C-allylation of 1- and 6-bromosugars with allylic sulfides and sulfones

Article abstract of DOI:10.1021/jo960749l

Reaction of the bromosugars 2,3,4,6-tetra-O-acetyl-α-D-galactopyranosyl bromide (1), methyl 2,3-anhydro-6-bromo-6-deoxy-α-D-allopyranoside (2), and methyl 2,3-anhydro-4-O-benzoyl-6-bromo-6-deoxy-α-D-allopyranoside (3) with the allylic sulfides and sulfones 4-9 in the presence of hexabutyldistannane under photolytic conditions gave the corresponding α-C-allyl galactosides 10-12 and the 6-C-allylated epoxysugars 13, 15, and 16 in 61-90% yield.

Full text of DOI:10.1021/jo960749l

J . Org. Chem. 1996, 61, 7463-7466
7463
C-Allyla tion of 1- a n d 6-Br om osu ga r s w ith Allylic Su lfid es a n d
Su lfon es
Fritiof Ponte´n and Go¨ran Magnusson*
Organic Chemistry 2, Center for Chemistry and Chemical Engineering, Lund University,
P.O. Box 124, S-221 00 Lund, Sweden
Received April 24, 1996X
Reaction of the bromosugars 2,3,4,6-tetra-O-acetyl-R-D-galactopyranosyl bromide (1), methyl 2,3-
anhydro-6-bromo-6-deoxy-R-D-allopyranoside (2), and methyl 2,3-anhydro-4-O-benzoyl-6-bromo-6-
deoxy-R-D-allopyranoside (3) with the allylic sulfides and sulfones 4-9 in the presence of
hexabutyldistannane under photolytic conditions gave the corresponding R-C-allyl galactosides 10-
12 and the 6-C-allylated epoxysugars 13, 15, and 16 in 61-90% yield.
In tr od u ction
hexabutyldistannane at room temperature using a Pyrex
filter gave in good yields the C-R-glycosides 10-12 (Table
1); none of the corresponding C-â-glycosides were iso-
lated. Using the same reaction conditions with the
6-bromoepoxy alcohol 28 gave the 6-alkylated galactosides
13-15. The yields were high for 13 and 15, whereas 14
could only be obtained in approximately 30% yield;
unidentified byproducts accounted for the remaining
material. When HO-4 was protected with a benzoyl
group (3), the reaction gave the 6-alkylated compound
16 in good yield. Debenzoylation of 16 with ethanolic
sodium ethoxide gave 14 (84%).
Sta r tin g Ma ter ia ls 1-9. Acetobromogalactose 1 is
a well-known building block in carbohydrate chemistry.
The 6-bromoepoxides 2 and 3 might seem more elusive
but are in fact easily prepared.8 We reported recently
the synthesis, in 68% yield over five steps, of epoxyalcohol
2 on a large scale, starting from methyl R-D-glucopyra-
noside.9
Chain elongation of saccharides, via the formation of
carbon-carbon bonds at positions 1 and 6, leads to chiral
compounds of potential value for the synthesis of natural
products and other important substances. Elongation at
the 1-position gives C-glycosides (hydrolytically stable
analogs of normal O-glycosides), a class of compounds
that has been the subject of intense synthetic and
biochemical interest recently, as witnessed by recent
reviews.1
The intermolecular free radical-induced coupling of
1-bromopyranoses with acrylonitrile and similar com-
pounds to give C-glycosides has been thoroughly inves-
tigated, largely through the work of Giese.2,3 These
reactions almost always lead to the exclusive formation
of C-R-glycopyranosides.
Free radical allylation of 6-bromosugars was performed
by Keck, using various allylstannanes and AIBN.4 In an
attempt to avoid the need for allylstannanes, a method
was developed where allylic sulfides and alkyl halides
were reacted in the presence of hexabutyldistannane
(irradiation of the latter initiated the radical chain
reaction).5 Similar allylations were reported by Curran.6
Despite the obvious potential for allylations using allyl
sulfides, no such reactions seem to have been reported
with halosugar substrates.
