Glycosynthase-assisted synthesis of some glycosylated scyllo-inositols

Article abstract of DOI:10.1071/CH06393

Three derivatives of scyllo-inositol, a 4-nitrophenyl ether, a benzyl ether, and an ester of 4-toluenesulfonic acid, have been treated with ?-d-galactopyranosyl fluoride and a glycosynthase to give the corresponding mono-glycosylated inositols. In one ins

Full text of DOI:10.1071/CH06393

Full Paper
CSIRO PUBLISHING
Aust. J. Chem. 2006, 59, 894–898
www.publish.csiro.au/journals/ajc
Glycosynthase-Assisted Synthesis of Some Glycosylated scyllo-Inositols
Adrian ScaffidiA and Robert V. StickA,B
A Chemistry M313, School of Biomedical, Biomolecular and Chemical Sciences,
University of Western Australia, Crawley WA 6009, Australia.
B Corresponding author. Email: rvs@chem.uwa.edu.au
Three derivatives of scyllo-inositol, a 4-nitrophenyl ether, a benzyl ether, and an ester of 4-toluenesulfonic acid, have
been treated with α-d-galactopyranosyl fluoride and a glycosynthase to give the corresponding mono-glycosylated
inositols. In one instance, a similar treatment with α-d-glucopyranosyl fluoride gave a mono- and a di-glycosylated
inositol.
Manuscript received: 25 October 2006.
Final version: 9 November 2006.
Introduction
and so allow it to act as an acceptor. Therefore, we first
prepared the 4-nitrophenyl ether 1 (Scheme 1); alterna-
tive acceptors were the benzyl ether 2 and the tosylate 3
(Scheme 2).
Glucosyl phosphatidyl inositol (GPI) anchors are impor-
tant elements in the ability of a cell to display essential
proteins on the outer surface.[1] There have been numer-
ous studies on the synthesis of the glycosylated inosi-
tol (GI) portion of these anchors,[2] and some syntheses
have used glycoside hydrolases, operating in a trans-
glycosylation mode, to construct the key glycosidic link-
age between the donor sugar and the inositol acceptor.[3]
It was suggested to us that it may be possible to gly-
cosylate, with either d-glucosyl or d-galactosyl donors,
an inositol (scyllo-inositol), catalyzed by a glycosynthase
(Abg E358G).[4] This paper reports the results of such an
investigation.
The tetrol 4, derived from myo-inositol, was easily con-
verted into the known alcohol 5,[5] and then the 4-nitrophenyl
ether 6; deacetylation then provided the desired scyllo-
inositol acceptor 1 (Scheme 1). Next, the known triol 7,
again derived from myo-inositol,[6] was selectively benzy-
lated, benzoylated, and tosylated to provide the fully protected
inositol 8, which could then be selectively transformed into
the alcohol 9; a remarkable series (Scheme 2).[7] Inversion of
configuration of the alcohol 9 then gave the new alcohol 10
that was a precursor of the scyllo-inositol acceptors 2 and 3,
by the diol 11 and the tetrol 12, respectively.
With the scyllo-inositol acceptors 1, 2, and 3, and tetra-O-
acetyl-α-d-glucopyranosyl and -galactopyranosyl fluoride to
hand, we investigated the glycosynthase-catalyzed glycosy-
lation reactions. We focused initially on the d-galacto donor,
as this ensured the formation of only mono-glycosylated
products.[4]
Results and Discussion
Some of the best acceptors for glycosynthase-catalyzed gly-
cosylations have been substituted aryl glycosides, which bear
a hydrophobic group at the anomeric position.[4] Inositols are
poly-hydroxylated cyclohexanes and lack an anomeric car-
bon; however, a phenyl ether, for example, should provide
a group that binds to the active site of the glycosynthase
Thus, treatment of pre-formed α-d-galactopyranosyl flu-
oride with the acceptor 1 and the glycosynthase Abg E358G
O
OH
OH
OAc
(a)(b)
OH
OH
(c)
OAc
AcO
O
OAc
OH
OAc
OH
4
5
OAc
1
OH
1
(d)
ArO
AcO
OAc
OAc
ArO
HO
OH
OH
OAc
Ar is 4-O2NC6H4
6
1
Scheme 1. (a) Ac2O, pyridine. (b) (i) AcOH/H2O; (ii) Ac2O, pyridine, CH2Cl2. (c) (i) Tf2O,
pyridine, CH2Cl2; (ii) 4-nitrophenol, Et3N, CH2Cl2. (d) 1 M HCl, MeOH.
