Iodosulfonation of alkenes with benzenesulfinic acid - N-iodosuccinimide - Facile preparation of αβ-unsaturated sulfones

Article abstract of DOI:10.1139/V06-051

Reaction of alkenes and alkenols with N-iodosuccinimide (NIS) and benzenesulfinic acid in dichloromethane at room temperature affords vic-iodophenylsulfonyl adducts in good to high yields. Treatment of the iodosulfones with neutral alumina in dichlorometh

Full text of DOI:10.1139/V06-051

667
Iodosulfonation of alkenes with benzenesulfinic
acid – N-iodosuccinimide — Facile preparation of
␣,␤-unsaturated sulfones1
Russell R. Wolff, Vikram Basava, Robert M. Giuliano, Walter J. Boyko, and
J. Herman Schauble
Abstract: Reaction of alkenes and alkenols with N-iodosuccinimide (NIS) and benzenesulfinic acid in dichloromethane at
room temperature affords vic-iodophenylsulfonyl adducts in good to high yields. Treatment of the iodosulfones with neu-
tral alumina in dichloromethane at room temperature results in dehydroiodination to give the corresponding vinyl sul-
fones in high yield and purity by this convenient two-step procedure. Application of the iodosulfonation–dehydroiodination
sequence to allylic alcohols and silyl ethers gave γ-oxygenated, α,β-unsaturated phenylsulfones, while the attempted
iodosulfonation of glycals, as intermediates to vinyl sulfones, resulted in addition of benzenesulfinic acid with double
bond shift (Ferrier rearrangement).
Key words: iodosulfonation, vinyl sulfones, benzenesulfinic acid, N-iodosuccinimide, dehydroiodination.
Résumé : La réaction d’alcènes et d’alcénols avec du N-iodosuccinimide (NIS) et de l’acide benzènesulfinique dans le
dichlorométhane à la température ambiante conduit à la formation d’adduits vic-iodophénylsulfonyles avec des rende-
ments allant de bons à élevés. Le traitement des iodosulfones avec de l’alumine neutre dans le dichlorométhane à la
température ambiante provoque une déshydroiodation qui fournit les vinylsulfones correspondantes avec un rendement
et une pureté élevés et qui complète cette méthode de synthèse pratique en deux étapes. L’application de la séquence
de réactions iodosulfonation–déshydroiodation à des alcools allyliques et à des éthers silylés conduit à la formation de
phénylsulfones γ-oxygénées et α,β-insaturées alors que les essais d’iodosulfonation de glycals, pour conduire à des
intermédiaires de vinyl sulfones, conduisent à une addition de l’acide benzènesulfinique avec un déplacement de la
double liaison (réarrangement de Ferrier).
Mots clés : iodosulfonation, vinyl sulfones, acide benzènesulfinique, N-iodosuccinimide, déshydroiodation.
[Traduit par la Rédaction] Wolff et al. 675
Introduction
catalyst, such as a Cu(II) or Hg(II) salt, is usually included
(18–20).
The two-step halosulfonation–dehydrohalogenation se-
quence is a useful method for conversion of alkenes to α,β-
unsaturated sulfones. The first step of this process has gener-
ally been carried out by the reaction of an alkene with an
arylsulfonyl halide to give a vic-halo(arylsulfonyl)alkane (1).
Such reactions with sulfonyl chlorides or bromides occur via
a radical-chain process, and require initiators such Cu(I, II)
(2–5) or Ru(II) (6) salts, peroxides (7–9), or UV irradiation
(5, 8, 10, 11).
