The preparation of 1-tributylstannyl glycals from 1-phenylsulfonyl glycals via Ni(0)-catalysed coupling with tributylstannylmagnesium bromide

Article abstract of DOI:10.1055/s-2001-10802

1-Phenylsulfonyl glycals undergo an easy Ni(0)-catalysed coupling with tributylstannylmagnesium bromide to give the corresponding 1-tributylstannyl glycals in good yield.

Full text of DOI:10.1055/s-2001-10802

SPECIAL TOPIC
331
The Preparation of 1-Tributylstannyl Glycals from 1-Phenylsulfonyl Glycals
via Ni(0)-Catalysed Coupling with Tributylstannylmagnesium Bromide
Andrew Gunn,a Krzysztof Jarowicki,a Philip Kocienski,*a Stephen Lockhartb
aDepartment of Chemistry, Leeds University, Leeds, LS2 9JT, UK
bDepartment of Chemistry, Glasgow University, Glasgow G12 8Q, UK
Received 7 November 2000
Dedicated to Professor Jean-François Normant on the occasion of his 65th birthday
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TIPSO
OTIPS
Abstract: 1-Phenylsulfonyl glycals undergo an easy Ni(0)-cata-
lysed coupling with tributylstannylmagnesium bromide to give the
corresponding 1-tributylstannyl glycals in good yield.
O
Key words: nickel, catalysis, coupling, sulfones, stannanes, gly-
cals, carbohydrates
1
t-BuLi (4.0 equiv.)
THF, –78 to 0 °C, 1.5 h
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The easy interconversion of 1-tributylstannyl glycals such
as 3 with their corresponding lithium derivatives 2
(Scheme 1) makes them valuable precursors for C-gly-
cosidation reactions.1,2 For example, 1-tributylstannyl
glycals undergo Pd-catalysed coupling with aryl or alke-
nyl halides3-10 whilst the lithium derivatives participate in
nucleophilic addition and substitution reactions1,2,11-15 il-
lustrated here by the formation of 4 and 5. Unfortunately,
the conditions typically used to metallate 3,4-dihydro-2H-
pyrans (t-BuLi/THF, -78 °C to -20 °C) are limited to a
narrow range of carbohydrate-derived substrates because
(a) the presence of polar oxygen substituents frequently
require excess t-BuLi for complete metallation, as in the
conversion of 1 to 2 and (b) convenient and common pro-
tecting groups such as benzyl ethers and tert-butyldimeth-
ylsilyl (TBS) groups are metallated under the strongly
basic conditions.1,16-19 The only general and mild method6
reported to date for the synthesis of 1-tributylstannyl gly-
cals from carbohydrate precursors entails substitution of
1-phenylsulfonyl glycals by tributylstannyl radicals illus-
trated by the conversion of 6 to 7 (Scheme 2). The method
is attractive because the sulfone 6 is readily available in
good yield and the radical substitution reaction occurs un-
der neutral conditions albeit at elevated temperature.
However, in our hands, the radical substitution frequently
requires up to 10 equivalents of tributylstannane, and even
then unreacted sulfone remains. We now report an effi-
cient and easy synthesis of 1-tributylstannyl glycals which
is based on the Ni(0)-catalysed coupling of tributylstan-
nylmagnesium bromide with 1-phenylsulfonyl glycals.
Bu3SnCl (2.5 equiv.)
–78 to 0 °C, 45 min
O
O
65% from 1
Li
SnBu3
85%
BuLi (1.0 equiv.)
2
3
THF, –78 °C, 10 min
ArBr, Pd(0)
PhH, ∆, 15 h
ROTf (1.0 equiv.)
–78 to 0 °C
41% from 3
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O
O
BnO
BnO
OAc
O
O
O
OBn
4
5
Scheme 1
Br was prepared by addition of MgBr2∑OEt2 to Bu3SnLi.21
In a separate flask, DIBALH (0.2 equivalent) was added
to a suspension of Ni(acac)2 (0.1 equivalent) and Ph3P
(0.2 equivalent) at 0-5 °C. The resultant brown solution
of the Ni(0) catalyst22 was added to Bu3SnMgBr∑LiBr at
-78 °C and after 5 minutes, the sulfone 6 was added. The
dark mixture was allowed to warm gradually to room tem-
perature overnight whereupon a standard extractive work-
up and chromatographic purification returned the desired
stannane 7.
A large scale synthesis of 1-tributylstannyl-D-xylal 12
(Scheme 3) demonstrates the ready accessibility of the
1-phenylsulfonyl glycals using the Beau protocol6 and the
practicality of the Ni(0)-catalysed coupling. Thus, 1-phe-
nylthio-D-xylopyranoside (8) was silylated using TBSCl
and imidazole in DMF but the reaction did not go to com-
pletion, even with a large excess of TBSCl at elevated
temperature; hence, a second silylation using TBSOTf
and Hünig's base was required to complete the silylation
(98% yield). Oxidation of the thioether 9 with m-chloro-
Our method was inspired by a report that alkenyl sulfones
undergo Ni(0)-catalysed substitution by Grignard re-
agents devoid of b-hydrogens.20 We reasoned that tribu-
tylstannylmagnesium bromide, easily prepared from
hexabutyldistannane in two steps, should undergo an anal-
ogous coupling with 1-phenylsulfonyl glycals. To test our
idea, we converted sulfone 6 to stannane 7 in 91% yield
(1 mmol scale) with no recovered starting material. The
experimental procedure is very easy: the Bu3SnMgBr∑Li-
Synthesis 2001, No. 2, 331–338 ISSN 0039-7881 © Thieme Stuttgart · New York

332
A. Gunn et al.
SPECIAL TOPIC
Ph
O
Ph
O
O
O
R
O
OTBS
O
O
O
O
Bu3SnH (3.0 equiv.)
AIBN (0.05 equiv.)
TBSO
TBSO
TBSO
TBSO
TBSO
H
O
O
O
R
O
PhMe, ∆, 3 h
71% (+21% recovered SM)
R
SO2Ph
SnBu3
ex D-mannose
ex D-galactose
ex L-rhamnose
6
7
Bu3SnMgBr•LiBr (2 equiv.)
Ni(acac)2 (0.1 equiv), PPh3 (0.2 equiv.)
R = SO2Ph
R = SnBu3
R = SO2Ph
R = SO2Ph
17
18
13
14
15
16
87%
68%
97%
R = SnBu3
R = SnBu3
DIBALH (0.2 equiv.)
THF–Et2O, –78 to 20 °C, 12 h
91%
Scheme 4
Scheme 2
fers new opportunities for C-glycosidation and
transmetallation reactions of the glycals derived from the
common monosaccharides glucose, xylose, galactose,
mannose and rhamnose.
peroxybenzoic acid (MCPBA) gave the sulfone 10 (80%)
which then underwent elimination on treatment with
MeLi to give the desired 1-phenylsulfonyl xylal 11 (89%).
Finally, the Ni(0) catalysed coupling of 11 with
Bu3SnMgBr•LiBr as described above gave the stannane
12 in 82% yield on a 17.5 mmol scale (57% overall).
Et2O and THF were freshly distilled from sodium benzophenone
ketyl under N2 prior to use. CH2Cl2 and toluene were freshly dis-
tilled from CaH2 under N2. DMF was distilled from CaH2 under re-
duced pressure (approx. 10 mmHg). MeOH was freshly distilled
from magnesium methoxide under N2 prior to use. Alumina refers
to activated neutral alumina, purchased from Acros and was deacti-
vated with 5% H2O. Flash chromatography was performed on Fish-
er Scientific ’Matrex Silica 60’ silica gel (35-70 micron particle
size). Specific optical rotations were measured at ambient tempera-
ture (21 3 °C) on an Optical Activity Polaar 2000 polarimeter using
a 5 mL cell with a 1 dm path length. IR spectra were recorded on a
Jasco 410 FT-IR spectrometer using a thin film supported between
NaCl plates, a KBr disk or a solution cell. 1H and 13C NMR spectra
were recorded in Fourier Transform mode on a Bruker DPX 400
spectrometer. All spectra were obtained in CDCl3 or C6D6 in 5 mm
diameter tubes, and the chemical shift (ppm) is quoted relative to the
residual signals of CDCl3 (dH = 7.27 ppm) or C6D6 (dH = 7.4 ppm).