We now report the successful free radical allylation at
both the 1- and 6-position of bromosugar substrates,
using essentially Keck’s procedure5 with different allylic
sulfides and sulfones. The epoxy alcohol products 13-
15 are currently under investigation as substrates in
ring-contractions leading to five-membered-ring R,â-
unsaturated aldehydes.7
The allyl sulfide 4 and sulfone 5 are commercially
available. The acrylic ester sulfide10 6 and sulfone11
7
were prepared as described in the literature. 3-Bromo-
2-(bromomethyl)propyl acetate12 (17) was treated with
tetrabutylammonium fluoride in acetonitrile to give, after
distillation, 2-(bromomethyl)propen-1-yl acetate13 (18) in
76% yield. In addition to being a strong base in aprotic
solvents, F- is nucleophilic enough to displace the
bromine in 18 to a substantial degree, when the reaction
mixture was left for more than 20 min. Therefore,
aqueous calcium nitrate was added in order to quench
F- as soon as the elimination was completed (CaF2 has
a low solubility). Treatment of 18 with thiophenol in the
presence of cesium carbonate,14 essentially as in the
preparation of the corresponding benzylthio analog,13
gave the allylic sulfide acetate 8 in 98% yield. The
sulfone acetate13 9 was prepared in 73% yield by treat-
ment of 18 with sodium benzenesulfinate (Scheme 1).
Resu lts a n d Discu ssion
Allyla tion of 1-3. Photolysis of a mixture of aceto-
bromogalactose 1, the sulfides and sulfones 4-9, and
Exp er im en ta l Section
1H-NMR-spectra were recorded at 23°C and 300 MHz using
CDCl3 as solvent and CHCl3 as internal standard (δ 7.26), or
X Abstract published in Advance ACS Abstracts, September 15, 1996.
(1) (a) Hanessian, S.; Pernet, A. G. Adv. Chem. Biochem. 1976, 33,
111. (b) Postema, M. H. R. Tetrahedron 1992, 48, 8545. (c) Levy, D.
E.; Tang, C. The Chemistry of C-Glycosides; Baldwin, J . E.; Magnus,
P. D., Eds.; Elsevier Science Ltd.: Oxford, 1995.
(2) Giese, B. Radicals in Organic Synthesis: Formation of Carbon-
Carbon Bonds; Baldwin, J . E., Ed.; Pergamon Press: New York, 1985.
(3) Giese, B.; Linker, T.; Muhn, R. Tetrahedron 1989, 45, 935.
(4) (a) Keck, G. E.; Yates, J . B. J . Am. Chem. Soc. 1982, 104, 5829.
(b) Keck, G. E.; Enholm, E. J .; Yates, J . B.; Wiley, M. R. Tetrahedron
1985, 41, 4079.
(8) Hanessian, S. Org. Synth. 1987, 65, 243.
(9) Ponte´n, F.; Magnusson, G. Acta Chem. Scand. 1994, 48, 566.
(10) Feldman, K. S.; Bobo, J . S.; Tewalt, G. L. J . Org. Chem. 1992,
57, 4573.
(11) Baldwin, J . E.; Adlington, R. M.; Birch, D. J .; Crawford, J . A.;
Sweeney, J . B. J . Chem. Soc., Chem. Commun. 1986, 1339.
(12) Ansari, A. A.; Frejd, T.; Magnusson, G. Carbohydr. Res. 1987,
161, 225.
(5) Keck, G. E.; Byers, J . H. J . Org. Chem. 1985, 50, 5442.
(6) Curran, D. P.; Yoo, B. Tetrahedron Lett. 1992, 33, 6931.
(7) (a) Sundin, A.; Frejd, T.; Magnusson, G. J . Org. Chem. 1986,
51, 3927. (b) Magnusson, G. Org. Prep. Proc. Int. 1990, 22, 547.
(13) Magnusson, G.; Lindqvist, F. J . Chem. Soc., Chem. Commun.
1990, 1080.
(14) Buter, J .; Kellogg, R. M. J . Org. Chem. 1981, 46, 4481.
