Scandium cation-exchanged montmorillonite catalyzed direct C-glycosylation of a 1,3-diketone, dimedone, with unprotected sugars in aqueous solution

Article abstract of DOI:10.1016/j.carres.2007.01.013

The condensation of dimedone with unprotected sugars in aqueous solution in the presence of a catalytic amount of Sc³⁺-montmorillonite (Sc³⁺-mont) gave 9-hydroxyalkyl-3,3,6,6,-tetramethyl-3,4,5,6,7,9-hexahydro-1H-xanthene-1,8(2H)-dio

Full text of DOI:10.1016/j.carres.2007.01.013

Carbohydrate Research 342 (2007) 913–918
Scandium cation-exchanged montmorillonite catalyzed direct
C-glycosylation of a 1,3-diketone, dimedone, with unprotected
sugars in aqueous solution
Shingo Sato,* Yuzo Naito and Kazuyori Aoki
Department of Chemistry and Chemical Engineering, Faculty of Engineering, Yamagata University, 4-3-16 Jonan,
Yonezawa-shi, Yamagata 992-8510, Japan
Received 20 November 2006; received in revised form 19 January 2007; accepted 23 January 2007
Available online 31 January 2007
Abstract—The condensation of dimedone with unprotected sugars in aqueous solution in the presence of a catalytic amount of Sc3+
-
montmorillonite (Sc3+-mont) gave 9-hydroxyalkyl-3,3,6,6,-tetramethyl-3,4,5,6,7,9-hexahydro-1H-xanthene-1,8(2H)-diones in good
yields, while the use of Sc(OTf)3 instead of Sc3+-mont gave the hydroxyalkyl-6,7-dihydrobenzofuran-4(5H)-one derivatives in good
yields. Furthermore, Sc3+-mont could be recycled without inactivation.
ꢀ 2007 Elsevier Ltd. All rights reserved.
Keywords: Sc3+-mont; Sc(OTf)3; Dimedone; C-Glycosylation; Water; Xanthene derivative; Benzofuran derivative; Recyclable
1. Introduction
catalyst was a mixture of catalyst and unreacted sugar
owing to the fact that they were inseparable.2 In an
attempt to recycle Sc(OTf)3 in these C-glycosylation
reactions, we examined the use of an immobilized Sc(III)
catalyst.
Some Sc(III)-immobilized catalysts have been devel-
oped.5 Among them, Kaneda and co-workers6 reported
that Sc3+-mont, prepared by cation exchange with a
mixture of Sc(OTf)3 and Na+-mont in water, catalyzed
the Michael addition of a 1,3-diketone to an enone in
water or without solvent to afford Michael adducts in
excellent yields, and was recyclable without inactivation.
We employed this Sc3+-mont instead of Sc(OTf)3 in our
direct C-glycosylation method.
Scandium(III) trifluoromethanesulfonate [Sc(OTf)3], an
environmentally benign, water-compatible catalyst,
shows a stronger Lewis acidity than other rare earth
metal trifluoromethanesulfonates.1
We recently developed a simple and direct C-glycosyl-
ation using Sc(OTf)3 with unprotected sugars in aque-
ous media.2 Most glycosylation reactions require
protecting groups on the sugar and involve expensive
substrates, precise reaction conditions, and complicated
manipulations, resulting in overall product yields that
are frequently low. The synthesis of phloroacetophe-
none mono- and bis-C-glycosides using this direct C-gly-
cosylation and their use in the synthesis of naturally
occurring flavonoid bis-C-glucopyranosides,3 and the
one-step synthesis of 1-deoxy-bis(3-indolyl)alditols4
have been accomplished. When Sc(OTf)3 was recycled
and subsequently employed in the same reaction, how-
ever, its activity was decreased. In addition, the recycled
2. Results and discussion
Sc3+-mont was prepared by the method of Kaneda and
co-workers, and the Sc3+ content of the product was
0.370 mmol/g by ICP analysis (Ref. 6: 0.396 mmol/g).