In case of 13C NMR spectra, the chemical shift (ppm) is quoted
relative to the middle signal of CDCl3 (dC = 77.2 ppm) or C6D6
(dC = 128.7 ppm). Multiplicities in 1H NMR spectra are quoted as:
s = singlet, d = doublet, t = triplet, q = quartet, m = multiplet,
br = broad. Coupling constants (J) are reported in Hz. Numbers in
parenthesis following the chemical shift in the 13C spectra refer to
the number of protons attached to the carbon as disclosed by the
Distortionless Enhancement by Phase Transfer (DEPT) technique,
with secondary pulses at 90° and 135°. Signal assignments are
based on COSY, HMQC and HMBC correlations. Low and high
resolution mass spectra were run on a JEOL MStation JMS-700
spectrometer.
OH
TBSO
TBSCl, imidazole
DMF, rt, 3 d
(a)
(b)
HO
HO
TBSO
O
O
TBSOTf, EtN(i-Pr)2
CH2Cl2, rt, 12 h
98% (100 mmol scale)
TBSO
SPh
SPh
9
8
MCPBA (2.1 equiv.), NaHCO3 (7.5 equiv.)
CH2Cl2, 0 °C → rt, 12 h
80% (98 mmol scale)
TBSO
TBSO
TBSO
TBSO
MeLi (1.5 equiv.)
O
O
THF, –78 °C, 20 min
89% (20 mmol scale)
TBSO
SO2Ph
SO2Ph
11
10
Bu3SnMgBr•LiBr (2 equiv.), Ni(0) (0.1 equiv.), PPh3 (0.2 equiv.)
THF–Et2O, –78 → 20 °C, 12 h
82% (17.5 mmol scale)
TBSO
TBSO
O
SnBu3
12
1,5-Anhydro-4,6-O-benzylidene-3-O-tert-butyldimethylsilyl-2-
deoxy-1-tributylstannyl-D-arabino-hex-1-enitol (7) (Scheme 2)
To a magnetically stirred solution of hexabutyldistannane (1.16 g,
1.01 mL, 2 mmol) in THF (10 mL), was added dropwise n-BuLi
(0.87 mL, 2.30 M in hexanes, 2 mmol) at a rate sufficient to main-
tain the internal temperature below 5 °C. After the addition was
complete, the yellow solution containing Bu3SnLi was stirred at
0-5 °C for 30 min whereupon a heterogeneous mixture of
MgBr2∑Et2O in Et2O (10 mL), prepared from 1,2-dibromoethane
(0.376 g, 0.17 mL, 2 mmol) and Mg (0.058 g, 2.4 mmol), was added
by cannula and the yellow suspension stirred at 0-5 °C for 5 min.
Scheme 3
In order to further probe the scope and generality of our
method (Scheme 4), we prepared the 1-phenylsulfonyl
glycals 13 (from D-galactose), 15 (from L-rhamnose) and
17 (from D-mannose) and converted them to the corre-
sponding stannanes 14, 16 and 18 in 87%, 97% and 68%
yields, respectively. The lower yield of the furanoid stan-
nane 18 reflects its high lability.
In a separate flask, a solution of DIBALH (0.13 mL, 1.5 M in tolu-
ene, 0.2 mmol) was added dropwise to a mixture of Ni(acac)2
(0.026 g, 0.1 mmol) and Ph3P (0.052 g, 0.2 mmol) in toluene (2.3
mL), at 0-5 °C. The dark brown mixture was stirred at r.t. for
15 min and then transferred by cannula, with the aid of a further
1 mL of Et2O, to the previously prepared Bu3SnMgBr∑LiBr, cooled
In conclusion, we have devised a simple, practical and ef-
ficient synthesis of 1-tributylstannyl glycals from readily
available 1-phenylsulfonyl glycals using a Ni(0)-cataly-
sed coupling with Bu3SnMgBr•LiBr. Our procedure of-
Synthesis 2001, No. 2, 331–338 ISSN 0039-7881 © Thieme Stuttgart · New York

SPECIAL TOPIC
The Preparation of 1-Tributylstannyl Glycals from 1-Phenylsulfonyl Glycals
333
to -78 °C. The brown mixture was stirred at -78 °C for 5 min and
then a solution of the sulfone 6 (0.489 g, 1 mmol) in THF (5 mL)
was added by cannula with the aid of a further 1 mL of THF. The
brown mixture was allowed to warm gradually to r.t. overnight, then
poured into rapidly stirred H2O (100 mL) and extracted with Et2O
(2 ¥ 50 mL). Filtration through Celite was necessary to separate the
layers. The combined organic layers were treated with Et3N (1 mL),
dried (Na2SO4), and concentrated in vacuo. The residue was puri-
fied by column chromatography on SiO2 (hexanes/Et2O containing
0.5% of Et3N) to give stannane 7 (0.580 g, 0.91 mmol, 91%) as a
colourless oil: [a]D -32.1° (c 1.6, CHCl3); Lit.6 [a]D -32° (c 1.6,
CHCl3).
13C NMR (100 MHz, CDCl3): d = 163.3 (0, C1), 137.9 (0, Ph),
128.9 (1, Ph), 128.3 (1, 2C, Ph), 126.2 (1, 2C, Ph), 116.2 (1, C2),
101.3 (1), 81.1 (1), 69.2 (1), 68.9 (2, C6), 68.4 (1), 29.1 (2, 3C,
C4H9Sn, JSn-C 21.4), 27.3 (2, 3C, C4H9Sn, JSn-C 54.4), 26.0 (3, 3C, t-
Bu), 18.5 (0, CSi), 13.9 (3, 3C, C4H9Sn), 9.9 (2, 3C, C4H9Sn, JSn-C
347.9, 332.3), -4.1 (3, CH3Si), -4.5 (3, CH3Si).
(150 mL) to yield sulfone 10 as white cubic crystals (48.6 g, 78.7
mmol, 80%), mp: 99-100 °C; [a]D -73.1° (c 0.9, CHCl3).
IR (KBr): n = 2929, 2858, 1576, 1328, 1252, 1140 cm-1.
1H NMR (400 MHz, CDCl3): d = 7.94-7.89 (m, 2H, Ph), 7.64-7.58
(m, 1H, Ph), 7.56-7.50 (m, 2H, Ph), 4.76 (d, 1H, J = 10.2 Hz), 4.64
(s, 1H, H1), 4.49 (s, 1H), 3.80-3.77 (m, 1H), 3.66-3.58 (m, 2H),
0.96, 0.91, 0.89 ( 3 ¥ s, 9H each, t-Bu), 0.18, 0.17, 0.15, 0.12, 0.08,
0.07 ( 6 ¥ s, 3H each, CH3Si).
13C NMR (100 MHz, CDCl3): d = 139.6 (0, Ph), 133.5 (1, Ph), 129.1
(2, 2C, Ph), 128.8 (2, 2C, Ph), 94.3 (1, C1), 70.8 (1), 68.9 (1), 66.7
(1), 64.6 (2, C5), 26.2 (3, 3C, t-Bu), 26.1 (3, 3C, t-Bu), 25.8 (3, 3C,
t-Bu), 18.4 (0, CSi), 18.3 (0, CSi), 18.1 (0, CSi), -4.3 (3, CH3Si),
-4.4 (3, CH3Si), -4.5 (3, CH3Si), -4.5 (3, CH3Si), -4.6 (3, CH3Si),
-4.7 (3, CH3Si).