Arylsulfonyl iodides are considerably more susceptible to
homolysis than the chlorides, typically undergoing slow ad-
dition to alkenes in the dark (12, 13), although being accel-
erated by ambient or applied visible light (12–16), Cu(II)
salts (17), or other radical initiators (12). Arylsulfonyl io-
dides are unstable reagents that are prepared from iodine and
sodium arylsulfinate. Direct iodosulfonation can also be car-
ried out with iodine and sodium arylsulfinate; however, a
Herein we describe an alternate synthesis of iodo(arylsul-
fonyl)alkanes by the reaction of alkenes with N-iodosuccini-
mide (NIS) and benzenesulfinic acid in dichloromethane at
room temperature. The free sulfinic acid is soluble in
organic solvents, and is stable for extended periods when
stored at 0 °C. Iodophenylsulfonyl adducts are obtained
regioselectively in good yields. We also report that treatment
of the iodosulfones with neutral alumina at room tempera-
ture results in facile elimination of HI, to give synthetically
useful vinyl sulfones in high yield and purity.
Results and discussion
Iodosulfonation products obtained from reaction of vari-
ous alkenes and alkenols with NIS and benzenesulfinic acid
are listed in Table 1. Reactions of cyclopentene, cyclohex-
ene, 1-methylcyclohexene, and norbornylene all gave high
Received 30 August 2005. Published on the NRC Research Press Web site at http://canjchem.nrc.ca on 17 May 2006.
R.R. Wolff, V. Basava, R.M. Giuliano,2 W.J. Boyko, and J.H. Schauble. Department of Chemistry, Villanova University,
Villanova, PA 19085, USA.
1This article is part of a Special Issue dedicated to Professor Walter A. Szarek.
2Corresponding author (e-mail: robert.giuliano@villanova.edu).
Can. J. Chem. 84: 667–675 (2006)
doi:10.1139/V06-051
© 2006 NRC Canada

668
Can. J. Chem. Vol. 84, 2006
Table 1. Iodophenylsulfonylation of alkenes using NIS – benzenesulfinic acid and dehydroiodination of
iodo(henylsulfonyl) compounds on neutral alumina.
Alkene
Iodosulfonylation
Product
Yielda
Dehydroiodination
Product
Yieldb
I
SO2Ph
SO2Ph
n
n
2 n =1
4 n = 2
91%
86% (73%)c
n
92%
95% (83%)c
1 n = 1
3 n = 2
n = 1, 2
Me
I
CH3
10%d, e
90%d
Me
SO2Ph
SO2Ph
6
5
SO2Ph
SO2Ph
85%f
89%
I
8
7a 2-endo-3-exo
7b 2-exo-3-endo
n-Pr
n-Pr
n-Pr
SO2Ph
n-Pr
83%f
92%f
80%f
I
n-Pr
n-Pr
SO2Ph
9a erythro, 9b threo
10a (Z), 10b(E)
I
92%
SO2Ph
SO2Ph
11a, 11b (cis, trans)
12
OH
I
PhO2S
OH
PhO2S
OH
R
R = H, Me, n-Pr
R
14 R = H
16 R = Me
18 R = n-Pr
R
60%
63%
83%
95%
92%
85%
13 R = H
15 R = Me
17 R = n-Pr
R
I
OTBDMS
PhO2S
OTBDMS
PhO2S
OTBDMS
19
SO2Ph
OTBDMS
77%f
92%f, g
21
R = H
SO2Ph
I
OTBDMS
20
22
Me
I
Me
PhO2S
OTBDMS
38%g
57%
PhO2S
OTBDMS
R = Me
24
23
aLiterature yields are in parenthesis.
bYields from the iodo(phenylsulfonyl) precursor.
cIodosulfone 3 was accompanied by 5% of the cis isomer (17).
dYield of side product from thermal elimination of 5. Elimination on alumina was not investigated.
eTosyl iodide gave 67% addition plus 10% thermal elimination product (17).
fCombined yield of isomers.
gElimination did not occur on neutral alumina; carried out using DABCO.
© 2006 NRC Canada

Wolff et al.
669
yields of single vic-iodosulfones having the trans configura-
tion. 1-Methylcyclohexene gave only trans-1-iodo-1-methyl-
2-(phenylsulfonyl)cyclohexane, having the anti-Markovnikov
regiochemistry, consistent with free radical, rather than ionic
addition. The same regiochemistry, previously observed for
reaction of alkenes with iodine and sodium arylsulfonates,
was rationalized as being due to the steric bulk of the
sulfinate anion, favoring rearside attack on the intermediate
three-membered ring iodonium intermediates at the less-
hindered position (18). However, an ionic pathway for such
iodosulfonation reactions appears unlikely, since we observe
that reaction of benzenesulfinic acid with NIS in dichloro-
methane-d2 at room temperature gives benzenesulfonyl io-
dide at a rate similar to that for iodosulfonation of alkenes.