We initially examined the C-glycosylation of phloro-
acetophenone, a key intermediate in flavonoid synthesis,
with D-glucose in 1:9 CH3CN–H2O at 80 ꢁC using the
*
Corresponding author. Tel./fax: +81 238 26 3121; e-mail: shingo-s@
yz.yamagata-u.ac.jp
0008-6215/$ - see front matter ꢀ 2007 Elsevier Ltd. All rights reserved.
doi:10.1016/j.carres.2007.01.013

914
S. Sato et al. / Carbohydrate Research 342 (2007) 913–918
HO
HO
OH
CH3
OH
CH3
Sc3+-mont (0.2 equiv)
in CH3CN-H2O (1:9)
D-glucose
(2.0 equiv)
HO
HO
HO
O
+
80 oC, for 19 h
OH
OH
OH
O
O
Y: 32%
Scheme 1. Sc3+-mont catalyzed C-glycosylation of phloroacetophenone with D-glucose.
prepared Sc3+-mont.2 However, contrary to our expec-
tations, the maximum yield of the desired C-(b-D-gluco-
pyranosyl)phloroacetophenone was 32%, lower than the
product yield was greatly improved, with yields up to
76%, and the amount of other glycosides produced
was negligible (entry 4). When Na+-mont was used in-
stead of Sc3+-mont as a catalyst under the same condi-
tions as above, the reaction proceeded, but the yield of
1 was much lower (26%, entry 6). When the reaction
temperature was increased to 60 ꢁC, the yield was the
same, but the reaction time could be shortened to 4 days
(entry 7). After simple washing, the Sc3+-mont was
again available for use in the reaction (entries 5 and 8–
11). Since even the fifth use gave 1 in the same 80% yield
as the first run (entry 11), we conclude that the activity
of Sc3+-mont remained constant.
2
48% yield obtained using Sc(OTf)3 (see Scheme 1).
We next examined the C-glycosylation of a more reac-
tive 1,3-diketone (dimedone) with unprotected D-ribose
to explore the utility of Sc3+-mont (see Table 1). In an
initial experiment, 2 mmol of dimedone and 1 mmol of
D-ribose in the presence of 0.1 mmol of Sc3+-mont was
stirred in 3 mL of 2:1 CH3CN–H2O at 50 ꢁC for 3 days.
The reaction proceeded more smoothly than the above
C-glycosylation of phloroacetophenone to afford a con-
densation product comprising of 2 equiv of dimedone
and 1equiv of ring-opened D-ribose, 3,3,6,6-tetra-
methyl-9-C-(D-ribo-tetritol-1-yl)-3,4,5,6,7,9-hexahydro-
1H-xanthene-1,8(2H)-dione (1) in 45% yield, together
with some other C-glycosides. The structure was verified
by NMR analysis of the acetate. The structure of prod-
uct 1 was similar to that of the product of condensation
of 2 equiv of indole and 1 equiv of unprotected sugar
using Sc(OTf)3.4 When the above reaction was carried
out in only 3 mL of water, 1 was obtained in the same
yield, 44%; however, the production of the other glyco-
sides was suppressed to a considerable extent (entry 3).
Since the Sc3+-mont formed a gel when 3 mL of water
was used and stirring was difficult, by increasing the vol-
ume of water used to 10 mL , it became possible to stir
the reaction mixture more easily without gelation. The
Interestingly, when Sc(OTf)3 was used instead of
Sc3+-mont under the same reaction conditions, the reac-
tion gave
a benzofuran derivative, 2-(D-erythro-
propanetriol-1-yl)-6,6-dimethyl-6,7-dihydrobenzofuran-
4(5H)-one (2), different from 1, in 72% yield, which was
the Knoevenagel condensation product of equal
amounts of dimedone and D-ribose (Table 2, entry 1).7
(The use of CH3CN–H2O or EtOH–H2O as a solvent
afforded a mixture of C-glycosides.) It is known that
these furan or furanylfuran derivatives can be synthe-
sized in good yield by the reaction of a 1,3-diketone, a
2,4-pentanedione and unprotected sugars in the presence
of ZnCl2,7a CeCl3,7b or Yb(OTf)3.7c When this reaction
was carried out in the presence of 0.05 equiv of Sc(OTf)3
at 75 ꢁC for 1 day, the yield of 2 was increased to 86%
Table 1. C-Glycosylation of dimedone with D-ribose
O
D-ribose
1 mmol
+
O
OHO
OH
H
H
H
O
O
OH
1
OH
Entry
Dimedone (equiv)
Promoter (equiv)
Solvent
Temp (ꢁC)