© CSIRO 2006
10.1071/CH06393
0004-9425/06/120894

Glycosynthase-Assisted Synthesis of Glycosylated scyllo-Inositols
895
O
O
O
O
O
O
O
O
O
(a)
O
(b)
BzO
HO
HO
HO
HO
HO
OBn
OH
OBn
7
O
O
O
O
O
(c)
(d)
(e)
BzO
HO
TsO
TsO
OBn
OBn
8
9
7
O
O
O
O
OH
O
O
1
1
(g)
(f)
HO
HO
OH
OBn
1
OH
TsO
HO
HO
OBn
HO
OBn
10
11
2
(g)
OH
OH
(h)
HO
BnO
OH
OTs
1
HO
HO
OH
OTs
OH
OH
12
3
Scheme 2. (a) BnBr, NaH, DMF. (b) BzCl, pyridine. (c) TsCl, pyridine. (d) BusNH2, MeOH. (e) (i) Oxalyl chloride, DMSO;
(ii) Et3N; (iii) NaBH4, EtOH. (f) Na, MeOH. (g) TFA/H2O. (h) Pd–C, H2, THF/H2O/MeOH.
HO
OH
OAc
O
OAc
OAc
O
(a)
(a)
AcO
O
AcO
OAc
OAr
ϩ
ϩ
1
HO
OH
OAc
OAc
OAc
F
AcO
13
HO
OH
OAc
O
O
AcO
O
AcO
OAc
OBn
2
HO
OH
OAc
AcO
F
14
OAc
O
OAc
AcO
O
AcO
OAc
OTs
OAc
HO
OH
OAc
AcO
(a)
15
O
ϩ
3
HO
OAc
OAc
OTs
OAc
OH
F
OAc
AcO
O
OAc
O
OAc
AcO
16
Scheme 3. (a) (i) Abg E358G, NH4HCO3, H2O; (ii) Ac2O, pyridine, DMAP.
gave, after workup and acetylation of the product, the
4-O-glycosylated inositol 13 (Scheme 3). This glycosylation
was much slower than with more conventional carbohy-
drate acceptors such as a recently described β-laminaribiosyl
fluoride,[8] perhaps to be expected, and needed one week
to approach completion (the yield of 13 was still high,
93%). The product, however, was as expected if the accep-
tor is viewed as a surrogate for a carbohydrate: the 4-
OH is then presented for normal glycosylation by Abg
E358G.[4]

896
A. Scaffidi and R. V. Stick
15
(c)
OAc
O
OAc
(a)
(b)
AcO
O
AcO
OAc
OH
13
14
OAc
OAc
AcO
17
Scheme 4. (a) (i) Pd–C, H2, Ac2O, THF; (ii) Ce(NH4)2(NO3)6, CH3CN/H2O. (b) Pd–C, H2,
THF/MeOH. (c) TsCl, pyridine.
OAc
O
OAc
AcO
AcO
O
AcO
OAc
OBn
OH
OAc
OAc
(a)
O
HO
HO
18
ϩ
2
OH
OAc
F
OAc
OAc
O
AcO
AcO
AcO
O
O
AcO
OAc
OBn
O
OAc
OAc
OAc
19
Scheme 5. (a) (i) Abg E358G, NH4HCO3, H2O; (ii) Ac2O, pyridine, DMAP.
OH
OH
The acceptor 2 was also treated with α-d-galactopyranosyl
fluoride and Abg E358G, and unsurprisingly gave the 4-O-
glycosylated inositol 14 (55%). However, under the same
conditions, the acceptor 3 gave what appeared to be two
mono-glycosylated products, one later identified as the 4-
O-glycosylated inositol 15 (64%) and the other tentatively
assigned as the 3-O-glycosylated inositol 16 (24%). This
latter assignment was based on the results of our previous
work with other ‘unnatural’acceptors such as 6-O-benzyl-d-
glucopyranose.[9] The structural assignments of 15 and 16
were not straightforward; the ‘equivalent’ hydrogen atoms
of the inositol ring are in fact diastereotopic, which com-
HO
HO
O
HO
OH
OBn
O
OH
OH
20
Scheme 6.