A radical pathway is further supported by our observation
that methyl vinyl ketone and the corresponding alcohol (3-
buten-2-ol) undergo iodosulfonylation with NIS – benzene-
sulfinic acid at similar rates. Additionally, Yus and co-
workers (21) have shown that reaction of α,β-unsaturated
carbonyl compounds with sodium p-toluenesulfinate and io-
dine gives α-iodo-β-sulfonyl adducts, as expected for free
radical addition.
Iodosulfonylation of E-4-octene gave a mixture of threo-
and erythro-4-iodo-5-phenylsulfonyl octanes (9a, 9b). This
result is of interest in light of a report by Skell and
McNamara (14) on reaction of phenylsulfonyl iodide with
cis- or trans-2-butene, both of which gave identical mixtures
of threo- and erythro-iodosulfones. The latter apparently
formed via a 3-phenylsulfonyl-2-butyl radical, which under-
goes conformational exchange at a rate competitive with that
for iodine abstraction from phenylsulfonyl iodide to give the
iodosulfonation product. No isomerization of starting
butenes was observed (as occurred for chlorosulfonation
with sulfonyl chlorides) (22), since iodine abstraction occurs
faster than reversion of the phenylsulfonyl-2-butyl radical to
alkene.
The mixture of erythro- and threo-4-iodo-5-(phenyl-
sulfonyl)octanes (9a, 9b) was inseparable by TLC. Although
1H NMR revealed the isomers to be present in 71:29 molar
ratio, their spectra were too similar to distinguish them.
However, dehydroiodination on neutral alumina (vide infra)
gave E- and Z-4-(phenylsulfonyl)octenes (10a, 10b) in 67:32
molar ratio. Providing that elimination occurs by an E2 pro-
cess, the major E isomer 10a derives from the erythro-
iodosulfone (9a) while the Z isomer 10b forms via the
threo-iodosulfone (9b).
Iodosulfonation of norbornylene gave a mixture of 2-endo-
iodo-3-exo-(phenylsulfonyl)norbornane (7a) and a second
compound, tentatively identified as the 2-exo-iodo-3-endo-
phenylsulfonyl isomer 7b in approximately equimolar ratio.
Formation of 7a is consistent with the intermediacy of the 3-
exo-(phenylsulfonyl)-2-norbornyl radical, which would be
trapped by iodine transfer from benzenesulfonyl iodide to
the endo face. In contrast, 7b apparently forms via the 2,3-
exo-iodonium intermediate resulting from iodonium (I+) transfer
from NIS to norbornylene, followed by endo attack by the
benzenesulfinate ion. It thus appears that iodosulfone forma-
tion via iodonium intermediates may be expected in cases in-
volving more nucleophilic alkenes such as norbornylene.
equimolar ratio, determined from the integrated intensities
for the CHI and CHSO2Ph peaks in the H NMR spectrum.
Vicinal coupling for H6 indicated the sulfonyl group to be
pseudoequatorial for the major isomer and pseudoaxial for
the minor one; however, since Jvic values for H3 could not
be determined; it was not possible to distinguish the two iso-
mers by NMR.
1
Dehydroiodination of α-iodo-β-alkylsulfonyl or arylsul-
fonyl compounds has previously been carried out using
pyridine in benzene under reflux (14), or triethylamine in
various solvents at room temperature, or with heating (12,
17–21, 23). In the present work, it was found that flash chro-
matography of trans-1-iodo-2-(phenylsulfonyl)cyclohexane
(3) on neutral alumina resulted in partial conversion to 1-
(phenylsulfonyl)cyclohexene (4). This led to the observation
that dehydroiodination could be carried out preparatively,
simply by stirring neutral alumina slurries of the iodo-
sulfones in dichloromethane at room temperature to yield
the corresponding α,β-unsaturated sulfones, generally in
very good to excellent yields (Table 1). This procedure
avoids the use of amine bases that may be incompatible with
some functional groups. However, dehydroiodination of the
iodosulfone TMBDS ethers 19, 21, and 23 (vide infra) did
not occur on alumina. In these cases, we found that the elim-
ination could be carried out using 1,4-diazabicyclo[2.2.2]oc-
tane (DABCO).