Time (day)
Yield (%)
1
2
3
4
5
6
7
8
9
2
2
2
3
3
3
3
3
3
3
3
Sc3+-mont (0.1)
CH3CN–H2O (2:1)
CH3CN–H2O (2:1)
H2O (3 mL)
50
50
50
50
50
50
60
60
60
60
60
3
2
3
7
7
7
4
4
4
4
4
45.5
27.6
44.0
76.0
78.9
26.0
77.8
80.7
77.7
80.3
79.8
Na+-mont (0.1)
Sc3+-mont (0.1)
Sc3+-mont (0.1)
H2O (10 mL)
H2O (10 mL)
H2O (10 mL)
H2O (10 mL)
H2O (10 mL)
H2O (10 mL)
H2O (10 mL)
H2O (10 mL)
Sc3+-mont (0.1) 2nd use
Na+-mont (0.1)
Sc3+-mont (0.1) 1st use
Sc3+-mont (0.1) 2nd use
Sc3+-mont (0.1) 3rd use
Sc3+-mont (0.1) 4th use
Sc3+-mont (0.1) 5th use
10
11

S. Sato et al. / Carbohydrate Research 342 (2007) 913–918
915
Table 2. Sc(OTf)3 catalyzed C-glycosylation of dimedone with D-ribose and D-glucose in water
sugar (1.0 equiv)
Sc(OTf)3
HO
O
in H2O
O
O
HO
OH
O
2
Entry
Dimedone (equiv)
Sugar
Sc(OTf)3 (equiv)
Temp (ꢁC)
Time (day)
Product
Yield (%)
1
2
3.0
1.5
D-Ribose
D-Ribose
0.1
0.05
60
75
4
1
2
2
72
86
HO
O
HO
HO
3
4
3.0
1.5
D-Glucose
D-Glucose
0.2
0.1
60
70
7
22 (6: 5)
OH
O
7
O
O
3.5
90
O
HO
OH
8
Table 3. Sc3+-mont catalyzed C-glycosylation of dimedone with other pentoses and glucose
Entry
Sugar (equiv)
Sc3+-mont (equiv)
Temp (ꢁC)
Time (day)
Product (%)
O
1
D-Xylose
0.1
60
4
3 (76)
O H
OHO
H
HO
H
OH
CH2OH
O
2
D-Arabinose
0.1
60
4
4 (79)
OHO
H
H O
OH
H
OH
CH2OH
O
3
L-Arabinose
0.1
60
4
5 (78)
O H
HO
HO
OHO
H
H
CH2OH
O
4
5
6
D-Glucose
D-Glucose
D-Glucose
0.1
0.1
0.2
60
70
60
4
2.5
7
6 (25)
6 (32)
6 (43)
O H
HO
H
OHO
H
OH
H
OH
CH2OH

916
S. Sato et al. / Carbohydrate Research 342 (2007) 913–918
(entry 2). These different products produced under the
same reaction conditions can be rationalized on the
basis of a reaction mechanism proposed by Kaneda
and co-workers,6b as follows: a dimedone and a D-ribose
are coordinated to the Sc center in the silicate layers of
Sc3+-mont, and the successive carbon–carbon bond for-
mation produces an intermediate. Another dimedone is
then coordinated, and a second carbon–carbon bond
formation between the intermediate and a dimedone
produces 1,6b while in the reaction using Sc(OTf)3 in
water, 2 is produced via carbon–carbon bond formation
between a dimedone and a D-ribose molecule.
The glycosylation of dimedone using 0.1 equiv of
Sc3+-mont in water (10 mL/1 mmol of sugar) was
applied to other pentoses, including D-xylose, D-arabinose,
and L-arabinose, and the results are summarized in
Table 3. The three pentoses also gave the desired
xanthenes 3, 4, and 5 in yields of 76%, 79%, and 78%,
respectively. Since a hexose, D-glucose showed a lower
reactivity (25%) under the same reaction conditions
(entry 4), a reaction using 0.2 equiv of Sc3+-mont at
60 ꢁC for 7 days gave 6 in a maximum yield of 43%
(entry 6). D-Glucose also showed a similar low reactivity
for a reaction using 0.2 equiv of Sc(OTf)3 in 10 mL of
H2O at 60 ꢁC for 7 days, affording the desired benzo-
furan derivative, 2-(D-arabino-tetritol-1-yl)-6,6-dimethyl-
6,7-dihydrobenzofuran-4(5H)-one (7), in a low yield of
22%, along with other glycosides including 5% of 6
(Table 2, entry 3). When this reaction was carried out
in the presence of 0.1 equiv of Sc(OTf)3 at 70 ꢁC for
3.5 days, the reaction proceeded smoothly to afford
2-(1,4-anhydro-D-erythro-tetrofuranosyl)-6,6-dimethyl-
6,7-dihydrobenzofuran-4(5H)-one (8) in a yield of 90%
without any other detectable glycosides. Compound 8
is a dehydration product between the C-1- and C-4-
OH side-chain groups in 7 (entry 4).7b,c Finally, we
applied this method to a gram-scale reaction. A suspen-
sion of 1.00 g of D-ribose, 2.78 g of dimedone, and
1.76 g of Sc3+-mont (0.1 equiv of Sc3+) in 100 mL of
water was stirred vigorously at 60 ꢁC for 4 days. After
purification by silica-gel column chromatography,
2.15 g of pure 1 was obtained (82%). The above result
verifies this synthetic method using Sc3+-mont to be
applicable to large-scale production.
