Stereoselectivity in deoxygenation of 5-hydroxy-5-phosphinyl-hexofuranoses (α-hydroxyphosphonates)

Article abstract of DOI:10.1016/S0008-6215(03)00235-0

The addition of dimethyl phosphonate to six different hexofuranos-5-uloses in the presence of DBU, followed by esterification with methoxalyl chloride and then radical reduction, afforded 5-deoxy-5-dimethoxyphosphinyl-D- and L-hexofuranoses. The stereosel

Full text of DOI:10.1016/S0008-6215(03)00235-0

Carbohydrate Research 338 (2003) 1641ꢀ1650
/
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Stereoselectivity in deoxygenation of 5-hydroxy-5-phosphinyl-
hexofuranoses (a-hydroxyphosphonates)
Tadashi Hanaya,* Ken-ichi Sugiyama, Heizan Kawamoto, Hiroshi Yamamoto
Department of Chemistry, Faculty of Science, Okayama University, Tsushima, Okayama 700-8530, Japan
Received 15 November 2002; received in revised form 21 April 2003; accepted 25 April 2003
Abstract
The addition of dimethyl phosphonate to six different hexofuranos-5-uloses in the presence of DBU, followed by esterification
with methoxalyl chloride and then radical reduction, afforded 5-deoxy-5-dimethoxyphosphinyl-
stereoselectivity of the deoxygenation and possible transition-state models are discussed.
# 2003 Elsevier Ltd. All rights reserved.
D- and L-hexofuranoses. The
Keywords: Phospho sugar; Deoxygenation; a-Hydroxyphosphonate
1. Introduction
of hexopyranose-type phospho sugars, only a few
methods for stereoselective introduction of a phosphinyl
group into the sugar moiety have been reported this far;
for example, the addition of a phosphonate to nitroalk-
enes8 and a-tosyloxyketones.7 We have recently em-
ployed a new method to introduce a phosphinyl group
at C-5 of hexofuranoses; namely, the addition of a
phosphonate to hexofuranos-5-ulose derivatives and
subsequent deoxygenation of the resulting 5-hydroxy
group to afford the corresponding 5-deoxy-5-phosphin-
yl derivatives.4c The exact stereoselectivity on C-5,
however, remained essentially unestablished for these
reactions. We now report a systematic investigation of
the stereoselectivity and synthetic efficiency for dehy-
droxylation of various a-hydroxyphosphonates (5-hy-
droxy-5-phosphinyl-hexofuranoses).
We have prepared various sugar analogs having a
phosphorus atom in the hemiacetal ring (phospho
sugars)1 because of considerable interest in their chemi-
cal properties and potential biological activity, as in the
case of imino sugars2 and thio sugars.3 Regarding
phospho sugars of the hexopyranose type, analogs 1 of
D
-glucose,4 2 of
D D
-mannose,5 3 of -galactose,6 and 4 of
-fucose7 have been synthesized.
L
2. Results and discussion
As starting materials, the 6-O-benzylhexofuranos-5-
uloses 8a (a-
8d (b- -lyxo), 8e (a-
corresponding 5,6-diols 5aꢀ
1). Thus, the epoxidation of 5aꢀ
sphine and diethyl azodicarboxylate (DEAD) afforded
the 5,6-anhydro derivatives (6aꢀe), which were treated
with benzyl alcohol and sodium hydride in 1,2-di-
D
-xylo),4c 8b (a-
D
-ribo), 8c (b-
-lyxo)5b were prepared from the
e in excellent yields (Scheme
e with triphenylpho-
D-arabino),
D
D
Although 5-deoxy-5-phosphinyl-D- and L-hexofura-
nose derivatives are key intermediates in the preparation
/
/
/
* Corresponding author. Fax: ꢁ81-86-2517853.
/
E-mail address: hanaya@cc.okayama-u.ac.jp (T. Hanaya).
0008-6215/03/$ - see front matter # 2003 Elsevier Ltd. All rights reserved.
doi:10.1016/S0008-6215(03)00235-0

1642
T. Hanaya et al. / Carbohydrate Research 338 (2003) 1641ꢀ
/1650
Scheme 1.
methoxyethane (DME) to give the 6-O-benzyl com-
pounds (7aꢀe), respectively. Oxidation of 7aꢀe with
pyridinium chlorochromate (PCC) gave the correspond-
-xylo-hexofuranos-
5-ulose derivative (8f)9 was prepared by reduction of 6a
with lithium alminum hydride and subsequent oxidation
with PCC.
of the 5-hydroxy group of 9, we found that application
of Dolan and MacMillan’s procedure11 was most
/
/
efficient for our purpose.$ Thus, compounds 9aꢀ
/
f were
first converted into the 5-O-methoxalyl derivatives
(10aꢀf) by use of methoxalyl chloride in the presence
ing 5-uloses 8aꢀ
/
e. The 6-deoxy-a-
D
/
of 4-dimethylaminopyridine (DMAP) and then reduced
with tributyltin hydride in the presence of AIBN,
Treatment of 8aꢀ
in the presence of DBU, respectively afforded the (5R)-
and (5S)-5-dimethoxyphosphinyl-5-hydroxy com-
pounds (9aꢀf) in the yields shown in Table 1. After
having examined various modified methods of the
Bartonꢀ
McCombie reaction10 for the deoxygenation
/
f with dimethyl phosphonate at 0 8C
affording the corresponding 5-deoxy-5-phosphinyl-
D-
hexofuranoses (11aꢀf) and the -hexofuranoses (12aꢀ
/
L
/
f), which were separable by column chromatography in
the yields and the ratios summarized in Table 1.
/
The (5R)-configuration for 11aꢀf and the (5S)-
/
/
configuration for 12aꢀ
/
f were assigned on the basis of
Table 1
Yields and ratios of 5-deoxy-5-phosphinyl compounds (11aꢀ
/
f, 12aꢀf)
/
Entry
1
5-Uloses
5-Hydroxy compounds
5-Deoxy compounds (yields from 9)
11a (50%), 12a (38%)
Ratio of 11:12
8a
(5R)-9a (64%)
(5S)-9a (27%)
(5R)-9b (47%)
(5S)-9b (44%)
(5R)-9c (72%)
(5S)-9c (24%)
(5R)-9d (68%)
(5S)-9d (24%)
(5R)-9e (76%)
(5S)-9e (19%)
(5R)-9f (85%)
(5S)-9f (6.6%)
57:43
2
3
4
5
6
8b
8c
8d
8e
8f
11b (29%), 12b (57%)
11c (16%), 12c (68%)
11d (29%), 12d (48%)
11e (16%), 12e (70%)
11f (24%), 12f (60%)
34:66
19:81
38:62
19:81
28:72

T. Hanaya et al. / Carbohydrate Research 338 (2003) 1641ꢀ
/1650
1643
the magnitudes of J4,5 values and the presence of the
no report seems to exist, to the best of our knowledge,
for the corresponding b-alkoxyphosphonate derivatives.