Experimental
General experimental procedures have been given previously.[10]
1,2,3,4,5-Penta-O-acetyl-6-O-(4-nitrophenyl)-scyllo-inositol 6
Trifluoromethanesulfonic anhydride (0.12 mL, 0.72 mmol) in CH2Cl2
(1 mL) was added dropwise to the alcohol 5[5] (200 mg, 0.51 mmol)
in pyridine/CH2Cl2 (1/1, 5 mL) and the solution stirred (5 h). A usual
workup (CH2Cl2) presumably gave the triflate of 5, which was treated
with 4-nitrophenol (140 mg, 1.0 mmol) and Et3N (0.50 mL, 3.6 mmol)
in CH2Cl2 (5 mL). The solution was stirred at 40◦C (3 h) before dilu-
tion with 1 M NaOH and extraction with CH2Cl2. The organic layer was
dried and concentrated to leave a pale yellow solid that was recrystal-
lized to yield the 4-nitrophenyl ether 6 as a solid (180 mg, 69%), mp
>230◦C (toluene/EtOAc). δH (500 MHz, [D6]DMSO) 1.74, 1.91, 1.93
(15H, 3s, CH3), 5.35 (dd, J2,3 ≈ J3,4 9.8, H3), 5.37–5.45 (m, H1/2,H5/4),
5.50 (dd, J1,6 ≈ J5,6 9.8, H6), 5.61 (dd, J 9.8, H2/1,H4/5), 7.15, 8.23
(AAꢀBBꢀ, J 9.2, Ar). δC (125.8 MHz, [D6]DMSO) 29.62, 29.70 (CH3),
79.13, 79.82 (C1,C2,C4,C5), 79.25 (C3), 85.89 (C6), 125.67, 135.47,
151.08, 173.14 (Ar), 178.46, 178.68, 178.81 (C=O). m/z (HR-MS FAB)
496.1447; [M + H]+ requires 496.1455.
1
plicates the H nuclear magnetic resonance spectrum and
makes the distinction from 16 difficult. We were not able to
determine the absolute configuration of the inositol portion
of 16. Lastly, we converted 13 and 14 into the same alco-
hol 17, from which 15 was easily derived and authenticated
(Scheme 4).
In a final experiment, we treated the acceptor 2 with α-d-
glucopyranosyl fluoride andAbg E358G, isolating the mono-
and di-glycosylated inositols 18 (38%) and 19 (40%), as
expected (Scheme 5). The two comparable yields may reflect
the improved acceptor ability of the glycosylated inositol 20
(Scheme 6) over the inositol 2.
It is tempting to speculate on the better yields obtained
in the galactosylation of the acceptors 1 (93%) and 3 (88%
in total), compared to that for 2 (55%). However, any ratio-
nalization in terms of aryl glycosides being generally better
acceptors than benzyl glycosides[4] seems a little unfounded
when one observes the yield of the glucosylation of 2 (78%
in total). The ester 3 is a novel acceptor and obviously binds
to the active site of the glycosynthase so that glycosylation
can occur at either of two hydroxyl groups.
1-O-(4-Nitrophenyl)-scyllo-inositol 1
One molar HCl in MeOH (10 mL) was added to the 4-nitrophenyl ether
6 (70 mg) in CH2Cl2 (3 mL) and the suspension stirred at 40◦C (24 h).
Concentration of the mixture followed by recrystallization yielded 1 as a
powder (28 mg, 70%), mp >230◦C (H2O). δH (500 MHz, [D6]DMSO)
2.98–3.20 (m, H2–H6), 4.23 (dd, J1,2 ≈ J1,6 9.3, H1), 4.80 (d, J 3.7, OH),
4.90 (2H, d, J 4.1, OH), 5.10 (2H, d, J 4.9, OH), 7.20, 8.15 (AAꢀBBꢀ,
J 9.0, Ar). δC (125.8 MHz, [D6]DMSO) 72.98, 73.95 (C2,C3,C5,C6),

Glycosynthase-Assisted Synthesis of Glycosylated scyllo-Inositols
897
73.84 (C4), 82.77 (C1), 116.58, 125.30, 140.18, 166.08 (Ar). m/z (HR-
4.90–5.15 (5H, m, OH), 7.40, 7.84 (AAꢀBBꢀ, J 8.4, Ar). δC (75.5
MHz, [D6]DMSO) 21.07 (CH3), 71.60, 73.92 (C2,C3,C5,C6), 73.49
(C4), 86.37 (C1), 127.64–143.43 (Ar). m/z (HR-MS FAB) 335.0820;
[M + H]+ requires 335.0800.
MS FAB) 301.0794; [M]+• requires 301.0798.
