A general and diastereoselective route to five-membered Carbocycles and Heterocycles from Acyclic Vinyl Sulfone-Modified Carbohydrates

Article abstract of DOI:10.1002/ejoc.200900957

Pentosyl and hexosyl acyclic vinyl sulfones having a suitably positioned leaving group reacted with externally delivered carbon, nitrogen, oxygen, and sulfur nucleophiles to afford a series of five-membered carbocycles and heterocycles in a diastereoselective fashion. This diversity-oriented synthetic method generates a wide range of chirally pure cyclic compounds from easily accessible starting materials and reagents,

Full text of DOI:10.1002/ejoc.200900957

FULL PAPER
DOI: 10.1002/ejoc.200900957
A General and Diastereoselective Route to Five-Membered Carbocycles and
Heterocycles from Acyclic Vinyl Sulfone-Modified Carbohydrates
Ananta Kumar Atta[a] and Tanmaya Pathak*[a]
Keywords: Acyclic vinyl sulfones / Carbohydrates / Carbocycles / Heterocycles / Desulfonylation
Pentosyl and hexosyl acyclic vinyl sulfones having a suitably
positioned leaving group reacted with externally delivered
carbon, nitrogen, oxygen, and sulfur nucleophiles to afford a
series of five-membered carbocycles and heterocycles in a
diastereoselective fashion. This diversity-oriented synthetic
method generates a wide range of chirally pure cyclic com-
pounds from easily accessible starting materials and rea-
gents.
various functional groups attached to the ring structure.[2,5]
Some of these strategies have also been utilized, albeit less
frequently, for the synthesis of tetrahydrothiophene deriva-
tives.[1t,6] A selection of the targeted structures by other
groups reported in the literature are depicted in Figure 1.
We were also intrigued by the number of five-membered
carbocycles or heterocycles as intermediates or final prod-
ucts having sulfone groups attached to the ring known so
far (Figure 2).
Introduction
The importance of five-membered heterocycles[1] and
carbocycles[2] in natural products and pharmaceuticals led
to outstanding developments in the area of synthetic strate-
gies for achieving these structures. Tetrahydrofurans, for ex-
ample, are among the most significant classes of heterocy-
cles in natural products, and consequently a wide range of
methods for synthesis has been developed.[1a–1c,1h,1l,1n,1s–1v,3]
The N-containing five-membered core is a structural motif
of particular interest in synthetic and medicinal chemistry,
as it is present in a large number of natural products and
biologically active compounds.[1d,1j–1t,1v,1w,4] The impor-
tance of natural products and pharmaceuticals containing
the cyclopentyl moiety has also led to the development of
numerous synthetic methods to construct such rings with
Figure 2. Five-membered carbocycles or heterocycles with sulfone
groups on the ring.
Results and Discussion
Figure 1. Five-membered carbocycle or heterocycle structures re-
ported by other groups.
Several attempts have been made in the past to develop
general strategies for the synthesis of five-membered car-
bocycles and heterocycles from carbohydrates. For example,
reactions like free radical cyclizations,[2a,2b] transition-
metal-mediated deoxygenative ring contractions,[2b,2f] and
olefin metathesis[2g] have been applied in the recent past for
the conversion of carbohydrates to carbocycles. On the
[a] Department of Chemistry, Indian Institute of Technology
Kharagpur
Kharagpur 721302, India
E-mail: tpathak@chem.iitkgp.ernet.in
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejoc.200900957.
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Route to Five-Membered Carbocycles and Heterocycles
other hand, carbohydrates were also found to be useful and DMSO/NaCl to generate single diastereomers 4 and 5,
starting materials for the synthesis of heterocycles.[1e–1g,1i] respectively. The THF solution of 1 was separately treated
However, to the best of our knowledge, virtually no method with 30% aq. ammonia and 40% aq. methylamine solutions
involving carbohydrates had the potential to be used as a to generate a mixture of products in each case; these mix-
general strategy for the synthesis of carbocycles as well as tures were also treated with K2CO3/MeOH to afford single
heterocycles containing O-, N-, and S-.
isomers 6 and 7, respectively. On the other hand, 1 was
In continuation of our research on the designing of stra- treated with neat benzylamine, 2-picolylamine, and 4-
tegies for the synthesis of carbocycles[7a,7b] and heterocy- picolylamine to generate mixtures; separate treatment of
cles[7c] starting from vinyl sulfone-modified carbohydrates,[8] these mixtures with K2CO3/MeOH generated single dia-
we envisioned that by properly designing acyclic vinyl sul- stereomers 8, 9, and 10, respectively. Pentosyl vinyl sulfone
fone-modified carbohydrates,[8b] it would be possible to syn- 1 also reacted with the oxygen nucleophile generated from
thesize analogs of carbocycles and heterocycles depicted in aq. KOH to afford a single isomer 11. Reaction of Na2S
Figure 1 and Figure 2. Since carbon and other heteroatomic with 1 afforded a tetrahydrothiophene derivative, which was
nucleophiles react efficiently at the electrophilic β-position oxidized with magnesium bis(monoperoxyphthalate) hexa-
of vinylic sulfones,[8] we opined that the vinyl sulfone group hydrate (MMPP) to form 12 in good overall yield
of the acyclic carbohydrate-modified vinyl sulfones with a (Scheme 2).
properly positioned leaving group as in A (Scheme 1) would
be in a position to react with externally delivered nucleo-
philes preferentially; intermediate B would then intramolec-
ularly attack the carbon atom bearing the mesylate group
in SN2 fashion, causing ring formation with complete
stereocontrol to afford compound C. It should be noted
that the selection of nucleophiles with two abstractable pro-
tons would rule out the possibility of formation of cyclo-
propanes D via intermediates BЈ as reported earlier,[7a,7b]
because in all cases the hydrogen atom attached to the in-
tramolecular nucleophile such as -CH, -NH, -OH, or -SH
(as in B) would be more easily abstracted than the proton
attached to the sulfone-bearing carbon atom. Since the
vinyl sulfone group is implanted on carbohydrate moieties,
the chiral environment of the parent carbohydrate molecule
would be transferred to the cyclic compounds.
Scheme 1. General strategy for the synthesis of five-membered
carbocycles and heterocycles.
Scheme 2. Synthesis of five-membered carbocycles and heterocycles
from pentosyl acyclic vinyl sulfone.
Following this strategy, carbon nucleophiles generated
from active methylene groups of dimethyl malonate, diethyl
malonate, and malononitrile were treated with the pentosyl
In order to establish the general reaction patterns of acy-
acyclic vinyl sulfone 1[7a] (Scheme 2), which yielded a mix- clic vinyl sulfones, hexosyl vinyl sulfone 13[7a] was treated
ture of compounds in each case. The mixture obtained from with carbon nucleophiles generated from dimethyl malonate
dimethyl malonate was treated with K2CO3/MeOH to ob- and diethyl malonate, as reported earlier, to afford 14 and
tain a single diastereomer 2 (Scheme 2). Compound 2 was 15, respectively (Scheme 3). However, malononitrile reacted
converted into the corresponding alcohol 3 by LAH in with 13 to generate 16 without base treatment. Compound
THF. Similarly, mixtures produced by diethyl malonate and 13 was treated with 30% aq. ammonia solution, 40% aq.
malononitrile were separately treated with K2CO3/EtOH methylamine solution, neat benzylamine, and 2-picolyl-
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amine in the same way described above to afford 17, 18, 19,
and 20, respectively. Vinyl sulfone 13 was treated with Na2S,
and the product was oxidized to compound 21 with MMPP
(Scheme 3). It should be noted that the stereochemistry at
C-3 of 1 and 13 was known, and it was expected that the
intramolecular backside attack would invert the configura-
tion of C-4 centers. Since the carbon center attached to
SO2Ar in cyclized products corresponding to C-2 of 1 or
13 would be the newly generated stereocenter, it was neces-
sary to establish the configuration of this center. The struc-
ture of compound 3 obtained from 2 was confirmed by the
X-ray diffraction analysis of the former (Figure 3). The ste-
reochemistry of compounds 4 and 5 were expected to be
similar to that of 2; a comparison of the spectroscopic data
of 4 and 5 with those of 2 also confirmed this hypothesis.
Compound 6 was treated with methyl iodide and benzyl
bromide separately to afford N-methylated 7 and N-benzyl-
ated 8, respectively. Since the stereochemistry of 8 was con-
firmed by the X-ray diffraction analysis (Figure 4), the con-
figurations at various carbon centers of 6 and 7 were auto-
1
matically established. The H NMR spectral pattern of 9
was comparable to that of 8, proving thereby the structural
similarities of the two compounds. We expected compounds
10, 11, and 12 to have the same stereochemistry like other
compounds in this series. The stereochemistry of SO2Ar-
bearing carbon of 14 was confirmed by COSY-NOESY ex-
periments, and we presumed that compounds 14 and 15 had
similar stereochemistries. Compound 17 was treated with
methyl iodide and benzyl bromide separately to afford N-
methylated 18 and N-benzylated 19, respectively. The
stereochemistry of 19 was also confirmed by COSY-
NOESY experiments, which established the similarity in the
Scheme 3. Synthesis of five-membered carbocycles and heterocycles
from hexosyl acyclic vinyl sulfone.
1
structural patterns of 17–19. The H NMR spectral pattern
of 20 was comparable to that of 19, proving thereby the
structural similarities of the two compounds. We expected
the chiralities on the ring carbons of 21 to be the same as
those of other compounds in this series.