The contrary stereoselection of the reduction of 10a
(entry 1) seems to depend upon the steric factor of the
substituents on C-3 as well as the conformation of the
long-range couplings (5J1,P, J2,P, and J3,P
NMR spectra (see, Table 2 and Fig. 1). Thus, the a-
gluco (for 11a,f), b- -altro (for 11c), b- -manno (for
11d), and a- -manno (for 11e) configurations were
)
in the H
5
4
7,8
1
D-
D
D
D
furanose ring. The 1,2-O-isopropylidene-a-
ribo-furanoses (a,b,f series) have the E4 conformational
preference, whereas the b- -arabino- and lyxo-fura-
noses (c,d series) are preferentially in the E1 form, and
D-xylo- and
confirmed by the large values of J4,5 (namely an anti
5
relationship of H-4/H-5) and the presence of J1,P
D
coupling, whereas the b-
(for 12c), a- -gulo (for 12d), and b-
configurations were confirmed by the large values of J4,5
L
-ido (for 12a,f), a-
L-galacto
L
L
-gulo (for 12e)
the 2,3-O-isopropylidene-a-
D-lyxo derivatives (e series)
exists mainly in the 8E form.16 As for the radical
intermediates existing in the E4 form (Fig. 1), the
rotamer A derived from 10a is disfavored because of
5
and the presence of J2,P coupling. The a-
uration for 11b was assigned from the small value of J4,5
D-allo config-
(thus, a gauche relationship of H-4/H-5) and the
5
steric hindrance between the bulky Rb (ꢂ
(ꢂCH2OBn) groups, whereas A derived from 10b
(RbꢂH, C-6ꢂCH2OBn) and 10f (RbꢂOBn, C-6ꢂ
/Bn) and C-6
presence of J2,P coupling, whereas the b-L-talo config-
/
uration for 12b was assigned from the small value of J4,5
and the large values of J4,P (thus, an anti relationship of
H-4/P-5). Meanwhile the C-5 configurations of the (5R
/
/
/
/
CH3) involve little steric hindrance. Another possible
rotamer B was thus proposed as a (5R)-predictive model
for the reduction of 10a, taking into account both the
electrostatic repulsion between two electronegative
groups and the steric repulsion between C-6 and the
Rb groups.
and 5S)-5-hydroxy-5-phoshinyl compounds (9aꢀ
assigned by comparison with the corresponding 5-deoxy
compounds (11aꢀf,12aꢀf), because the similar charac-
teristic tendency of the corresponding coupling con-
stants and the chemical shifts is expected for 9aꢀf due to
almost identical conformations.
Deoxygenation of (5R)-9a afforded the (5R)-5-deoxy
product ( -glucofuranose derivative) 11a (50%) and the
(5S)-5-deoxy product ( -iodofuranose derivative) 12a
/f) were
/
/
/
In the case of A? derived from 10c, the effective
shielding provided by the Rb (ꢂH) group, which has a
/
syn-periplanar relationship with C-5, leads to good
stereoselectivity (entry 3). However, in the case of A?
derived from 10d, steric hindrance similar to the a series
caused interconversion into another rotamer similar to
B to a considerable extent (but still in favor of the A?
form) and lower (5S)-selectivity (entry 4). Meanwhile,
the rigid dioxolane ring of the A? rotamer derived from
10e scarcely causes such repulsion with C-6 and the
freely rotating 3-O-benzyl group, and thus leads to good
stereoselectivity (entry 5).
D
L
(38%). The epimer (5S)-9a also gave 11a and 12a in
almost the same ratio and yields as those from (5R)-9a.
These results indicate that an epimerization takes place
at C-5 via a radical intermediate during the reduction of
the methoxalyl esters [(5R)- and/or (5S)-10] and there-
fore the ratios of 5-deoxy products 11 and 12 are not
related to the C-5 configuration of the corresponding
precursors 9.
In summary, this work demonstrates a new procedure
The deoxygenation of other 5-hydroxy compounds
for the introduction of a Cꢀ
/
P bond into sugars and
analyzes its stereoselectivity. By using the 5-deoxy-5-
phosphinyl-hexofuranoses obtained in this work and
their corresponding enantiomers, convenient syntheses
of a variety of new phospho sugars are anticipated. We
are currently investigating the more detailed mechanism
concerning stereoselectivity of the deoxygenation as well
as the enhancement of stereoselectivity by using lower
reaction temperatures.
(9bꢀ/f) afforded predominantly the corresponding (5S)-
5-deoxy products (12bꢀ
/
f) (Table 1, entries 2ꢀ6). In
/
order to account for the (5S)-diastereoselectivity of the
radical reduction of 10, we propose rotamer A (arising
from 10b,f) and A? (arising from 10c,d,e) of the radical
intermediate, from the viewpoint of electronic factors
(Fig. 2). That is to say, the opposition of the phosphinyl
group and electronegative oxygen atom in the furanose
ring diminishes intramolecular electrostatic repulsion.13
Moreover, the overlapping of the radical p orbital with
the best electron-donating sC4ꢀC3 bond stabilizes the
transition state by hyperconjugation.14 Although me-
chanistic proposals have been reported for the radical-
mediated reduction of a-bromo-b-alkoxycarboxylates,15
3. Experimental
3.1. General methods
All reactions were monitored by TLC (Merck silica gel
60F, 0.25 mm) with an appropriate solvent system [(A)
$
1:3 and (B) 1:1 EtOAcꢀ/hexane, (C) EtOAc, (D) 1:19
Although the deoxygenation of the secondary hydroxy
MeOHꢀCHCl3]. Column chromatography was per-
formed with Daiso Silica Gel IR-60/210w. Components
were detected by exposing the plates to UV light and/or
/
group on the a-carbon of phosphinyl group has been
reported,12 the procedures described were not efficient for
the corresponding tertiary hydroxy group in our system.