4-O-Benzyl-2-O-(4-methylphenylsulfonyl)-scyllo-inositol
1,3,5-Orthoformate 10
General Experimental Procedure for Glycosynthase Reactions
(i) Dimethyl sulfoxide (0.23 mL, 3.2 mmol) in CH2Cl2 (1 mL) was
added dropwise to oxalyl chloride (0.15 mL, 1.7 mmol) in CH2Cl2
(10 mL) at −55◦C and the solution stirred (0.5 h). The alcohol 9[7]
(500 mg, 1.1 mmol) in CH2Cl2 (5 mL) was then added dropwise and
the resulting solution stirred at −55◦C (1.5 h). The solution was then
warmed to −30◦C, followed by the dropwise addition of Et3N (1.1 mL,
7.9 mmol). The solution was warmed to room temperature and a usual
workup (CH2Cl2) presumably yielded the intermediate ketone as a solid
(450 mg) that was used in the next step without purification.
(ii) Sodium borohydride (135 mg, 3.6 mmol) was added to the ketone
from (i) (450 mg) in THF/MeOH (1/1, 15 mL) and the suspension
stirred (1 h). Usual workup (EtOAc) followed by flash chromatogra-
phy (EtOAc/toluene, 1/9) returned the alcohol 10 as a solid (440 mg,
97%), mp 163–165◦C. δH (300 MHz) 2.45 (s, CH3), 3.78 (d, J6,OH
11.9, OH), 4.15–4.20, 4.35–4.40, 4.60–4.65 (3m, H1,H3,H4,H5), 4.26–
4.35 (m, H6), 4.58, 4.78 (ABq, J 11.4, CH2Ph), 5.15–5.20 (m, H2),
5.45 (s, H7), 7.30–7.40 (m, Ph), 7.32, 7.80 (AAꢀBBꢀ, J 8.3, Ar). δC
(75.5 MHz) 21.65 (CH3), 66.09, 67.48, 68.26, 69.61, 71.89, 71.96 (C1–
C6), 72.00 (CH2Ph), 102.07 (C7), 127.94–145.57 (Ar). m/z (HR-MS
FAB) 435.1095; [M + H]+ requires 435.1114.
A small piece of Na was added to MeOH (10 mL) and the
resulting solution was added to tetra-O-acetyl-α-d-glucopyranosyl
or -galactopyranosyl fluoride and the solution stirred (1 h) before
neutralization with resin (Amberlite IR-120, H+), filtered and con-
centrated to return an oil, presumably either α-d-glucopyranosyl
or -galactopyranosyl fluoride. This oil in aqueous NH4HCO3 solution
(150 mM, 5 mL) was then added to the acceptor inositol in H2O (15 mL).
The glycosynthase, Abg E358G (0.2 mg) was then added and the solu-
tion kept at 25◦C (7 days). The solvent was removed under reduced
pressure and the resulting residue was dissolved in Ac2O (2 mL) and
pyridine (5 mL) containing DMAP (1–2 mg) and the solution stirred
at 50◦C (3 h). The mixture was quenched with MeOH, followed by a
usual workup (CH2Cl2), to give a brown residue that was subjected to
flash chromatography (EtOAc/light petroleum, 3/7 to 1/1) to furnish the
appropriate peracetylated glycosylated inositol.
Tetra-O-acetyl-4-O-(4-nitrophenyl)-1-O-(tetra-O-acetyl-
β-D-galactopyranosyl)-scyllo-inositol 13
Using the general experimental procedure, tetra-O-acetyl-α-d-
galactopyranosyl fluoride (115 mg, 0.33 mmol) and
1 (20 mg,
0.07 mmol) afforded 13 as a glass (48 mg, 93%), [α]D −16.3◦. δH
2-O-Benzyl-scyllo-inositol 1,3,5-Orthoformate 11
(500 MHz) 1.81–2.12 (24H, 7s, CH3), 3.88–3.93 (m, H5ꢀ), 4.00 (dd,
A small piece of Na was added to MeOH (10 mL) and the resulting solu-
tion was added to the alcohol 10 (500 mg) inTHF (10 mL). The solution
was refluxed overnight before neutralization with resin (Amberlite IR-
120, H+) and filtered. The filtrate was concentrated to give a solid that
was subjected to flash chromatography (EtOAc/toluene, 1/4) to give the
diol 11 as a solid (285 mg, 89%), mp 113–115◦C. δH (300 MHz) 3.65–
3.75 (2H, m, OH), 4.30–4.35, 4.36–4.40, 4.42–4.48 (3m, H1–H6), 4.68
(s, CH2Ph), 5.47 (s, H7), 7.30–7.40 (m, Ph). δC (75.5 MHz) 67.00, 69.03
(C1,C3,C4,C6), 70.52, 73.05 (C2,C5), 71.99 (CH2Ph), 102.01 (C7),
127.95–136.46 (Ph). m/z (HR-MS FAB) 281.1037; [M + H]+ requires
281.1025.