It should be noted that, in most of the cases, after the
attack of a nucleophile at the electron-deficient methylene
carbon of 1 or 13, the mixture is constituted of two dia-
stereomers generated by the scrambling of the carbon cen-
ter attached to the -SO2Ar group. This was confirmed by
1
the H NMR spectra of any of the mixtures in which the
peak of mesylate was absent. These compounds were con-
verted to single diastereomers like 2, 4, 5–10 (Scheme 2),
14, 15, and 17–20 (Scheme 3) by treating the mixtures with
K2CO3/MeOH. However, the K2CO3/MeOH system hy-
drolyzed the products generated by the reaction of ma-
lononitrile and 1; therefore, the original mixture was treated
with DMSO/NaCl at an elevated temperature to afford a
single compound 5. We presume that under these reaction
conditions the epimeric mixture (at SO2Ar-bearing carbon)
Figure 3. The crystal structure of compound 3.
It is clear from most of the reported synthetic strategies
isomerized to the more stable epimer. Another malononi- for the preparation of five-membered carbocycles and
trile product, 16, obtained as a single epimer from 13 heterocycles that the carbon or the heteroatom that is des-
(Scheme 3), did not undergo any further transformation tined to become part of the ring structure is a constituent
when treated with DMSO/NaCl. The structure of 16, con- of the predesigned substrate undergoing the cyclization
sidered as an exception, was confirmed by X-ray diffraction reaction.[1a–1g,1j,1m–1q,1t,1v,1w,2a–2c,2f,2i,9] All these strate-
analysis (Figure 5).
gies,[1a–1g,1j,1m–1q,1t,1v,1w,2a–2c,2f,2i,9] therefore require the te-
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Route to Five-Membered Carbocycles and Heterocycles
moved from the desulfonylated product to afford 23. Benzyl
protected amine 8 and furanose derivative 11 were desulfo-
nylated by the same reagent to afford compounds 24 and
25, respectively, in moderate yields. Compounds 14 and 18
were also desulfonylated to afford 26 and 27, respectively. It
is known that the desulfonylation is initiated by an electron
transfer to the sulfone group; the loss of arenesulfinate
anion generates a β-hydroxy or β-alkoxy carbanion, which
undergoes elimination to afford an olefin.[10] This phenom-
ena may explain the formation of olefin compounds 22, 24–
27. We also observed earlier that olefin formation during
desulfonylation of furanose systems was the most domina-
ting reaction pathway.[11]
Table 1. Desulfonylation of selected compounds.
Figure 4. The crystal structure of compound 8.
Figure 5. The crystal structure of compound 16.
dious synthesis of separate starting materials for the prepa-
ration of carbocycles as well as each of N-, O-, or S-con-
taining heterocycles.[1,2,9] We, on the other hand, used a di-
versity-oriented synthetic method by reacting easily access-
ible starting materials like 1 or 13 with inexpensive nucleo-
philes like amines, KOH, Na2S, dialkyl malonates, and ma-
lononitrile.
All compounds, 2–12, 14–21, generated so far had the
sulfone group attached to them. Since one of our target
group of molecules was five-membered carbocycles and het-
erocycles without the sulfone group (Figure 1), we experi-
mented with several desulfonylating agents known in the
literature[10] for the desulfonylation of a group of selected
compounds. Na(Hg) mediated reduction, the most widely
used radical-based method for the desulfonylation of or-
ganic molecules,[10] was used for the desulfonylation of com-
However, in one case exclusive desulfonylation generated
pound 2 to afford 22 (Table 1). In the case of compound 6, the deoxy derivative 23. It appears that the presence of an
it was necessary to block the free NH group with Boc be- electron-withdrawing group like “Boc” used for the protec-
fore desulfonylation with Na(Hg); the Boc group was re- tion of the ring nitrogen prevented olefin formation. We
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A. K. Atta, T. Pathak
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Compound 3: To a well-stirred solution of 2 (0.15 g, 0.27 mmol) in
dry THF (20 mL) was added LAH (0.06 g, 1.62 mmol) at 0 °C un-
der argon, and the mixture was stirred at ambient temperature.
After 6 h, saturated NH4Cl solution was added, and the product
was extracted with EtOAC (3ϫ15 mL). The combined organic
layer was dried with anhyd. Na2SO4 and filtered; the filtrate was
concentrated under reduced pressure. The residue was purified over
silica gel to afford 3 (0.08 g, 60%). White solid, m.p 132 °C, [α]2D4
also used the other well-known electron-transfer method
with Mg metal in methanol,[10] but the products were ob-
tained in reduced yields. The Mg-MeOH-NiBr2 desulfo-
nylating reagent, used successfully in the synthesis of 2,3-
dideoxyaminopentofuranosides,[11] failed to generate any
desulfonylated compounds. In an alternative approach, the
exocyclic sulfonyl groups of 12 and 21 were removed by
DBU treatment via an elimination process to generate a
new series of vinyl sulfones 28 and 29, respectively (Table 1).
1
= +3.5 (c = 0.30, CHCl3). H NMR (400 MHz, CDCl3): δ = 1.66
(dd, J = 8.4, 14.0 Hz, 1 H), 1.99–2.05 (m, 1 H), 2.32–2.37 (m, 1
H), 2.44 (s, 3 H), 2.94 (br. s, 1 H), 3.45 (d, J = 11.2 Hz, 1 H), 3.53–
3.75 (m, 6 H), 3.85 (br. s, 1 H), 4.34 (d, J = 12 Hz, 1 H), 4.48–4.57
(m, 4 H), 7.17–7.19 (m, 2 H), 7.26–7.36 (m, 10 H), 7.76 (d, J =
8.4 Hz, 2 H) ppm. 13C NMR (100 MHz, CDCl3): δ = 21.6, 32.6
(CH2), 51.3, 51.5, 63.5 (CH2), 66.0 (CH2), 68.6 (CH2), 69.0, 71.6
(CH2), 73.7 (CH2), 81.0, 127.8, 127.9, 128.0, 128.1, 128.4, 128.5,
128.6, 130.0, 135.1, 136.7, 136.9, 145.0 ppm. HRMS (ES+): calcd.
for C29H34O6SNa [M + Na]+ 533.1974; found 533.1978.
Conclusions
We have established that suitably functionalized acyclic
chiral vinyl sulfones can be used effectively for the synthesis
of carbocycles, pyrrolidines, tetrahydrofurans, and tetra-
hydrothiophenes by externally delivering different nucleo-
philes in a diastereoselective fashion to substrates like 1 or
13. It should be noted that our strategy avoids the prior
synthesis of separate starting materials for the preparation
of carbocycles as well as each of O-, N-, or S-containing
heterocycles. Since each of our starting materials, 1 or 13,
is capable of producing a plethora of cyclic compounds by
reacting with simple nucleophiles, this expedient and gene-
ral strategy would certainly enrich the arsenal of synthetic
chemists interested in the preparation of any of these five-
membered cyclic compounds.
Compound 4: To a well-stirred solution of compound 1 (0.15 g,
0.283 mmol) in 1,4-dioxane (10 mL) was added the solution of di-
ethyl malonate (0.2 mL, 1.42 mmol) in oil-free NaH (0.02 g,
0.85 mmol). The mixture was stirred under N2. After 5 h, dioxane
was removed under vacuum, and the reaction mixture was poured
into saturated aq. NaHCO3 solution. The product was extracted
with EtOAc (3ϫ20 mL). The combined organic layer was dried
with anhyd. Na2SO4 and filtered; the filtrate was concentrated un-
der reduced pressure. The residue was just passed through a silica
gel column. A solution of the residue in EtOH (20 mL) was treated
with K2CO3 (0.117 g, 0.85 mmol). After 5 h, EtOH was removed
under reduced pressure, and the residue was poured into saturated
aq. NaHCO3 solution. The aqueous part was washed with EtOAc
(3ϫ20 mL). The combined organic layer was dried with anhyd.
Na2SO4 and filtered; the filtrate was concentrated under reduced
pressure. The residue was purified over silica gel to afford 4 (0.13 g,
82%). Colorless oil, [α]2D7 = +85.1 (c = 0.29, CHCl3). 1H NMR
(400 MHz, CDCl3): δ = 1.08 (t, J = 7.2 Hz, 3 H), 1.23 (t, J =
7.2 Hz, 3 H), 2.30 (dd, J = 8.0, 14.0 Hz, 1 H), 2.43 (s, 3 H), 2.92
(dd, J = 9.6, 13.6 Hz, 1 H), 3.01–3.05 (m, 1 H), 3.68–3.84 (m, 3
H), 4.00–4.06 (m, 2 H), 4.14–4.31 (m, 4 H), 4.41 (d, J = 12.0 Hz,
1 H), 4.49 (d, J = 12.0 Hz, 1 H), 4.53–4.56 (m, 1 H), 7.05–7.07 (m,
2 H), 7.23–7.34 (m, 10 H), 7.78 (d, J = 8.4 Hz, 2 H) ppm. 13C
NMR (100 MHz, CDCl3): δ = 13.8, 13.9, 21.6, 33.5 (CH2), 50.2,
60.4, 61.6 (CH2), 61.9 (CH2), 65.7 (CH2), 68.1, 71.5 (CH2), 73.0
(CH2), 78.8, 127.2, 127.3, 127.4, 127.5, 128.1, 128.2, 128.6, 129.9,
135.1, 137.5, 138.3, 144.9, 168.9, 169.9 ppm. HRMS (ES+): calcd.
for C33H38O8SNa [M + Na]+ 617.2186; found 617.2185.