We were also interested in application of the
iodophenylsulfonation–dehydroiodination sequence to the
synthesis of γ-oxygenated, α,β-unsaturated phenylsulfones
by using allylic alcohols or their derivatives as substrates.
Products derived from allylic alcohols could thus serve as
precursors to phenylsulfonyl-substituted, α,β-unsaturated ke-
tones, which are established heterodienes in Diels–Alder re-
actions (24), as well as other synthetic applications involving
conjugate additions (25). γ-Alkoxy-α,β-unsaturated phenyl-
sulfones are useful as substrates in [3+2] cycloadditions, via
π-allyl palladium complexes, as a method for cyclopentenone
annulation (26), and also in six-membered ring annulations
by a conjugate addition–alkylation sequence (27).
Examples of the allylic alcohols used as substrates in the
iodophenylsulfonation–elimination sequence are shown in
Table 1. Treatment of allyl alcohol with benzensulfinic acid
and NIS in dry dichloromethane overnight gave a 54% yield
of iodophenylsulfone 13. The NMR spectrum indicated a
single regioisomer, resulting from addition of the
phenylsulfonyl group to the less-substituted carbon, consis-
tent with our results for other unsymmetrically substituted
alkenes. Treatment of the iodophenylsulfone with neutral
alumina gave a nearly quantitative yield of the γ-hydroxy-α,
β-unsaturated sulfone 14, the structure of which was con-
firmed by comparison of physical data with reported values
for this compound prepared by either microwave- or ultra-
sound-assisted alkylation of sodium benzenesulfinate by
Villemin and Aloum (28).
Similarly, treatment of 3-butene-2-ol with benzenesulfinic
acid and NIS gave iodophenylsulfone 15 as a mixture of
diastereomers. Again, a single regiochemistry of addition
was observed. Elimination w ith alumina occurred smoothly
to give the known (29) γ-hydroxy-α,β-unsaturated sulfone
16. An isomeric vinyl sulfone, 3-(phenylsulfonyl)-3-buten-2-
ol, was previously prepared by the addition of phenyl vinyl
1,3-Cyclohexadiene gave a mixture of cis/trans-3-iodo-6-
(phenylsulfonyl)cyclohexene (11a, 11b) in approximately
© 2006 NRC Canada

670
Can. J. Chem. Vol. 84, 2006
Scheme 1.
sulfone to acetaldehyde. Oxidation gave 3-(benzenesul-
fonyl)-3-buten-2-one, which was shown to undergo hetero-
Diels–Alder reactions with vinyl ethers in high yield at or
below room temperature (24). It is anticipated that the
ketone derived by oxidation of 16 would also be useful as a
heterodiene. Similarly, (E)-1-(phenylsulfonyl)-hex-1-en-3-ol
(18) (30) was prepared from 1-hexen-3-ol in good overall
yield by regioselective iodosulfonation–elimination.
Both 2-cyclohexen-1-ol and 2-methyl-2-cyclohexen-1-ol
were unsuitable as substrates for the synthesis of vinyl sul-
fones using the iodophenylsulfonation–elimination sequence
because of side reactions. Better results were obtained using
the tert-butyldimethylsilyl (TBDMS) ethers of these cyclic
allylic alcohols. The attempted synthesis of 3-(tert-butyl-
dimethylsiloxy)-1-(phenylsulfonyl)cyclohexene (21) from 2-
cyclohexen-1-ol by this method resulted in a mixture of
vinyl sulfones 21 and 22 because of a lack of regio-
selectivity in the initial addition step. Treatment of the
TBDMS ether of 2-methyl-2-cyclohexen-1-ol gave diastere-
omeric 2-iodo-3-phenylsulfonyl derivatives (23), which were
converted to vinyl sulfone 24, albeit in lower overall yield
than was observed for the other cases. Vinyl sulfone 21 was
used in the synthesis of annulated cyclopentenones by Trost
et al. (26).
