantim_2006@rediff.com (S. Mukherjee).
Figure 1. A strategy to generate isonucleosides.
0040-4039/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.tetlet.2012.06.121

4930
S. Mukherjee et al. / Tetrahedron Letters 53 (2012) 4929–4932
Method I:
(i) BF3.Et2O
CH2Cl2, 0 °C, 15 min
(ii) Et3SiH (4 equiv.), 2 h, rt
R1
R2
R1
R2
O
O
R1
R2
R3
R2
R1
O
O
+
O
R3
O
C
OH
R3
O
O
R3
A
B
Method II:
(i) Et3SiH (4.0 equiv.),
CH2Cl2, 0 °C, 15 min
(ii) BF3.Et2O (2 equiv.), 2 h, rt
R1
R2
O
R1
R2
O
O
OH
R3
O
R3
B
A
Method III:
BF3.Et2O (2 equiv.),
CH2Cl2, 0 °C, 15 min
2 h, rt
R1
R2
O
R3
R2
R1
O
R1
R2
O
O
R3
O
C
O
O
R3
A
R1 = CH2OBn/Vinyl/Pentenyl, R2 = H/CH2OBn, R3 = OBn/Oallyl/H
Scheme 1. Deoxygenation of anomeric carbon and dimerization of sugar.
Table 1
Reaction of sugar derivatives with BF3ꢀEt2O–Et3SiH
Entry Starting sugar Deoxygenated product
Yield (%)
Method I Method II
Dimeteric product
Yield (%)
Method I Method II
O
O
O
BnO
BnO
BnO
OBn
O
O
1
42
27
78
67
33
37
75
72
O
OH
OH
O
BnO
BnO
BnO
12
BnO
13
O
BnO
5
O
O
O
BnO
BnO
BnO
BnO
BnO
BnO
OBn
O
O
OBn
2
O
6
O
BnO 14
BnO
O
O
15
BnO
OBn
C3H7
O
O
O
O
C3H7
C3H7
C3H7
BnO
3
4
35
38
72
72
35
36
80
78
O
OH
7
16
O
BnO
BnO
O
17
O
O
O
O
O
O
O
OH
8
O
O
O
O
18
O
O
19
O
O
O
BnO
BnO
BnO
BnO
BnO
BnO
O
O
OBn
5
6
7
42
45
44
75
71
69
32
36
38
73
79
70
OH
O
20
O
9
21
BnO
H
O
BnO
H
BnO
BnO
H
O
O
O
O
H
O
O
BnO
BnO
OBn
OBn
O
O
O
OH
O
O
H
H
H
O
H
10
22
23
O
O
BnO
O
O
O
O
O
OH
O
O
O
O
24
11
25
the use of BF3ꢀEt2O as the sole reagent furnished the dimeric prod-
ucts exclusively in 70–80% yields (Method III).17 All the products
were characterized by 1H and 13C NMR besides MS analyses.18
The presence of an extra CH2 signal (ꢁd 70.0) and absence of the
anomeric carbon signal in the 13C NMR spectra, coupled with the
absence of signals for isopropylidene methyl and the anomeric
proton in the 1H NMR spectra of the deoxygenated products indi-
cated the successful reduction of the anomeric position. However,

S. Mukherjee et al. / Tetrahedron Letters 53 (2012) 4929–4932
4931
the anomeric proton and carbon signals appeared at ꢁd 5.2 and ꢁd
Grubbs catalyst
(1st generation),
CH2Cl2, rt,16h,
82%
98.0, respectively, as expected, in the NMR spectra of the dimeric
products, which showed peaks for half the number of nuclei due
to C2 symmetric nature of the molecules. Mass spectral analyses
of the dimeric products showed the appropriate molecular ion
peaks.
