The cyanation reaction of O-acetylated S-glycosyl phosphorothioates.

Article abstract of DOI:10.1016/S0008-6215(00)00216-0

The reaction of alpha- and beta-1-S-phosphorothioates of per-O-acetylated monosaccharides (galactose, xylose, glucose) with trimethylsilyl cyanide in the presence of boron trifluoride etherate has been investigated. It has been established that in dichlor

Full text of DOI:10.1016/S0008-6215(00)00216-0

www.elsevier.nl/locate/carres
Carbohydrate Research 329 (2000) 687–691
Note
The cyanation reaction of O-acetylated S-glycosyl
phosphorothioates
Wies*lawa Kudelska *
Institute of Chemistry, Faculty of Pharmacy, Medical Uni6ersity of Lodz, PL-90-151 Lodz,
Muszyn´skiego 1, Poland
Received 8 May 2000; accepted 12 July 2000
Abstract
The reaction of a- and b-1-S-phosphorothioates of per-O-acetylated monosaccharides (galactose, xylose, glucose)
with trimethylsilyl cyanide in the presence of boron trifluoride etherate has been investigated. It has been established
that in dichloromethane 1,2-O-cyanoethylidene derivatives of aldoses are formed in high yields. When the reaction
was carried out in acetonitrile, peracetylated galactosyl cyanide was formed as the major product. © 2000 Elsevier
Science Ltd. All rights reserved.
Keywords: S-Glycosyl phosphorothioate; Cyanation; 1,2-O-[1-(exo- and endo-Cyano)ethylidene]-glycopyranose; Glycosyl cyanide
1,2 - O - (1 - Cyanoethylidene)glycopyranoses
and isomeric glycosyl cyanides (anhydroal-
dononitriles) are valuable intermediates in or-
ganic synthesis. Methods for the synthesis of
1,2-O-cyanoethylidene sugar derivatives in-
volve transformations of glycosyl halides in
the reaction: (a) with sodium or potassium
cyanide and tetra-n-butylammonium halide
[1–3] and (b) with silver cyanide [4–6]. How-
ever, the corresponding glycosyl isocyanides
have also been generated in the latter ap-
proach [7]. Russian authors, who primarily
examined this class of compounds, not only
elaborated the appropriate methods of synthe-
sis [1–3,5,6], but applied these reagents to the
stereo- and regiospecific synthesis of di- [3,8]
and polysaccharides [9–13].
glycosyl halides and mercuric(II) cyanide [14–
18], from acetylated sugars and trimethylsilyl
cyanide [19,20], by conversion of anhydro-1-
deoxy-1-nitroalditols [21] and by dehydration
of anhydroaldonoamides [22]. A novel method
for the synthesis of O-benzylated glycosyl
cyanides has previously been described [23],
which is based on the reaction of correspond-
ing
S-glycosyl
phosphorothioate
with
trimethylsilyl cyanide in the presence of a
Lewis acid.
We report herein an alternative and efficient
procedure for the synthesis of per-O-acetyl-
ated 1,2-O-1-cyanoethylidene glycopyranoses
in the reaction of appropriate S-glycosyl
phosphorothioate with trimethylsilyl cyanide
in the presence of a Lewis acid as a catalyst.
The cyanation of S-galactosyl phosphoroth-
ioate with trimethylsilyl cyanide in the pres-
ence of a Lewis acid in acetonitrile produced
the corresponding glycosyl cyanide in high
yield.
Glycosyl cyanides have been prepared from
* Corresponding author. Fax: 48-42-6788398.
E-mail address: kudelska@ich.pharm.am.lodz.pl (W.
Kudelska).
0008-6215/00/$ - see front matter © 2000 Elsevier Science Ltd. All rights reserved.
PII: S0008-6215(00)00216-0

688
W. Kudelska / Carbohydrate Research 329 (2000) 687–691
Fig. 1. S-Glycosyl phosphorothioates 1–5 applied to the cyanation reaction and products formed 6, 10, 11.
most reactive of
D
-pyranoses investigated
The per-O-acetylated S-1,2-trans and 1,2-
cis-glycosyl phosphorothioate derivatives of
-galactose 1, 2, -glucose 3, 4 and -xylose 5
from amongst 1,2-trans isomers 1, 3, 5
cyanated. The physical properties of 7(a, b)–
9(a, b) were in agreement with those reported
D
D
D
used in these investigations are listed in the
Fig. 1. They have been prepared in the reac-
tion of trialkylammonium salt of O,O-dialkyl
phosphorothioic acid with acetylated glycosyl
halides [24] or 1-O-acetyl sugars [25]. These
glycosyl donors are stable, non-toxic and
odorless reagents. In earlier studies, they have
been applied to the synthesis of glycosyl
disulfides [24] and glycosyl 1-O-acyl esters
[26].