Table 2
1H and 31P NMR parameters for compounds 9aꢀ
/
f, 11aꢀ
/
f, and 12aꢀ/f in CDCl3
Chemical shifts/d
CH2O-3 b,c
CH2O-6 b,c
31P
a
Compound
H-1 H-2 H-3 H-4 H-5
H-6
H-6? P(OMe)2
CMe2
(5R)-9a
(5S)-9a
11a
5.99 4.59 4.43 4.54 (4.93) d
6.01 4.50 4.25 4.47 (4.58) d
5.87 4.60 4.08 4.52 2.82
5.93 4.53 3.81 4.48 2.67
5.79 4.57 4.37 4.49 (2.98) d
5.75 4.50 4.41 4.43 (3.10) d
5.65 4.38 4.05 4.49 2.64
5.77 4.52 4.52 4.49 2.50
5.87 4.62 4.60 4.62 (3.50) d
5.91 4.64 4.31 4.69 (3.51) d
5.94 4.64 4.43 4.58 2.61
5.87 4.61 4.32 4.46 2.61
5.74 4.71 4.14 4.15 (4.75) d
5.67 4.81 4.33 4.08 (5.21) d
5.65 4.80 4.01 4.19 2.99
5.70 4.71 3.76 4.15 2.82
4.91 4.57 5.00 4.32 (4.75) d
4.97 4.49 4.85 4.32 (4.36) d
4.81 4.54 4.77 4.29 2.71
4.88 4.48 4.59 4.29 2.62
5.99 4.58 4.16 4.48 (5.08) d
6.07 4.63 4.22 4.39 (3.91) d
5.85 4.59 4.10 4.24 2.64
5.95 4.61 3.87 4.22 2.45
3.88
3.92
4.00
3.74
3.76
3.80
3.79
3.76
3.80
3.83
3.99
3.82
3.79
3.91
3.46
3.71
3.74
3.75
3.69
3.80
3.58
3.93
3.76, 3.74
1.49, 1.33
1.52, 1.32
1.51, 1.33
1.52, 1.31
1.58, 1.36
1.58, 1.34
1.58, 1.33
1.58, 1.35
1.53, 1.34
1.57, 1.34
1.44, 1.30
1.55, 1.33
1.54, 1.44
1.51, 1.45
1.48, 1.41
1.52, 1.41
1.48, 1.32
1.46, 1.23
1.42, 1.31
1.40, 1.25
1.50, 1.32
1.51, 1.34
1.50, 1.31
1.50, 1.32
4.63, 4.60 e
4.36, 4.15 e
4.63, 4.55 e
4.50, 4.18 f
4.74, 4.56 f
4.68, 4.52y
4.66, 4.53 f
4.76, 4.60 f
4.66, 4.625 f
4.56, 4.46 f
4.59, 4.55 f
4.47, 4.45 f
4.67, 4.11 g
4.84, 4.53 e
4.87, 4.46 e
4.76, 4.16 f
(3.26) h
4.69, 4.64 e
4.52, 4.48 f
4.59, 4.56 e
4.49, 4.31 f
4.54, 4.48 f
4.53, 4.51 f
4.47, 4.38 f
4.50, 4.48 f
4.60, 4.60
26.3
23.6
31.9
32.1
25.9
24.3
30.9
29.7
25.8
25.7
31.6
30.5
23.8
26.1
32.1
32.2
25.2
24.1
31.3
32.4
25.5
25.1
33.5
33.6
3.84, 3.80
3.67, 3.64
3.755, 3.74
3.77, 3.76
3.79, 3.73
3.74, 3.72
3.68, 3.60
3.77, 3.76
3.78, 3.775
3.67, 3.64
3.75, 3.73
3.84, 3.76
3.73, 3.715
3.65, 3.61
3.76, 3.71
3.81, 3.76
3.85, 3.80
3.73, 3.71
3.76, 3.74
3.87, 3.80
3.86, 3.82
3.72, 3.71
3.78, 3.74
12a
(5R)-9b
(5S)-9b
11b
12b
(5R)-9c
(5S)-9c
11c
4.52, 4.52
4.63, 4.59 f
4.51, 4.51
12c
3.795 3.78
(5R)-9d
(5S)-9d
11d
3.88
3.90
3.99
3.77
3.88
3.96
3.98
3.88
1.54
1.47
1.34
1.06
3.78
3.75
3.93
3.64
3.82
3.85
3.94
3.82
4.41, 4.56 f
4.60, 4.55 f
4.56, 4.54 f
4.49, 4.30 f
4.63, 4.56 f
4.64, 4.58 f
4.61, 4.55 f
4.57, 4.51 f
12d
(5R)-9e
(5S)-9e
11e
(3.36) h
(3.26) h
(3.32) h
4.77, 4.62 g
4.70, 4.50 f
4.64, 4.60 e
4.70, 4.45f
12e
(5R)-9f
(5S)-9f
11f
12f
Coupling constants/Hz
Compound
J1,2
J1,P
J2,3
J2,P
J3,4
J3,P
J4,5
J4,P
J5,6
J5,6?
J5,P
J6,6? J6,P
J6?,P
(5R)-9a
(5S)-9a
11a
3.7
3.7
3.7
4.0
3.7
3.7
3.7
3.4
3.7
4.0
1.5
0
0
0
2.8
3.0
3.0
3.1
8.6
8.5
9.1
0
0.5
4.0
9.2
9.8
9.2
9.5
9.8
25.6 13.4
7.9 14.5
0
1.8
0
1.0
0
1.2
0
0
10.8
10.1
5.2
7.0
2.8
4.3
5.2
4.0
19.8
18.6
16.5 28.7
10.9 26.2
15.6 12.2
12a
0
2.1
1.2
0
1.0
0.8
0
(5R)-9b
(5S)-9b
11b
0
4.3
4.0
14.3
12.2
13.4
0
10.1 12.2 11.0
0
4.4
i
1.7
0
0.7
0
2.2
2.0
8.3
4.6
3.7
9.0
24.2
21.6
10.0 7.6
9.7 8.2
10.0
7.8
12b
(5R)-9c
(5S)-9c
0
8.5
i
33.4
i
i
0.8
0
0
1.0
0
ꢀ
/
17.1 17.1
9.8 21.4
1.2
4.3
0
2.5
9.8

Table 2 (Continued)
Coupling constants/Hz
Compound
J1,2
J1,P
J2,3
J2,P
J3,4
J3,P
J4,5
J4,P
J5,6
J5,6?