H
O
O
O
H
O
O
O
The proposed mechanism for the formation of two products in-
volves the cleavage of the acetonide ring aided by complexation
with BF3, producing an oxocarbenium intermediate that either
undergoes reduction with triethylsilyl hydride to produce the C-
1-deoxygenated product or dimerizes. However, addition of Et3SiH
before BF3ꢀEt2O ensures that the initially formed silicon–complex
intermediate can facilitate the transfer of hydride ion on to the
anomeric carbon, leading to the formation of deoxygenated prod-
uct only (Fig. 2). Formation of the dimer as the sole product using
only BF3ꢀEt2O is also in full agreement with the mechanism.
Subsequently, to support the formation of dimers, one of the di-
meric products, the diallyl-divinyl-1,4-dioxane derivative 19, was
treated with 1st generation Grubbs catalyst in CH2Cl2 to isolate
the bis(pyranofuro)dioxane derivative 2619 in 82% yield upon ring
closing metathesis reaction (Scheme 2).
O
O
O
O
O
O
19
26
Scheme 2. Ring closing metathesis of the olefin 19–26.
OBn
O
DEAD, PPh3,
12
THF, 6-Chloropurine,
rt,18h, 56%
N
BnO
N
N
N
Cl
27
OH
Since 3-hydroxytetrahydrofuran derivatives are key intermedi-
ates for some important isonucleosides, we exploited the tetrahy-
O
(i) MeOH, NH3 (saturated),
rt, 48h
(ii) H2-Pd/C (10%),
MeOH, rt, 12h, 51%
drofuran derivative 12 as
a
representative example for
N
HO
N
isonucleoside synthesis. Thus, insertion of 6-chloropurine base on
12 under Mitsunobu reaction condition using DEAD-Ph3P in THF
produced the protected nucleoside 2719 in 56% yield (Scheme 3).
Substitution of chloro group by amine upon treatment with meth-
anolic ammonia followed by hydrogenolytic cleavage of the benzyl
groups furnished in 51% yield (in two steps) the targeted b-isonu-
N
NH2
N
28
Scheme 3. Conversion of 12 to the isonucleoside 28.
cleoside 28 as foam, ½a D25
ꢂ
+27.2 (c 0.24, MeOH) {lit4b
½
a 2D5
for its
ꢂ
enantiomer ꢃ26.6 (c 0.27, MeOH)}; ESIMS, m/z: 274 (M+Na)+.
Inclusion of the chloropurine ring was evident from the presence
of two singlets at d 8.33 and 8.64 in the 1H NMR spectrum, and
the signals at d 130.9, 144.9, 150.7, 151.5, and 151.7 in the 13C
NMR spectrum of 27.
reaction condition and shedding of the protecting groups provided
an isonucleoside. This strategy could be used to other systems.
Acknowledgments
In conclusion, this work describes a method for the deoxygen-
ation of anomeric carbon using Lewis acid catalyzed reduction
with triethylsilane. Tinkering with the reagent addition order also
generated dimeric products, which became the exclusive products
by avoiding the silane reagent. Subsequent inclusion of a nucleo-
base on one of the deoxygenated products under Mitsunobu
The authors (S.M. and B.G.R.) gratefully acknowledge CSIR for
providing them with Senior Research Fellowships, and B. Achari,
ex-scientist of the institute for helping to edit the manuscript.
References and notes
1. (a) Defaye, J.; Garcia Fernández, J. M. Carbohydr. Res. 1994, 251, 17–31; (b)
Garcia Fernández, J. M.; Schnelle, R. R.; Defaye, J. Tetrahedron: Asymmetry 1995,
6, 307–312; (c) Kennedy, I. A.; Hemscheidt, T.; Britten, J. F.; Spenser, I. D. Can. J.
Chem. 1995, 73, 1329–1337.
2. (a) Benito, J. M.; Gomez Garcia, M.; Mellet, C. O.; Garcia Fernández, J. M.;
Defaye, J. Org. Lett. 2001, 3, 549–552; (b) Rubio, E. M.; Mellet, C. O.; Garcia
Fernández, J. M. Org. Lett. 2003, 5, 873–876; (c) Garcia Fernández, J. M.; Mellet,
C. O.; Defaye, J. J. Org. Chem. 1998, 63, 3572–3580.
OR
O
H-SiEt3
OR
O
O
O
BF3.OEt2
RO
O
RO
BF3.OEt2
3. Uriel, C.; Ventura, J.; Gómez, A. M.; Cristóbal López, J.; Fraser-Reid, B. J. Org.
Chem. 2012, 77, 795–800.