Experimental Section
General Methods: See Supporting Information.
Compound 2: To a well-stirred solution of compound 1 (0.20 g,
0.38 mmol) in 1,4-dioxane. (10 mL) was added the solution of di-
methyl malonate (0.2 mL, 1.9 mmol) in oil-free NaH (0.027 g,
1.14 mmol). The mixture was stirred under N2. After 4–5 h, diox-
ane was removed under vacuum, and the reaction mixture was
poured into saturated aq. NaHCO3 solution. The product was ex-
tracted with EtOAc (3ϫ20 mL). The combined organic layer was
dried with anhyd. Na2SO4 and filtered; the filtrate was concen-
trated under reduced pressure. The residue was passed through a
silica gel column. A solution of the residue in MeOH (20 mL) was
treated with K2CO3 (0.158 g, 1.14 mmol). After 5 h, MeOH was
removed under reduced pressure, and the residue was poured into
saturated aq. NaHCO3 solution. The aqueous part was washed
with EtOAc (3ϫ20 mL). The combined organic layer was dried
with anhyd. Na2SO4 and filtered; the filtrate was concentrated un-
der reduced pressure. The residue was purified over silica gel to
afford 2 (0.18 g, 85%). Colorless oil, [α]2D4 = +96.5 (c = 0.30,
Compound 5: To a well-stirred solution of compound 1 (0.20 g,
0.38 mmol) in 1,4-dioxane (40 mL) was added the solution of ma-
lononitrile (0.10 mL, 1.9 mmol) in oil-free NaH (0.027 g,
1.14 mmol). Then the mixture was stirred under N2. After 5 h, di-
oxane was evaporated, the reaction mixture was poured into satu-
CHCl ). IR (CHCl ): ν = 1458, 1498, 1560, 1637, 1654, 1719, rated aq. NaHCO3 solution, and the product was extracted with
˜
3
3
1735 cm–1. 1H NMR (400 MHz, CDCl3): δ = 2.33 (dd, J = 8.0,
EtOAc (3ϫ20 mL). The combined organic layer was dried with
14.0 Hz, 1 H), 2.43 (s, 3 H), 2.91 (dd, J = 9.6, 14.0 Hz, 1 H), 3.05 anhyd. Na2SO4 and filtered; the filtrate was concentrated under
(q, J = 5.6, 12.8 Hz, 1 H), 3.54 (s, 3 H), 3.68–3.72 (m, 2 H), 3.74
(s, 3 H), 3.75–3.81 (m, 1 H), 4.28 (q, J = 11.6, 16.8 Hz, 2 H), 4.41
(d, J = 12.0 Hz, 1 H), 4.47 (d, J = 12.0 Hz, 1 H), 4.53–4.55 (m, 1
reduced pressure. The residue was passed through a silica gel col-
umn. The residue was heated at 120–130 °C with a mixture of NaCl
(0.12 g, 1.9 mmol) in DMSO (15 mL) and H2O (1.5 mL). After
H), 7.05–7.07 (m, 2 H), 7.21–7.35 (m, 10 H), 7.78 (d, J = 8.0 Hz, 30 h, saturated aq. NaHCO3 solution was added, and the mixture
2 H) ppm. 13C NMR (100 MHz, CDCl3): δ = 21.6, 33.6 (CH2), was extracted with EtOAc (3ϫ20 mL). The combined organic layer
50.4, 52.5, 53.0, 60.3, 65.6 (CH2), 68.0, 71.5 (CH2), 73.0 (CH2), was dried with anhyd. Na2SO4 and filtered; the filtrate was concen-
78.7, 127.2, 127.4, 127.5, 128.1, 128.2, 128.6, 130.0, 135.1, 137.5,
138.3, 145.0, 169.4, 170.4 ppm. HRMS (ES+): calcd. for
C31H34O8SNa [M + Na]+ 589.1872; found 589.1871.
trated under reduced pressure. The residue was purified over silica
gel to afford 5 (0.14 g, 79%). Gummy liquid, [α]2D7 = +62.2 (c =
0.09, CHCl ). IR (CDCl ): ν = 1155, 1304, 1454, 1498, 1597, 2252,
˜
3
3
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Route to Five-Membered Carbocycles and Heterocycles
1
2873, 3031 cm–1. H NMR (400 MHz, CDCl3): δ = 2.49 (s, 3 H), J = 13.2 Hz, 1 H), 4.36–4.48 (m, 5 H), 7.15–7.16 (m, 2 H), 7.20–
2.74 (dd, J = 8.0, 14.4 Hz, 1 H), 2.84 (dd, J = 9.2, 14.8 Hz, 1 H),
2.97–3.02 (m, 1 H), 3.79–3.83 (m, 2 H), 3.91 (t, J = 8.4 Hz, 1 H),
7.33 (m, 15 H), 7.73 (d, J = 8.4 Hz, 2 H) ppm. 13C NMR
(100 MHz, CDCl3): δ = 21.6, 52.3 (CH2), 58.1 (CH2), 67.0, 68.6,
4.36 (d, J = 12.4 Hz, 1 H), 4.51–4.55 (m, 3 H), 4.62 (d, J = 11.6 Hz, 68.8 (CH2), 72.0 (CH2), 73.4 (CH2), 79.4, 127.0, 127.5, 127.6, 127.8,
1 H), 7.17–7.19 (m, 2 H), 7.29–7.37 (m, 8 H), 7.41 (d, J = 8.4 Hz, 128.2, 128.4, 128.5, 128.7, 130.0, 135.4, 137.5, 138.1, 138.2, 144.9
2 H), 7.75 (d, J = 8.0 Hz, 2 H) ppm. 13C NMR (100 MHz, CDCl3): ppm. HRMS (ES+): calcd. for C33H36NO4S [M + H]+ 542.2365;
δ = 21.8, 36.5, 38.2 (CH2), 53.9, 65.5 (CH2), 68.1, 71.8 (CH2), 73.8
(CH2), 78.0, 113.7, 115.0, 127.5, 127.7, 127.9, 128.1, 128.4, 128.5,
128.6, 130.5, 133.9, 136.5, 137.2, 146.2 ppm. HRMS (ES+): calcd.
for C29H28N2O4SNa [M + Na]+ 523.1668; found 523.1667.
found 542.2358. Method B: Compound 6 (0.04 g, 0.089 mmol) was
stirred at 0 °C with K2CO3 (0.05 g, 0.36 mmol) and BnBr (0.06 mL,
0.53 mmol) in MeOH. The mixture was stirred at room tempera-
ture under N2. After 7 h, the reaction mixture was poured into a
saturated aq. solution of NH4Cl, and the product was extracted
with EtOAc (3ϫ20 mL). The combined organic layer was dried
with anhyd. Na2SO4 and filtered; the filtrate was concentrated un-
der reduced pressure to get a residue. The residue was purified over
silica gel to afford 8 (0.026 g, 55%).
Compound 6: To a well-stirred solution of compound 1 (0.25 g,
0.472 mmol) in THF (30 mL) was added 30% aq. NH3 solution
(5 mL). After 5 h, THF was evaporated under reduced pressure,
saturated aq. NaHCO3 solution was added, and the product was
extracted with EtOAc (3ϫ20 mL). The combined organic layer was
dried with anhyd. Na2SO4 and concentrated under reduced pres-
sure. The residue was passed through a silica gel column. A solu-
tion of the residue in MeOH (20 mL) was treated with K2CO3
(0.196 g, 1.42 mmol). After 5 h, MeOH was removed under reduced
pressure, and the residue was poured into saturated aq. NaHCO3
solution. The aqueous part was washed with EtOAc (3ϫ20 mL).
The combined organic layer was dried with anhyd. Na2SO4 and
filtered; the filtrate was concentrated under reduced pressure. The
residue was purified over silica gel to afford 6 (0.148 g, 75%).
Gummy liquid, [α]2D7 = +22.2 (c = 0.20, CHCl3). 1H NMR
(400 MHz, CDCl3): δ = 2.45 (s, 3 H), 3.25 (dd, J = 6.4, 12.4 Hz, 1
H), 3.31–3.37 (m, 2 H), 3.57–3.62 (m, 1 H), 3.65–3.70 (m, 2 H),
4.30 (d, J = 11.6 Hz, 1 H), 4.38–4.49 (m, 2 H), 4.52 (q, J = 12.0,
15.2 Hz, 2 H), 7.11–7.13 (m, 2 H), 7.26–7.37 (m, 10 H), 7.78 (d, J
= 8.4 Hz, 2 H) ppm. 13C NMR (100 MHz, CDCl3): δ = 21.6, 46.4
(CH2), 63.0, 68.3 (CH2), 70.4, 71.6 (CH2), 73.4 (CH2), 80.3, 127.5,
127.6, 127.7 (2ϫC), 128.2, 128.3, 130.0, 135.4, 137.3, 138.0, 145.0
ppm. HRMS (ES+): calcd. for C26H30NO4S [M + H]+ 452.1896;
found 452.1882.