S0022-3263(96)00749-9 CCC: $12.00 © 1996 American Chemical Society

7464 J . Org. Chem., Vol. 61, No. 21, 1996
Ponte´n and Magnusson
Ta ble 1. Allyla tion a of th e Br om osu ga r s 1-3 w ith th e Allylic Su lfid es a n d Su lfon es 4-9
4 and 5 are commercially available. The naming of compounds
10-16 and the assignments of 1H NMR spectra in the
supporting information is based on the atom numbering shown
for compounds 10 and 13 in Table 1.
Sch em e 1
2-[(P h en ylth io)m eth yl]p r op -2-en -1-yl Aceta te (8). 2-
-(Bromomethyl)propen-1-ylacetate13 (18, 135 mg, 0.70 mmol)
was dissolved in CH3CN (7 mL), and thiophenol (0.10 mL, 0.97
mmol) and Cs2CO3 (257 mg, 0.79 mmol) were added. After
20 min, 18 had been consumed (GC, RSL-150 nonpolar
polydimethoxysiloxane capillary column, 60 °C). The reaction
mixture was poured into water (50 mL), the water phase was
extracted with diethyl ether (4 × 20 mL), and the ether
solution was dried (Na2SO4) and concentrated. Chromatog-
raphy (SiO2, heptane/EtOAc 6:1) of the residue gave pure 8
(152 mg, 98%). 1H-NMR data (CDCl3): δ 7.37-7.17 (m, 5 H),
5.10 (br s, 1 H), 5.03 (br s, 1 H), 4.68 (br s, 2 H), 3.59 (br s, 2
H), 2.08 (s, 3 H). 13C-NMR data (CDCl3): δ 170.6, 139.3, 135.6,
130.6, 128.9, 126.7, 116.5, 65.3, 37.8, 20.9. HRMS calcd for
C12H14O2S (M+): 222.0715, found 222.0714.
in C6D6 using C6D5H as internal standard (δ 7.30). 13C-NMR
spectra were recorded at 23 °C and 75 MHz using CDCl3 or
C6D6 as solvent and internal standard (δ 77.0 and 128.0,
respectively). TLC analysis was performed on Merck SiO2 60
F254 precoated aluminum sheets; spots were visualized with
UV light, I2, or by 5% anisaldehyde in ethanolic sulfuric acid.
Liquid chromatography was performed on Matrex SiO2 60
(35-70 µm). Hexabutyldistannane was purified by flash
chromatography (SiO2, heptane) and stored under argon at 4
°C. Benzene was distilled and stored over molecular sieves
(4 Å). Compounds 1,9 2,10 and 3,8,10 6,11 7,12 and 1713were
prepared according to the published procedures. Compounds
2-[(P h en ylsu lfon yl)m eth yl]p r op -2-en -1-yl Aceta te (9).
2-(Bromomethyl)prop-2-en-1-yl-acetate13 (18, 505 mg, 2.60
mmol) was dissolved in DMF (15 mL), and sodium benzene-
sulfinate (850 mg, 5.20 mmol) was added. After 15 h, the
reaction mixture was poured into water (20 mL), the water

C-Allylation of 1- and 6-Bromosugars
J . Org. Chem., Vol. 61, No. 21, 1996 7465
phase was extracted with ether (4 × 10 mL), and the ether
solution was dried (Na2SO4) and concentrated. Chromatog-
raphy (SiO2, heptane/EtOAc 8:1) of the residue gave pure 9
(482 mg, 73%) as a syrup, which crystallized upon standing
(b) Acetobromogalactose (1, 96 mg, 0.24 mmol) and sulfone
9 (176 mg, 0.69 mmol) were dissolved in dry benzene (1.5 mL).
Hexabutyldistannane (0.18 mL, 0.35 mmol) was added, and
the mixture was treated as in the preparation of 10 (b) to give
12 (93 mg, 89%) and recovered 9 (107 mg, 60%), after 7 h of
irradiation and purification by chromatography.