4. (a) Kakefuda, A.; Shute, S.; Nagahata, T.; Sek, J.; Sasaki, T.; Matsuda, A.
Tetrahedron 1994, 50, 10167–10182; (b) Bravo, F.; Diaz, Y.; Castillón, S.
Tetrahedron: Asymmetry 2001, 12, 1635–1643.
5. (a) Nair, V.; Nuesca, Z. M. J. Am. Chem. Soc. 1992, 114, 7951–7953; (b) Diaz, Y.;
Bravo, F.; Castillón, S. J. Org. Chem. 1999, 64, 6508–6511.
6. Lei, Z.; Zhang, L. H. Tetrahedron: Asymmetry 2000, 11, 2899–2906.
7. Yoshimura, Y.; Asami, K.; Matsui, H.; Tanaka, H.; Takahata, H. Org. Lett. 2006, 8,
6015–6018.
8. Yoshimura, Y.; Kitano, K.; Satoh, H.; Watanabe, M.; Miura, S.; Sakata, S.; Sasaki,
T.; Matsuda, A. J. Org. Chem. 1996, 61, 822–823.
9. Roy, A.; Achari, B.; Mandal, S. B. Tetrahedron Lett. 2006, 47, 3875–3879.
10. (a) Prokop, J.; Murray, D. H. J. Pharm. Sci. 1965, 54, 359–365; (b) Leyland, D. L.;
Kotick, M. P. Carbohydr. Res. 1974, 38, C9–C11.
11. Chandrasekhar, S.; Prakash, S. J.; Rao, C. L. J. Org. Chem. 2006, 71, 2196–2199.
12. Haque, A.; Panda, J.; Ghosh, S. Indian J. Chem. 1999, 38B, 8–9.
13. Maity, J. K.; Mukherjee, S.; Drew, M. G. B.; Achari, B.; Mandal, S. B. Carbohydr.
Res. 2007, 342, 2511–2521.
14. Khan, A. R.; Tripathi, R. P.; Bhaduri, A. P. Indian J. Chem 1996, 35B, 405–408.
15. Rosenthal, A.; Sprinzl, M. Carbohydr. Res. 1971, 16, 337–342.
16. Acton, E. M.; Goerner, R. N.; Uh, H. S.; Ryan, K. J.; Henry, D. W. J. Med. Chem.
1979, 22, 518–525.
Et2O.F3B
OR
O
OR
O
OR
O
Dimer
O
RO
OH
OH
O
RO
RO
Et2O.F3B
Et
Et Si Et
H
RO
O
RO
O
O
O
RO
RO
BF3
Figure 2. Mechanism for the formation of the products.

4932
S. Mukherjee et al. / Tetrahedron Letters 53 (2012) 4929–4932
17. General procedure for the preparation of deoxygenated and dimeric products:
Method I: To a solution of 5 (1.0 g, 2.70 mmol) in CH2Cl2 (20 mL) at 0 °C was
added freshly distilled BF3ꢀEt2O (0.68 mL, 2.0 equiv) and the mixture was
allowed to stir for 15 min under N2 atmosphere. Et3SiH (1.7 mL, 4.0 equiv) was
added to it and the reaction was allowed to continue for 2 h. The mixture was
diluted with water (10 mL); the CH2Cl2 was separated, washed with water
(2 ꢄ 5 mL), dried (Na2SO4) and evaporated to yield a mixture of two products.
These were separated by column chromatography on silica gel (60–120 mesh)
using EtOAc–petroleum ether (1:49) and EtOAc–petroleum ether (1:4) to
furnish 13 (556 mg, 33%) and 12 (356 mg, 42%), respectively as viscous liquids.