J5,P
J6,6? J6,P
J6?,P
11c
12c
4.0
4.0
4.6
4.9
4.9
4.6
0
1.5
0
0.8
1.0
4.9
5.4
5.3
5.5
5.8
5.8
5.5
5.5
0
0
1.8
3.1
4.6
4.2
4.3
4.6
2.8
3.4
3.1
3.1
2.8
3.1
3.0
2.9
0
10.1
9.2
3.7
11.3
3.3
0.5
6.7
6.1
1.0
4.2
5.8
7.3
0
3.7
5.5
3.4
4.0
20.5
20.4
9.5
9.2
9.8
8.8
9.2
9.8
8.6
9.8
9.2
9.8
28.7 11.9
13.1 16.6
1.0
0
0
(5R)-9d
(5S)-9d
11d
0
0
9.5
18.3
0
0
0
27.1 12.1
17.7 28.4
10.5 29.3
26.6 12.8
10.0 19.8
15.3 29.3
10.6 28.1
15.6
1.0
0
0
0
10.1
10.4
2.8
3.4
5.2
3.7
19.8
18.5
12d
1.1
0
0
(5R)-9e
(5S)-9e
11e
2.1
0
0
0
1.0
0
0.9
0
0
1.5
0
10.7
10.4
2.8
4.0
4.9
3.7
19.2
18.3
12e
0
1.2
0
1.1
0
(5R)-9f
(5S)-9f
11f
4.0
4.0
4.0
3.9
1.2
0
0
2.1
0
1.0
0
5.8
5.8
7.7
15.9
18.3
1.1
0
0
10.4
10.6
7.3
7.2
19.2
16.0
12f
0
2.4
1.5
18.0
a
JPOMe
ꢂ
/
10.7ꢀ
The assignment of CH2O-3 or -6 signals may have to be interchanged.
Ph: d 7.24ꢀ7.38 (m, 10 H) except for (5S)-9a [d 7.12 (dd, 2 H), 7.27ꢀ7.33 (m, 8 H)], 12a [d 7.18 (dd, 2 H), 7.26ꢀ
/
11.0 Hz.
b
c
/
/
/
7.32 (m, 8 H)], and (5R and 5S)-9f, 11f, 12f [d 7.26ꢀ7.37 (m,
/
5 H)].
d
HO-5.
2Jꢂ
10.7ꢀ
11.6ꢀ11.9 Hz.
2Jꢂ
10.4 Hz.
MeO-1.
Uncertain because of overlapping with other signals.
e
f
/
/
11.0 Hz.
2Jꢂ
/
/
g
h
i
/

1646
T. Hanaya et al. / Carbohydrate Research 338 (2003) 1641ꢀ1650
/
by spraying them with 20% H2SO4ꢀEtOAc (with
/
subsequent heating). Optical rotations were measured
with a JASCO P-1020 polarimeter in CHCl3. The NMR
spectra were measured in CDCl3 with Varian VXR-500
(500 MHz for 1H) and VXR-200 (81 MHz for 31P)
spectrometers at 25 8C. Chemical shifts are reported as
d values relative to tetramethylsilane (internal standard
1
for H) and 85% phosphoric acid (external standard for
31P). The mass spectra were taken on a VG-70SE
instrument and are given in terms of m/z (relative
intensity) compared with the base peak.
3.2. 3-O-Benzyl-1,2-O-isopropylidene-b-D-
mannofuranose (5d)
To a suspension of 1,2;5,6-di-O-isopropylidene-b-
D-
mannofuranose17 (360 mg, 1.38 mmol) and NaH (60%
in mineral oil, 166 mg, 4.15 mmol) in DME (7.0 mL),
benzyl bromide (0.400 mL, 3.36 mmol) at 0 8C was
added. The mixture was stirred for 3 h, diluted with satd
NH4Cl (15 mL), and extracted with CHCl3 three times.
The combined organic layers were dried (Na2SO4), and
concentrated in vacuo to give the 3-O-benzyl derivative:
Rf 0.35 (A). The residue was dissolved in 70% aqueous
AcOH (5.0 mL) and the solution was stirred at rt for 4 h.
The mixture was concentrated in vacuo and the residue
purified by column chromatography with 1:1 EtOAcꢀ
/
hexane as an eluant to give 5d (390 mg, 91%) as a
1
colorless syrup: [a]D22
ꢃ36.98 (c 2.60); Rf 0.11 (B); H
/
NMR: d 1.34, 1.61 (2s, 3 H each, CMe2), 2.70 (br s, 2 H,
HO-5,6), 3.70 (dd, 1 H, J6,6? 11.5, J5,6? 5.1 Hz, H?-6), 3.83
(dd, 1 H, J5,6 3.9 Hz, H-6), 4.06 (dd, 1 H, J4,5 9.6, J3,4 7.3
Hz, H-4), 4.24 (dd, 1 H, J2,3 5.0 Hz, H-3), 4.40 (ddd, 1
H, H-5), 4.58, 4.87 (2d, 1 H each, 2J 11.5 Hz, CH2O-3),
Fig. 1. The most favored conformations for the 5-deoxy-5-
4.64 (t, 1 H, J1,2 4.1 Hz, H-2), 5.73 (d, 1 H, H-1), 7.32ꢀ
/
phosphinyl-hexofuranoses (11aꢀ
/
f and 12aꢀf) and geometrical
/
7.39 (m, 5 H, Ph). Anal. Calcd for C16H22O6: C, 61.92;
H, 7.15. Found: C, 61.79; H, 7.21.
relationships where couplings between P and H exist.
3.3. 5,6-Anhydro-3-O-benzyl-1,2-O-isopropylidene-a-D-
allofuranose (6b)
To a solution of 5b18 (603 mg, 1.94 mmol) and
triphenylphosphine (612 mg, 2.33 mmol) in dry toluene
(12 mL) was added diethyl azodicarboxylate (DEAD,
0.360 mL, 2.32 mmol). The mixture was refluxed for 3 h
and evapolated in vacuo. The residue was purified by
column chromatography with 1:2 EtOACꢀ
eluant to give 6 (525 mg, 93%) as a colorless syrup: [a]D26
106.38 (c 1.28), Rf 0.74 (B); 1H NMR: d 1.36, 1.59 (2s,
/hexane as an
ꢁ
/
3 H each, CMe2), 2.75 (dd, 1 H, J6,6? 4.9, J5,6? 2.8 Hz, H?-
6), 2.79 (t, 1 H, J5,6 4.6 Hz, H-6), 3.19 (td, 1 H, J4,5 4.3
Hz, H-5), 3.66 (dd, 1 H, J3,4 8.9 Hz, H-4), 4.21 (dd, 1 H,
J2,3 3.4 Hz, H-3), 4.57 (t, 1 H, J1,2 3.7 Hz, H-2), 4.57,
2
4.75 (2d, 1 H each, J 11.6 Hz, CH2O-3), 5.75 (d, 1 H,
Fig. 2. Plausible conformation for the radical intermediate A
(from 10b,f), A? (from 10c,d,e), B (from 10a) and the direction
of reduction.