3. Conclusion
Sc3+-mont showed a weaker Lewis acidity in compari-
son to Sc(OTf)3 in the direct C-glycosylation of phloro-
acetophenone with unprotected sugar in aqueous media.
However, in the reaction of a 1,3-diketone with an
Table 4. Physicochemical data
Compound
no.
Mp (ꢁC) [a]D (MeOH)
IR (cmꢀ1
)
Elemental analysis
(C, H %)
FABMS
(M+H)+
22
1
Colorless prisms
133–134 ½aꢁD +222 (c 1.025) 3238, 2960, 1600, 1421,
Calcd for
C21H30O7ÆCH3CH2OH: C,
395
1390, 1221, 1072, 1032
62.71; H, 8.24. Found: C,
62.42; H, 8.56
Calcd for C13H18O5Æ0.5H2O: 255
C, 62.71; H, 8.24. Found: C,
59.44; H, 7.13
Calcd for
C21H30O7Æ0.4CH3CH2OH:
C, 63.41; H, 7.91. Found: C,
63.44; H, 8.10
Calcd for
C21H30O7ÆCH3CH2OH: C,
62.71; H, 8.24. Found: C,
62.91; H, 8.17
Calcd for
22
2
3
Colorless viscous oil
Colorless prisms
—
½aꢁD +0.59 (c 1.015) 3400, 2960, 2935, 2875,
1660, 1452, 1223, 1115,
1036
21
117–118 ½aꢁD +181 (c 1.020) 3398, 2956, 1616, 1392,
395
395
395
425
1225, 1117, 1072, 1032
22
4
5
6
Colorless prisms
Colorless prisms
Colorless prisms
123–124 ½aꢁD ꢀ219 (c 1.035) 3402, 2956, 1612, 1392,
1259, 1225, 1088, 1032
21
119–120 ½aꢁD +213 (c 1.055) 3400, 2956, 1612, 1390,
1259, 1225, 1088, 1032
C21H30O7ÆCH3CH2OH: C,
62.71; H, 8.24. Found: C,
62.77; H, 8.14
21
163–164 ½aꢁD +202 (c 1.025) 3384, 2956, 1601, 1392,
Calcd for
1259, 1225, 1072, 1030
C22H32O8Æ0.3CH3CH2OH:
C, 61.97; H, 7.78. Found: C,
62.12; H, 8.13
Calcd for C14H20O6: C,
59.14; H, 7.09. Found: C,
59.39; H, 7.36
21
7
8
Colorless prisms
149–150 ½aꢁD ꢀ18.5 (c 1.015) 3433, 3319, 3265, 2970,
285
367
2929, 1658, 1450, 1410,
1296, 1082, 1028
22
Pale-yellow viscous oil
—
½aꢁD ꢀ92.2 (c 1.000) 3373, 2958, 2873, 1664,
Calcd for
1577, 1450, 1225, 1117,
C
14H18O5Æ0.5CH3OH: C,
1051, 1036
61.69; H, 7.14. Found: C,
61.80; H, 7.31

S. Sato et al. / Carbohydrate Research 342 (2007) 913–918
917
Table 5. 1H NMR data
Chemical shifts (ppm)
Compound no.