Method II: Et3SiH was added to the substrate solution followed by BF3ꢀEt2O,
using the same protocol as described in Method I. The products identified were
12 (78%), 14 (67%), 16 (72%), 18 (72%), 20 (75%), 22 (71%) and 24 (69%) with the
respective sugar derivatives 5–11. Method III: BF3ꢀEt2O (2 equiv) was added to
the well stirred substrate solution at 0 °C. After 15 min more at 0 °C, the
stirring was continued for 2 h at room temperature. A cold solution of 5%
NaHCO3 (10 mL) was then added. Usual work-up and purification afforded the
dimeric products 13 (75%), 15 (72%), 17 (80%), 19 (78%), 21 (73%), 23 (79%) and
25 (70%), respectively with 5–11.
1H, J = 12.0 Hz), 4.62 (d, 1H, J = 12.0 Hz), 5.16 (d, 1H, J = 10.5 Hz), 5.24 (d, 1H,
J = 17.4 Hz), 5.77ꢃ5.90 (m, 1H), 7.27ꢃ7.35 (m, 5H); 13C NMR (CDCl3, 75 MHz):
d 68.5 (CH2), 70.9 (CH2), 73.3 (CH2), 73.4 (CH2), 74.6 (CH), 79.1 (CH), 83.9 (CH),
116.9 (CH2), 127.5 (CH), 127.7 (2 ꢄ CH), 128.3 (2 ꢄ CH), 134.2 (CH), 137.9 (C);
ESIMS, m/z: 287 (M+Na)+.
Characterization data of the dimeric products: Compound 13: ½a D25
ꢃ9.1 (c 0.32,
ꢂ
CHCl3); 1H NMR (CDCl3, 300 MHz): d 3.72–3.74 (t-like, 2H, J = 2.8, 3.0 Hz), 4.00
(d, 1H, J = 2.9 Hz), 4.12 (d, 1H, J = 3.5 Hz), 4.47–4.54 (m, 3H), 4.61 (d, 1H,
J = 12.0 Hz), 4.66 (d, 1H, J = 12.0 Hz), 5.16 (d, 1H, J = 3.6 Hz), 7.28–7.32 (m,
10H); 13C NMR (CDCl3, 75 MHz): d 67.6 (CH2), 71.8 (CH2), 73.3 (CH2), 76.6 (CH),
79.7 (CH), 82.5 (CH), 97.0 (CH), 127.5–128.3 (10 ꢄ CH), 137.4 (C), 138.0 (C);
ESIMS, m/z: 647 (M+ Na)+. Compound 15: ½a 2D5
ꢂ
–23.4 (c 0.54, CHCl3); 1H NMR
d 3.52 (d, 1H, J = 9.8 Hz), 3.65 (d, 1H, J = 9.8 Hz), 3.68
(CDCl3, 300 MHz):
(partially merged d, 1H, J = 10.5 Hz), 3.72 (d , 1H, J = 10.5 Hz), 4.16–4.21 (m,
2H), 4.46 (d, 1H, J = 12.0 Hz), 4.49 (d, 1H, J = 10.7 Hz), 4.51–4.61 (m, 3H), 4.72
(d, 1H, J = 12.0 Hz), 5.13 (d, 1H, J = 3.9 Hz), 7.24–7.28 (m, 15H); 13C NMR
(CDCl3, 75 MHz)): d 69.4 (CH2), 71.1 (CH2), 72.2 (CH2), 73.2 (CH2), 73.4 (CH2),