Compound 9: A solution of compound 1 (0.10 g, 0.189 mmol) was
treated with neat 2-picolylamine (0.2 mL, 1.89 mmol) following the
procedure described for 6 to afford 9 (0.087 g, 85%). Colorless oil,
[α]2D7 = +50.8 (c = 0.19, CHCl3). 1H NMR (400 MHz, CDCl3): δ =
2.41 (s, 3 H), 2.75–2.80 (m, 1 H), 3.04–3.08 (m, 1 H), 3.19 (t, J =
8.8 Hz, 1 H), 3.62–3.67 (m, 2 H), 3.74–3.79 (m, 2 H), 4.21 (d, J =
14.4 Hz, 1 H), 4.39–4.50 (m, 5 H), 7.12–7.17 (m, 3 H), 7.25–7.32
(m, 10 H), 7.37 (d, J = 7.6 Hz, 1 H), 7.58–7.62 (m, 1 H), 7.74 (d,
J = 8.4 Hz, 2 H), 8.50 (d, J = 4.4 Hz, 1 H) ppm. 13C NMR
(100 MHz, CDCl3): δ = 21.6, 52.6 (CH2), 59.5 (CH2), 66.9, 68.7,
68.8 (CH2), 72.1 (CH2), 73.4 (CH2), 79.3, 122.1, 122.9, 127.6, 127.7,
127.8, 128.3, 128.4, 128.6, 130.0, 135.4, 136.5, 137.6, 138.1, 145.0,
149.0, 158.6 ppm. HRMS (ES+): calcd. for C32H35N2O4S [M +
H]+ 543.2318; found 543.2346.
Compound 10: Compound 1 (0.20 g, 0.37 mmol) was converted to
10 (0.139 g, 66%) by following the procedure described for the
preparation of 9. White liquid, [α]2D4 = +14.4 (c = 0.20, CHCl3). 1H
NMR (400 MHz, CDCl3): δ = 2.42 (s, 3 H), 2.63–2.66 (m, 2 H),
3.03–3.13 (m, 2 H), 3.46 (d, J = 14.8 Hz, 1 H), 3.59–3.63 (m, 1 H),
3.72–3.75 (m, 2 H), 4.16 (d, J = 14.8 Hz, 1 H), 4.35–4.48 (m, 4 H),
7.15–7.16 (m, 2 H), 7.24–7.37 (m, 12 H), 7.74 (d, J = 8.0 Hz, 2 H),
8.49 (br. s, 2 H) ppm. 13C NMR (100 MHz, CDCl3): δ = 21.6, 52.5
(CH2), 57.0 (CH2), 67.0, 68.6, 68.9 (CH2), 72.0 (CH2), 73.4 (CH2),
79.1, 123.5, 127.6, 127.7, 127.8 (2ϫC), 127.9, 128.3, 128.4, 130.0,
135.2, 137.3, 137.8, 145.1, 148.7, 149.0 ppm. HRMS (ES+): calcd.
for C32H35N2O4S [M + H]+ 543.2318; found 543.2336.
Compound 7: Method A: A solution of compound 1 (0.15 g,
0.283 mmol) in THF (10 mL) was treated with 40% aq. methyl-
amine solution (5 mL) following the procedure described for 6 to
afford 7 (0.117 g, 89%). Colorless oil, [α]2D7 = +61.2 (c = 0.24,
1
CHCl3). H NMR (400 MHz, CDCl3): δ = 2.36 (s, 3 H), 2.45 (s, 3
H), 2.57–2.65 (m, 2 H), 3.22 (t, J = 9.2 Hz, 1 H), 3.57–3.61 (m, 1
H), 3.71–3.77 (m, 2 H), 4.33 (d, J = 12.0 Hz, 1 H), 4.41–4.47 (m,
4 H), 7.16–7.18 (m, 2 H), 7.25–7.37 (m, 10 H), 7.79 (d, J = 8.0 Hz,
2 H) ppm. 13C NMR (100 MHz, CDCl3): δ = 21.7, 40.8, 55.7
(CH2), 68.5 (CH2), 68.6, 69.1, 71.7 (CH2), 73.4 (CH2), 79.5, 127.6,
127.8, 128.2, 128.4, 128.5, 130.1, 135.4, 137.5, 138.1, 145.1 ppm.
HRMS (ES+): calcd. for C27H32NO4S [M + H]+ 466.2052; found
466.2031. Method B: Compound 6 (0.05 g, 0.11 mmol) was stirred
at 0 °C with K2CO3 (0.06 g, 0.44 mmol) and MeI (0.04 mL,
0.66 mmol) in MeOH. The mixture was stirred at room tempera-
ture under N2. After 7 h, the reaction mixture was poured into a
saturated aq. solution of NH4Cl, and the product was extracted
with EtOAc (3ϫ20 mL). The combined organic layer was dried
with anhyd. Na2SO4 and filtered; the filtrate was concentrated un-
der reduced pressure to obtain a residue. The residue was purified
over silica gel to afford 7 (0.034 g, 65%).
Compound 11: To a well-stirred solution of compound 1 (0.15 g,
0.283 mmol) in THF (10 mL) was added 10% aq. KOH solution.
After 30 h, THF was evaporated under reduced pressure, saturated
aq. NaHCO3 solution was added, and the product was extracted
with EtOAc (3ϫ20 mL). The combined organic layer was dried
with anhyd. Na2SO4 and filtered; the filtrate was concentrated un-
der reduced pressure. The residue was purified over silica gel to
afford 11 (0.11 g, 86%). White gum, [α]2D7 = +37.0 (c = 0.26,
CHCl3). 1H NMR (400 MHz, CDCl3): δ = 2.46 (s, 3 H), 3.70 (d, J
= 5.6 Hz, 2 H), 3.85 (t, J = 8.4 Hz, 1 H), 4.02–4.07 (m, 2 H), 4.21
(t, J = 9.2 Hz, 1 H), 4.43 (d, J = 12.0 Hz, 1 H), 4.45–4.52 (m, 3
H), 4.58 (d, J = 11.6 Hz, 1 H), 7.15–7.17 (m, 2 H), 7.26–7.33 (m,
8 H), 7.37 (d, J = 8.0 Hz, 2 H), 7.77 (d, J = 8.0 Hz, 2 H) ppm. 13C
NMR (100 MHz, CDCl3): δ = 21.6, 66.4 (CH2), 67.9 (CH2), 70.1,
71.6 (CH2), 73.4 (CH2), 79.5, 81.8, 127.6, 127.7, 127.8, 128.3, 128.4,
130.2, 135.1, 137.0, 137.9, 145.4 ppm. HRMS (ES+): calcd. for
C26H28O5SNa [M + Na]+ 475.1550; found 475.1555.
Compound 8: Method A: A solution of compound 1 (0.25 g,
0.472 mmol) was treated with neat benzylamine (0.5 mL,
4.72 mmol) following the procedure described for 6 to afford 8
(0.209 g, 82%). White solid, m.p 82 °C, [α]2D4 = +2.7 (c = 0.09,
CHCl3). 1H NMR (400 MHz, CDCl3): δ = 2.42 (s, 3 H), 2.60–2.64
Compound 12: To a well-stirred solution of compound 1 (0.30 g,
0.566 mmol) in MeOH (30 mL) was added Na2S (0.053 g,
(m, 1 H), 2.95–2.99 (m, 1 H), 3.11 (t, J = 9.2 Hz, 1 H), 3.37 (d, J 0.679 mmol). The mixture was heated at 50 °C with stirring under
= 13.6 Hz, 1 H), 3.62–3.66 (m, 1 H), 3.69–3.79 (m, 2 H), 4.13 (d, N2. After 1 h, MeOH was concentrated to dryness under reduced
Eur. J. Org. Chem. 2010, 872–881
© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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877

A. K. Atta, T. Pathak
FULL PAPER
pressure, and the residue was poured into saturated aq. NaHCO3
solution. The aqueous part was washed with EtOAc (3ϫ20 mL).
The combined organic layer was dried with anhyd. Na2SO4 and
filtered; the filtrate was concentrated under reduced pressure. The
residue was dissolved in dry MeOH (15 mL), and magnesium mon-
operoxyphthalate hexahydrate (0.98 g, 1.98 mmol) was added. Af-
ter 5 h, MeOH was removed under reduced pressure, and the resi-
due was poured into saturated aq. NaHCO3 solution. The aqueous
part was washed with EtOAc (3ϫ20 mL). The combined organic
layer was dried with anhyd. Na2SO4 and filtered; the filtrate was
concentrated under reduced pressure. The residue was purified over
silica gel to afford 12 (0.18 g, 65%). White liquid, [α]2D4 = +24.7 (c
= 0.16, CHCl3). 1H NMR (400 MHz, CDCl3): δ = 2.42 (s, 3 H),
3.37–3.53 (m, 3 H), 3.83 (d, J = 4.4 Hz, 2 H), 4.05–4.11 (m, 1 H),
4.40–4.54 (m, 4 H), 4.77 (t, J = 6.4 Hz, 1 H), 7.10 (d, J = 3.6 Hz,
2 H), 7.26–7.35 (m, 10 H), 7.74 (d, J = 8.0 Hz, 2 H) ppm. 13C
NMR (100 MHz, CDCl3): δ = 21.7, 50.2 (CH2), 62.9 (CH2), 63.0,
64.7, 73.2 (CH2), 73.9 (CH2), 74.4, 127.8, 127.9, 128.0, 128.3, 128.5,
128.7, 130.3, 134.3, 136.2, 137.1, 146.0 ppm. HRMS (ES+): calcd.
for C26H28O6S2Na [M + Na]+ 523.1225; found 523.1217.