Ley and co-workers (31) have developed synthetically
useful alkylation reactions of anions derived from 2-ben-
zensulfonyl tetrahydropyran. We decided to attempt the
application of our iodophenylsulfonation reaction to dihy-
dropyran and to glycals. The only products obtained from
dihydropyran upon treatment with NIS – benzenesulfinic
acid, were those resulting from addition of benzenesulfinic
acid, suggesting that protonation of the double bond occurs
faster than iodination, or alternatively, hydrogen atom ab-
straction by the adduct of DHP and benzenesulfonyl radical
is again faster than iodination. We also attempted iodo-
phenylsulfonation of dihydropyran using NIS and tetra-N-
butylammonium benzenesulfinate and observed a significant
amount of adduct 25 (apparently resulting from trapping of
dihydropyran iodonium ion by succinimide), along with
iodophenylsulfone 26 and other products that were not iden-
tified (Scheme 1).
Iodophenylsulfonation of glycals was also attempted using
NIS and benzenesulfinic acid in an effort to prepare carbo-
hydrate vinyl sulfones. Ley and co-workers (31a) had ob-
served that benzenesulfinic acid adds to tri-O-acetyl-L-glucal
with double bond migration (Ferrier rearrangement). This
same result was also observed in our study for the reaction
of either tri-O-acetyl-D-glucal or di-O-acetyl-L-rhamnal, when
treated with benzenesulfinic acid in the presence or absence
of N-iodosuccinimide. In both cases, the Ferrier rearrang-
ment product was obtained, with no evidence of iodophenyl-
sulfone formation. Di-O-acetyl-L-rhamnal gave an 86% yield
of the anomeric phenylsulfone adducts 27 when treated with
excess benzenesulfinic acid at room temperature (Scheme 2).
In summary, a convenient two-step synthesis of α,β-unsat-
urated sulfones has been developed using iodophenyl-
sulfonation of alkenes or alkenols with NIS – benzenesulfinic
acid, followed by dehydroiodination on neutral alumina at
room temperature. The overall process is highly regio-
selective for unsymmetrical alkenes, giving vinyl sulfones
that can be used for a variety of synthetic applications.
O
N
I
PhSO2NBu4
O
+
NIS
I
O
O
CH2Cl2, CH3CN
O
SO2Ph
25
26
Scheme 2.
AcO
AcO
PhSO2H
(4 equiv)
O
O
CH
CH
3
3
SO Ph
2
NIS
86%
OAc
27
Experimental
Preparation of benzenesulfinic acid
A stirred solution of sodium benzene sufinate (10.0 g,
61.0 mmol) in distilled water (25 mL) under nitrogen at 0 °C
was slowly acidified to pH 1 by dropwise addition of
12 mol/L HCl. The white crystalline benzenesulfinic acid
was filtered and air dried on a Büchner funnel, then stored at
0 °C (7.35 g, (85% yield); mp 82–86 °C (lit. value (32) mp
77 to 78 °C; (33) mp 82–84 °C).
General procedure for iodophenylsulfonation of alkenes
using NIS – benzenesulfinic acid
To a stirred solution of NIS (225 mg, l.0 mmol) in CH2Cl2
(50 mL) was added benzenesulfinic acid (142 mg,
1.0 mmol) and stirring continued for -5 min to effect solu-
tion. The alkene (1.0 mmol) was added, and the reaction
mixture was stirred for 30 min to 2 h at room temperature
(monitored by TLC on silica gel using hexane – ethyl ace-
tate, 1:1 v/v as eluent), then extracted with satd. aq. NaHCO3
and NaHSO3 (50 mL, each), dried (MgSO4), and filtered.