78.0 (CH), 83.9 (CH), 86.1(C), 96.3 (CH), 127.2–128.1 (15 ꢄ CH), 137.7 (C), 138.0
(C), 138.3 (C); ESIMS, m/z: 887 (M+ Na)+. Compound 17: ½a 2D5
ꢂ
–74.6 (c 0.21,
18. Characterization data of the deoxygenated products: Compound 12: ½a D25
ꢂ
ꢃ19.8 (c
CHCl3); 1H NMR (CDCl3, 300 MHz): d 0.89 (t, 3H, J = 7.4 Hz), 1.34–1.43 (m, 2H),
1.98–2.11 (m, 2H), 3.99 (d, 2H, J = 3.0 Hz), 4.53 (d, 1H, J = 12.1 Hz), 4.64 (d, 1H,
J = 12. 1 Hz), 5.08 (dd, 1H, J = 3.4, 7.3 Hz), 5.19 (d, 1H, J = 3.8 Hz), 5.62–5.73 (m,
2H), 7.31 (brs, 5H); 13C NMR (CDCl3, 75 MHz): d 14.1 (CH3), 23.0 (CH2), 30.5
(CH2), 72.4 (CH2), 77.5 (CH), 77.6 (CH), 84.7 (CH), 97.8 (CH), 123.9 (CH), 128.0
(2 ꢄ CH), 128.2 (CH), 128.8 (2 ꢄ CH), 135.6 (CH), 137.9 (C); ESIMS, m/z: 543
0.96, CHCl3); 1H NMR (CDCl3, 300 MHz): d 2.29 (br s, 1H), 3.62–3.76 (m, 3H),
3.89 (br d, 1H, J = 2.4 Hz), 4.12 (dd, 1H, J = 3.9, 9.9 Hz), 4.31 (br s, 2H), 4.50 (br d,
2H, J = 11.4 Hz), 4.61 (d, 2H, J = 11.7 Hz), 7.30–7.32 (m, 10H); 13C NMR (CDCl3,
75 MHz): d 68.6 (CH2), 72.2 (CH2), 73.4 (CH2), 73.5 (CH2), 75.0 (CH), 79.2 (CH),
84.3 (CH), 127.5–128.5 (10 ꢄ CH), 137.9 (C), 138.1(C); ESIMS, m/z: 337
(M+Na)+. Compound 14:
½
a 2D5
ꢂ
+49.3 (c 0.76, CHCl3); 1H NMR (CDCl3,
(M + Na)+. Compound 19: ½a 2D5
ꢂ
–84.6 (c 0.46, CHCl3); 1H NMR (CDCl3, 600 MHz)
300 MHz): d 3.56 (d, 1H, J = 10.3 Hz), 3.63 (d, 1H, J = 10.3 Hz), 3.72 (d, 1H,
J = 10.0 Hz), 3.80 (d, 1H, J = 10.0 Hz), 3.87 (d, 1H, J = 9.7 Hz), 3.99 (partially
merged dd, 1H, J = 3.2, 9.7 Hz), 4.02 (br s, 1H), 4.15 (br d, 1H, J = 7.7 Hz), 4.28
(br d, 1H, J = 10.8 Hz), 4.45 (d, 1H, J = 11.8 Hz), 4.50 (d, 1H, J = 11.8 Hz), 4.53 (d,
1H, J = 12.0 Hz), 4.58 (d, 1H, J = 12.0 Hz), 4.66 (d, 2H, J = 12.0 Hz), 7.23–7.35 (m,
15H); 13C NMR (CDCl3, 75 MHz): d 69.5 (CH2), 72.7 (CH2), 73.2 (CH2), 73.5
(CH2), 73.8 (CH2), 74.0 (CH2), 75.4 (CH), 86.1 (C), 87.1 (CH), 127.3 (2 ꢄ CH),
127.4 (CH), 127.5 (2 ꢄ CH), 127.6 (CH), 127.8 (2 ꢄ CH), 127.9 (CH), 128.2
(2 ꢄ CH), 128.3 (2 ꢄ CH), 128.5 (2 ꢄ CH), 136.9 (C), 137.8 (C), 138.1(C); ESIMS,