57.0, 66.8, (CH2) 67.0, 72.5 (CH2), 73.4 (CH2), 74.1 (CH2), 76.0,
78.4, 115.0, 117.0, 127.6 (2ϫC), 127.9, 128.0 (2ϫC), 128.1, 128.3,
128.4, 128.5, 130.4, 136.0, 137.1, 137.3, 137.4, 145.8 ppm. HRMS
(ES+): calcd. for C37H36N2O5SNa [M + Na]+ 643.2242; found
643.2242.
Compound 17: Compound 13 (0.22 g, 0.338 mmol) was converted
to 17 (0.14 g, 73%) by following the procedure described for the
preparation of 6. Colorless oil, [α]2D7 = –0.86 (c = 0.40, CHCl3). 1H
NMR (400 MHz, CDCl3): δ = 2.43 (s, 3 H), 3.15 (dd, J = 7.2,
11.6 Hz, 1 H), 3.24 (t, J = 6.0 Hz, 1 H), 3.32 (dd, J = 8.4, 11.2 Hz,
1 H), 3.46 (dd, J = 5.2, 10.0 Hz, 1 H), 3.55 (dd, J = 3.6, 10.0 Hz,
1 H), 3.72–3.77 (m, 1 H), 3.86 (q, J = 4.8, 10.8 Hz, 1 H), 4.24 (d,
J = 11.6 Hz, 1 H), 4.36–4.39 (m, 2 H), 4.44–4.53 (m, 3 H), 4.68 (d,
J = 11.2 Hz, 1 H), 7.19–7.36 (m, 17 H), 7.74 (d, J = 8.4 Hz, 2 H)
ppm. 13C NMR (100 MHz, CDCl3): δ = 21.6, 46.5 (CH2), 63.9,
70.2, 70.3 (CH2), 71.2 (CH2), 73.0 (CH2), 73.3 (CH2), 77.9, 79.4,
127.5, 127.6, 127.7, 127.8, 128.1, 128.2, 128.3, 128.4 (2ϫC), 130.0,
135.3, 137.1, 138.1, 138.6, 145.0 ppm. HRMS (ES+): calcd. for
C34H38NO5S [M + H]+ 572.2471; found 572.2438.
Compound 18: Method A: Compound 13 (0.25 g, 0.38 mmol) was
converted to 18 (0.191 g, 85%) by following the procedure de-
scribed for the preparation of 7. White oil, [α]2D7 = +86.7 (c = 0.40,
Compound 14: Compound 13 (0.20 g, 0.37 mmol) was converted
to 14 (0.139 g, 66%) by following the procedure described for the
preparation of 2. White liquid, [α]2D4 = +52.9 (c = 0.33, CHCl3). IR
1
CHCl3). H NMR (400 MHz, CDCl3): δ = 2.39 (s, 3 H), 2.45 (s, 3
(CHCl ): ν = 1086, 1147, 1257, 1654, 1725, 1736 cm–1. 1H NMR
˜
3
H), 2.59–2.64 (m, 1 H), 2.76 (t, J = 5.6 Hz, 1 H), 3.27 (t, J =
8.8 Hz, 1 H), 3.60–3.70 (m, 2 H), 3.80–3.85 (m, 1 H), 3.88–3.91 (m,
1 H), 4.28 (d, J = 11.6 Hz, 1 H), 4.39 (d, J = 12.0 Hz, 1 H), 4.43–
4.48 (m, 3 H), 4.56 (d, J = 11.2 Hz, 1 H), 4.73 (d, J = 11.6 Hz, 1
H), 7.19–7.21 (m, 2 H), 7.28–7.38 (m, 15 H), 7.76 (d, J = 8.4 Hz,
2 H) ppm. 13C NMR (100 MHz, CDCl3): δ = 21.6, 42.3, 55.5
(CH2), 67.9, 69.2, 70.3 (CH2), 71.5 (CH2), 72.5 (CH2), 73.2 (CH2),
78.8, 79.4, 127.4, 127.5, 127.6, 127.7, 127.8, 128.0, 128.2 (2ϫC),
128.3, 128.4, 129.9, 135.4, 137.1, 138.3, 138.5, 144.9 ppm. HRMS
(ES+): calcd. for C35H40NO5S [M + H]+ 586.2624; found 586.2656.
Method B: Compound 17 (0.040 g, 0.069 mmol) was converted to
18 (0.023 g, 57%) by following the procedure described for the
preparation of 7 (Method B).
(400 MHz, CDCl3): δ = 2.26 (dd, J = 9.6, 12.8 Hz, 1 H), 2.44 (s, 3
H), 2.75 (dd, J = 8.4, 12.8 Hz, 1 H), 3.00 (dd, J = 5.6, 10.4 Hz, 1
H), 3.27 (s, 3 H), 3.42 (dd, J = 4.4, 10.8 Hz, 1 H), 3.59 (dd, J =
2.8, 10.8 Hz, 1 H), 3.64–3.69 (m, 4 H), 4.04 (d, J = 12.0 Hz, 1 H),
4.29–4.33 (m, 1 H), 4.39–4.48 (m, 4 H), 4.57 (d, J = 12.0 Hz, 1 H),
4.70 (d, J = 10.4 Hz, 1 H), 7.18 (d, J = 6.4 Hz, 2 H), 7.19–7.39 (m,
15 H), 7.77 (d, J = 8.4 Hz, 2 H) ppm. 13C NMR (100 MHz,
CDCl3): δ = 21.6, 36.1 (CH2), 52.3, 52.4, 55.4, 60.8, 68.3, 70.1
(CH2), 70.2 (CH2), 72.5 (CH2), 73.4 (CH2), 75.8, 77.8, 127.3, 127.5,
127.6 (2ϫC), 127.9, 128.0, 128.2, 128.3, 128.4, 128.6, 130.0, 134.7,
137.3, 138.1, 138.6, 145.1, 169.9, 170.7 ppm. HRMS (ES+): calcd.
for C39H42O9SNa [M + Na]+ 709.2447; found 709.2444.
Compound 15: Compound 13 (0.20 g, 0.308 mmol) was converted
to 15 (0.13 g, 62%) by following the procedure described for the
preparation of 4. Colorless oil, [α]2D7 = +30.4 (c = 0.20, CHCl3). 1H
NMR (400 MHz, CDCl3): δ = 0.94 (t, J = 7.2 Hz, 3 H), 1.18 (t, J
= 7.2 Hz, 3 H), 2.22 (dd, J = 9.6, 12.8 Hz, 1 H), 2.43 (s, 3 H), 2.78
(dd, J = 8.4, 12.8 Hz, 1 H), 2.97 (dd, J = 5.6, 10.4 Hz, 1 H), 3.40
(dd, J = 4.4, 10.4 Hz, 1 H), 3.57 (dd, J = 2.8, 10.8 Hz, 1 H), 3.56–
3.78 (m, 3 H), 4.05–4.21 (m, 3 H), 4.31–4.55 (m, 6 H), 4.68 (d, J
= 10.4 Hz, 1 H), 7.17–7.35 (m, 17 H), 7.77 (d, J = 8.0 Hz, 2 H)
ppm. 13C NMR (100 MHz, CDCl3): δ = 13.5, 14.0, 21.6, 36.2
(CH2), 54.9, 60.9, 61.4 (CH2), 68.4, 70.1 (CH2), 72.2 (CH2), 73.3
(CH2), 75.9, 78.0, 127.2, 127.6, 127.8, 127.9, 128.1, 128.4, 128.6,
130.0, 134.6, 137.3, 138.1, 138.8, 145.0, 169.5, 170.2 ppm. HRMS
(ES+): calcd. for C41H46O9SNa [M + Na]+ 737.2760; found
737.2760.
Compound 19: Method A: Compound 13 (0.225 g, 0.34 mmol) was
converted to 19 (0.174 g, 76%) by following the procedure de-
scribed for the preparation of 8. Semisolid, [α]2D4 = –41.6 (c = 0.09,
1
CHCl3). H NMR (400 MHz, CDCl3): δ = 2.39 (s, 3 H), 2.72 (dd,
J = 4.0, 7.2 Hz, 1 H), 3.17–3.27 (m, 2 H), 3.49 (d, J = 13.2 Hz, 1
H), 3.64–3.74 (m, 2 H), 3.80–3.85 (m, 1 H), 3.89–3.93 (m, 1 H), 4.0
(d, J = 13.2 Hz, 1 H), 4.33–4.39 (m, 4 H), 4.50–4.53 (m, 2 H), 4.69
(d, J = 11.2 Hz, 1 H), 7.09–7.11 (m, 2 H), 7.20–7.32 (m, 20 H),
7.37 (d, J = 4.4 Hz, 2 H) ppm. 13C NMR (100 MHz, CDCl3): δ =
21.6, 51.9 (CH2), 60.1 (CH2), 67.2, 68.9, 70.7 (CH2), 72.4 (CH2),
73.0 (CH2), 73.2 (CH2), 78.6, 79.5, 127.0, 127.4, 127.6
(2ϫC),127.7, 127.8 (2ϫC), 127.9, 128.0 (2ϫC), 128.1 (2ϫC),
128.2 (2ϫC), 128.3 (2ϫC), 128.5 (2ϫC), 128.6, 128.8, 129.8,
135.7, 137.4, 138.3, 138.7, 138.8, 144.7 ppm. HRMS (ES+): calcd.
for C41H44NO5S [M + H]+ 662.2940; found 662.2934. Method B:
Compound 17 (0.03 g, 0.047 mmol) was converted to 19 (0.018 g,
51%) by following the procedure described for the preparation of
8 (Method B).