HRMS (FAB+mode): m/z calcd for C29H56O6SSi3Na (M+Na)+:
639.3003. Found: 639.3010.
1,5-Anhydro-3,4-bis-O-(tert-butyldimethylsilyl)-2-deoxy-1-phe-
nylsulfonyl-D-threo-pent-1-enitol (11)
Stannane 12 (Scheme 3)
Phenyl 2,3,4-Tris-O-(tert-butyldimethylsilyl)-1-thio-b-D-xylopy-
ranoside (9)
To a solution of sulfone 10 (12.4 g, 20.0 mmol) in anhyd THF
(200 mL), at -78 °C, was added MeLi∑LiBr (20.0 mL, 1.5 M,
30.0 mmol) dropwise and the yellow solution stirred at -78 ºC
for 20 min. The reaction mixture was then poured into a mixture of
sat. sodium bicarbonate (550 mL) and Et2O (100 mL). The organic
layer was separated and the aqueous layer extracted with CH2Cl2
(100 mL). The combined organic extracts were dried (Na2SO4) and
concentrated in vacuo to give a white solid. The crude product was
recrystallised from hexanes (60 mL) to give unsaturated sulfone
11 as white crystals (8.6 g, 17.7 mmol, 89%), mp: 111-112 °C: [a]D
-93.8° (c = 1.0, CHCl3).
To a solution of phenyl 1-thio-b-D-xylopyranoside23 (8) (24.23 g,
100 mmol) in DMF (280 mL) were added imidazole (51.10 g,
750 mmol) and TBSCl (54.30 g, 360 mmol). After 3 days at r.t., the
mixture was poured into H2O (1.4 L) and extracted with Et2O.
The organic layer was washed with H2O, dried (Na2SO4) and con-
centrated in vacuo. The colourless residue (61 g) was purified by
column chromatography (SiO2, hexanes/Et2O, 20:1) to yield a mix-
ture of di- and tri-protected compounds as a clear oil (51 g). The
mixture was dissolved in anhyd CH2Cl2 (200 mL). i-Pr2NEt
(40.5 mL, 231.1 mmol) was added followed by TBSOTf (dropwise)
(31.9 mL, 139.0 mmol). After 12 h at r.t., the reaction was washed
with 5% HCl (2 ¥ 260 mL) then H2O (2 ¥ 260 mL), and the aqueous
layers extracted with CH2Cl2. The organic extracts were dried
(Na2SO4). The solvent was evaporated in vacuo to give a red oil,
which was purified by column chromatography (SiO2, hexanes/
Et2O, 50:1 to 10:1) to give 9 as a colourless oil (57.2 g, 98 mmol,
98%, 2 steps): [a]D -70.5° (c 1, CHCl3).
IR (KBr): n = 2956, 2928, 2896, 2856, 1645, 1327, 1254, 1117,
1077 cm-1.
1H NMR (400 MHz, CDCl3): d = 7.95-7.90 (m, 2H, Ph), 7.64-7.58
(m, 1H, Ph), 7.54-7.48 (m, 2H, Ph), 6.06 (dd, 1H, J = 5.2, 1.2 Hz,
H2), 4.03 (dd, 1H, J = 11.2, 1.5 Hz, H5), 4.00 (ddd, 1H, J = 11.3,
3.0, 1.2 Hz, H5), 3.97-3.92 (m, 1H, H3), 3.65 (quintet, 1H, J = 1.4
Hz, H4), 0.88, 0.70 (2 ¥ s, 9H each, t-Bu), 0.12, 0.11, 0.00, -0.06
(4 ¥ s, 3H each, CH3Si).
13C NMR (100 MHz, CDCl3): d = 153.0 (0, C1), 138.6 (0, Ph),
133.8 (1, Ph), 129.2 (2, 2C, Ph), 128.6 (2, 2C, Ph), 107.0 (1, C2),
68.7 (2, C5), 68.3 (1, C4), 65.1 (1, C3), 25.9 (9, 3C, t-Bu), 25.6 (9,
3C, t-Bu), 18.1 (0, CSi), 17.9 (0, CSi), -4.2 (3, CH3Si), -4.5 (3,
CH3Si), -4.7 (3, CH3Si), -4.8 (3, CH3Si).
IR (film): n = 2929, 2857, 1133 cm-1.
1H NMR(400 MHz, CDCl3): d = 7.51-7.46 (m, 2H, Ph), 7.31-7.23
(m, 2H, Ph), 7.23-7.15 (m, 1H, Ph), 5.36 (apparent s, 1H), 4.58 (d,
1H, J = 10.8 Hz, H-5), 3.86 (apparent s, 1H), 3.71 (apparent s, 1H),
3.57 (d, 1H, J = 11.9 Hz, H-5), 3.55 (apparent s, 1H), 0.99, 0.94,
0.92 (3 ¥ s, 9H each, t-Bu), 0.16, 0.13, 0.10 (3 ¥ s, 3H each, CH3Si),
0.11 (s, 9H, CH3Si).
+
MS (CI, NH3): m/z (%) = 502 (MNH4 , 100).
13C NMR (100 MHz, CDCl3): d = 138.0 (0, Ph), 130.5 (1, 2C, Ph),
128.9 (1, 2C, Ph), 126.5 (1, Ph), 88.7 (1, C1), 73.3 (1), 71.3 (1), 69.9
(1), 61.4 (2, C5), 26.3 (9, 3C, t-Bu), 26.3 (9, 3C, t-Bu), 25.9 (9, 3C,
t-Bu), 18.6 (0, CSi), 18.5 (0, CSi), 18.1 (0, CSi), -4.3 (3, CH3Si),
-4.4 (3, CH3Si), -4.5 (3, 2C, CH3Si), -4.5 (3, CH3Si), -4.6 (3,
CH3Si).
Anal. Calcd for C23H40O5Si2S: C, 56.98; H, 8.32. Found: C, 57.07;
H, 8.31.
1,5-Anhydro-3,4-bis-O-(tert-butyldimethylsilyl)-2-deoxy-1-
tributylstannyl-D-threo-pent-1-enitol (12)
Stannane 12 (9.06 g, 14.35 mmol, 82%) prepared from sulfone
11 (8.5 g, 17.5 mmol), using the procedure described above for
the preparation of stannane 7, was obtained as a colourless oil: [a]D
-83.7° (c 1, n-hexane).
HRMS (FAB+mode): m/z calcd for C29H56O4SSi3Na (M+Na)+:
607.3105. Found: 607.3099.
IR (film): n = 2956, 2929, 2857, 1600, 1112, 1092 cm-1.
2,3,4-Tris-O-(tert-butyldimethylsilyl)-b-D-xylopyranosylPhenyl
Sulfone (10)
1H NMR (400 MHz, C6D6): d = 5.30 (dd, 1H, J = 3.8, 1.0 Hz, JSn-
H = 27.7 Hz, H2), 4.33 (dt, 1H, J = 1.1, 4.1 Hz, H3), 4.28 (dd, 1H,
J = 10.7, 2.3 Hz, H5), 4.13-4.07 (m, 1H, H4), 4.04 (ddd, 1H,
J = 10.7, 6.0, 1.2 Hz, H5), 2.05-1.01 (m, 27H, C4H9Sn), 1.26, 1.21
(2 ¥ s, 9H each, t-Bu), 0.42, 0.41, 0.33, 0.27 (4 ¥ s, 3H each, CH3Si).
13C NMR (100 MHz, C6D6): d = 165.5 (0, C1), 114.6 (1, C2), 71.3
(1, C4), 68.7 (1, C3), 68.2 (2, C5), 30.1 (2, 3C, JSn-C 21.4, C4H9Sn),
28.3 (2, 3C, JSn-C 55.4, C4H9Sn), 26.8 (3, 3C, t-Bu), 26.7 (3, 3C,
Thioglycoside 9 (57.23 g, 97.9 mmol) was dissolved in CH2Cl2
(1500 mL) and the solution cooled in an ice-bath. Sodium bicarbon-
ate (61.3 g, 730 mmol) was added followed by 50% MCPBA was
(71.4 g, 206 mmol). The reaction mixture was allowed to warm to
r.t. overnight. The solution was then washed with sat. sodium sulfite
(2 ¥ 1.25 L), then sat. sodium sulfite/bicarbonate (1:1, 2 ¥ 1.25 L).