1
3
4
5
6
2
7
8
H-10
4.46(dd)
4.86(dd)
3.62(dd)
3.30(ddd)
3.56(dd)
3.44(dd)
4.27(dd)
4.62(dd)
3.40(dd)
3.53(ddd)
3.45(dd)
3.34(dd)
4.40(dd)
4.76(dd)
3.16(dd)
3.47(ddd)
3.59(dd)
3.41(dd)
4.41(dd)
4.76(dd)
3.20(dd)
3.46(ddd)
3.59(dd)
3.40(dd)
4.17(dd)
4.61(dd)
3.59(dd)
3.34(dd)
3.46(ddd)
H-10
4.39(dd)
3.66(m)
3.55(ddd)
3.45(ddd)
4.78(dd)
3.53(dt)
3.59(m)
4.52(d)
4.15(dd)
4.11(m)
H-20
H-20
H-30
H-40
H-50a
H-50b
H-60a
H-60b
H-30a
H-30b
H-40a
H-40b
OH
3.49(ddd) 4.03(dd)
3.57(dd)
3.31(dd)
3.43(dt)
4.38(t)
4.61(d)
4.64(d)
5.18(d)
3.63(dd)
5.11(d)
5.14(d)
4.51(t)
4.72(d)
5.47(d)
(Xanthene moiety)
CH3
(Benzofuran moiety)
0.96(s, ·2)
1.01(s, ·2)
0.96(s, ·2)
1.03(s, ·2)
0.97(s, ·2)
1.02(s)
1.03(s)
1.90(d)
2.02(d)
2.18(d)
2.31(dd)
0.97(s, ·2)
1.02(s)
1.03(s)
1.92(d)
2.02(d)
2.18(d)
2.29(dd)
0.95(s, ·2)
1.02(s)
1.03(s)
1.90(d)
2.05(d)
2.21(d)
2.31(dd)
CH3
1.06(s)
1.07(s)
2.31(s)
2.77(s)
1.06(s)
1.07(s)
2.31(s)
2.76(s)
1.06(s)
1.07(s)
2.32(s)
2.79(s)
CH2
1.88(d)
2.01(d)
2.18(d)
2.30(dd)
1.91(d)
2.03(d)
2.20(d)
2.29(dd)
CH2
H-3
6.42(s)
6.43(s)
6.63(s)
7.3
0
J1 ,2
0
J value (Hz)
J1,2
7.3
5.8
7.3
5.6
1.2
2.2
0
J1 ,OH
6.8
2.2
2.2
9.0
5.7
2.8
7.0
2.2
5.6
3.7
5.6
6.1
7.5
1.2
1.2
8.5
2.7
5.8
7.7
2.3
1.1
8.9
2.8
5.9
6.9
2.0
6.9
2.0
8.0
0
J1 ,3
J1,CH
J2,3
J3,4
2
0
J2 ,3 a
0
3.7
3.9
5.8
11.0
5.6
4.6
6.8
0
J2 ,3 b
0
0
J2 ,OH
J4,5a
J4,5b
J5a,b
J5,6a
J5,6b
J6a,b
7.3
0
J3 a,b
0
J3 OH
11.0
10.8
11.0
11.0
3.6
6.7
10.9
15.6
17.1
5.6
8.2
5.6
11.0
5.6
3.9
4.5
2.4
9.5
0
J3 ,4 a
0
0
J3 ,4 b
0
0
J4 a,b
15.9
17.0
15.9
17.0
15.9
17.0
15.7
17.0
0
J4 ,OH
JCH
2
unprotected sugar in water, Sc3+-mont had excellent cat-
alytic activity and a different selectivity from Sc(OTf)3,
giving 9-hydroxyalkyl-3,3,6,6,-tetramethyl-3,4,5,6,7,9-
hexahydro-1H-xanthene-1,8(2H)-dione as the sole prod-
uct in good yield, while Sc(OTf)3 resulted in the produc-
tion of hydroxyalkyl-6,7-dihydrobenzofuran-4(5H)-one
derivatives. We are now exploring whether this differ-
ence in selectivity holds for other substrates.
were determined on a AS ONE ATM-01 melting point
apparatus and are uncorrected. Optical rotations were
recorded on a JASCO DIP-370 polarimeter. IR spectra
were recorded on a Horiba FT-720 IR spectrometer in
the form of KBr disks. NMR spectra were recorded
on a Varian Inova 500 spectrometer using Me4Si as
the internal standard. Mass spectral data were obtained
by fast-atom bombardment (FAB) using glycerol as a
matrix on a JEOL JMS-AX505HA instrument. Elemen-
tal analyses were performed on a Perkin–Elmer PE 2400
II instrument.