Compound 16: Compound 13 (0.20 g, 0.308 mmol) was converted
to 16 (0.13 g, 62%) by following the procedure described for the
preparation of 5 without DMSO treatment. White solid, m.p
135 °C, [α]2D7 = +61.0 (c = 0.20, CHCl ). IR (CHCl ): ν = 1086,
Compound 20: Compound 13 (0.20 g, 0.308 mmol) was converted
˜
3
3
1190, 1304, 1317, 1454, 1597, 2253, 2365 cm–1. 1H NMR
to 20 (0.168 g, 83%) by following the procedure described for the
1
(400 MHz, CDCl3): δ = 2.48 (s, 3 H), 2.57 (q, J = 7.6, 13.2 Hz, 1 preparation of 9. Colorless oil, [α]2D7 = –4.2 (c = 0.53, CHCl3). H
H), 2.86 (m, 1 H), 2.97 (m, 1 H), 3.36 (t, J = 12.8 Hz, 1 H), 3.48– NMR (400 MHz, CDCl3): δ = 2.39 (s, 3 H), 2.86 (dd, J = 7.6,
3.50 (m, 2 H), 3.96 (d, J = 9.6 Hz, 1 H), 4.34 (d, J = 12.0 Hz, 1
H), 4.45–4.53 (m, 3 H), 4.61 (q, J = 10.8, 21.6 Hz, 2 H), 5.08 (d, J = 14.4 Hz, 1 H), 3.87–3.95 (m, 2 H), 4.16 (d, J = 14.4 Hz, 1 H),
= 11.6 Hz, 1 H), 7.26–7.39 (m, 17 H), 7.75 (d, J = 7.6 Hz, 2 H) 4.36–4.43 (m, 4 H), 4.48–4.55 (m, 2 H), 4.69 (d, J = 11.2 Hz, 1 H),
ppm. 13C NMR (100 MHz, CDCl3): δ = 21.7, 34.6, 38.0 (CH2), 7.10–7.15 (m, 3 H), 7.24–7.33 (m, 16 H), 7.55–7.60 (m, 1 H), 7.69
11.2 Hz, 1 H), 3.29–3.37 (m, 2 H), 3.61–3.68 (m, 2 H), 3.76 (d, J
878
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Eur. J. Org. Chem. 2010, 872–881

Route to Five-Membered Carbocycles and Heterocycles
(d, J = 8.0 Hz, 2 H), 8.49 (d, J = 4.4 Hz, 1 H) ppm. 13C NMR
H), 3.62–3.74 (m, 2 H), 3.85 (q, J = 9.4, 21.3 Hz, 1 H), 4.14 (d, J
(100 MHz, CDCl3): δ = 21.6, 52.2 (CH2), 61.3 (CH2), 66.8, 68.7, = 26.6 Hz, 1 H), 4.54 (s, 2 H), 5.79–5.83 (m, 2 H), 7.20–7.32 (m,
70.5 (CH2), 72.3 (CH2), 72.9 (CH2), 73.2 (CH2), 78.4, 79.3, 121.9,
10 H) ppm. 13C NMR (50 MHz, CDCl3): δ = 59.7 (CH2), 60.5
122.8, 127.4, 127.5, 127.6 (2ϫC), 127.7, 127.8, 128.1, 128.2, 128.3, (CH2), 70.3, 73.4 (CH2), 74.4 (CH2), 126.8, 127.5, 127.6, 128.0,
128.4, 129.8, 135.6, 136.4, 137.3, 138.2, 138.6, 144.7, 148.9, 158.9
128.2, 128.3, 128.6, 129.4, 138.5, 140.1 ppm. HRMS (ES+): calcd.
ppm. HRMS (ES+): calcd. for C40H43N2O5S [M + H]+ 663.2893; for C19H22NO [M + H]+ 280.1701; found 280.1693.
found 663.2880.
Compound 25: Compound 11 (0.12 g, 0.265 mmol) was converted
to 25 (0.03 g, 55%) by following the procedure described for the
Compound 21: Compound 13 (0.15 g, 0.23 mmol) was converted
to 21 (0.084 g, 62%) by following the procedure described for the
preparation of 12. White liquid, [α]2D4 = –46.7 (c = 0.09, CHCl3).
1H NMR (400 MHz, CDCl3): δ = 2.44 (s, 3 H), 3.32–3.41 (m, 3
H), 3.58 (dd, J = 3.6, 10.4 Hz, 1 H), 3.76–3.80 (m, 1 H), 3.86–3.87
(m, 1 H), 4.23–4.32 (m, 3 H), 4.43–4.49 (m, 2 H), 4.64–4.69 (m, 3
H), 7.13–7.15 (m, 2 H), 7.26–7.39 (m, 15 H), 7.66 (m, J = 8.4 Hz,
2 H) ppm. 13C NMR (100 MHz, CDCl3): δ = 21.7, 49.6 (CH2),
62.9, 64.6, 68.5 (CH2), 71.9 (CH2), 73.2 (CH2), 73.3 (CH2), 73.9,
74.0, 127.7, 127.8, 127.9, 128.0, 128.1, 128.3, 128.5, 128.6, 128.7,
130.4, 133.5, 135.9, 137.6, 137.7, 146.1 ppm. HRMS (ES+): calcd.
for C34H36O7S2Na [M + Na]+ 643.1800; found 643.1804.
1
preparation of 22. White oil, [α]2D7 = +129.2 (c = 0.14, CHCl3). H
NMR (400 MHz, CDCl3): δ = 3.52 (d, J = 4.8 Hz, 2 H), 4.55–4.75
(m, 4 H), 5.0 (br. s, 1 H), 5.80–5.81 (m, 1 H), 5.98 (d, J = 6.0 Hz,
1 H), 7.26–7.35 (m, 5 H) ppm. 13C NMR (100 MHz, CDCl3): δ =
72.7 (CH2), 73.3 (CH2), 75.4 (CH2), 85.4, 126.9, 127.5, 127.6, 128.0,
128.3, 138.2 ppm. HRMS (ES+): calcd. for C12H14O2Na [M +
Na]+ 213.0892; found 213.0892.
Compound 26: Compound 14 (0.05 g, 0.073 mmol) was converted
to 26 (0.017 g, 56%) by following the procedure described for the
preparation of 22. Colorless liquid, [α]2D7 = +52.2 (c = 0.07, CHCl3).
1H NMR (400 MHz, CDCl3): δ = 2.91 (d, J = 17.2 Hz, 1 H), 3.23–
3.28 (m, 1 H), 3.36 (s, 3 H), 3.48–3.53 (m, 1 H), 3.60–3.62 (m, 2
H), 3.72 (s, 3 H), 4.03 (d, J = 7.2 Hz, 1 H), 4.42 (d, J = 12.0 Hz, 1
H), 4.47 (d, J = 12.0 Hz, 1 H), 4.55 (d, J = 12.0 Hz, 1 H), 4.64 (d,
J = 12.0 Hz, 1 H), 5.61 (br. s, 1 H), 5.69–5.70 (m, 1 H), 7.22–7.35
(m, 10 H) ppm. 13C NMR (100 MHz, CDCl3): δ = 40.4 (CH2),
52.2, 52.8, 53.4, 61.8, 70.1 (CH2), 70.9 (CH2), 73.2 (CH2), 77.7,
127.1, 127.2, 127.5, 127.6, 128.1, 128.3, 129.2, 130.0, 138.2, 138.7,
171.0, 172.8 ppm. HRMS (ES+): calcd. for C25H28O6Na [M +
Na]+ 447.1783; found 447.1784.
Compound 22: To a well-stirred solution of compound 2 (0.08 g,
0.141 mmol) in MeOH (15 mL) was added Na2HPO4 (0.12 g,
0.846 mmol). After 15–20 min Na(Hg) (0.05 g) was added and
stirred at room temperature under N2. After 5–6 h, the reaction
mixture was filtered through Celite, and the solids were washed
with EtOAc. The clear filtrate was concentrated under reduced
pressure. The residue was purified over silica gel to afford 22
(0.023 g, 54%). White liquid, [α]2D7 = +265.7 (c = 0.08, CHCl3). H
1
NMR (400 MHz, CDCl3): δ = 2.82 (d, J = 17.2 Hz, 1 H), 3.28–
3.33 (m, 1 H), 3.44–3.46 (m, 2 H), 3.58 (s, 3 H), 3.74 (s, 3 H), 3.85
(br. s, 1 H), 4.43 (s, 2 H), 5.61–5.63 (m, 1 H), 5.70–5.72 (m, 1 H),
7.24–7.34 (m, 5 H) ppm. 13C NMR (100 MHz, CDCl3): δ = 40.4
(CH2), 51.4, 52.4, 53.9, 61.2, 69.3 (CH2), 73.1 (CH2), 127.5, 127.6,
128.3, 129.0, 130.1, 138.1, 170.8, 172.7 ppm. HRMS (ES+): calcd.
for C17H20O5Na [M + Na]+ 327.1204; found 327.1208.