H-1), 7.30ꢀ/7.42 (m, 5 H, Ph). Anal. Calcd for C16H20O5:
C, 65.74; H, 6.90. Found: C, 65.57; H, 6.99.

T. Hanaya et al. / Carbohydrate Research 338 (2003) 1641ꢀ
/1650
1647
3.4. 5,6-Anhydro-3-O-benzyl-1,2-O-isopropylidene-b-
altrofuranose (6c)
D-
3.7. 3,6-Di-O-benzyl-1,2-O-isopropylidene-b-D-
altrofuranose (7c)
By employing the same procedures as described for 6b,
compound 5c19 gave 6c (92%) as a colorless syrup: [a]2D3
By employing the same procedures as those described
for 7b, compound 6c gave 7c (89%) as a colorless syrup;
ꢃ
1.838 (c 1.66), Rf 0.37 (A); 1H NMR: d 1.35, 1.55 (2s,
/
[a]2D3
ꢃ
0.348 (c 2.50); Rf 0.29 (A); 1H NMR: d 1.32, 1.49
/
3 H each, CMe2), 2.66 (dd, 1 H, J6,6? 4.9, J5,6? 2.4 Hz, H?-
6), 2.88 (dd, 1 H, J5,6 4.0 Hz, H-6), 3.22 (ddd, 1 H, J4,5
7.0 Hz, H-5), 3.80 (dd, 1 H, J3,4 2.1 Hz, H-4), 4.14 (d, 1
H, J2,3 0 Hz, H-3), 4.57, 4.58 (2d, 1 H each, 2J 12.0 Hz,
CH2O-3), 4.68 (d, 1 H, J1,2 4.0 Hz, H-2), 5.93 (d, 1 H, H-
(2s, 3 H each, CMe2), 2.20 (br s, 1 H, HO-5), 3.60 (dd, 1
H, J6,6? 9.5, J5,6? 6.1 Hz, H?-6), 3.71 (dd, 1 H, J5,6 3.4 Hz,
H-6), 3.98 (ddd, 1 H, J4,5 8.5 Hz, H-5), 4.10 (dd, 1 H, J3,4
2.0 Hz, H-4), 4.26 (d, 1 H, J2,3 0 Hz, H-3), 4.55, 4.575
(2d, 1 H each, 2J 11.7 Hz, CH2O-3), 4.59 (s, 2 H, CH2O-
6), 4.64 (d, 1 H, J1,2 3.9 Hz, H-2), 5.91 (d, 1 H, H-1),
1), 7.29ꢀ7.38 (m, 5 H, Ph). Anal. Calcd for C16H20O5:
/
C, 65.74; H, 6.90. Found: C, 65.59; H, 7.01.
7.27ꢀ7.37 (m, 10 H, Ph). Anal. Calcd for C23H28O6: C,
/
68.98; H, 7.05. Found: C, 69.12; H, 7.04.
3.5. 5,6-Anhydro-3-O-benzyl-1,2-O-isopropylidene-b-D-
mannofuranose (6d)
3.8. 3,6-Di-O-benzyl-1,2-O-isopropylidene-b-D-
mannofuranose (7d)
By employing the same procedures as those described
for 6b, compound 5d gave 6d (89%) as a colorless syrup:
1
[a]2D4
ꢁ
/
18.1 8 (c 1.66), Rf 0.22 (A); H NMR: d 1.35,
By employing the same procedures as those described
for 7b, compound 6d gave 7d (87%) as a colorless syrup;
1.62 (2s, 3 H each, CMe2), 2.70 (dd, 1 H, J6,6? 4.9, J5,6?
2.2 Hz, H?-6), 2.87 (dd, 1 H, J5,6 3.9 Hz, H-6), 3.69 (t, 1
H, J4,5 7.3, J3,4 6.8 Hz, H-4), 3.70 (ddd, 1 H, H-5), 4.15
(dd, 1 H, J2,3 4.9 Hz, H-3), 4.62 (dd, 1 H, J1,2 3.9 Hz, H-
[a]2D1
ꢃ
18.08 (c 1.03); Rf 0.52 (B); 1H NMR: d 1.32, 1.49
/
(2s, 3 H each, CMe2), 2.20 (br s, 1 H, HO-5), 3.60 (dd, 1
H, J6,6? 9.5, J5,6? 6.1 Hz, H?-6), 3.71 (dd, 1 H, J5,6 3.4 Hz,
H-6), 3.98 (ddd, 1 H, J4,5 8.5 Hz, H-5), 4.10 (dd, 1 H, J3,4
2.0 Hz, H-4), 4.26 (d, 1 H, J2,3 0 Hz, H-3), 4.55, 4.575
(2d, 1 H each, 2J 11.7 Hz, CH2O-3), 4.59 (s, 2 H, CH2O-
6), 4.64 (d, 1 H, J1,2 3.9 Hz, H-2), 5.91 (d, 1 H, H-1),
2
2), 4.69, 4.81 (2d, 1 H each, J 12.2 Hz, CH2O-3), 5.70
(d, 1 H, H-1), 7.31 [t, 1 H, Jm,p 7.3 Hz, Ph(p)], 7.36 [t, 2
H, Jo,m 7.3 Hz, Ph(m)], 7.42 [d, 2 H, Ph(o)]. Anal. Calcd
for C16H20O5: C, 65.74; H, 6.90. Found: C, 65.81; H,
6.95.
7.27ꢀ7.37 (m, 10 H, Ph). Anal. Calcd for C23H28O6: C,
/
68.98; H, 7.05. Found: C, 69.21; H, 7.09.
3.6. 3,6-Di-O-benzyl-1,2-O-isopropylidene-a-D-
allofuranose (7b)
3.9. 3,6-Di-O-benzyl-1,2-O-isopropylidene-a-D-ribo-
hexofuranos-5-ulose (8b)
To a suspension of sodium hydride (60% in mineral oil,
100 mg, 2.50 mmol) and benzyl alcohol (2.0 mL, 19.3
mmol) in DME (2.0 mL), a solution of 6b (388 mg, 1.25
mmol) in DME (2.0 mL) at 0 8C was added. The
mixture was stirred at 50 8C for 6 h, diluted with
saturated NH4Cl (20 mL), and extracted with CHCl3
three times. The combined organic layers were washed
with water, dried (Na2SO4), and concentrated in vacuo.
The residue was purified by column chromatography
To a suspension of PCC (560 mg, 2.60 mmol) and finely
powdered molecular sieves 4A (1.0 g) in dry CH2Cl2 (10
mL) was added a solution of 7b (410 mg, 1.02 mmol) in
dry CH2Cl2 (4 mL). The mixture was stirred at 25 8C for
4 h. After addition of 2-propanol (2 mL), the mixture
was diluted with ether. The precipitates were filtered off
through Celite and the filtrate was evaporated in vacuo.