The organic layer was dried (Na2SO4) and the solvent evaporated in
vacuo to give a white solid which was recrystallised from EtOH
Synthesis 2001, No. 2, 331–338 ISSN 0039-7881 © Thieme Stuttgart · New York

334
A. Gunn et al.
SPECIAL TOPIC
t-Bu), 19.0 (0, CSi), 18.9 (0, CSi), 14.6 (3, 3C, C4H9Sn), 10.6 (2,
3C, JSn-C 345.1, 329.5, C4H9Sn), -3.2 (3, CH3Si), -3.4 (3, CH3Si),
-3.7 (3, CH3Si), -3.9 (3, CH3Si).
HRMS (CI): m/z calcd for C29H63O3Si2120Sn (M+H)+: 635.3338.
IR (film): n = 2956, 2928, 2856, 1576, 1463, 1378, 1369, 1254,
1212, 1098, 1065 cm-1.
1H NMR (400 MHz; C6D6): d = 5.61 (d, 1H, J = 2.6 Hz, JSn-H = 10.1
Hz, H2), 5.00 (dd, 1H, J = 6.7, 2.5 Hz, H3), 4.91 (dt, 1H, J = 5.9,
6.4 Hz, H5), 4.56 (t, 1H, J = 6.3 Hz, H4), 4.50 (d, 2H, J = 6.5 Hz,
H6), 1.98-1.16 (m, 27H, C4H9Sn), 1.77, 1.63 (2 ¥ s, 3H each), 1.19
(s, 9H, t-Bu), 0.32, 0.31 (2 ¥ s, 3H each, Me2Si).
Found: 635.3328
Stannanes 14, 16 and 18 (Scheme 4)
13C NMR (100 MHz, C6D6): d = 169.0 (0, C1), 117.6 (1, C2), 109.5
(0), 86.9 (1, C4), 74.8 (1, C3), 74.4 (1, C4), 67.6 (2, C6), 30.0 (2,
3C, JSn-C 21.9, C4H9Sn), 28.2 (2, 3C, JSn-C 55.7, C4H9Sn), 27.7 (3),
26.7 (3, 3C, t-Bu), 26.4 (3), 10.8 (2, 3C, JSn-C 353.9, 338.3, C4H9Sn),
14.6 (3, 3C, C4H9Sn), -3.6 (3, CH3Si), -4.1 (3, CH3Si).
Stannanes 14, 16 and 18 were prepared on a 1 mmol scale using the
procedure described above for the preparation of stannane 7. All
stannanes decomposed gradually on storage at ≥ 0 °C but their life-
time could be increased to months by storage in the freezer (approx.
-10 °C) with a few drops of Et3N per mmol.
HRMS (CI, isobutane): m/z calcd for C27H55O4Si120Sn (M+H)+:
591.2897. Found: 591.2897.
2,6-Anhydro-4-O-(tert-butyldimethylsilyl)-5-deoxy-1,3-O-iso-
propylidene-6-tributylstannyl-D-arabino-hex-5-enitol (14)
Stannane 14 was obtained in 87% yield as a colourless oil: [a]D
-8.8° (c 1.04, CHCl3).
Unsaturated Sulfone 6 (Scheme 5).
IR (film): n = 2955, 2927, 2855, 1609, 1463, 1378, 1338, 1252,
Ph
1187, 1142, 1071 cm-1.
Ph
O
1H NMR (400 MHz, CDCl3): d = 4.66 (t, 1H, J = 1.7 Hz,
JSn-H = 28.6 Hz, H5), 4.59 (ddd, 1H, J = 4.7, 1.6, 0.8 Hz, H4), 4.06
(ddd, 1H, J = 4.7, 1.7, 1.5 Hz, H3), 3.98 (dd, 1H, J = 12.5, 1.9 Hz,
H1), 3.92 (dd, 1H, J = 12.5, 2.0 Hz, H1), 3.68 (br s, 1H, H2), 1.60-
0.86 (m, 27H, C4H9Sn), 1.48 (s, 3H, CH3C), 1.46 (s, 3H, CH3C),
0.92 (s, 9H, t-Bu), 0.12, 0.11 (2 ¥ s, 3H each, CH3Si).
O
O
O
O
TBSOTf (1.8 equiv.)
EtN(i-Pr)2 (3.6 equiv.)
TBSO
HO
TBSO
TBSO
CH2Cl2, rt, 12 h
72%
O
SPh
SPh
19
20
13C NMR (100 MHz, CDCl3): d = 163.2 (0, C6), 112.5 (1, C5), 98.9
(0), 68.4 (1, C2), 66.2 (1, C3), 65.5 (1, C4), 63.9 (2, C1), 29.5 (3),
29.1 (2, 3C, JSn-C 20.6, C4H9Sn), 27.4 (2, 3C, JSn-C 56.4, C4H9Sn),
26.2 (3, 3C, t-Bu), 19.1 (3), 18.7 (0, CSi), 13.9 (3, 3C, C4H9Sn), 9.8
(2, 3C, JSn-C 347.1, 331.5, C4H9Sn), -3.9 (3, CH3Si), -4.0 (3,
CH3Si).
MCPBA (2.5 equiv.)
NaHCO3 (12.5 equiv.)
CH2Cl2, rt, 12 h
83%
Ph
Ph
O
O
O
O
MeLi (1.5 equiv.)
TBSO
TBSO
TBSO
HRMS (CI, isobutane): m/z calcd for C27H55O4Si120Sn (M+H)+:
591.2897. Found: 591.2899
THF, –78 °C, 20 min
O
O
88%
SO2Ph
PhO2S
1,5-Anhydro-3,4-bis-O-(tert-butyldimethylsilyl)-2,6-dideoxy-1-
tributylstannyl-L-arabino-Hex-1-enitol (16)
21
6
Stannane 16 was obtained in 97% yield as a colourless oil:
[a]D+38.2° (c 1.03, CHCl3).
Scheme 5
IR (film): n = 2956, 2929, 2857, 1607, 1462, 1377, 1361, 1255,
1112, 1072, 1048 cm-1.
Phenyl 2,3-Bis-(O-tert-butyldimethylsilyl)-4,6-O-benzylidene-1-
thio-b-D-glucopyranoside (20)
1H NMR (400 MHz, CDCl3): d = 4.68 (d, 1H, J = 2.7 Hz, JSn-
H = 27.7 Hz, H2), 4.11 (dd, 1H, J = 2.8, 5.7 Hz, H3), 3.74 (dq, 1H,
J = 7.4, 6.6 Hz, H5), 3.49 (dd, 1H, J = 5.8, 7.8 Hz, H4), 1.62-0.87
(m, 27H, C4H9Sn), 1.26 (d, 3H, J = 6.6 Hz, H6), 0.92, 0.90 (2 ¥ s,
9H each, t-Bu), 0.11 (s, 3H, CH3Si), 0.11 (s, 3H, CH3Si), 0.10 (s,
3H, CH3Si), 0.09 (s, 3H, CH3Si).
13C NMR (100 MHz, CDCl3): d = 162.8 (0, C1), 114.7 (1, C2), 75.7
(1, 2C, C4,C5), 71.4 (1, C3), 29.1 (2, 3C, JSn-C 21.1, C4H9Sn), 27.4
(2, 3C, JSn-C 55.4, C4H9Sn), 26.4 (3, 3C, t-Bu), 26.2 (3, 3C, t-Bu),
18.5 (0, CSi), 18.2 (0, CSi), 18.0 (3, C6), 13.9 (3, 3C, C4H9Sn), 9.8
(2, 3C, JSn-C 344.1, 330.9, C4H9Sn), -3.2 (3, CH3Si), -3.3 (3,
CH3Si), -3.8 (3, CH3Si), -4.0 (3, CH3Si).