4. Experimental
Sc(OTf)3, purchased from Taiheiyo Kinzoku Co. Ltd.,
and Na+-mont (Kunipia F, Kunimine Industry Co.
Ltd.) were directly used without any further purifica-
tion. The ICP analysis was carried out by using a Shima-
dzu ICPS 7000 instrument. The solvents used in this
reaction were purified by distillation. Reactions were
monitored by TLC on 0.25-mm Silica Gel F254 plates
(E. Merck) using UV light, and a 7% ethanolic solution
of phosphomolybdic acid with heat as a visualization
agent. For separation and purification, flash column
chromatography was performed on silica gel (230–400
mesh, Fuji-Silysia Co. Ltd., BW-300). Melting points
4.1. General procedure
4.1.1. 3,3,6,6-Tetramethyl-9-C-(D-ribo-tetritol-1-yl)-3,4,5,
6,7,9-hexahydro-1H-xanthene-1,8(2H)-dione
(1).
A
suspension of dimedone (420 mg, 3 mmol), D-ribose
(150 mg, 1 mmol), and Sc3+-mont (270 mg, 0.1 mmol)
in 10 mL of water was stirred at 60 ꢁC for 4 days. The
reaction mixture was cooled, filtered and washed with
MeOH (3 mL). The filtrate was evaporated in vacuo.
The residue was purified by silica-gel column chroma-
tography (10:1 CHCl3–MeOH). The crude product
including 1 was recrystallized from ethanol to give pure

918
S. Sato et al. / Carbohydrate Research 342 (2007) 913–918
Table 6. 13C NMR spectra
Carbon no.
Compound no.
1
3
4
5
6
2
7
8
CH3
CH2
27.33
27.78(·2)
28.99
27.33
27.71(·2)
28.89
27.48
27.75(·2)
28.94
27.51
27.77(·2)
28.95
27.34
27.71(·2)
28.88
27.84
27.91
27.82
27.93
27.77
27.89
31.43
31.52
31.46
31.46
31.51
31.51
33.69
33.72
35.00
33.65
34.58
33.65
34.60
35.03(·2)
37.20
34.86
36.31
34.87
36.26
34.81
36.25
37.17
37.17
37.29
37.30
C3,6
47.0(br, ·2) 48.49(br, ·2) 46.8(br, ·2) 46.69(br, ·2) 46.5(br, ·2) 51.26(C6)
51.26(C6)
63.16
65.89
70.82
72.34
51.20(C6)
70.28
72.72
74.40
75.62
C10
50.83
50.77
62.35
70.89
72.02
90.06
50.88
63.49
70.86
72.11
88.67
50.90
63.49
70.89
72.13
88.70
50.79
63.70
70.29
71.26
71.34
90.96
62.81
67.22
73.02
C50 or 60
C20,30,40,50 70.52
63.45
71.35
90.57
102.59(C3)
119.51(C3a)
157.16(C2)
165.38(C7a)
101.99(C3)
119.58(C3a)
157.82(C2)
165.07(C7a)
104.45(C3)
119.61(C3a)
153.94(C2)
166.39(C7a)
C8a,9a
113.21
113.98
175.95
192.08
112.52
113.41
175.64
192.24
112.76
114.06
175.89
192.20
112.73
114.09
175.79
192.11
112.46
113.27
175.54
192.14
C4a,10a
C1(C@O)
193.45(C4, C@O) 193.22(C4, C@O) 193.18(C4, C@O)
1 (315 mg, 80%) as colorless prisms. The other xanth-
enes 3, 4, 5, and 6 and benzofuran 7 were also isolated
in the same manner. See Tables 1 and 3 for details and
Tables 4–6 for physicochemical and NMR spectral data.
References
1. (a) Kobayashi, S. Eur. J. Org. Chem. 1999, 15–27; (b) Koba-
yashi, S.; Sugiura, M.; Kitagawa, H.; Lam, W. W.-L. Chem.
Res. 2002, 102, 2227–2302, and references cited therein.
2. Sato, S.; Akiya, T.; Suzuki, T.; Onodera, J.-I. Carbohydr.
Res. 2004, 339, 2611–2614.