1
at -20 °C. Mp 35.5-37.5 °C; H-NMR data (CDCl3): δ 7.90
(m, 2 H), 7.53-7.70 (m, 3 H), 5.36 (br s, 1 H), 5.01 (br s, 1 H),
4.62 (br s, 2 H), 3.86 (br s, 2 H), 2.06 (s, 3 H). Anal. Calcd for
C12H14O4S: C, 56.7, H, 5.6; found: C 56.7, H, 5.5.
Meth yl 2,3-An h yd r o-6-d eoxy-6-(p r op -2-en -1-yl)-r-D-a l-
lop yr a n osid e (13). (a) Methyl 2,3-anhydro-6-bromo-6-deoxy-
R-D-allopyranoside6 (2, 239 mg, 1.00 mmol) and sulfide 4 (0.44
mL, 3.00 mmol) were dissolved in dry benzene (6 mL).
Hexabutyldistannane (0.75 mL, 1.50 mmol) was added, and
the mixture was treated as in the preparation of 10 (a) to give
13 as a syrup (157 mg, 78%) after 13 h of irradiation and
purification by chromatography. [R]23D +116° (c 0.87, CHCl3).
1H-NMR data (C6D6): δ 5.95 (ddt, 1 H, J ) 6.6, 10.4, 17.0 Hz),
5.20 (ddd, 1 H, J ) 1.6, 3.5, 17.1 Hz), 5.13 (ddd, 1 H, J ) 1.3,
3.2, 10.2 Hz), 4.54 (d, 1 H, J ) 3.0 Hz), 3.75 (dt, 1 H, J ) 2.4,
9.5 Hz), 3.41 (dt, 1 H, J ) 1.7, 9.6 Hz), 3.30 (s, 3 H), 3.11 (dd,
1 H, J ) 3.1, 4.1 Hz), 3.05 (dd, 1 H, J ) 1.7, 4.1 Hz), 2.45 (m,
1 H), 2.25 (m, 1 H), 2.05 (m, 1 H), 1.60 (m, 2 H). 13C-NMR
data (C6D6): δ 138.6, 114.9, 94.9, 70.1, 68.6, 55.6, 55.2, 53.7,
31.3, 30.4. HRMS calcd for C10H20O4N (M + NH4+): 218.1392,
found 218.1387.
C-P r op en -1-yl 2,3,4,6-Tetr a -O-a cetyl-r-D-ga la ctop yr a -
n osid e (10). (a) Acetobromogalactose (1, 414 mg, 1.01 mmol)
and sulfide 4 (0.44 mL, 3.00 mmol) were dissolved in dry
benzene (5.5 mL). Hexabutyldistannane (0.75 mL, 1.50 mmol)
was added, and the mixture was degassed by purging with Ar
during sonification for 20-30 min at 15-25 °C. The flask was
sealed with a rubber septum and the mixture was irradiated
at rt for 5 h with a modified mercury lamp (Osram HQL 700W)
equipped with a Pyrex filter. The reaction mixture was added
to an SiO2 column and chromatographed (toluene/EtOAc 1:0
f 3:1, gradient) to give 10 (272 mg, 73%) as a syrup. [R]23
D
+84° (c 0.9, CHCl3). 1H-NMR data (CDCl3): δ 5.76 (dddd, 1
H, J ) 6.5, 7.1, 10.0, 16.6 Hz), 5.42 (dd, 1 H, J ) 2.4, 3.1 Hz),
5.28 (dd, 1 H, J ) 4.8, 9.3 Hz), 5.22 (dd, 1 H, J ) 3.1, 9.3 Hz),
5.13 (ddd, 1 H, J ) 1.6, 3.0, 16.6 Hz), 5.12 (ddd, 1 H, J ) 1.4,
3.0, 10.0 Hz), 4.30 (ddd, 1 H, J ) 4.7, 5.2, 10.3 Hz), 4.21 (dd,
1 H, J ) 8.9, 12.5 Hz), 4.09 (m, 2 H), 2.46 (m, 1 H), 2.29 (m,
1 H), 2.12, 2.07, 2.04, 2.03 (4 s, 3 H each). 13C-NMR data
(CDCl3): δ 170.5, 170.1, 169.9, 169.8, 133.3, 117.6, 71.4, 68.2,
67.9, 61.4, 30.9, 20.8, 20.7, 20.6. HRMS calcd for C17H25O9
(M + H): 373.1499; found 373.1487.