J1,2 ≈ J1,6 9.8, H1), 4.07 (dd, J6 ,6 11.2, J5 ,6 6.8, H6ꢀ), 4.15 (dd, J5 ,6
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
6.6, H6ꢀ), 4.57 (d, J1 ,2 8.3, H1 ), 4.60 (dd, J3,4 ≈ J4,5 9.8, H4), 4.92 (dd,
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
J2 ,3 10.4, J3 ,4 3.5, H3 ), 5.05 (dd, H2 ), 5.13 (dd, J 9.8, H3/5), 5.23 (dd,
J 9.8, H5/3), 5.27 (dd, J 9.8, H2/6), 5.32–5.35 (m, H4ꢀ), 5.36 (dd, J 9.8,
H6/2), 7.00, 8.15 (AAꢀBBꢀ, J 9.2, Ar). δC (125.8 MHz) 20.27–20.64
(CH3), 60.96 (C6ꢀ), 66.82 (C4ꢀ), 68.64 (C2ꢀ), 69.66, 70.52 (C3,C5),
70.67 (C5ꢀ), 70.91 (C3ꢀ), 70.91, 71.65 (C2,C6), 75.74 (C1), 77.39 (C4),
100.89 (C1ꢀ), 116.00, 125.82, 142.53, 163.21 (4C, Ar), 169.04–170.36
(C=O). m/z (HR-MS FAB) 800.2261; [M + H]+ requires 800.2249.
Tetra-O-acetyl-4-O-benzyl-1-O-(tetra-O-acetyl-β-D-
galactopyranosyl)-scyllo-inositol 14
1-O-Benzyl-scyllo-inositol 2
Using the general experimental procedure, tetra-O-acetyl-α-d-
The diol 11 (200 mg) in TFA/H2O (9/1, 15 mL) was kept at room tem-
perature (24 h). Concentration of the mixture afforded 2 as a powder
(190 mg), mp >230◦C. δH (300 MHz, [D6]DMSO) 2.93–3.20 (m, H1–
H6), 3.35 (s, CH2Ph), 4.70–4.84 (5H, m, OH), 7.20–7.42 (m, Ph).
δC (75.5 MHz, [D6]DMSO) 73.58 (CH2Ph), 73.85 (C4), 74.03, 74.35
(C2,C3,C5,C6), 83.12 (C1), 126.94–139.78 (Ph). m/z (HR-MS FAB)
269.1033; [M − H]+ requires 269.1025.
galactopyranosyl fluoride (130 mg, 0.37 mmol) and
2 (20 mg,
0.07 mmol) afforded 14 as a glass (31 mg, 55%), [α]D −6.5◦. δH
(600 MHz) 1.93–2.13 (24H, 6s, CH3), 3.70 (dd, J3,4 ≈ J4,5 9.5, H4), 3.87
(dd, J5 ,6 ≈ J5 ,6 6.8, H5ꢀ), 3.92 (dd, J1,2 ≈ J1,6 9.5, H1), 4.07 (dd, J6 ,6
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
11.3, H6ꢀ), 4.14 (dd, H6ꢀ), 4.55 (d, J1 ,2 8.0, H1ꢀ), 4.60 (s, CH2Ph), 4.91
ꢀ
ꢀ
(dd, J2 ,3 10.4, J3 ,4 3.4, H3ꢀ), 5.02 (dd, H2ꢀ), 5.05 (dd, J 9.5, H2/6),
5.10 (dd, J 9.5, H3/5), 5.13 (dd, J 9.5, H6/2), 5.17 (dd, J 9.5, H5/3),
5.32 (d, H4ꢀ), 7.18–7.34 (Ph). δC (150.9 MHz) 20.53–20.93 (8C, CH3),
61.19 (C6ꢀ), 67.06 (C4ꢀ), 68.85, 72.43 (C2,C6), 70.31 (C2ꢀ), 70.81 (C5ꢀ),
71.19 (C3ꢀ), 71.60, 72.14 (C3,C5), 75.36 (CH2Ph), 76.06 (C1), 77.93
(C4), 101.04 (C1ꢀ), 127.85–137.58 (Ph), 169.25–170.57 (8C, C=O).
m/z (HR-MS FAB) 769.2530; [M + H]+ requires 769.2555.