To a solution of alcohol 196 (3.62 g, 7.6 mmol) and i-Pr2NEt
(3.53 g, 4.7 mL, 27.36 mmol) in CH2Cl2 (76 mL) was added drop-
wise at 0 °C TBSOTf (3.61 g, 3.1 mL, 13.68 mmol). The solution
was stirred at r.t. overnight, poured into H2O, the organic layer sep-
arated, and the aqueous layer extracted with CH2Cl2 (50 mL). The
combined organic extracts were dried (Na2SO4) and concentrated
in vacuo. The residue was purified by column chromatography
(SiO2, hexanes/Et2O, 20:1 to 2:1) to give thioglycoside 20 (3.22 g,
5.47 mmol, 72%) as a white solid, mp: 63-64 °C (90% EtOH/H2O);
[a]D -70.8° (c 1, CHCl3).
IR (CCl4): n = 2955, 2930, 2857, 1471, 1381, 1251, 1217 cm-1.
HRMS (CI, isobutane): m/z calcd for C30H65O3Si2120Sn (M+H)+:
649.3499. Found: 649.3495
1H NMR (400 MHz, CDCl3): d = 7.52-7.42 (m, 4H, Ph), 7.40-7.24
(m, 6H, Ph), 5.46 (s, 1H, CHPh), 4.89 (d, 1H, J = 7.3 Hz, H1), 4.33
(dd, 1H, J = 10.3, 4.6 Hz, H6), 3.87 (dd, 1H, J = 8.2, 5.7 Hz, H3),
3.78-3.69 (m, 3H, H6, H2, H4), 3.66 (dt, 1H, J = 4.4, 9.6 Hz, H5),
0.95, 0.84 (2 ¥ s, 9H each), 0.22, 0.15, 0.05, 0.03 (4 ¥ s, 3H each).
13C NMR (100 MHz, CDCl3): d = 137.4 (0, Ph), 135.2 (0, Ph), 131.4
(1, 2C, Ph), 129.3 (1, Ph), 129.1 (1, 2C, Ph), 128.3 (1, 2C, Ph), 127.5
(1, Ph), 126.7 (1, 2C, Ph), 102.4 (1), 89.7 (1, C1), 81.7 (1, C4), 77.3
(1, C3), 76.3 (1, C2), 69.4 (2, C6), 68.7 (1, C5), 26.4 (3, 3C, t-Bu),
26.4 (3, 3C, t-Bu), 18.6 (0, C-Si), 18.4 (0, C-Si), -2.6 (3, CH3Si),
-2.8 (3, CH3Si), -3.2 (3, CH3Si), -3.2 (3, CH3Si).
1,4-Anhydro-3-O-(tert-butyldimethylsilyl)-2-deoxy-5,6-O-iso-
propylidene-1-tributylstannyl-D-arabino-hex-1-enitol (18)
Stannane 18 was obtained in 68% yield as a colourless oil by a slight
modification of the procedure used for the preparation of stannane
7. The high lability of 18 required Al2O3 deactivated with 5% H2O
and a mixture of hexanes/Et2O, 50:1 to 10:1 containing 0.5% of
Et3N for the chromatography.
[a]D -30.9° (c 1.15, CHCl3).
Synthesis 2001, No. 2, 331–338 ISSN 0039-7881 © Thieme Stuttgart · New York

SPECIAL TOPIC
The Preparation of 1-Tributylstannyl Glycals from 1-Phenylsulfonyl Glycals
335
+
MS (CI, NH3): m/z (%) = 589 (M+H+, 6), 606 (MNH4 , 7).
Anal. Calcd for C31H48O5SSi2: C, 63.22; H, 8.21. Found: C, 63.10;
H, 8.35.
O
O
O
O
MCPBA (2.5 equiv.)
NaHCO3 (12.5 equiv.)
O
O
O
O
O
O
2,3-Di-O-(tert-butyldimethylsilyl)-4,6-O-benzylidene-b-D-glu-
copyranosyl Phenyl Sulfone (21)
CH2Cl2, rt, 12 h
92%
SO2Ph
SPh
22
To a solution of 1-thioglycoside 20 (2.92 g, 4.96 mmol) in CH2Cl2
(55 mL), cooled in an ice-bath, was added NaHCO3 (5.25 g,
62.5 mmol) followed by dropwise addition of a dried (Na2SO4)
solution of MCPBA (50%, 4.3 g, 12.5 mmol) in CH2Cl2 (55 mL).
The mixture was allowed to warm gradually to r.t. overnight, then
washed twice with a mixture of sat. NaHCO3 and sodium thiosul-
fate (1:1, 100 mL) and the aqueous layers were extracted with
CH2Cl2 (50 mL). The combined organic extracts were treated with
Et3N (5 mL), dried (Na2SO4), and concentrated in vacuo. The crude
product was purified by column chromatography (SiO2, hexanes/
Et2O, 10:1 to 2:1 containing 0.5% of Et3N to give sulfone 21
(2.55 g, 4.11 mmol, 83%) as a pale yellow amorphous solid: [a]D
-52.5° (c 1, CHCl3).
23
MeLi (2.2 equiv.)
THF, –78 °C, 20 min
96%
O
O
O
O
TBSCl (1.2 equiv.)
imidazole (2.5 equiv.)
TBSO
HO
O
O
DMF, rt, 12 h
88%
SO2Ph
SO2Ph
24
13
Scheme 6
IR (CCl4): n = 2955, 2930, 2858, 1471, 1377, 1329, 1257 cm-1.
1H NMR(400 MHz, CDCl3): d = 7.97-7.92 (2H, Ph), 7.72-7.65
(1H, Ph), 7.50-7.43 (2H, Ph), 7.53-7.48 (2H, Ph), 7.43-7.35 (3H,
Ph), 5.58 (s, 1H, CHPh), 4.71 (dd, 1H, J = 1.6, 1.2 Hz, H1), 4.58 (t,
1H, J = 1.6 Hz, H2), 4.32 (dd, 1H, J = 10.3, 5.1 Hz, H6), 4.26 (dd,
1H, J = 10.5, 6.6 Hz, H4), 3.99 (dt, 1H, J = 5.1, 10.2 Hz, H5), 3.94
(dt, 1H, J = 6.7, 1.2 Hz, H3), 3.75 (t, 1H, J = 10.2 Hz, H6), 0.95,
0.90 (2 ¥ s, 9H each), 0.16, 0.12 (2 ¥ s, 3H each), 0.13 (s, 6H).
13C NMR (100 MHz, CDCl3): d = 138.3 (0, Ph), 137.5 (0, Ph), 134.1
(1, Ph), 129.4 (1, 2C, Ph), 129.2 (1, 2C, Ph), 129.1 (1, Ph), 128.4 (1,
2C, Ph), 126.2 (1, 2C, Ph), 101.5 (1), 94.8 (1, C1), 81.2 (1, C4), 76.1
(1, C3), 72.9 (1, C2), 69.5 (2, C6), 65.0 (1, C5), 25.9 (3, 3C, t-Bu),
25.9 (3, 3C, t-Bu), 18.2 (0, C-Si), 18.1 (0, C-Si), -3.9 (3, CH3Si),
-4.4 (3, CH3Si), -4.6 (3, CH3Si), -4.9 (3, CH3Si).
H6), 3.98 (dd, 1H, J = 13.1, 1.6 Hz, H6), 3.67-3.58 (m, 2H, H2,
H3), 3.43 (d, 1H, J = 1.4 Hz, H5), 1.48, 1.39, 1.37, 1.10 (4 ¥ s, 3H
each).