3. (a) Sato, S.; Nojiri, T.; Onodera, J.-I. Carbohydr. Res. 2005,
340, 389–393; (b) Sato, S.; Akiya, T.; Nishizawa, H.;
Suzuki, T. Carbohydr. Res. 2006, 341, 964–970.
4.1.2. 6,6-dimethyl-2-(D-erythro-propanetriol-1-yl)-6,7-
dihydrobenzofuran-4(5H)-one (2). A solution of dime-
done (420 mg, 3 mmol), D-ribose (150 mg, 1 mmol),
and Sc(OTf)3 (49 mg, 0.1 mmol) in 10 mL of water
was stirred at 60 ꢁC for 4 days. The reaction mixture
was cooled, sodium phosphate (0.15 mmol) was added,
and the solution was then evaporated in vacuo. The resi-
due was purified by silica-gel column chromatography
(10:1 CHCl3–MeOH). This column chromatography
operation was repeated to give pure 2 (183 mg, 72%)
as a colorless, viscous oil. See Table 2 for details and
Tables 4–6 for physicochemical and NMR spectral
data.
4. (a) Sato, S.; Sato, T. Carbohydr. Res. 2005, 340, 2251–2255;
(b) Sato, S.; Masukawa, H.; Sato, T. Carbohydr. Res. 2006,
341, 2731–2736.
5. (a) Kobayashi, S.; Nagayama, S. J. Am. Chem. Soc. 1996,
118, 8977–8978; (b) Kobayashi, S.; Nagayama, S. J. Org.
Chem. 1996, 61, 2256–2257; (c) Kobayashi, S.; Nagayama,
S. J. Am. Chem. Soc. 1997, 119, 10049–10053; (d) Koba-
yashi, S.; Wakabayashi, T. Tetrahedron Lett. 1998, 39,
5389–5392; (e) Kobayashi, S.; Aoki, Y. Tetrahedron Lett.
1998, 39, 7345–7348; (f) Kobayashi, S.; Wakabayashi, T.;
Yasuda, M. J. Org. Chem. 1998, 63, 4868–4869; (g)
Manabe, K.; Iimura, S.; Sun, X.-M.; Kobayashi, S. J.
Am. Chem. Soc. 2002, 124, 11971–11978.
4.1.3. 6,6-Dimethyl-2-C-(a-D-erythro-tetrofuranosyl)-6,7-
dihydrobenzofuran-4(5H)-one. Pure compound 8, iso-
lated using the procedure mentioned in Section 4.1.2,
was also obtained as a pale-yellow, viscous oil. See
Table 2 for details and Tables 4–6 for physicochemical
and NMR spectral data.
6. (a) Ebitani, K.; Ide, M.; Mitsudome, T.; Mizugaki, T.;
Kaneda, K. Chem. Commun. (Cambridge) 2002, 690–691;
(b) Kawabata, T.; Mizugaki, T.; Ebitani, K.; Kaneda, K. J.
Am. Chem. Soc. 2003, 125, 10486–10487; (c) Kawabata, T.;
Mizugaki, T.; Ebitani, K.; Kaneda, K. Tetrahedron Lett.
2001, 42, 8329–8332; (d) Kaneda, K. J. Synth. Org. Chem.
2003, 61, 436–444.
7. (a) Kozikowski, A. P.; Lin, G. Q.; Springer, J. P. Tetra-
hedron Lett. 1987, 28, 2211–2214; (b) Misra, A. K.;
Agnihotri, G. Carbohydr. Res. 2004, 339, 1382–1387; (c)
Rodrigues, F.; Canac, Y.; Lubineau, A. Chem. Commun.
(Cambridge) 2000, 2049–2050; (d) Hersant, Y.; Abou-
Jneid, R.; Canac, Y.; Lubineau, A.; Philippe, M.; Semeria,
D.; Radisson, X.; Scherrmann, M.-C. Carbohydr. Res.
2004, 339, 741–745; (e) Rieman, I.; Papadopoulos, M. A.;
Knorst, M.; Fessner, W.-D. Aust. J. Chem. 2002, 55, 147–
154; (f) Gonzalez, F. G. Adv. Carbohydr. Chem. 1956, 11,
97–143.
Acknowledgments
The authors thank Professor Hideyuki Tagaya (Yama-
gata University) for supplying Na+-mont, Professor
Masatoshi Endo (Yamagata University) for the ICP
analysis, and Mr. Minoru Tsunoda and Mr. Masahiro
Miura for their technical assistance.