(b) Methyl 2,3-anhydro-6-bromo-6-deoxy-R-D-allopyranoside
(2, 33 mg, 0.14 mmol) and sulfone 5 (71 mg, 0.39 mmol) were
dissolved in dry benzene (0.8 mL). Hexabutyldistannane (0.08
mL, 0.16 mmol) was added, and the mixture was treated as
in the preparation of 10 (b) to give 13 (24 mg, 88%), after 17
h of irradiation and purification by chromatography.
(b) Acetobromogalactose (1, 409 mg, 0.99 mmol) and sulfone
5 (1.189 g, 3.01 mmol) were dissolved in dry benzene (5 mL).
Hexabutyldistannane (0.70 mL, 1.39 mmol) was added, and
the mixture was treated as above to give 10 (322 mg, 87%)
after 9 h of irradiation and purification by chromatography.
C-2-(E t h oxyca r b on yl)p r op -2-en -1-yl 2,3,4,6-Tet r a -O-
a cetyl-r-D-ga la ctop yr a n osid e (11). (a) Acetobromogalac-
tose (1, 143 mg, 0.35 mmol) and sulfide 6 (226 mg, 1.02 mmol)
were dissolved in dry benzene (2 mL). Hexabutyldistannane
(0.25 mL, 0.50 mmol) was added, and the mixture was treated
as in the preparation of 10 (a) to give 11 as a syrup (111 mg,
71%) after 12 h of irradiation and purification by chromatog-
Met h yl 2,3-An h yd r o-6-d eoxy-6-(2-(et h oxyca r b on yl)-
p r op -2-en -1-yl)-r-D-a llop yr a n osid e (14). (a) Methyl 2,3-
anhydro-6-bromo-6-deoxy-R-D-allopyranoside6 (2, 164 mg, 0.69
mmol) and sulfide 6 (445 mg, 2.00 mmol) were dissolved in
dry benzene (4 mL). Hexabutyldistannane (0.50 mL, 1.00
mmol) was added, and the mixture was treated as in the
preparation of 10 (a) to give 14 as a syrup (60 mg, 32%) and
recovered 6 (23 mg, 14%), after 12 h of irradiation and
purification by chromatography. [R]23 +108° (c 1.3, CHCl3).
D
1H-NMR data (CDCl3): δ 6.15 (br s, 1 H), 5.55 (m, 1 H), 4.86
(d, 1 H, J ) 3.0 Hz), 4.19 (q, 2 H, J ) 7.1 Hz), 3.65 (ddd, 1 H,
J ) 1.7, 9.4, 9.7 Hz), 3.59-3.50 (m, 2 H), 3.46 (s, 3 H), 3.44
(dd, 1 H, J ) 1.7, 4.2 Hz), 2.55 (dddd, 1 H, J ) 4.5, 4.9, 10.6,
15.1 Hz), 2.30 (dddd, 1 H, J ) 5.3, 6.0, 9.9, 15.2 Hz), 2.05 (dddd,
1 H, J ) 2.7, 5.9, 10.7, 13.7 Hz), 1.95 (d, 1 H, J ) 9.8 Hz), 1.54
(ddt, 1 H, J ) 4.7, 9.6, 14.1 Hz), 1.28 (t, 3 H, J ) 7.1 Hz).