ꢀ
ꢀ
ꢀ
ꢀ
3-O-Benzyl-1-O-(4-methylphenylsulfonyl)-scyllo-
inositol 12
The alcohol 10 (300 mg) in THF/H2O (9/1, 20 mL) was stirred at
40◦C (3 h). Concentration of the mixture gave the tetrol 12 as a pow-
der (290 mg), mp 175–177◦C. δH (300 MHz, [D6]DMSO) 2.40 (CH3),
3.00–3.25 (m, H2–H6), 4.37 (dd, J1,2 ≈ J1,6 9.5, H1), 4.75 (s, CH2Ph),
4.99 (d, J 4.2, OH), 5.03 (d, J 4.8, OH), 5.09 (d, J 5.6, OH), 5.28 (d, J 6.8,
OH), 7.23–7.45 (m, Ph), 7.38, 7.81 (AAꢀBBꢀ, J 8.0, Ar). δC (75.5 MHz,
[D6]DMSO) 21.10 (CH3), 71.23, 71.61, 73.32, 73.92, 82.69, 86.32 (C1–
C6), 73.79 (CH2Ph), 127.05–143.51 (Ar). m/z (HR-MS FAB) 425.1247;
[M + H]+ requires 425.1270.
Tetra-O-acetyl-4-O-(4-methylphenylsulfonyl)-1-O-(tetra-O-acetyl-
β-D-galactopyranosyl)-scyllo-inositol 15 and
Tetra-O-acetyl-3-O-(4-methylphenylsulfonyl)-1-O-(tetra-O-acetyl-
β-D-galactopyranosyl)-scyllo-inositol 16
(i) Using the general experimental procedure, tetra-O-acetyl-α-
d-galactopyranosyl fluoride (210 mg, 0.60 mmol) and 3 (40 mg,
0.12 mmol) afforded a colourless powder (89 mg, 89%), shown to be
a mixture of 15 and 16 in a ratio of 5/2. Compound 15: δC (125.8 MHz)
60.99 (C6ꢀ), 100.88 (C1ꢀ). Compound 16: δC (125.8 MHz) 20.16–21.48
(9C, CH3), 60.93 (C6ꢀ), 66.81–77.07 (C1–C6,C2ꢀ–C5ꢀ), 100.67 (C1ꢀ),
127.38–145.06 (Ar), 168.93–170.31 (8C, C=O).
1-O-(4-Methylphenysulfonyl)-scyllo-inositol 3
Palladium-on-activated-charcoal (20 mg, 10% w/w) was added to the
tetrol 12 (100 mg) in THF/H2O/MeOH (1/2/2, 10 mL) and the suspen-
sion stirred under an atmosphere of hydrogen (24 h). Filtration through
Celite followed by concentration of the filtrate gave 3 as a powder
(75 mg), mp 218–220◦C. δH (300 MHz, [D6]DMSO) 2.43 (s, CH3),
2.95–3.10, 3.15–3.25 (2m, H2–H6), 4.35 (dd, J1,2 ≈ J1,6 9.6, H1),
(ii) 4-Toluenesulfonyl chloride (22 mg, 0.12 mmol) was added to
the alcohol 17 (12 mg, 0.02 mmol) in pyridine (2 mL) and the result-
ing solution stirred at 50◦C (2 h) before being quenched with H2O. A

898
A. Scaffidi and R. V. Stick
usual workup (EtOAc) followed by flash chromatography (EtOAc/light
petroleum, 1/1) furnished the tosylate 15 as a glass (16 mg, 87%), [α]D
−9.7◦. δH (500 MHz) 1.85–2.14 (24H, 7s, CH3), 2.42 (s, ArCH3), 3.87
(Ph). δC (150.9 MHz) 20.23–20.77 (8C, CH3), 61.63 (C6ꢀ), 67.96–77.71
(C1–C6,C2ꢀ–C5ꢀ), 75.21 (CH2Ph), 100.65 (C1ꢀ), 127.66–137.41 (Ph),
169.15–170.45 (8C, C=O). m/z (HR-MS FAB) 769.2551; [M + H]+
requires 769.2555.