The residue was purified by column chromatography
with 1:3 EtOAcꢀ
92%) as colorless needles: mp 76ꢀ
hexane); [a]2D6
/
hexane as an eluant to give 7b (462 mg,
77 8C (from 1:1
68.9 8 (c 1.03); Rf 0.46 (B);
/
with 1:3 EtOAcꢀhexane as an eluant to give 11 (369 mg,
/
91%) as a colorless syrup: [a]D24
ꢁ41.58 (c 1.22), Rf 0.47
/
EtOAcꢀ
/
ꢁ
/
1H NMR: d 1.35, 1.58 (2s, 3 H each, CMe2), 2.40 (br s, 1
H, HO-5), 3.52 (dd, 1 H, J6,6? 10.1, J5,6? 7.9 Hz, H?-6),
3.56 (dd, 1 H, J5,6 3.4 Hz, H-6), 3.95 (dd, 1 H, J3,4 8.9,
J2,3 4.3 Hz, H-3), 4.08 (dd, 1 H, J4,5 3.7 Hz, H-4), 4.14
(dt, 1 H, H-5), 4.53, 4.55 (2d, 1 H each, J 12.0 Hz,
CH2O-6), 4.54 (t, 1 H, J1,2 3.7 Hz, H-2), 4.54, 4.74 (2d, 1
1
(B). H NMR: d 1.35, 1.58 (2s, 3 H each, CMe2), 3.83
(dd, 1 H, J3,4 9.2, J2,3 4.3 Hz, H-3), 4.29, 4.33 (2d, 1 H
each, J6,6? 18.6 Hz, H2-6), 4.53 (t, 1 H, J1,2 3.4 Hz, H-2),
4.55 (d, 1 H, H-4), 4.57, 4.585 (2d, 1 H each, 2J 12.2 Hz,
CH2O-6), 4.60, 4.73 (2d, 1 H each, 2J 12.2 Hz, CH2O-3),
2
5.78 (d, 1 H, H-1), 7.29ꢀ7.39 (m, 10 H, Ph). Anal. Calcd
/
2
H each, J 11.9 Hz, CH2O-3), 5.73 (d, 1 H, H-1), 7.27ꢀ
/
for C23H26O6: C, 69.33; H, 6.58. Found: C, 69.19; H,
6.68.
7.36 (m, 10 H, Ph). Anal. Calcd for C23H28O6: C, 68.98;
H, 7.05. Found: C, 68.78; H, 7.01.

1648
T. Hanaya et al. / Carbohydrate Research 338 (2003) 1641ꢀ1650
/
3.10. 3,6-Di-O-benzyl-1,2-O-isopropylidene-b-
arabino-hexofuranos-5-ulose (8c)
D-
3.13.1. 3,6-Di-O-benzyl-5-dimethoxyphosphinyl-1,2-O-
isopropylidene-a-
-xylo-hexofuranoses (9a). 4c (5R)-Epi-
D
mer: Colorless syrup (64% from 8a); Rf 0.58 (C), (5S)-
Epimer: Colorless syrup (27% from 8a); Rf 0.30 (C).
By employing the same procedures with 8b, compound
7c was treated with PCC for 6 h to give 8c (90%) as a
colorless syrup: [a]D26
ꢃ3.438 (c 1.22); Rf 0.35 (A), 0.69
/
3.13.2. 3,6-Di-O-benzyl-5-dimethoxyphosphinyl-1,2-O-
1
(B); H NMR: d 1.26, 1.32 (2s, 3 H each, CMe2), 4.38,
4.70 (2d, 1 H each, J6,6? 18.3 Hz, H2-6), 4.53 (br s, 1 H,
J3,4 0.5, J2,3 0 Hz, H-3), 4.58, 4.63 (2d, 1 H each, 2J 11.6
isopropylidene-a-
Colorless needles (47% from 8b); mp 107ꢀ
2:1 EtOAcꢀ 37.3 8 (c 1.07); Rf 0.26 (C);
hexane); [a]2D7
FAB MS m/z 509 (Mꢁ1; 12), 451 (10), 419 (6), 361 (9),
181 (34), 91 (100). Found: m/z 509.1960. Calcd for
C25H34O9P: Mꢁ1, 509.1941. (5S)-Epimer: Colorless
syrup (44% from 8b); [a]D27
41.08 (c 1.06); Rf 0.34
(C). FAB MS m/z 509 (Mꢁ1; 18), 451 (10), 419 (9), 361
(6), 181 (24), 91 (100). Found: m/z 509.1951. Calcd for
C25H34O9P: Mꢁ1, 509.1941.
D-ribo-hexofuranose (9b). (5R)-Epimer:
/
109 8C (from
/
ꢁ
/
Hz, CH2O-3), 4.59 (s, 2 H, CH2O-6), 4.62 (d, 1 H, J1,2
4.0 Hz, H-2), 4.62 (br s, 1 H, H-4), 5.98 (d, 1 H, H-1),
7.28ꢀ7.37 (m, 10 H, Ph). Anal. Calcd for C23H26O6: C,
ꢂ
/
/
/
/
69.33; H, 6.58. Found: C, 69.19; H, 6.75.
ꢁ
/
/
3.11. 3,6-Di-O-benzyl-1,2-O-isopropylidene-b-D-lyxo-
hexofuranos-5-ulose (8d)
/
By employing the same procedures with 8b, compound
7d was treated with PCC for 8 h to give 8d (88%) as a
3.13.3. 3,6-Di-O-benzyl-5-dimethoxyphosphinyl-1,2-O-
isopropylidene-b- -arabino-hexofuranose (9c). (5R)-Epi-
mer: Colorless syrup (72% from 8c); [a]D26
7.578 (c
1.82); Rf 0.55 (C); FAB MS m/z 509 (Mꢁ1; 15), 451
(14), 419 (9), 361 (8), 181 (31), 91 (100). Found: m/z
509.1932. Calcd for C25H34O9P: Mꢁ1, 509.1941. (5S)-
Epimer: Colorless prisms (24% from 8c); mp 95ꢀ96 8C
(from 3:1 EtOAcꢀ 15.18 (c 1.28); Rf 0.39
hexane); [a]2D6
D
1
colorless syrup: [a]D26
NMR: d 1.40, 1.53 (2s, 3 H each, CMe2), 4.30 (dd, 1 H,
J3,4 6.7, J2,3 5.2 Hz, H-3), 4.38, 4.42 (2d, 1 H each, J6,6?