for
ethylidene]-a-
and a-
1,2-O-[1-(exo-
and
endo-cyano)-
-gluco- [1,2]
D
-galacto- [1,2], a-
D
D
-xylopyranoses [3]. The forma-tion of
a mixture of isomeric nitriles 7(a, b) and
2,3,4,6 - tetra - O - acetyl - b -
D
- galactopyra-
Table 1
Synthesis of 1,2-O-cyanoethylidene sugar derivatives
The cyanation reactions of 1–5 (1 molar
equivalent) were carried out in aprotic sol-
vents (dichloromethane or acetonitrile) using
trimethylsilyl cyanide and the required cata-
lytic amounts of boron trifluoride etherate.
The time necessary to complete the reaction
31
was determined by P NMR monitoring. The
products were isolated and separated by
column chromatography. The results of cya-
nation of 1–5 in dichloromethane are summa-
rized in the Table 1. Per-O-acetylated
1,2-O-[1-exo and endo-cyano)ethylidene]-a- -
D
glycopyranoses 7(a, b)–9(a, b) were obtained,
with high preponderance of the exo isomers,
in yields ranging from 41 to 75%. Low tem-
1
perature 31P and H NMR monitoring (−
60925 °C) revealed that 1,2-trans-S-glycosyl
phosphorothioates were more reactive than
the corresponding 1,2-cis anomers. The for-
mer started to react around −40 °C and the
latter above 0 °C. Substrate 1 proved to be the

W. Kudelska / Carbohydrate Research 329 (2000) 687–691
689
nosyl cyanide (10) [2,18,27] (Fig. 1) was ob-
served in 34 and 26% yield, respectively, when
at room temperature the time necessary to
complete the cyanation in dichloromethane
was extended to 25 h. Under these conditions
(dichloromethane, 25 h, room temperature)
the cyanation of 3 yielded only 8(a, b). The
cyanation of 1–5 was also investigated using
acetonitrile as a solvent. Treatment of 1 with
trimethylsilyl cyanide in the presence of boron
trifluoride etherate in acetonitrile for 4 h at
room temperature generated the cyanide 10
and 7(a, b) in 60 and 6% yield, respectively.
There was a marked contrast in the course of
the cyanation between the gluco and galacto
series. Diastereomeric 8(a, b) were the major
products isolated in 58% yield when acetoni-
trile was applied in cyanation of 3 or 4 (72 h
at room temperature). The reaction of 5 with
trimethylsilyl cyanide in the presence of boron
trifluoride etherate in acetonitrile at room
temperature for 25 h yielded the mixture of
and 101.25 MHz, respectively. Solvents were
dried and distilled prior to use. Trimethylsilyl
cyanide 98% and BF3·Et2O were purchased
from Aldrich
Starting materials.—O-Acetylated 1-S-
phosphorothioates 1, 3, 5 were prepared by
the procedure described in Ref. [24] and sub-
strates 2 and 4 by the procedure described in
Ref. [25]. Column chromatography was per-
formed on Silica Gel 60 (E. Merck) (70–230
mesh, ASTM) with 3:1 (v/v) toluene–EtOAc
(Solvent A), benzene (Et2O (Solvent B). Thin-
layer chromatography (TLC) was conducted
on layers (0.2 mm) of Silica Gel 60 F254 pre-
coated on plastic sheets (E. Merck, Cat. No
5748) with 3:1 (v/v) Et2O–petroleum ether.
Components on TLC plates were detected by
spraying 10% (v/v) H2SO4 in CH3OH, and
heating for several minutes at 140 °C.
The reaction of S-glycosyl phosphorothioates
with Me3SiCN in the presence of BF3·Et2O
1
(31P and H NMR low temperature analysis in
CD2Cl2).—To the cooled solution (ꢀ −
70 °C) of 1–4 (0.051 g, 0.1 mmol) or 5 (0.044
g, 0.1 mmol) in 0.5 mL of CD2Cl2 placed in 5
mm NMR tube, Me3SiCN (0.04 mL, 0.3
mmol) and one drop of BF3·Et2O were added
by syringe and the reaction course was fol-
isomeric nitriles: 2,3,4-tri-O-acetyl-b- -xy-
D
lopyranosyl cyanide (11) [16,28] (36% yield)
(Fig. 1) and 9(a, b) (13.3% yield). The quanti-
tative formation of O-trimethylsilyl phospho-
31
rothioate 6 (l P NMR CD2Cl2: ꢀ50.5 ppm)
(Fig. 1) was observed in all the examined
reactions (according to the 31P NMR data).