Compound 27: Compound 18 (0.10 g, 0.17 mmol) was converted
to 27 (0.05 g, 80%) by following the procedure described for the
1
preparation of 22. White oil, [α]2D7 = +58.3 (c = 0.09, CHCl3). H
NMR (400 MHz, CDCl3): δ = 2.47 (s, 3 H), 3.21 (d, J = 13.2 Hz,
1 H), 3.51–3.56 (m, 1 H), 3.62 (br. s, 2 H), 3.72–3.75 (m, 1 H), 3.84
(d, J = 13.6 Hz, 1 H), 4.49–4.57 (m, 2 H), 4.68–4.71 (m, 1 H), 4.77–
4.80 (m, 1 H), 5.68–5.69 (m, 1 H), 5.75 (br. s, 1 H), 7.16–7.39 (m,
10 H) ppm. 13C NMR (100 MHz, CDCl3): δ = 42.7, 62.8 (CH2),
71.6 (CH2), 72.5 (CH2), 73.3 (CH2), 73.9, 81.0, 127.3, 127.4, 127.5,
127.7, 128.2 (3ϫC), 138.5, 139.0 ppm. HRMS (ES+): calcd. for
C21H26NO2 [M + H]+ 324.1953; found 324.1958.
Compound 23: To a well-stirred solution of compound 6 (0.20 g,
0.44 mmol) in DCM was added Boc-anhydride (0.4 mL) and a
catalytic amount of DMAP (0.03 g), and the mixture was stirred
at room temperature under N2. After 5 h, DCM was concentrated
to dryness under reduced pressure. The residue was purified over
silica gel to afford the Boc-protected derivative (0.207 g, 85%). The
Boc-protected compound was desulfonylated (yield 52%) by fol-
lowing the procedure described for the preparation of 22. After
desulfonylation, the Boc-protected compound (0.08 g, 0.201 mmol)
was treated with 50% TFA in DCM under N2. After 2 h, the reac-
tion mixture was poured into a saturated aq. NaHCO3 solution,
and the product was extracted with DCM (3ϫ20 mL). The com-
bined organic layer was dried with anhyd. Na2SO4 and filtered; the
filtrate was concentrated under reduced pressure. The residue was
purified over silica gel to afford compound 23 (0.064 g, 95%). Col-
orless oil, [α]2D7 = +47.4 (c = 0.14, CHCl3). 1H NMR (400 MHz,
CDCl3): δ = 1.91–1.96 (m, 2 H), 2.86–2.92 (m, 1 H), 3.13–3.20 (m,
1 H), 3.25 (q, J = 5.2, 12.0 Hz, 1 H), 3.64–3.68 (m, 1 H), 3.77 (dd,
J = 5.6, 9.6 Hz, 1 H), 4.05–4.08 (m, 1 H), 4.41 (d, J = 12.4 Hz, 1 H),
4.53–4.59 (m, 3 H), 7.26–7.34 (m, 10 H) ppm. 13C NMR (100 MHz,
CDCl3): δ = 31.5 (CH2), 44.0 (CH2), 62.3, 69.2 (CH2), 71.0
(CH2), 73.4 (CH2), 79.1, 127.3, 127.4, 127.5, 127.7, 128.2, 128.3,
138.3, 138.5 ppm. HRMS (ES+): calcd. for C19H24NO2 [M + H]+
298.1809; found 298.1797.
Compound 28: To a well-stirred solution of compound 12 (0.11 g,
0.22 mmol) in DCM (20 mL) was added DBU (0.15 mL,
1.10 mmol). The solution was stirred at room temperature under
N2. After 3–4 h, the reaction mixture was poured into a saturated
aq. solution of NaHCO3, and the product was extracted with DCM
(3ϫ20 mL). The combined organic layer was dried with anhyd.
Na2SO4 and filtered; the filtrate was concentrated under reduced
pressure. The residue was purified over silica gel to afford the 28
(.061 g, 82%). White oil, [α]2D4 = +87.0 (c = 0.43, CHCl3). 1H NMR
(400 MHz, CDCl3): δ = 3.58 (q, J = 6.8, 13.2 Hz, 1 H), 3.95–4.06
(m, 2 H), 4.56–4.60 (m, 2 H), 4.65–4.69 (m, 2 H), 4.74–4.77 (m, 1
H), 6.66–6.68 (m, 1 H), 6.72 (d, J = 6.8 Hz, 1 H), 7.26–7.37 (m, 10
H) ppm. 13C NMR (100 MHz, CDCl3): δ = 61.6, 63.8 (CH2), 73.0
(CH2), 73.9 (CH2), 74.7, 127.8, 127.9, 128.0, 128.4, 128.5, 128.7,
133.8, 137.0, 137.5, 137.8 ppm. HRMS (ES+): calcd. for
C19H20O4SNa [M + Na]+ 367.0980; found 367.0977.
Compound 29: Compound 21 (0.12 g, 0.193 mmol) was converted
to 29 (0.066 g, 73%) by following the procedure described for the
preparation of 28. Glassy liquid, [α]2D4 = +101.4 (c = 0.10, CHCl3).
1H NMR (400 MHz, CDCl3): δ = 3.61 (dd, J = 3.2, 10.8 Hz, 1 H),
3.71–3.76 (m, 2 H), 4.29–4.48 (m, 5 H), 4.61 (d, J = 12.0 Hz, 1 H),
4.68 (d, J = 10.8 Hz, 1 H), 4.82 (d, J = 10.8 Hz, 1 H), 6.62–6.65
(m, 1 H), 6.76 (d, J = 6.8 Hz, 1 H), 7.19–7.21 (m, 2 H), 7.25–7.38
Compound 24: Compound 8 (0.10 g, 0.185 mmol) was converted
to 24 (0.04 g, 77%) by following the procedure described for the
preparation of 22. White oil, [α]2D4 = +6.6 (c = 0.13, CHCl3). 1H
NMR (200 MHz, CDCl3): δ = 3.21–3.30 (m, 1 H), 3.40–3.56 (m, 2
Eur. J. Org. Chem. 2010, 872–881
© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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879

A. K. Atta, T. Pathak
FULL PAPER
(m, 11 H), 7.46 (d, J = 7.2 Hz, 2 H) ppm. 13C NMR (100 MHz,
CDCl3): δ = 63.5, 68.2 (CH2), 71.7 (CH2), 73.2 (CH2), 73.4 (CH2),
73.8, 75.2, 127.6, 127.9, 128.0, 128.1, 128.2, 128.3, 128.5, 128.6,
135.2, 135.8, 136.7, 137.9 ppm. HRMS (ES+): calcd. for
C27H28O5SNa [M + Na]+ 487.1555; found 487.1521.
1999, 55, 13471–13494; d) T. J. Donohoe, L. Mitchell, M. J.
Waring, M. Helliwell, A. Bell, N. J. Newcombe, Tetrahedron
Lett. 2001, 42, 8951–8954; e) D. Diez, M. T. Beneitez, I. S.
Marcos, N. M. Garrido, P. Basabe, J. G. Urones, Tetrahedron:
Asymmetry 2002, 13, 639–646; f) T. K. Maishal, D. K. Singha-
Mahapatra, K. Paranjap, A. Sarker, Tetrahedron Lett. 2002, 43,
2263–2267; g) B. M. Trost, B. S. Brown, E. J. McEachern, O.
Kuhn, Chem. Eur. J. 2003, 9, 4442–4451; h) M. Maükosza, M.
Barbasiewicz, D. Krajewski, Org. Lett. 2005, 7, 2945–2948.
a) A. Padwa, B. H. Norman, Tetrahedron Lett. 1988, 29, 3041–
3044; b) N. A. Sasaki, I. Sagnard, Tetrahedron 1994, 50, 7093–
7108; c) M. B. Berry, D. Craig, P. S. Jones, G. J. Rowlands, Be-
ilstein J. Org. Chem. 2007, 3, DOI: 10.1186/1860-5397-3-39; d)
A. L. Perez, R. R. Machin, J. Adrio, J. C. Carretero, Angew.
Chem. Int. Ed. 2007, 46, 9261–9264; e) A. L. Perez, J. Adrio,
J. C. Carretero, J. Am. Chem. Soc. 2008, 130, 10084–10085; f)
S. Fukuzawa, H. Oki, Org. Lett. 2008, 10, 1747–1750; g) R.
Chenevert, F. Jacques, P. Giguere, M. Dasser, Tetrahedron:
Asymmetry 2008, 19, 1333–1338; h) P. Merino, I. Delso, T. Te-
jero, F. Cardona, M. Marradi, E. Faggi, C. Parmeggiani, A.
Goti, Eur. J. Org. Chem. 2008, 2929–2947.
a) P. Auvray, P. Knochel, J. F. Normant, Tetrahedron Lett.
1985, 26, 4455–4458; b) R. L. Danheiser, B. R. Dixon, R. W.
Gleson, J. Org. Chem. 1992, 57, 6094–6097; c) H. Miyaoka, M.
Tamura, Y. Yamada, Tetrahedron Lett. 1998, 39, 621–624; d)
M. A. Clark, B. K. Goering, J. Li, B. Ganem, J. Org. Chem.
2000, 65, 4058–4069; e) L. Hyldtoft, R. Madsen, J. Am. Chem.
Soc. 2000, 122, 8444–8452; f) M. Ono, K. Nishimura, H. Tsu-
bouchi, Y. Nagaoka, K. Tomioka, J. Org. Chem. 2001, 66,
8199–8203; g) C. Mukai, R. Ukon, N. Kuroda, Tetrahedron
Lett. 2003, 44, 1583–1586; h) D. Diez, M. T. Beneitez, I. S.