: d 3.98 (t, 2H, J = 3.6 Hz), 3.99 (partially merged dd, 1H, J = 6.0, 13.2 Hz), 4.11
(dd, 1H, J = 5.4, 13.2 Hz), 4.75 (dd, 1H, J = 3.6, 7.2 Hz), 5.18–5.21 (m, 2H), 5.28
(dd, 1H, J = 1.2, 17.4 Hz), 5.32 (d, 1H, J = 10.8 Hz), 5.43 (d, 1H, J = 17.4 Hz), 5.82–
5.88 (m, 1H), 5.95–6.01(m, 1H); 13C NMR (CDCl3, 150 MHz): d 71.0 (CH2), 76.9
(CH), 82.2 (CH), 84.2 (CH), 97.3 (CH), 117.6 (CH2), 119.4 (CH2), 131.9 (CH),
133.8 (CH); ESIMS, m/z: 359 (M + Na)+. Compound 21: ½a 2D5
ꢂ
–35.7 (c 0.31,
CHCl3); 1H NMR (CDCl3, 300 MHz): d 2.11–2.15 (m, 2H), 3.45–3.55 (m, 2H),
3.62–3.66 (m, 2H), 4.44–4.59 (m, 4H), 4.72 (brd, 1H, J = 3.1 Hz), 5.85 (d, 1H,
J = 3.7 Hz), 7.27-7.31 (m, 10H); 13C NMR (CDCl3, 75 MHz): d 34.2 (CH2), 64.8
(CH2), 65.2 (CH2), 72.5 (CH2), 73.0 (CH2), 81.4 (CH), 89.2 (C), 104.8 (CH),127.4
(4 ꢄ CH), 127.6 (2 ꢄ CH), 128.2 (4 ꢄ CH), 137.5 (C), 138.1 (C); ESIMS, m/z: 675
m/z: 457 (M+ Na)+. Compound 16: ½a 2D5
ꢂ
ꢃ12.8 (c 0.81, CHCl3); 1H NMR (CDCl3,
300 MHz): d 0.91 (t, 3H, J = 7.3 Hz), 1.35–1.47 (m, 2H), 1.73 (br s, 1H), 2.03–
2.16 (m, 2H), 3.67 (d, 1H, J = 9.8 Hz), 3.79 (d, 1H, J = 3.2 Hz), 4.21 (dd, 1H, J = 4.4,
9.8 Hz), 4.40 (s, 1H), 4.60 (s, 2H), 4.83 (br t-like, 1H), 5.65–5.71 (m, 2H), 7.32 (br
s, 5H); 13C NMR (CDCl3, 75 MHz): d 13.6 (CH3), 22.6 (CH2), 29.7 (CH2), 71.9
(CH2), 73.2 (CH2), 75.2 (CH), 75.8 (CH), 85.5 (CH), 124.6 (CH), 127.3 (2 ꢄ CH),
127.5 (CH), 128.2 (2 ꢄ CH), 134.5 (CH), 137.8 (C); ESIMS, m/z: 285 (M+Na)+,
(M + Na)+. Compound 23: ½a 2D5
ꢂ
–7.8 (c 0.46, CHCl3); 1H NMR (CDCl3, 300 MHz):
d 3.63 (t, 1H, J = 8.4 Hz), 3.87 (dd, 1H, J = 6.6, 8.4 Hz), 3.98ꢃ4.05 (m, 2H,), 4.57
(d, 1H, J = 11.7 Hz), 4.64 (d, 1H, J = 3.9 Hz), , 4.74 (t, 1H, J = 11.7 Hz), 4.78 (d, 1H,
J = 4.5 Hz), 5.31 (d, 1H, J = 3.6 Hz), 7.28ꢃ7.37 (m, 5H); 13C NMR (CDCl3,
75 MHz): d 69.2 (CH2), 72.5 (CH2), 77.4 (CH), 78.2 (CH), 79.8 (CH), 86.0 (CH),
98.1 (CH), 128.0 (2 ꢄ CH), 128.5 (3 ꢄ CH), 137.4 (C); ESIMS, m/z: 491(M+Na)+.