ꢃ
/
54.4 8 (c 4.26); Rf 0.49 (A); H
ꢁ
/
/
2
18.0 Hz, H2-6), 4.47, 4.53 (2d, 1 H each, J 11.9 Hz,
CH2O-6), 4.49, 4.77 (2d, 1 H each, 2J 11.6 Hz, CH2O-3),
4.56 (d, 1 H, H-4), 4.69 (dd, 1 H, J1,2 4.3 Hz, H-2), 5.75
/
/
/
ꢁ
/
(d, 1 H, H-1), 7.26ꢀ/7.34 (m, 10 H, Ph). Anal. Calcd for
(C). Anal. Calcd for C25H33O9P: C, 59.05; H, 6.54.
Found: C, 58.08; H, 6.64.
C23H26O6: C, 69.33; H, 6.58. Found: C, 69.48; H, 6.73.
3.12. 3-O-Benzyl-6-deoxy-1,2-O-isopropylidene-a-
xylo-hexofuranos-5-ulose (8f)9
D-
3.13.4. 3,6-Di-O-benzyl-5-dimethoxyphosphinyl-1,2-O-
isopropylidene-b-
mer: Colorless syrup (68% from 8d); [a]D20
1.61); Rf 0.46 (C); FAB MS m/z 509 (Mꢁ
(14), 419 (14), 361 (16), 181 (39), 91 (100). Found: m/z
509.1969. Calcd for C25H34O9P: Mꢁ1, 509.1941. (5S)-
Epimer: Colorless prisms (24% from 8d); mp 108ꢀ
109 8C (from 3:1 EtOAcꢀ 49.88 (c
hexane); [a]2D4
D
-lyxo-hexofuranose (9d). (5R)-Epi-
42.68 (c
1; 26), 451
ꢃ
/
By employing the same procedures with 8b, 3-O-benzyl-
6-deoxy-1,2-O-isopropylidene-a- -glucofuranose was
treated with PCC for 4 h to give 8f (97%) as colorless
prisms: mp 57ꢀ58 8C (from 1:2 EtOAcꢀ
hexane); [a]2D6
89.58 (c 1.04) [lit.9a 91% yield by use of CrO3ꢀ
2Py, mp
888 (c 1.0)]; Rf 0.51 (A); H NMR: d
/
D
/
/
/
/
ꢃ
56ꢀ
/
/
/
ꢃ
/
1
/
57 8C, [a]2D2
ꢃ
/
1.66); Rf 0.32 (C). Anal. Calcd for C25H33O9P: C,
59.05; H, 6.54. Found: C, 59.13; H, 6.41.
1.33, 1.47 (2s, 3 H each, CMe2), 2.23 (s, 3 H, H-6), 4.27
(d, 1 H, J3,4 3.7, J2,3 0 Hz, H-3), 4.48, 4.59 (2d, 1 H each,
2J 11.9 Hz, CH2O-3), 4.61 (d, 1 H, J1,2 3.7 Hz, H-2),
4.63 (d, 1 H, H-4), 6.08 (d, 1 H, H-1), 7.23 [m, 2 H,
Ph(o)], 7.31 [m, 1 H, Ph(p)], 7.33 [m, 2 H, Ph(m)].
3.13.5. Methyl 6-O-benzyl-5-dimethoxyphosphinyl-2,3-
O-isopropylidene-a-
Epimer: Colorless needles (76% from 8e5b); mp 85ꢀ
86 8C (from 2:1 EtOAcꢀ 60.88 (c 1.70);
hexane); [a]2D1
D-lyxo-hexofuranoside (9e). (5R)-
/
/
ꢁ
/
3.13. The general procedures for preparation of (5R)-
and (5S)-5-dimethoxyphosphinyl-hexofuranoses (9a
Rf 0.40 (C). Anal. Calcd for C19H29O9P: C, 52.78, H,
6.76. Found: C, 52.66, H, 6.89. (5S)-Epimer: Colorless
/f)
ꢀ
syrup (19% from 8e); [a]D21
Anal. Calcd for C19H29O9P: C, 52.78; H, 6.76. Found:
C, 52.59; H, 6.80.
ꢁ36.68 (c 1.16); Rf 0.32 (C).
/
DBU (0.44 mL, 2.9 mmol) was dropwise added to a
solution of 8 (2.42 mmol) in dimethyl phosphonate (10.0
mL, 109 mmol) at 0 8C and the solution was stirred at
this temperature for 30 min under argon. The mixture
was treated with saturated NH4Cl (30 mL) at rt for 4 h
and extracted with CHCl3 three times. The combined
organic layers were washed with water, dried (Na2SO4),
and evaporated in vacuo. The residue was separated by
column chromatography with a gradient eluant of 1:1
3.13.6. 3-O-Benzyl-6-deoxy-5-dimethoxyphosphinyl-1,2-
O-isopropylidene-a-
D
-xylo-hexofuranose (9f). (5R)-Epi-
mer: Colorless syrup (85% from 8f); [a]D26
1.04); Rf 0.49 (C). Anal. Calcd for C18H27O8P: C, 53.73;
ꢃ16.88 (c
/
H, 6.76. Found: C, 53.66; H, 6.73. (5S)-Epimer: Color-
less syrup (6.6% from 8f); [a]D26
EtOAcꢀ
/
hexane0/EtOAc to give (5R)-9 and (5S)-9.
ꢃ37.68 (c 1.05); Rf 0.25
/

T. Hanaya et al. / Carbohydrate Research 338 (2003) 1641ꢀ
/1650
1649
(C). Anal. Calcd for C18H27O8P: C, 53.73; H, 6.76.
Found: C, 53.51; H, 6.66.
Colorless needles (68% from 9c); mp 69ꢀ
2:1 EtOAcꢀ
hexane); [a]2D6
FAB MS m/z 493 (Mꢁ
(46), 91 (100). Found: m/z 493.1979. Calcd for
C25H34O8P: Mꢁ1, 493.1992.
/
70 8C (from
/
ꢁ
/
20.98 (c 1.21); Rf 0.45 (C).
1; 12), 435 (14), 237 (24), 185
/
3.14. General procedures for preparation of the 5-deoxy-
5-dimethoxyphosphinyl-hexofuranoses (11a
/
f and 12a
/
f)
/
ꢀ
ꢀ
Methoxalyl chloride (1.00 mL, 10.8 mmol) was added to
a solution of 9 (2.16 mmol) and 1,4-dimethylaminopyr-
idine (DMAP, 1.32 g, 10.8 mmol) in dry MeCN (15 mL)
at 0 8C. The mixture was stirred at 0 8C for 30 min under
argon, and the most of solvent was distilled off in vacuo.