Marcos, N. M. Garrido, P. Basabe, F. Sanz, H. B. Broughton,
J. G. Urones, Org. Lett. 2003, 5, 4361–4364; i) T. J. Donohoe,
L. Mitchell, M. J. Waring, M. Helliwell, A. Bell, N. J. New-
combe, Org. Biomol. Chem. 2003, 1, 2173–2186; j) S. Chakra-
borty, R. N. Austin, D. Deng, J. T. Groves, J. D. Lipscomb, J.
Am. Chem. Soc. 2007, 129, 3514–3515; k) N. Coia, D. Bouyssi,
G. Balme, Eur. J. Org. Chem. 2007, 3158–3165; l) A. G. Cam-
paa, B. Bazdi, N. Fuentes, R. Robles, J. M. Cuerva, J. E. Oltra,
S. Porcel, A. M. Echavarren, Angew. Chem. Int. Ed. 2008, 47,
7515–7519.
a) H.-J. Akenbach, D. J. Brauer, G. F. Merhof, Tetrahedron
1997, 53, 6019–6026; b) F. Schieweck, H. J. Altenbach, Tetrahe-
dron: Asymmetry 1998, 9, 403–406; c) L. S. Jeong, H. R. Moon,
S. J. Yoo, S. N. Lee, M. W. Chunl, Y.-H. Lim, Tetrahedron Lett.
1998, 39, 5201–5204; d) H. S. Lee, H. Kohn, Heterocycles 2003,
60, 47–56; e) E. Gallienne, M. Benazza, G. Demailly, J. Bolte,
M. Lemaire, Tetrahedron 2005, 61, 4557–4568; f) N. S. Kumar,
B. M. Pinto, J. Org. Chem. 2006, 71, 2935–2943; g) B. S. Mor-
gan, S. M. Roberts, P. Evans, Tetrahedron Lett. 2006, 47, 5273–
5276; h) M. T. Mwangi, M. D. Schulz, N. B. Bowden, Org.
Lett. 2009, 11, 33–36.
CCDC-735067, -735068, -735069 (for compounds 3, 8 and 16) con-
tain the supplementary crystallographic data for this paper. These
data can be obtained free of charge from The Cambridge Crystallo-
graphic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
[4]
Supporting Information (see footnote on the first page of this arti-
1
cle): General experimental methods, H and 13C NMR spectra for
the new compounds, and NOESY-COSY data for 14 and 19.
Acknowledgments
T. P. thanks the Department of Science and Technology (DST),
New Delhi for financial support. A. K. A. thanks the Council for
Scientific and Industrial Research, New Delhi for a fellowship.
DST is also thanked for the creation of a 400 MHz facility under
the IRPHA (Intensification of Research in High Priority Areas)
program and the DST-FIST (Department of Science and Technol-
ogy Fund for Improvement of Science and Technology Infrastruc-
ture) for the single-crystal X-ray diffraction facility.
[5]
[1] For reviews on N-, O-, and S-containing heterocycles, see: a)
T. L. B. Boivin, Tetrahedron 1987, 43, 3309–3362; b) J. C. Har-
mange, B. Figadere, Tetrahedron: Asymmetry 1993, 4, 1711–
1754; c) M. Pichon, B. Figadere, Tetrahedron: Asymmetry 1996,
7, 927–964; d) P. Remuzon, Tetrahedron 1996, 52, 13803–13835;
e) P. Merino, S. Franco, F. L. Merchan, T. Tejero, Synlett 2000,
442–454; f) W. R. Bowman, C. F. Bridge, P. Brookes, J. Chem.
Soc. Perkin Trans. 1 2000, 1–14; g) W. R. Bowman, M. O.
Cloonan, S. L. Krinte, J. Chem. Soc. Perkin Trans. 1 2001,
2885–2902; h) J. Hartung, Eur. J. Org. Chem. 2001, 619–632; i)
W. R. Bowman, A. J. Fletcher, G. B. S. Potts, J. Chem. Soc. Per-
kin Trans. 1 2002, 2747–2762; j) El S. H. El-Ashry, A. El Nemr,
Carbohydr. Res. 2003, 338, 2265–2290; k) F.-X. Felpin, J. Lebre-
ton, Eur. J. Org. Chem. 2003, 3693–3712; l) K. C. Majumdar,
P. K. Basu, P. P. Mukhopadhyay, Tetrahedron 2004, 60, 6239–
6278; m) S. Husinec, V. Savic, Tetrahedron: Asymmetry 2005,
16, 2047–2061; n) K. C. Majumdar, P. K. Basu, P. P. Mukho-
padhyay, Tetrahedron 2005, 61, 10603–10642; o) P. Q. Huang,
Synlett 2006, 1133–1149; p) G. Pandey, P. Banerjee, S. R. Ga-
dre, Chem. Rev. 2006, 106, 4484–4517; q) F. Bellina, R. Rossi,
Tetrahedron 2006, 62, 7213–7256; r) A. Minatti, K. Muniz,
Chem. Soc. Rev. 2007, 36, 1142–1152; s) J. P. Wolfe, Eur. J. Org.
Chem. 2007, 571–582; t) K. C. Majumdar, P. K. Basu, S. K.
Chattopadhyay, Tetrahedron 2007, 63, 793–826; u) E. Bellur, H.
Feista, P. Langera, Tetrahedron 2007, 63, 10865–10888; v) J. P.
Wolfe, Synlett 2008, 2913–2937; w) A. Yazici, S. G. Pyne, Syn-
thesis 2009, 339–368.
[2] For reviews on carbocycles, see: a) A. M. Grau, J. M. Contelles,
Chem. Soc. Rev. 1998, 27, 155–162; b) P. I. Dalko, P. Sinay,
Angew. Chem. Int. Ed. 1999, 38, 773–778; c) J. W. Herndon,
Tetrahedron 2000, 56, 1257–1280; d) R. C. Hartley, S. T. Cald-
well, J. Chem. Soc. Perkin Trans. 1 2000, 477–501; e) S. E. Gib-
son, N. Mainolfi, Angew. Chem. Int. Ed. 2005, 44, 3022–3037;
f) L. A. Paquette, J. Organomet. Chem. 2006, 691, 2083–2088;
g) R. Madsen, Eur. J. Org. Chem. 2007, 399–415; h) S. Das, S.
Chandrasekhar, J. S. Yadav, R. Gree, Chem. Rev. 2007, 107,
3286–3337; i) F. Denes, F. Beaufils, P. Renaud, Synlett 2008,
2389–2399; j) B. Heasley, Eur. J. Org. Chem. 2009, 1477–1489.
[3] a) C. Clark, P. Hermans, O. Meth-Cohn, H. C. Taljaard, G.
van Vuuren, J. Chem. Soc., Chem. Commun. 1986, 1378–1380;
b) C. Marot, P. Rollin, Tetrahedron Lett. 1994, 35, 8377–8380;
c) D. Craig, N. J. Ikin, N. Mathews, A. M. Smith, Tetrahedron
[6]
[7]
[8]
[9]
a) A. K. Atta, T. Pathak, J. Org. Chem. 2009, 74, 2710–2727;
b) R. Bhattacharya, D. Dey, T. Pathak, Eur. J. Org. Chem.
2009, 5255–5260; c) R. Bhattacharya, A. K. Atta, D. Dey, T.
Pathak, J. Org. Chem. 2009, 74, 669–674.
a) N. S. Simpkins, Sulfones in Organic Synthesis, Pergamon
Press, Oxford, 1993; b) For a review on vinyl sulfones derived
from carbohydrates see, T. Pathak, Tetrahedron 2008, 64, 3605–
3628.
a) B. Clique, S. Vassiliou, N. Monteiro, G. Balme, Eur. J. Org.
Chem. 2002, 1493–1499; b) C.-C. Wang, S.-Y. Luo, C.-R. Shie,
S.-C. Hung, Org. Lett. 2002, 4, 847–849; c) H. Ishibashi, T.
Sato, M. Ikeda, Synthesis 2002, 695–713; d) M. Lombardo, S.
Licciulli, C. Trombini, Tetrahedron Lett. 2003, 44, 9147–9149;
e) F. A. Davis, B. Yang, J. Deng, J. Org. Chem. 2003, 68, 5147–
5152; f) I. N. N. Namboothiri, M. Ganesh, S. M. Mobin, M.
Cojocaru, J. Org. Chem. 2005, 70, 2235–2243; g) Q. Zhang, W.
Xu, X. Lu, J. Org. Chem. 2005, 70, 1505–1507; h) G. Biswas,
S. Ghorai, A. Bhattacharjya, Org. Lett. 2006, 8, 313–316; i)
880
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© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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Route to Five-Membered Carbocycles and Heterocycles
J. L. Chiara, A. Garcia, E. Sesmilo, T. Vacas, Org. Lett. 2006,
8, 3935–3938; j) L. F. de Oliveira, V.-E. U. Costa, Tetrahedron
Lett. 2006, 47, 3565–3567; k) J. Hartung, M. E. Pulling, D. M.
Smith, D. X. Yang, J. R. Norton, Tetrahedron 2008, 64, 11822–
11830.
[10] For a review on desulfonylation, see: C. Najera, M. Yus, Tetra-
hedron 1999, 55, 10547–10658.
[11] I. Das, T. Pathak, Org. Lett. 2006, 8, 1303–1306.
Received: August 23, 2009
Published Online: December 22, 2009
Eur. J. Org. Chem. 2010, 872–881
© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
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