13C NMR (100 MHz, CDCl3): d = 135.0 (0, Ph), 134.4 (1, Ph), 130.4
(1, 2C, Ph), 128.9 (1, 2C, Ph), 112.1 (0), 98.5 (0), 91.0 (1, C1), 79.0
(1, C2), 70.5 (1, C5), 68.8 (1, C3), 66.0 (1, C4), 62.6 (2, C6), 28.7
(3), 26.7 (3), 26.3 (3), 18.7 (3).
MS (CI, isobutane): m/z (%) = 385 (M+H+, 100).
Anal. Calcd for C18H24O7S: C, 56.23; H, 6.29. Found: C, 56.20; H,
6.32.
2,6-Anhydro-5-deoxy-1,3-O-isopropylidene-phenylsulfonyl-D-
arabino-hex-5-enitol (24)
MS (CI, NH3): m/z (%) = 621 (M+H+, 100), 638 (MNH4 , 30).
+
Sulfone 23 (5 g, 13 mmol) treated with MeLi∑LiBr (29 mmol,
2.2 equiv) 6,24 gave alcohol 24 (4.08 g, 12.5 mmol, 96%) as a white
solid. The crude product was sufficiently pure to use in the next step
without further purification. An analytical sample was recrystal-
lised from EtOH, mp: 73-74 °C; [a]D -85.3° (c 1.21, CHCl3).
Anal. Calcd for C31H48O7SSi2: C, 59.96; H, 7.79. Found: C, 59.95;
H, 8.00.
1,5-Anhydro-4,6-O-benzylidene-3-O-(tert-butyldimethylsilyl)-
2-deoxy-1-phenylsulfonyl-D-arabino-hex-1-enitol (6)
Sulfone 21 (2.3 g, 3.7 mmol) treated with MeLi∑LiBr6,24 gave un-
saturated sulfone 6 (1.60 g, 3.27 mmol, 88%) as a white solid after
recrystallisation from hexanes/Et2O, mp: 160-161 °C (Lit.6 mp:
160-161 °C); [a]D -54.9° (c 1.3, CHCl3); Lit.6 [a]D -54° (c 1.3,
CHCl3).
13C NMR (100 MHz, CDCl3): d = 151.8 (0, C1), 138.0 (0, Ph),
136.9 (0, Ph), 134.3 (1, Ph), 129.4 (1, 2C, Ph), 129.3 (1, Ph), 128.8
(1, 2C, Ph), 128.4 (1, 2C, Ph), 126.1 (1, 2C, Ph), 111.7 (1, C2),
101.7 (1), 79.3 (1), 71.5 (1), 67.9 (2, C6), 67.6 (1), 25.9 (3, 3C, t-
Bu), 18.3 (0, CSi), -4.3 (3, CH3Si), -4.7 (3, CH3Si).
IR (CHCl3): n = 3562, 3031, 3017, 2997, 2921, 1651, 1586, 1448,
1383, 1353, 1327 cm-1.
1H NMR (400 MHz, CDCl3): d = 8.02-7.97 (m, 2H, Ph), 7.67-7.61
(m, 1H, Ph), 7.59-7.52 (m, 2H, Ph), 6.02 (t, 1H, J = 1.7 Hz, H5),
4.51 (ddd, 1H, J = 11.5, 4.5, 1.9 Hz, H4), 4.18 (dt, 1H, J = 4.6, 1.2
Hz, H3), 4.04-3.95 (m, 3H, H2, H1), 2.55 (d, 1H, J = 11.5 Hz,
OH), 1.42, 1.04 (2 ¥ s, 3H each).
13C NMR (100 MHz, CDCl3): d = 151.4 (0, C6), 138.6 (0, Ph),
133.9 (1, Ph), 129.1 (1, 2C, Ph), 128.5 (1, 2C, Ph), 108.1 (1, C5),
99.3 (0), 71.0 (1, C2), 64.3 (1, C3), 63.8 (1, C4), 62.2 (2, C1), 28.8
(3), 18.7 (3).
Unsaturated Sulfone 13 (Scheme 6)
MS (CI, isobutane): m/z (%) = 327 (M+H+, 55).
2,3:4,6-Di-O-isopropylidene-b-D-galactopyranosyl Phenyl Sul-
fone (23)
2,6-Anhydro-4-O-(tert-butyldimethylsilyl)-5-deoxy-1,3-O-iso-
propylidene-6-phenylsulfonyl-D-arabino-hex-5-enitol (13)
To a solution of the crude sulfone 24 (3.96 g, 12 mmol) in DMF
(80 mL) was added imidazole (2.04 g, 30 mmol) followed by
TBSCl (2.18 g, 14.4 mmol). The solution was stirred at r.t. over-
night, then poured into H2O (200 mL) and extracted with Et2O
(2 ¥ 100 mL). The combined organic extracts were dried (Na2SO4),
concentrated in vacuo, and the residue purified by chromatography
to give the unsaturated sulfone 13 as an amorphous white solid
(4.64 g, 10.5 mmol, 88%): [a]D -84.8° (c 1.16, CHCl3).
Oxidation of 2225 (5.28 g, 15 mmol) according to the procedure
described for the preparation of 21 gave sulfone 23 (5.28 g,
13.8 mmol, 92%) as a pale yellow solid, mp: 131-132 °C (hexanes/
Et2O): [a]D -33.4° (c 1.04, CHCl3)
IR (CCl4): n = 3069, 2990, 2887, 1586, 1448, 1382, 1330, 1276,
1225 cm-1.
1H NMR(400 MHz, CDCl3): d = 8.06-8.01 (m, 2H, Ph), 7.73-7.67
(m, 1H, Ph), 7.62-7.55 (m, 2H, Ph), 4.56 (dd, 1H, J = 7.5, 1.5 Hz,
H1), 4.37 (t, 1H, J = 1.6 Hz, H4), 4.02 (dd, 1H, J = 13.1, 2.1 Hz,
Synthesis 2001, No. 2, 331–338 ISSN 0039-7881 © Thieme Stuttgart · New York

336
A. Gunn et al.
SPECIAL TOPIC
IR (CCl4): n = 3070, 2993, 2952, 2929, 2858, 1732, 1651, 1471,
(3), 26.73 (3), 26.08 (3, 3C, t-Bu), 18.29 (0, C-Si), 17.83 (3, C6),
-3.77 (3, CH3Si), -4.69 (3, CH3Si).
1448, 1382, 1340 cm-1.
1H NMR (400 MHz, CDCl3): d = 8.02-7.97 (m, 2H, Ph), 7.65-7.59
(m, 1H, Ph), 7.56-7.50 (m, 2H, Ph), 5.96 (t, 1H, J = 1.7 Hz, H5),
4.67 (ddd, 1H, J = 4.1, 1.8, 0.7), 4.06 (dt, 1H, J = 4.1, 1.5 Hz), 4.02
(br s, 1H), 3.99 (dd, 1H, J = 12.9, 1.6 Hz), 3.95 (dd, 1H, J = 12.9,
2.0 Hz, H1), 1.38, 1.02 (2 ¥ s, 3H each), 0.90 (s, 9H, t-Bu), 0.10,
0.09 (2 ¥ s, 3H each, CH3Si).
13C NMR (100 MHz, CDCl3): d = 150.5 (0, C6), 138.5 (0, Ph),
133.8 (1, Ph), 129.1 (1, 2C, Ph), 128.6 (1, 2C, Ph), 109.5 (1, C5),
98.9 (0), 71.4 (1), 66.2 (1), 65.5 (1), 62.5 (2, C1), 28.9 (3), 25.9 (3,
3C, t-Bu), 18.6 (3), 18.5 (0, CSi), -4.1 (3, CH3Si), -4.2 (3, CH3Si).