In summary, depending on the stereochem-
istry of S-glycosyl phosphorothioates em-
ployed, as well as the reaction conditions
either cyanoethylidene derivatives of sugars or
glycosyl cyanides are formed. In comparison
with hitherto described methods, the reaction
conditions described herein are mild, the reac-
tion time is shortened considerably and the
temperature decreased. Thus, this cyanation
reaction provides a useful approach to the
cyanated sugars.
1
lowed by 31P and H NMR spectroscopy at
time intervals and temperatures ranging from
−60 to 25 °C.
General procedure 1. 1,2-O-[(1-(exo)- and
(endo)-cyano)ethylidene]-aldopyranoses [7(a,
b), 8(a, b), 9(a, b)].—To the cooled solution
(−10 °C) of thiophosphate 1 or 3 (0.512 g, 1
mmol) or 5 (0.44 g, 1 mmol) in dry CH2Cl2 (5
mL), Me3SiCN (0.297 g, 0.4 mL, 3 mmol),
,
then 4 A MS and finally BF3·Et2O (0.015 mL,
0.12 mmol) was added. The reaction of sub-
strate 2 or 4: to the solution of 2 or 4 (0.512 g,
1 mmol) in dry CH2Cl2 (5 mL), Me3SiCN (0.4
,
mL, 3 mmol) and 4 A MS and finally
BF3·Et2O (0.015 mL, 0.12 mmol) were added.
The resulting solution was stirred for the time
and temperature indicated in Table 1. The
solution was then filtered (Celite) and washed
with CH2Cl2 (ꢀ30 mL). The organic layer
was washed with satd NaHCO3 (2×15 mL),
water (15 mL), and dried (MgSO4). The sol-
vent was evaporated in vacuo and the syrupy
1. Experimental
General methods.—Melting points were de-
termined with Boetius PHMK 05 apparatus
and are uncorrected. Optical rotations were
determined with the Perkin–Elmer 241 MC
1
13
31
apparatus. H, C and P NMR spectra were
measured in CDCl3 solutions on a Bruker
DPX spectrometer operating at 250.13, 62.9
residue
was
subjected
to
column
chromatography.

690
W. Kudelska / Carbohydrate Research 329 (2000) 687–691
2.03, 2.02 (3s, 9 H, 3×OAc), 1.69 [s,
CH3(CCN)] (in agreement with lit. [1] H
NMR spectrum).
From substrate 4. Isolation of products by
column chromatography (solvent A), 8(a, b),
(0.19 g, 53.2%).
3,4,6-Tri-O-acetyl-1,2-O-[1-(exo- and endo-
cyano)ethylidene]-h- -galactopyranose [7(a,
1
D
b)].—From substrate 1. 13C NMR spectra of
the crude reaction mixture [7(a, b) and 6%
(from 6)]: l 169.9, 169.4, 169.3, 169.1 (CꢀO),
117.2 (CN, endo), 116.4 (CN, exo), 98.6
(CCN, exo), 98.2 (CCN, endo), 96.8 (C1),
72.3, 70.7, 69.4, 65.0, 61.0 (C2-C6, exo), 75.6,
69.6, 69.0, 65.6, 60.7 (C2ꢁC6, endo), 26.5
(C(CN)CH3, endo), 25.5 (C(CN)CH3, exo),
20.9, 20.2, 20.0 (COCH3, exo, endo); 6% (76.3,
76.2, 53.3, 31.9).
3,4-Di-O-acetyl-1,2-O-[(1-exo and endo-
cyano)ethylidene]-h- -xylopyranose 9(a, b).—
D
From substrate 5. 13C NMR of the crude
reaction mixture [9(a, b) and 6% (from 6)]: l
170.4, 169.8, 169.2, 168.9 (CꢀO), 117.7 (CN,
endo), 116.9 (CN, exo), 100.0 (CCN, endo),
99.3 (CCN, exo), 97.4 (C1, endo), 96.9 (C1,
exo), 76.0 (C2, endo), 74.9 (C2, exo), 68.3 (C3,
exo), 67.2 (C4, exo), 66.9 (C3, endo), 66.0 (C4,
endo), 62.0 (C5, endo), 59.7 (C5, exo), 26.9
(C(CN)CH3, endo), 25.1 (C(CN)CH3, exo),
21.6, 21.5, 20.9 (COCH3) (in agreement with
lit. [3] 13C NMR spectrum); 6% (76.9, 76.8,
53.8, 32.5).