13C-NMR data (CDCl3): δ 167.1, 142.7, 140.3, 124.7, 94.5, 69.6,
68.4, 60.7, 55.8, 54.1, 30.2, 28.1, 14.2. HRMS calcd for
C13H24O6N (M + NH4+): 290.1604, found 290.1623.
raphy. [R]23 +71° (c 1.3, CHCl3). 1H-NMR data (CDCl3): δ
D
6.27 (d, 1 H, J ) 1.0 Hz), 5.64 (d, 1 H, J ) 1.0 Hz), 5.40 (dd,
1 H, J ) 1.9, 3.2 Hz), 5.30 (dd, 1 H, J ) 5.4, 9.8 Hz), 5.20 (dd,
1 H, J ) 3.3, 9.8 Hz), 4.45 (ddd, 1 H, J ) 4.8, 5.2, 10.3 Hz),
4.19 (dq, 2 H, J ) 1.0, 7.1 Hz), 4.14-4.08 (m, 2 H), 4.02 (dd,
1 H, J ) 8.3, 13.8 Hz), 2.63, 2.58 (dABq, 2 H, J ) 4.8, 10.3,
15.2 Hz), 2.10, 2.07, 2.01, 2.00 (4 s, 12 H), 1.27 (t, 3 H, J ) 7.1
Hz). 13C-NMR data (CDCl3): δ 170.5, 170.1, 170.0, 169.7,
166.4, 136.3, 127.5, 71.3, 68.0, 67.8, 67.6, 61.4, 60.9, 28.2, 20.8,
20.7, 20.6, 14.1. HRMS calcd for C20H32O11N (M + NH4+):
462.1975, found 462.1979.
(b) Acetobromogalactose (1, 55 mg, 0.13 mmol) and sulfone
7 (83 mg, 0.33 mmol) were dissolved in dry benzene (0.7 mL).
Hexabutyldistannane (0.10 mL, 0.20 mmol) was added, and
the mixture was treated as in the preparation of 10 (b) to give
11 (35 mg, 61%) and recovered 1 (19 mg, 35%) and 7 (25 mg,
30%), after 7 h of irradiation and purification by chromatog-
raphy.
(b) Methyl 2,3-anhydro-6-bromo-6-deoxy-R-D-allopyranoside
(2, 70 mg, 0.29 mmol) and sulfone 7 (189 mg, 0.74 mmol) were
dissolved in dry benzene (1.8 mL). Hexabutyldistannane (0.22
mL, 0.44 mmol) was added, and the mixture was treated as
in the preparation of 10 (b) to give 14 (11 mg, 14%) and
recovered 7 (125 mg, 66%), after 13 h of irradiation and
purification by chromatography.
(c) Compound 16 (88 mg, 0.23 mmol) was dissolved in
ethanol (99.5%, 2 mL) and ethanolic sodium ethoxide (0.1 mL,
approximately 0.7 M) was added. The reaction was monitored
by TLC (SiO2, toluene/EtOAc 3:1). After 6 h, NH4Cl(s) was
added, the mixture was filtered, and the filtrate was concen-
trated. The residue was chromatographed (SiO2, heptane/
EtOAc 1:1) to give 14 (52 mg, 84%).
C-2-(Acet oxym et h yl)p r op -2-en -1-yl 2,3,4,6-Tet r a -O-
a cetyl-r-D-ga la ctop yr a n osid e (12). (a) Acetobromogalac-
tose (1, 235 mg, 0.57 mmol) and sulfide 8 (375 mg, 1.69 mmol)
were dissolved in dry benzene (3 mL). Hexabutyldistannane
(0.42 mL, 0.84 mmol) was added, and the mixture was treated
as in the preparation of 10 (a) to give 12 as a syrup (182 mg,
72%) after 13 h of irradiation and purification by chromatog-
Meth yl 2,3-An h ydr o-6-deoxy-6-(2-(acetoxym eth yl)pr op-
2-en -1-yl)-R-D-a llop yr a n osid e (15). (a) Methyl 2,3-anhydro-
6-bromo-6-deoxy-R-D-allopyranoside6 (2, 604 mg, 2.52 mmol)
and sulfide 8 (1.66 g, 7.46 mmol) were dissolved in dry benzene
(14 mL). Hexabutyldistannane (1.90 mL, 3.79 mmol) was
added, and the mixture was treated as in the preparation of
10 (a) to give 15 as a syrup (621 mg, 90%) and recovered 8
(707 mg, 43%), after 4 h of irradiation and purification by
raphy. [R]23 +72° (c 1.6, CHCl3). 1H-NMR data (CDCl3): δ
D
5.41 (dd, 1 H, J ) 2.4, 2.9 Hz), 5.27 (dd, 1 H, J ) 5.0, 9.3 Hz),
5.21 (dd, 1 H, J ) 3.2, 9.3 Hz), 5.17 (br s, 1 H), 5.06 (br s, 1
H), 4.60, 4.52 (ABq, 2 H, J ) 13.3 Hz), 4.43 (ddd, 1 H, J ) 3.9,
4.9, 10.8 Hz), 4.22-4.05 (m, 3 H), 2.50 (dd, 1 H, J ) 11.0, 15.4
Hz), 2.25 (dd, 1 H, J ) 3.9, 15.4 Hz), 2.12, 2.08, 2.022, 2.017
(4 s, 15 H). 13C-NMR data (CDCl3): δ 170.5, 170.0, 169.9,
169.7, 139.7, 115.9, 70.5, 68.4, 68.2, 67.8, 67.5, 66.6, 61.3, 30.0,
20.8, 20.7, 20.6. HRMS calcd for C20H32O11N (M + NH4+):
462.1975, found 462.1982.