Anal. Calcd for C26H28O8: C, 66.66; H, 6.02; Found: C, 66.47; H, 6.11. Compound
301 (M+K)+. Compound 18:
½
a 2D5
ꢂ
ꢃ14.0 (c 0.64, CHCl3); 1H NMR (CDCl3,
300 MHz): d 2.30 (br s, 1H), 3.70 (dd, 1H, J = 1.8, 11.6 Hz), 3.80 (br dd-like, 1H),
4.04–4.13 (m, 2H), 4.17 (dd, 1H, J = 4.3, 9.7 Hz), 4.36 (br dd-like, 1H), 4.50 (dd,
1H, J = 4.0, 7.0 Hz), 5.18 (dd, 1H, J = 1.4, 10.3 Hz), 5.25–5.31 (m, 2H), 5.37 (dd,
1H, J = 1.0, 17.2 Hz), 5.86–6.04 (m, 2H); 13C NMR (CDCl3, 75 MHz): d 71.6 (CH2),
73.8 (CH2), 75.7 (CH), 82.1 (CH), 86.0 (CH), 117.4 (CH2), 118.6 (CH2), 134.0 (CH),
25: ½a 2D5
ꢂ
–8.7 (c 0.33, CHCl3); 1H NMR (CDCl3, 300 MHz): d 3.67ꢃ378 (m, 2H),
3.94ꢃ3.98 (m, 2H), 4.05 (d, 1H, J = 3.9 Hz), 4.11 (dd, 1H, J = 5.1, 12.9 Hz),
4.47ꢃ4.54 (m , 1H), 4.52 (d, 1H, J = 12.0 Hz), 4.61 (d, 1H, J = 12.0 Hz), 5.15 (d,
1H, J = 3.6 Hz), 5.16 (d, 1H, 9.9 Hz), 5.25 (dd, 1H, J = 1.2, 17.1 Hz), 5.76ꢃ5.89 (m,
1H), 7.27ꢃ7.33 (m, 5H); 13C NMR (CDCl3, 75 MHz): d 67.5 (CH2), 70.7 (CH2),
73.2 (CH2), 77.2 (CH), 79.6 (CH), 82.4 (CH), 97.0 (CH), 117.3 (CH2), 127.4 (CH),
127.5 (2 ꢄ CH), 128.2 (2 ꢄ CH), 133.8 (CH), 138.0 (C); ESIMS, m/z: 547 (M+Na)+.
134.7 (CH); ESIMS, m/z: 193 (M+Na)+. Compound 20: ½a 2D5
ꢂ
+21.9 (c 0.22,
CHCl3); 1H NMR (CDCl3, 300 MHz): d 1.99 (d, 1H, J = 15.0 Hz), 2.08 (d, 1H,
J = 15.0 Hz), 3.32 (d, 1H, J = 9.8 Hz), 3.39 (d, 1H, J = 9.8 Hz), 3.53 (d, 1H,
J = 9.8 Hz), 3.67 (d, 1H, J = 9.8 Hz), 3.76 (d, 1H, J = 9.5 Hz), 3.94 (d, 1H,
J = 9.5 Hz), 4.26 (s, 2H), 4.50 (d, 1H, J = 12.0 Hz), 4.56 (d, 1H, J = 11.7 Hz), 4.57
(d, 1H, J = 12.0 Hz), 4.70 (d, 1H, J = 11.7 Hz), 7.29–7.34 (m, 10H); 13C NMR
(CDCl3, 75 MHz): d 35.2 (CH2), 65.9 (CH2), 66.1 (CH2), 71.0 (CH2), 72.5 (CH2),
73.0 (CH2), 74.4 (CH), 89.2 (C), 127.5–128.4 (10 ꢄ CH), 137.3 (C), 138.0 (C);
19. Spectral data: Compound 26: ½a D25
ꢂ
ꢃ93.2 (c 0.61, CHCl3); 1H NMR (CDCl3,
300 MHz):
d 3.99 (d, 1H, J = 3.8 Hz), 4.04 (d, 1H, J = 2.3 Hz), 4.11 (d, 1H,