The residue was treated with aq NH4Cl (20 mL) and
extracted with CHCl3. The combined organic layer was
washed with water, dried (Na2SO4) and evaporated in
vacuo to give the 5-O-methoxalyl derivative 10 as a pale
yellow syrup. The crude 10 was coevaporated with dry
toluene and dissolved in the same solvent (15 mL).
Tributyltin hydride (0.87 mL, 3.24 mmol) and AIBN (54
mg, 0.33 mmol) were added under argon. The mixture
3.14.7. 3,6-Di-O-benzyl-5-deoxy-5-dimethoxyphos-
phinyl-1,2-O-isopropylidene-b- -mannofuranose (11d).
Colorless syrup (29% from 9d); [a]D26
38.38 (c 1.77);
Rf 0.30 (C). FAB MS m/z 493 (Mꢁ1; 9), 435 (11), 237
(24), 185 (36), 91 (100). Found: m/z 493.1998. Calcd for
C25H34O8P: Mꢁ1, 493.1992.
D
ꢃ
/
/
/
3.14.8. 3,6-Di-O-benzyl-5-deoxy-5-dimethoxyphos-
phinyl-1,2-O-isopropylidene-a- -gulofuranose (12d). Col-
orless needles (48% from 9d); mp 70ꢀ71 8C (from 2:1
EtOAcꢀ 47.38 (c 1.05); Rf 0.20 (C). FAB
hexane); [a]2D6
MS m/z 493 (Mꢁ1; 22), 435 (19), 237 (29), 185 (38), 91
(100). Found: m/z 493.2012. Calcd for C25H34O8P: Mꢁ
L
/
/
ꢃ
/
/
/
was stirred at 80 8C for 2ꢀ
vacuo. The residue was separated by column chromato-
graphy with a gradient eluant of 1:1 EtOAcꢀhexane0
EtOAc to give 11 and 12.
/
6 h and then concentrated in
1, 493.1992.
/
/
3.14.9. Methyl
6-O-benzyl-5-deoxy-5-dimethoxyphos-
-mannofuranoside (11e).
Colorless prisms (16% from 9e); mp 65ꢀ67 8C (from
2:1 EtOAcꢀ 49.5 8 (c 1.48); Rf 0.45 (C).
hexane); [a]2D0
FAB MS: 417 (Mꢁ1; 21), 401 (12), 385 (11), 177 (19),
137 (11), 91 (100). Found: m/z 417.1691. Calcd for
C19H30O8P: Mꢁ1, 417.1679.
phinyl-2,3-O-isopropylidene-a-
D
/
3.14.1. 3,6-Di-O-benzyl-5-deoxy-5-dimethoxyphos-
phinyl-1,2-O-isopropylidene-a-
-glucofuranose (11a)4c.
Colorless syrup (50% from 9a); Rf 0.60 (C).
/
ꢁ
/
D
/
/
3.14.2. 3,6-Di-O-benzyl-5-deoxy-5-dimethoxyphos-
phinyl-1,2-O-isopropylidene-b-
L
-idofuranose
Colorless syrup (38% from 9a); Rf 0.38 (C).
(12a)4c.
3.14.10. Methyl 6-O-benzyl-5-deoxy-5-dimethoxyphos-
phinyl-2,3-O-isopropylidene-b- -gulofuranoside (12e).
Colorless syrup (70% from 9e); [a]D20
65.88 (c 2.81);
Rf 0.38 (C). FAB MS: 417 (Mꢁ1; 32), 401 (18), 385
(15), 177 (15), 91 (100). Found: m/z 417.1682. Calcd for
C19H30O8P: Mꢁ1, 417.1679.
L
ꢁ
/
3.14.3. 3,6-Di-O-benzyl-5-deoxy-5-dimethoxyphos-
phinyl-1,2-O-isopropylidene-a- -allofuranose (11b). Col-
orless syrup (29% from 9b); [a]D27
40.88 (c 1.06); Rf
0.45 (C), 0.30 (D). FAB MS m/z 493 (Mꢁ1; 18), 435
(22), 237 (11), 185 (16), 91 (100). Found: m/z 493.1980.
Calcd for C25H34O8P: Mꢁ1, 493.1992.
/
D
ꢁ
/
/
/
3.14.11. 3-O-Benzyl-5,6-dideoxy-5-dimethoxyphos-
phinyl-1,2-O-isopropylidene-a- -glucofuranose
Colorless syrup (24% from 9f); [a]D26
30.58 (c 6.47);
Rf 0.46 (C). FAB MS m/z 387 (Mꢁ1; 32), 329 (11), 298
(9), 261 (16), 221 (41), 91 (100). Found: m/z 387.1561.
Calcd for C18H28O7P: Mꢁ1, 387.1573.
/
D
(11f).
ꢃ
/
3.14.4. 3,6-Di-O-benzyl-5-deoxy-5-dimethoxyphos-
phinyl-1,2-O-isopropylidene-b- -tallofuranose (12b). Col-
orless needles (57% from 9b); mp 62ꢀ63 8C (from 2:1
EtOAcꢀ 60.08 (c 0.71); Rf 0.42 (C), 0.37
hexane); [a]2D7
(D). FAB MS m/z 493 (Mꢁ1; 11), 435 (18), 237 (14),
185 (20), 91 (100). Found: m/z 493.1999. Calcd for
C25H34O8P: Mꢁ1, 493.1992.
/
L
/
/
/
ꢁ
/
/
3.14.12. 3-O-Benzyl-5,6-dideoxy-5-dimethoxyphos-
phinyl-1,2-O-isopropylidene-b-
-idofuranose (12f)7. Col-
orless syrup (60% from 9f); [a]2D6 37.78 (c 2.42) [lit.,7
[a]2D1
368 (c 2.16)]; Rf 0.29 (C).
L
/
ꢃ
/
ꢃ
/
3.14.5. 3,6-Di-O-benzyl-5-deoxy-5-dimethoxyphos-
phinyl-1,2-O-isopropylidene-b- -altrofuranose
Colorless syrup (16% from 9c); [a]D26
6.068 (c 1.67);
Rf 0.55 (C). FAB MS m/z 493 (Mꢁ1; 20), 435 (22), 345
(10), 237 (11), 185 (26), 91 (100). Found: m/z 493.2011.
Calcd for C25H34O8P: Mꢁ1, 493.1992.
D
(11c).
ꢁ
/
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/
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3.14.6. 3,6-Di-O-benzyl-5-deoxy-5-dimethoxyphos-
phinyl-1,2-O-isopropylidene-a- -galactofuranose (12c).
L
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