chromatography. [R]23 +97° (c 0.56, CHCl3). 1H-NMR data
D
(CDCl3): δ 5.04 (br s, 1 H), 4.97 (br s, 1 H), 4.85 (d, 1 H, J )
3.2 Hz), 4.52 (s, 2 H), 3.63 (ddd, 1 H, J ) 1.6, 9.3, 9.8 Hz),
3.56 (dd, 1 H, J ) 3.2, 4.2 Hz), 3.52 (m, 1 H), 3.45 (s, 3 H),
3.44 (m, 1 H), 2.29 (m, 1 H), 2.08 (s, 3 H), 2.14-1.97 (m, 2 H),
1.52 (m, 1 H). 13C-NMR data (CDCl3): δ 170.8, 143.2, 112.6,

7466 J . Org. Chem., Vol. 61, No. 21, 1996
Ponte´n and Magnusson
94.5, 69.6, 68.4, 66.8, 55.8, 55.73, 55.69, 54.1, 29.4, 20.9.
HRMS calcd for C13H24O6N (M + NH4+): 290.1604, found
290.1606. Compound 15 was acetylated with Ac2O and
pyridine: 1H-NMR data (CDCl3): δ 5.06 (br s, 1 H), 4.95 (br s,
1 H), 4.87 (d, 1 H, J ) 2.4 Hz), 4.85 (dd, 1 H, J ) 1.5, 9.3 Hz),
4.51 (br s, 2 H), 3.82 (ddd, 1 H, J ) 2.4, 9.6, 9.7 Hz), 3.53 (dd,
1 H, J ) 2.8, 4.2 Hz), 3.51 (dd, 1 H, J ) 1.4, 4.2 Hz), 3.47 (s,
3 H), 2.29 (ddd, 1 H, J ) 4.9, 5.1, 10.2 Hz), 2.13 (s, 3 H), 2.08
(s, 3 H), 2.10-2.00 (m, 1H), 1.73 (m, 1 H), 1.50 (m, 1 H).
(b) Methyl 2,3-anhydro-6-bromo-6-deoxy-R-D-allopyranoside
(2, 175 mg, 0.73 mmol) and sulfone 9 (466 mg, 1.83 mmol) were
dissolved in dry benzene (4 mL). Hexabutyldistannane (0.55
mL, 1.10 mmol) was added, and the mixture was treated as
in the preparation of 10 (b) to give 15 (167 mg, 84%) and
recovered 2 (20 mg, 11%), after 13 h of irradiation and
purification by chromatography.
2.38 mmol) were dissolved in dry benzene (4.4 mL). Hexabu-
tyldistannane (0.60 mL, 1.20 mmol) was added, and the
mixture was treated as in the preparation of 10 (b) to give 16
(208 mg, 70%) and recovered 3 (58 mg, 21%), after 11 h of
irradiation and purification by chromatography.