J = 17.1 Hz), 4.23 (td, 1H, J = 1.4, 2.1, 17.1 Hz), 4.48 (br t, 1H, J = 2.1 Hz), 5.21 (d,
1H, J = 3.8 Hz), 6.02–6.07 (m, 1H), 6.11–6.16 (m, 1H); 13C NMR (CDCl3,
75 MHz): d 65.0 (CH2), 71.8 (CH), 78.9 (CH), 80.1 (CH), 98.0 (CH), 121.4 (CH),
ESIMS, m/z: 351 (M+Na)+. Compound 22: ½a 2D5
ꢂ
ꢃ16.8 (c 0.53, CHCl3); 1H NMR
132.8 (CH); ESIMS, m/z: 303 (M+Na)+. Compound 27: viscous liquid; ½a 2D5
ꢂ
+54.2
(CDCl3, 300 MHz): d 1.77 (br s, 1H), 3.61 (t, 1H, J = 8.4 Hz), 3.86 (dd, 1H, J = 6.6,
8.4 Hz), 3.95 (d, 1H, J = 10.2 Hz), 4.00 (d, 1H, J = 3.0 Hz), 4.03ꢃ4.11 (m, 1H), 4.32
(br s, 1H), 4.42 (d, 1H, J = 4.2 Hz), 4.57 (d, 1H, J = 12.0 Hz), 4.72 (t, 1H,
J = 4.5 Hz), 4.78 (d, 1H, J = 12.0 Hz), 7.29ꢃ7.37 (m, 5H); 13C NMR (CDCl3,
75 MHz): d 70.2 (CH2), 72.4 (CH2), 74.5 (CH2), 76.7 (CH), 79.1 (CH), 80.1 (CH),
88.2 (CH), 127.9ꢃ128.4 (5 ꢄ CH), 137.6 (C); ESIMS, m/z: 259 (M+Na)+. Anal.
Calcd for C13H16O4: C, 66.09; H, 6.83; Found: C, 66.26; H, 6.91. Compound 24:
(c 0.43, CHCl3); 1H NMR (CDCl3, 600 MHz): d 3.78 (dd, 1H, J = 6.0, 9.6 Hz), 3.84
(dd, 1H, J = 6.0, 9.6 Hz), 4.04 (d, 1H, J = 11.4 Hz), 4.17 (dd, 1H, J = 7.8, 9.6 Hz),
4.24 (dd, 1H, J = 6.6, 9.6 Hz), 4.28 (dd, 1H, J = 6.0, 10.8 Hz), 4.32 (d, 1H,
J = 11.4 Hz), 4.37 (t-like, 1H, J = 4.8, 5.4 Hz), 4.57 (d, 1H, J = 12.0 Hz), 4.63 (d, 1H,
J = 12.0 Hz), 5.45 (q, 1H, J = 6.6 Hz), 7.29–7.37 (m, 10H), 8.33 (s, 1H), 8.64 (s,
1H); 13C NMR (CDCl3, 150 MHz): d 55.6 (CH), 67.8 (CH2), 69.5 (CH2), 73.6 (CH2),
74.1 CH2), 77.3 (CH), 80.9 (CH), 127.8–128.5 (10 ꢄ CH), 130.9 (C), 135.8 (C),
137.5 (C), 144.9 (CH), 150.7 (C), 151.5 (CH), 151.7 (C); ESIMS, m/z: 473
(M+Na)+, 475 (M+Na)+.
½
a 2D5
ꢂ
ꢃ20.4 (c 0.93, CHCl3); 1H NMR (CDCl3, 300 MHz): d 2.46 (d, 1H, J = 2.4 Hz),
3.63ꢃ3.74 (m, 3H), 3.83 (d. 1H, J = 3.6 Hz), 3.96 (dd, 1H, J = 5.4, 12.9 Hz), 4.08
(t-like, 1H, J = 9.6, 10.8 Hz), 4.09 (t, 1H, J = 9.6 Hz), 4.28ꢃ4.31 (m, 2H), 4.52 (d,