(ddd, J5 ,6 ≈ J5 ,6 6.6, J4,5 1.0, H5ꢀ), 3.93, 4.87, 5.07, 5.14, 5.20, 5.23
ꢀ
ꢀ
ꢀ
ꢀ
(6dd, J 9.7, H1–H6), 4.06 (dd, J6 ,6 11.2, H6ꢀ), 4.1 (dd, H6ꢀ), 4.55 (d,
Next to elute was 19 as a glass (47 mg, 40%), [α]D −13.8◦. Par-
ꢀ
ꢀ
J1 ,2 8.0, H1ꢀ), 4.90 (dd, J2 ,3 10.4, J3 ,4 3.4, H3ꢀ), 5.05 (dd, H2ꢀ), 5.34
(dd, H4ꢀ), 7.30, 7.70 (AAꢀBBꢀ, J 8.3, Ar). δC (125.8 MHz) 20.27–21.56
(9C, CH3), 60.99 (C6ꢀ), 66.86–77.25 (C1–C6,C2ꢀ–C5ꢀ), 100.88 (C1ꢀ),
127.54–145.05 (Ar), 169.06–170.41 (8C, C=O). m/z (HR-MS FAB)
833.2163; [M + H]+ requires 833.2174.
tial δH (600 MHz) 1.90–2.11 (33H, 11s, CH3), 3.56 (ddd, J4
9.8,
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀꢀ,5ꢀꢀ
5.5, 1.8, H5ꢀꢀ), 3.60 (ddd, J4 ,5 9.9, J5 ,6 4.2, 2.2, H5ꢀ), 4.00
ꢀ ꢀ ꢀ ꢀ
ꢀꢀ ꢀꢀ
ꢀꢀ,6ꢀꢀ
J5
(dd, J6 ,6 12.4, H6ꢀ), 4.16 (dd, J6 ,6 12.1, H6ꢀꢀ), 4.34 (dd, H6ꢀ),
ꢀ
ꢀ
4.36 (dd, H6ꢀꢀ), 4.43 (d, J1 ,2 7.9, H1ꢀꢀ), 4.54 (dd, J1 ,2 8.1, H1ꢀ),
ꢀꢀ ꢀꢀ
ꢀ
ꢀ
4.57 (s, CH2Ph), 4.77 (dd, J3 ,4 8.3, H4ꢀ), 4.87 (dd, J3 ,4 8.1, H4ꢀꢀ),
7.15–7.31 (Ph). δC (150.9 MHz) 20.19–20.74 (CH3), 61.45, 62.06
(C6ꢀ,C6ꢀꢀ), 67.67–77.62 (C1–C6,C2ꢀ–C5ꢀ,C2ꢀꢀ–C5ꢀꢀ), 75.14 (CH2Ph),
100.56, 100.75 (C1ꢀ,C1ꢀꢀ), 127.61–137.37 (Ph), 169.22–170.40 (C=O).
m/z (HR-MS FAB) 1057.3419; [M + H]+ requires 1057.3400.
ꢀ
ꢀ
ꢀꢀ ꢀꢀ
2,3,5,6-Tetra-O-acetyl-1-O-(tetra-O-acetyl-β-D-galactopyranosyl)-
scyllo-inositol 17
(i) Palladium-on-activated-charcoal (5 mg, 10% w/w) was added to the
benzyl ether 14 (15 mg) inTHF/MeOH (1/4, 10 mL) and the suspension
stirred under an atmosphere of hydrogen (24 h). Filtration through Celite
and concentration of the filtrate followed by recrystallization gave the
alcohol 17 as plates (11 mg, 87%), mp 215–218◦C (CH2Cl2/Pr2i O), [α]D
−11.6◦. δH (600 MHz) 1.95–2.14 (24H, 8s, CH3), 2.37 (bs, OH), 3.74
Acknowledgments
We thank Steve Withers for the generous supply of a range
of glycosynthases, without which this work would not have
been possible, and Keith Stubbs for suggesting an inositol as
an acceptor.
(dd, J3,4 ≈ J4,5 9.8, H4), 3.88 (ddd, J5 ,6 ≈ J5 ,6 6.6, J4 ,5 1.0, H5ꢀ),
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
3.92 (dd, J1,2 ≈ J1,6 9.8, H1), 4.07 (dd, J6 ,6 11.2, H6ꢀ), 4.15 (dd, H6ꢀ),
ꢀ
4.56 (d, J1 ,2 8.0, H1ꢀ), 4.93 (dd, J2 ,3 10.4, J3 ,4 3.5, H3ꢀ), 4.99 (dd, J
9.8), 5.04 (dd, H2ꢀ), 5.05–5.08 (m, 2H), 5.16 (dd, J 9.8), 5.34 (dd, H4ꢀ).