HRMS (EI): m/z calcd for C21H34O4SiS (M+): 410.1947. Found:
410.1945
4-O-(tert-Butyldimethylsilyl)-2,3-O-isopropylidene-a-L-rham-
nopyranosyl Phenyl Sulfone (27)
Oxidation of 26 (3.77 g, 9.2 mmol) with 50% MCPBA according to
the procedure described above for the preparation of 21 gave sul-
fone 27 (3.80 g, 8.58 mmol, 93%) as a pale yellow solid, mp 138-
139 °C (hexanes/Et2O): [a]D -58.8° (c 1.04, CHCl3).
IR (CCl4): n = 3070, 2933, 2895, 2895, 1448, 1382, 1341, 1321
cm-1.
+
MS (CI, NH3): m/z (%) = 458 (MNH4 , 100).
1H NMR(400 MHz, CDCl3): d = 7.96-7.90 (m, 2H, Ph), 7.75-7.69
(m, 1H, Ph), 7.65-7.58 (m, 2H, Ph), 4.98 (s, 1H, H1), 4.93 (d, 1H,
J = 6.1 Hz, H2), 4.23 (dd, 1H, J = 7.3, 6.1 Hz, H3), 4.17 (dq, 1H,
J = 6.2, 9.6 Hz, H5), 3.31 (dd, 1H, J = 7.4, 9.6 Hz, H4), 1.52, 1.41
(2 ¥ s, 3H each), 1.10 (d, 3H, J = 6.2 Hz, H6), 0.90 (s, 9H, t-Bu),
0.16, 0.08 (2 ¥ s, 3H each, CH3Si).
13C NMR (100 MHz, CDCl3): d = 136.4 (0, Ph), 134.5 (1, Ph), 129.4
(1, 2C, Ph), 129.2 (1, 2C, Ph), 109.2 (0), 91.0 (1, C1), 78.9 (1, C3),
75.2 (1, C4), 71.4 (1, C5), 70.3 (1, C2), 28.1 (3), 26.4 (3), 26.0 (3,
3C, t-Bu), 18.3 (0, C-Si), 18.0 (3, C6), -3.8 (3, CH3Si), -4.7 (3,
CH3Si).
Anal. Calcd for C21H32O6SSi: C, 57.24; H, 7.32. Found: C, 57.13;
H, 7.28.
Unsaturated Sulfone 15
OTBS
O
OH
O
O
O
O
TBSOTf, EtN(i-Pr)2
O
CH2Cl2, rt, 12 h
97%
PhS
SPh
26
25
+
MS (CI, NH3): m/z (%) = 460 (MNH4 , 100).
MCPBA (2.5 equiv.)
NaHCO3 (12.5 equiv.)
CH2Cl2, rt, 12 h
93%
Anal. Calcd for C21H34O6SSi: C, 56.98; H, 7.74. Found: C, 56.93;
H, 7.75.
OTBS
OTBS
1,5-Anhydro-3,4-bis-O-(tert-butyldimethylsilyl)-2,6-dideoxy-1-
phenylsulfonyl-L-arabino-hex-1-enitol (15)
TBSO
(a)
(b)
MeLi (2.2 equiv.)
THF, –78 °C, 20 min
O
O
O
O
Sulfone 27 (3.50 g, 7.9 mmol) was treated with MeLi∑LiBr
(17.4 mmol, 2.2 equiv) to give the elimination product (3.14 g) as a
mixture of two regioisomeric alcohols (1:1) as a result of silyl group
migration. The crude product was dissolved in CH2Cl2 (52 mL) and
i-Pr2NEt (2.53 g, 3.14 mL, 19.6 mmol) was added. The solution was
then cooled in an ice-bath and TBSOTf (2.60 g, 2.22 mL, 9.8 mmol)
was added dropwise. The solution was stirred in an ice-bath for 2 h
and then poured into H2O (100 mL). The organic layer was separat-
ed and the aqueous layer extracted with CH2Cl2 (50 mL). The com-
bined organic extracts were dried (Na2SO4) and concentrated in
vacuo. The residue was purified by column chromatography (SiO2,
hexanes/Et2O, 50:1 to 1:1) to give unsaturated sulfone 15 (3.44 g,
6.89 mmol, 87% for two steps) as a colourless solid, mp 70-71 °C
(90% EtOH/H2O): [a]D+64.9° (c 1.19, CHCl3)
TBSOTf, EtN(i-Pr)2
CH2Cl2, rt, 2 h
SO2Ph
SO2Ph
15
87% (2 steps)
27
Scheme 7
Phenyl 4-O-(tert-Butyldimethylsilyl)-2,3-O-isopropylidene-1-
thio-a-L-rhamnopyranoside (26)
To a solution of alcohol 2526 (2.96 g, 10 mmol) and i-Pr2NEt
(3.10 g, 4.2 mL, 24 mmol) in CH2Cl2 (100 mL) was added dropwise
at 0 °C TBSOTf (3.17 g, 2.7 mL, 12 mmol). The solution was al-
lowed to warm to r.t. overnight and then poured into H2O (200 mL).
The organic layer was separated and the aqueous layer extracted
with CH2Cl2 (50 mL). The combined organic extracts were dried
(Na2SO4) and concentrated in vacuo. The residue was purified by
column chromatography (SiO2, hexanes followed by hexanes/Et2O,
2:1) to give thioglycoside 26 (4.0 g, 9.7 mmol, 97%) as a colourless
oil: [a]D -186° (c 1.01, CHCl3).
IR (CCl4): n = 2955, 2894, 2857, 1649, 1471, 1447, 1382, 1377,
1362, 1340, 1257 cm-1.
1H NMR (400 MHz, CDCl3): d = 7.96-7.91 (m, 2H, Ph), 7.65-7.59
(m, 1H, Ph), 7.55-7.49 (m, 2H, Ph), 6.05 (dd, 1H, J = 4.5, 1.1 Hz,
H2), 4.21 (ddq, 1H, J = 7.0, 3.8, 1.5 Hz, H5), 4.05 (ddd, 1H,
J = 4.5, 3.2, 1.4 Hz, H3), 3.61 (ddd, 1H, J = 3.6, 3.4, 1.2 Hz, H4),
1.20 (d, 3H, J = 6.9 Hz, H6), 0.89, 0.76 (2 ¥ s, 9H each, t-Bu), 0.14,
0.11, 0.04, 0.00 (4 ¥ s, 3H each, CH3Si).
13C NMR (100 MHz, CDCl3): d = 150.9 (0, C1), 138.6 (0, Ph),
133.7 (1, Ph), 129.1 (1, 2C, Ph), 128.6 (1, 2C, Ph), 107.2 (1, C2),
78.3 (1, C5), 72.9 (1, C4), 67.6 (1, C3), 25.9 (3, 3C, t-Bu), 25.8 (3,
3C, t-Bu), 18.1 (0, CSi), 18.0 (0, CSi), 15.5 (3, C6), -4.2 (3, 2C,
CH3Si), -4.4 (3, CH3Si), -4.6 (3, CH3Si).
IR (film): n = 3060, 2932, 2896, 2857, 1584, 1474, 1462, 1440,
1381 cm-1.
1H NMR (400 MHz; C6D6): d = 7.68-7.63 (m, 2H, PhS), 7.26-7.15
(m, 3H, PhS), 6.19 (s, 1H, H1), 4.58 (d, 1H, J = 5.6 Hz, H2), 4.49
(dq, 1H, J = 9.6, 6.2 Hz, H5), 4.32 (dd, 1H, J = 7.1, 5.7 Hz, H3),
3.83 (dd, 1H, J = 9.6, 7.2 Hz, H4), 1.68, 1.39 (2 ¥ s, 3H each), 1.50
(d, 3H, J = 6.2 Hz, H6), 1.26 (s, 9H, t-Bu), 0.54, 0.37 (2 ¥ s, 3H
each, CH3Si).