Isolation products by column chromatogra-
phy, (solvent B). Total yield 7(a, b) (0.225 g,
63%).
7a (0.1 g, 28%): colourless syrup; [h]D20
+
91.4° (c 1.34, CHCl3), lit. +92.7° (c 1.10,
1
CHCl3) [1,2]; H NMR (selected): l 5.87 (d,
J1,2 5.0 Hz, 1 H, H-1), 2.08, 2.07 (3s, 3×
OAc), 1.86 [s, CH3(CCN)] in agreement with
1
Isolation of products by column chro-
matography (solvent A). Total yield 9(a, b)
(0.214 g, 75%): 9a (0.185 g, 65%), 9(a, b) (0.02
g, 7%), 9b (0.008 g, 3%).
the lit. [1] H NMR spectrum.
1
7(a, b) (0.125 g, 35%). 7b, H NMR (se-
lected): l 5.75 (d, J1,2 4.5 Hz, 1 H, H-1), 2.03,
2.06 (3s, 3×OAc), 1.79 [s, CH3(CCN)] in
9a: colourless syrup, [h]1D8 −22.1° (c 2.4,
1
agreement with the lit. [1] H NMR spectrum.
1
CHCl3), lit. −23.2° (c 1.0, CHCl3) [3]; H
From substrate 2. Isolation of products by
column chromatography (solvent A), 7(a, b)
(0.146 g, 40.9%).
NMR: l 5.66 (d, J1,2 4.5 Hz, 1 H, H-1), 5.26
(t, J2,3 2.75, J3,4 3.0 Hz, 1 H, H-3), 4.89 (m, 1
H, H-4), 4.30 (ddd, J2,3 2.75, J1,2 4.5 Hz, 1 H,
H-2), 3.97 (dd, J4,5% 6.0, J5,5% 12.0 Hz, 1 H,
H-5%), 3.59 (dd, J4,5 8.0, J5,5%=12.0 Hz, 1 H,
H-5), 2.13, 2.09 (2s, 2×OAc), 1.91 [s,
3,4,6-Tri-O-acetyl-1,2-O-[1-(exo- and endo-
cyano)ethylidene]-h- -glucopyranose 8(a, b).—
D
From substrate 3. 13C NMR of the crude
reaction mixture [8(a, b) and 6% (from 6)]: l
170.6, 169.6, 169.1 (CꢀO), 116.6 (CN), 100.1
(CCN, endo), 98.9 (CCN, exo), 98.2 (C1,
endo), 97.5 (C1, exo), 74.2, 70.0, 69.3, 67.4,
62.2 (C2ꢁC6), 24.5 (C(CN)CH3), 21.5, 20.8
(COCH3); 6% (76.9, 76.7, 53.8, 32.5).
1
CH3(CCN)] (in agreement with lit. [3] H
NMR spectrum).
9b: colourless syrup, [h]1D8 +30.9° (c 0.93,
1
CHCl3), lit. +30.4° (c 1.6, CHCl3) [3]. H
NMR: l 5.52 (d, J1,2 3.25 Hz, 1 H, H-1), 5.38
(m, 1 H, H-3), 4.72 (m, 1 H, H-4), 4.10–4.01
(m, 2 H, H-2, H-5%), 3.88 (dd, J4,5 2.5 Hz,
J5,5%=13.0 Hz, 1 H, H-5), 2.16, 2.13 (2s, 2×
OAc), 1.79 [s, CH3(CCN)] (in agreement with
Isolation of products by column chro-
matography (solvent A). Total yield 8(a, b)
(0.209 g, 58.5%).
8a (0.189 g, 52.9%): colourless crystals, mp
76–77 °C, lit. 77–78 °C [1,2,4]; [h]1D8 +14.3°
(c 1.86, CHCl3), lit. +13.6° (c 2.90, CHCl3)
[1,2], lit. +13.8° (c 1.02, CHCl3) [4]; 1H NMR
(selected): l 5.81 (d, J1,2 5.1 Hz, 1 H, H-1),
2.14, 2.10 (2s, 9 H, 3×OAc). 1.92 [s,
CH3(CCN)] in agreement with lit. [1] 1H
NMR spectrum.
1
lit. [3] H NMR spectrum).