δC (150.9 MHz) 20.38–20.77 (CH3), 60.91 (C6ꢀ), 66.88–76.09 (C1–
C6,C2ꢀ–C5ꢀ), 100.91 (C1ꢀ), 169.10–170.68 (8C, C=O). m/z (HR-MS
FAB) 679.2115; [M + H]+ requires 679.2086.
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
References
[1] T. Kinoshita, K. Ohishi, J. Takeda, J. Biochem. (Tokyo) 1997,
122, 251.
[2] K. Pekari, R. R. Schmidt, J. Org. Chem. 2003, 68, 1295.
doi:10.1021/JO026380J
[3] J. B. Hart, L. Kröger, A. Falshaw, R. Falshaw, E. Farkas, J. Thiem,
A. L. Win, Carbohydr. Res. 2004, 339, 1857. doi:10.1016/
J.CARRES.2004.05.016
[4] S. J. Williams, S. G. Withers, Aust. J. Chem. 2002, 55, 3.
doi:10.1071/CH02005
[5] A. Hosoda, E. Nomura,A. Murakami, K. Koshimizu, H. Ohigashi,
K. Mizuno, H. Taniguchi, Bioorg. Med. Chem. 2002, 10, 1855.
doi:10.1016/S0968-0896(02)00010-X
[6] S. J.Angyal, Carbohydr. Res. 2000, 325, 313. doi:10.1016/S0008-
6215(99)00306-7
[7] K. M. Sureshan, M. S. Shashidhar, T. Praveen, R. G. Gonnade,
M. M. Bhadbhade, Carbohydr. Res. 2002, 337, 2399. doi:10.1016/
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[8] A. Scaffidi, R. V. Stick, K. A. Stubbs, Aust. J. Chem., submitted.
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779. doi:10.1071/CH04025
(ii) Palladium-on-activated-charcoal (10 mg, 10% w/w) was added
to the phenyl ether 13 (25 mg, 0.03 mmol) in THF/Ac2O (9/1, 5 mL)
and the suspension stirred under an atmosphere of hydrogen (2 h). Fil-
tration through Celite and concentration of the filtrate gave a residue
that was treated with Ce(iv) ammonium nitrate (165 mg, 0.30 mmol) in
CH3CN/H2O (5/1, 5 mL) and the mixture stirred at 0◦C (1.5 h). Usual
workup (EtOAc) followed by flash chromatography (EtOAc/toluene,
13/7) returned the alcohol 17 as plates (16 mg, 75%). The 1H and 13
NMR spectra were in agreement with those reported for 17 in (i).
C
Tetra-O-acetyl-4-O-benzyl-1-O-(tetra-O-acetyl-β-D-glucopyranosyl)-
scyllo-inositol 18 and
Tetra-O-acetyl-4-O-benzyl-1-O-[tetra-O-acetyl-β-D-glucopyranosyl-
(1→4)-tri-O-acetyl-β-D-glucopyranosyl]-scyllo-inositol 19
Using the general experimental procedure, tetra-O-acetyl-α-d-
glucopyranosyl fluoride (78 mg, 0.22 mmol) and 2 (30 mg, 0.11 mmol)
yielded first 18 as a glass (32 mg, 38%), [α]D −17.5◦. δH (600 MHz)
1.93–2.09 (24H, 7s, CH3), 3.64–3.67 (m, H5ꢀ), 3.68 (dd, J3,4 ≈ J4,5 9.5,
H4), 3.88 (dd, J1,2 ≈ J1,6 9.5, H1), 4.03 (dd, J6 ,6 12.4, J5 ,6 2.1, H6ꢀ),
ꢀ
ꢀ
ꢀ
ꢀ
4.36 (dd, J5 ,6 4.7, H6ꢀ), 4.58 (d, J1 ,2 8.1, H1ꢀ), 4.60 (s, CH2Ph), 4.86
[10] A. Scaffidi, B. W. Skelton, R. V. Stick, A. H. White, Aust. J. Chem.
2006, 59, 426. doi:10.1071/CH06137
ꢀ
ꢀ
ꢀ
ꢀ
(dd, J2 ,3 9.5, H2ꢀ), 4.98–5.17 (m, H2,H3,H3ꢀ,H4ꢀ,H5,H6), 7.17–7.34
ꢀ
ꢀ