2-(Br om om eth yl)p r op -2-en -1-yl Aceta te (18). 3-Bromo-
2-(bromomethyl)propyl acetate12 (7.87 g, 28.7 mmol) was
dissolved in a stirred solution of tetrabutylammonium fluoride
in MeCN (0.194 M, 78.2 mmol, 400 mL). After 17 min, the
starting material had been consumed (GC, RSL-150, nonpolar
polydimethoxysiloxane capillary column, 100 °C), and an
aqueous solution of calcium nitrate (400 mL, approximately 2
M) was added to quench the fluoride ions. The bulk of CH3-
CN was removed, and the aqueous residue was extracted with
ether (4 × 100 mL). The ether extract was dried (Na2SO4)
and concentrated to give crude 18 (5.0 g). Distillation of the
crude product gave pure 18 (4.21 g, 76%). Bp 52-56 °C/1
mmHg. 1H-NMR data (CDCl3): δ 5.38 (m, 1 H), 5.27 (m, 1
H), 4.71 (s, 2 H), 4.01 (d, J ) 0.8 Hz, 2 H), 2.10 (s, 3 H). 13C-
NMR data (CDCl3): δ 170.4, 140.2, 118.2, 64.3, 32.5, 28.8.
Anal. Calcd for C6H9BrO2: C 37.3, H 4.7. Found: C 37.4; H,
4.7.
Meth yl 2,3-An h yd r o-4-O-ben zoyl-6-d eoxy-6-(2-(eth oxy-
car bon yl)pr op-2-en -1-yl)-r-D-allopyr an oside (16). (a) Meth-
yl 2,3-anhydro-4-O-benzoyl-6-bromo-6-deoxy-R-D-allopyrano-
side (3, 249 mg, 0.73 mmol) and sulfide 6 (487 mg, 2.19 mmol)
were dissolved in dry benzene (4.1 mL). Hexabutyldistannane
(0.55 mL, 1.10 mmol) was added, and the mixture was treated
as in the preparation of 10 (a) to give 16 as a syrup (209 mg,
76%) after 4 h of irradiation and purification by chromatog-
raphy. [R]23 +157° (c 1.1, CHCl3). 1H-NMR data (CDCl3): δ
D
Ack n ow led gm en t. This work was supported by the
Swedish Natural Science Research Council.
8.05 (m, 2 H), 7.58 (m, 1 H), 7.45 (m, 2 H), 6.15 (br s, 1 H),
5.52 (m, 1 H), 5.13 (dd, 1 H, J ) 1.6, 9.6 Hz), 4.94 (d, 1 H, J
) 2.9 Hz), 4.13 (q, 2 H, J ) 7.0 Hz), 4.02 (dt, 1 H, J ) 2.1, 9.6
Hz), 3.63 (dd, 1 H, J ) 1.5, 4.1 Hz), 3.59 (dd, 1 H, J ) 3.0, 4.1
Hz), 3.53 (s, 3 H), 2.58 (ddd, 1 H, J ) 4.6, 10.4, 14.9 Hz), 2.33
(m, 1 H), 1.84 (m, 1 H), 1.59 (m, 1 H), 1.21 (t, 3 H, J ) 7.1 Hz).
13C-NMR data (CDCl3): δ 166.9, 166.0, 140.0, 133.5, 129.8,
128.5, 124.9, 94.6, 71.4, 65.6, 60.6, 56.0, 54.8, 51.5, 30.1, 28.0,
14.1. HRMS calcd for C20H28O7N (M + NH4+): 394.1866, found
394.1859.
Su p p or tin g In for m a tion Ava ila ble: 1H NMR spectra
and 1H NMR data with peak assignments for all title com-
pounds described in the Experimental Section (20 pages). This
material is contained in libraries on microfiche, immediately
follows this article in the microfilm version of the journal, and
can be ordered from the ACS; see any current masthead page
for ordering information.
(b) Methyl 2,3-anhydro-4-O-benzoyl-6-bromo-6-deoxy-R-D-
allopyranoside (3, 271 mg, 0.79 mmol) and sulfone 7 (606 mg,
J O960749L