General procedure 2. Per-O-acetylaldopyran-
osyl cyanides 10 and 11.—To a stirred solu-
tion of glycosyl phosphorothioate 1 (0.512 g, 1
mmol) or 5 (0.44 g, 1 mmol) in CH3CN (5
,
mL), 4 A MS, Me3SiCN (0.297 g, 0.4 mL, 3
mmol) and BF3·Et2O (0.015 mL, 0.12 mmol)
were added. The mixture was stirred at rt for
time indicated. The reaction mixture was then
1
8(a, b) (0.02 g, 5.6%). 8b: H NMR (sel-
ected): l 5.72 (d, J1,2 5.0 Hz, 1 H, H-1), 2.04,

W. Kudelska / Carbohydrate Research 329 (2000) 687–691
691
Acknowledgements
diluted with EtOAc (50 mL) and filtered
through Celite 535. The filtrate was washed
with satd NaHCO3 (3×40 mL), water (20
mL), dried (MgSO4) and evaporated in vacuo.
The syrupy or semi-crystalline mixture was
subjected to column chromatography (solvent
A or solvent B).
Financial support from the Medical Univer-
sity of Lodz (502-13-438) is gratefully ac-
knowledged. We thank J. Pluskowski for
technical assistance.
1-Deoxy-2,3,4,6-tetra-O-acetyl-i-
pyranosyl cyanide (3,4,5,7-tetra-O-acetyl-2,6-
anhydro - - glycero - - manno - heptononitrile)
(10).—From substrate 1, time 4 h, rt. Isola-
tion of products by column chromatography
(solvent A) gave 7(a, b) (0.022 g, 6.2%) and 10
(0.213 g, 59.7%).
D
-galacto-
References
D
L
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10: colourless crystals, mp 169–170 °C, lit.
169–170 °C [18]; [h]1D8 +34.1° (c 1.33,
CHCl3), lit. +35.7° (c 3.74, CHCl3) [18] lit.
1
+37.8° (c 0.98, CHCl3) [27]; H NMR: l 5.54
(t, J2,3 10.0 Hz, 1 H, H-2), 5.44 (dd, J4,5 1.25,
J3,4 3.5 Hz, 1 H, H-4), 5.00 (dd, J2,3 10.0, J3,4
3.5 Hz, 1 H, H-3), 4.28 (d, J1,2 10.2 Hz, 1 H,
H-1), 4.12 (d, 2 H, H-6, 6%), 3.94 (dt, J5,6=J5,6%
6.5 Hz, 1 H, H-5), 2.19, 2.12, 2.06, 2.00 (4s, 12
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SSSR, Ser. Khim., 11 (1977) 2574–2578.
1
H, 4(OAc) (in agreement with the lit. [18] H
NMR spectrum). 13C NMR: l 170.2, 169.8,
169.7, 168.7 (CꢀO), 114.3 (CN), 75.2 (C5),
70.6 (C3), 66.7 (C4), 66.5 (C2), 65.9 (C1), 61.1
(C6), 20.4-20.3 (COCH3) in agreement with
the lit. [18] 13C NMR spectrum.
[10] L.V. Backinovsky, N.E. Nifant’ev, A.S. Shashkov, N.K.
Kochetkov, Bioorg. Khim., 10 (9) (1984) 1212–1228.
[11] A.F. Bochkov, I.V. Obruchnikov, V.N. Kalinevich, N.K.
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From substrate 2. Time 25 h, rt. Isolation
of products by column chromatography (sol-
vent A) gave 7(a, b) (0.01 g, 2.8%) and 10
(0.153 g, 42.8%).
1-Deoxy-2,3,4-tri-O-acetyl-i-
osyl cyanide (3,4,5-tri-O-acetyl-2,6-anhydro-
-gulononitrile (11).—From substrate 5, time
D
-xylopyran-
D
25 h, rt. Isolation of products by column
chromatography (solvent A). Total yield 9(a,
b) and 11 (0.165 g, 57.9%): 9(a, b) (0.038 g,
13.3%), 9(a, b) and 11 (0.025 g, 8.8%), 11
(0.102 g, 35.8%).
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1280.
11: colourless crystals, mp 130–131 °C, lit.
132–133 °C [28]; [h]1D8 −57.1° (c 1.0, CHCl3),
1
lit. −57.9° (c 0.8, CHCl3) [28]; H NMR: l
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5.2–5.0 (m, 2 H, H-3, H-4), 4.92 (m, J5,6 3.9,
J5,6% 6.7 Hz, 1 H, H-5), 4.50 (d, J1,2 6.7 Hz, 1
H, H-2), 4.24 (dd, J5,6 3.9, J6,6% 12.5 Hz, 1 H,
H-6), 3.60 (dd, J5,6 6.65, J6,6% 12.5 Hz, 1 H,
H-6%), 2.12, 2.11, 2.08 (3s, 3×OAc) (in agree-
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149.
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922–926.
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1
ment with lit. [28] H NMR spectrum).