13C NMR (100 MHz, CDCl3): d = 133.93 (0, PhS), 131.94 (1, 2C,
PhS), 129.15 (1, 2C, PhS), 127.62 (1, PhS), 109.35 (0), 84.16 (1,
C1), 79.08 (1, C3), 76.94 (1, C2), 76.42 (1, C4), 67.81 (1, C5), 28.32
+
MS (CI, NH3): m/z (%) = 516 (MNH4 , 100).
Anal. Calcd for C24H42O5SSi2: C, 57.79; H, 8.49. Found: C, 57.85;
H, 8.75.
Synthesis 2001, No. 2, 331–338 ISSN 0039-7881 © Thieme Stuttgart · New York

SPECIAL TOPIC
The Preparation of 1-Tributylstannyl Glycals from 1-Phenylsulfonyl Glycals
337
Unsaturated Sulfone 17
(EtOH/H2O): [a]D -97.7° (c 1.14, CHCl3). The compound slowly
decomposes at r.t. and should be kept in a freezer.
O
O
H
IR (CCl4): n = 2990, 2887, 1448, 1381, 1341, 1225, 1155, 1083
O
O
cm-1.
O
O
MCPBA (2.5 equiv.)
NaHCO3 (12.5 equiv.)
H
O
O
1H NMR (400 MHz, CDCl3): d = 7.92-7.85 (m, 2H, Ph), 7.65-7.58
(m, 1H, Ph), 7.53-7.46 (m, 2H, Ph), 5.99 (d, 1H, J = 2.7 Hz, H2),
5.02 (dd, 1H, J = 6.9, 2.7 Hz, H3), 4.50 (dd, 1H, J = 6.0, 6.7 Hz,
H4), 4.39 (q, 1H, J = 6.2 Hz, H5), 3.99 (dd, 1H, J = 8.7, 6.5 Hz,
H6), 3.73 (dd, 1H, J = 8.7, 6.0 Hz, H6), 1.34, 1.32 (2 ¥ s, 3H each),
0.86 (s, 9H, t-Bu), 0.08 (s, 6H, CH3Si).
O
O
DCM, rt, 12 h
87%
PhS
SO2Ph
29
28
MeLi (5.5 equiv.)
THF, –78 °C, 80 min
13C NMR (100 MHz, CDCl3): d = 157.7 (0, C1), 138.2 (0, Ph),
134.5 (1, Ph), 129.4 (1, 2C, Ph), 128.7 (1, 2C, Ph), 111.0 (1, C2),
109.2 (0), 88.3 (1, C4), 73.0 (1, C3), 72.5 (1, C5), 65.9 (2, C6), 26.6
(3), 25.8 (3, 3C, t-Bu), 25.5 (3), 18.3 (0, C-Si), -4.6 (3, CH3Si),
-4.9 (3, CH3Si).
O
H
O
O
O
TBSO
HO
H
O
TBSCl, imidazole
O
DMF, rt, 12 h
73% (2 steps)
+
SO2Ph
SO2Ph
MS (CI, NH3): m/z (%) = 458 (MNH4 , 100).
30
17
Anal. Calcd for C21H32O6SSi: C, 57.24; H, 7.32. Found: C, 57.36;
H, 7.29.
Scheme 8
When 2.2 equiv of MeLi•LiBr was used in the b-elimination reac-
tion, the desired unsaturated sulfone 17 was accompanied by a sec-
ond product 32 (17:32 ~ 1:1) corresponding to the adduct derived
from addition of the metallated sulfone 31 to the acetone released in
the b-elimination reaction as shown in Scheme 9. However, by in-
creasing the amount of MeLi to 5.5 equiv, changing the order of ad-
dition and increasing the reaction time, the acetone was presumably
trapped by the excess MeLi leading to an increase in yield of 17
from 51% to 73% and a decrease in the amount of 32 (17:32 = 6:1).
2,3:5,6-Di-O-isopropylidene-b-D-mannofuranosyl Phenyl Sul-
fone (29)
Oxidation of thioglycoside 2827 (6.69 g, 19 mmol) with 50% MCP-
BA according to the procedure used for the preparation of 21 gave
sulfone 29 (6.32 g, 16.4 mmol, 87%) as a pale yellow solid, mp:
118-119 °C (hexanes/Et2O) (Lit.28 mp: 119.5-120.5 °C):
[a]D+56.6° (c 1.08, CHCl3) {Lit.28 [a]D+46.6° (c 0.98, CHCl3)}
IR (CCl4): n = 3070, 2989, 2939, 2880, 1479, 1448, 1381, 1330,
O
H
O
H
1262 cm-1.
O
O
HO
1H NMR(400 MHz, CDCl3): d = 8.00-7.95 (m, 2H, Ph), 7.68-7.61
(m, 1H, Ph), 7.56-7.50 (m, 2H, Ph), 5.10 (dd, 1H, J = 6.0, 4.1 Hz,
H2), 4.77 (dd, 1H, J = 6.0, 3.9 Hz, H3), 4.57 (d, 1H, J = 4.0 Hz,
H1), 4.34 (dt, 1H, J = 6.3, 4.9 Hz, H5), 4.02 (dd, 1H, J = 8.8, 6.2
Hz, H6), 3.99 (dd, 1H, J = 8.9, 4.9 Hz, H6), 3.74 (dd, 1H, J = 6.5,
3.9 Hz, H4), 1.42, 1.34, 1.26,1.03 (4 ¥ s, 3H each).
O
H2O
O
O
O
Li
PhO2S
PhO2S
O
17
31
13C NMR (100 MHz, CDCl3): d = 138.8 (0, Ph), 133.9 (1, Ph), 129.9
(1, 2C, Ph), 128.6 (1, 2C, Ph), 114.3 (0), 109.4 (0), 94.4 (1, C1),
82.8 (1, C4), 80.2 (1), 79.9 (1), 72.9 (1, C5), 66.4 (2, C6), 26.9 (3),
25.4 (3), 24.6 (3), 24.1 (3).
O
H
O
O
H2O
O
O
+
MS (CI, NH3): m/z (%) = 402 (MNH4 , 100).
OH
PhO2S
Anal. Calcd for C18H24O7S: C, 56.23; H, 6.29. Found: C, 56.12; H,
6.28.
32
Scheme 9
1,4-Anhydro-3-O-(tert-butyldimethylsilyl)-2-deoxy-5,6-O-iso-
propylidene-1-phenylsulfonyl-D-arabino-hex-1-enitol (17)
To a rapidly stirred solution of MeLi∑LiBr (34 mL, 1.3 M in Et2O,
44 mmol) in THF (80 mL) at -78 °C was added over 1 h a solution
of sulfone 29 (3.07 g, 8.0 mmol) in THF (80 mL). After the addition
was complete, the solution was stirred at -78 °C for 10 min, and
then transferred slowly by cannula, under N2, into a rapidly stirred
solution of sat. NaHCO3 (200 mL) placed in a 1 L flask and cooled
in an ice-bath (very vigorous reaction). The mixture was then ex-
tracted with Et2O (2 ¥ 100 mL), dried (Na2SO4), and concentrated
in vacuo. The crude product (2.75 g) was then dissolved in DMF
(54 mL), whereupon imidazole (1.36g, 20 mmol) was added fol-
lowed by TBSCl (1.45 g, 9.6 mmol). The solution was stirred at r.t.
overnight, then poured into H2O (300 mL), and extracted with Et2O
(2 ¥ 100 mL). The combined extracts were dried (Na2SO4) and con-
centrated in vacuo. The residue was purified by column chromatog-
raphy (SiO2, hexanes/Et2O, 10:1 to 1:1 containing 0.5% Et3N) to
give 17 (2.58 g, 5.86 mmol, 73%) as a white solid, mp 50-51 °C
Acknowledgement
We thank Mr Tony Ritchie (Glasgow University) for mass spectra
and the EPSRC for financial support.
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Article Identifier:
1437-210X,E;2001,0,02,0331,0338,ftx,en;C13400SS.pdf
Synthesis 2001, No. 2, 331–338 ISSN 0039-7881 © Thieme Stuttgart · New York