Flash chromatography on silica gel (60–200 mesh) using
hexane – ethyl acetate (1:1) as eluent gave the oily liquid
iodosulfones. No dehydroiodination products were detected,
except in the case of iodosulfone 5, which was accompanied
by -10% of 1-methyl-2-(phenylsulfonyl)cyclohexene (6).
trans-1-Iodo-2-(phenylsulfonyl)cyclopentane (1)
Yield: 322 mg (96%). H NMR (300 MHz, CDCl3) δ:
7.98 (m, 2H, Ph-H), 7.71 (m, 1H, Ph-H), 7.65 (m, 2H, Ph-
H), 4.64 (ddd, 1H, H1, J1,2 = 4.2 Hz, J1,5a = 3.2 Hz, J1,5b
3.0 Hz), 3.94 (ddd, 1H, H2, J1,2 = 4.2 Hz, J2,3a= 3.1 Hz,
J2,3b = 3.0 Hz), 2.5–1.8 (cms, 6H, H3–5
13C NMR
(75.4 MHz, CDCl3) δ: 138.8, 134.4, 129.8, 128.8 (Ph), 75.2
(C2), 40.87 (C5), 26.36, 25.41, 20.48 (C1,3,4). The cyclopen-
1
=
)
1
tane ring H shifts are consistent with literature values for
the corresponding 1-iodo-2-p-toluenesulfone (17).
trans-1-Iodo-2-(phenylsulfonyl)cyclohexane (3)
Yield: 238 mg (86%). H NMR (300 MHz, CDCl3) δ:
8.10–7.92 (m, 2H, Ph-H), 7.77–7.69 (m, 1H, Ph-H), 7.69–
7.60 (m, 2H, Ph-H), 5.14 (bs, 1H, H1), 3.41 (bs, 1H, H2),
1.95–0.82 (cms, 8H, H3–6). 13C NMR (75.4 MHz, CDCl3) δ:
138.2 (Ci), 134.3 (Cp), 129.7 (Co), 128.8 (Cm), 67.86 (C2),
1
© 2006 NRC Canada

Wolff et al.
671
1
34.0 (C6); 25.9, 23.6, 22.6, 21.5 (C1, C3–5). The H NMR
shifts are consistent with published data (17).
coupling; J2,3 and J6,7 were not determined. 13C NMR
(75.4 MHz, CDCl3) for 9b δ: 138.47 (s, Ci), 134.33 (d, Cp),
129.53 (d, Cm and Co), 68.66 (d, C5), 42.34 (t, C3), 33.27 (t,
C6), 30.62 (d, C4), 23.04 (t, C2), 21.63 (t, C7), 14.30 (q, C8),
13.16 (q, C1).
trans-1-Iodo-1-methyl-2-(phenylsulfonyl)cyclohexane (5)
Yield: 328 mg (90%). IR (KBr, cm–1) νmax: 1300 (SO2,
1
ν
asym), 1130 (SO2, νsym). H NMR (300 MHz, CDCl3) δ:
7.92 (m, 2H, Ph-H), 7.64 (m, 1H, Ph-H), 7.55 (m, 1H, Ph-
H), 3.70 (bs, 1H, H2), 2.01 (s, 3H, CH3), 2.2–1.1 (cms, 8H,
cis/trans-3-Iodo-6-(phenylsulfonyl)cyclohexene (11a, 11b)
3–6). The cyclohexyl 1H shifts agree with those reported for
Yield: 319 mg (92% combined yield); single component
H
1
by TLC on silica gel; -1:1 molar ratio determined by H
trans-1-iodo-1-methyl-2-tosylcyclohexane (17). In addition
to the iodosulfone 5, column chromatography also gave 1-
methyl-2-(phenylsulfonyl)cyclohexene (6, 24 mg, 10%)
NMR. Configurations at C3 could not be assigned since vici-
nal couplings for H3 were unobtainable owing to peak over-
1
1
lap. For 11a: H NMR (300 MHz, CDCl3) δ: 7.88 (m, 2H,
identified by comparison of the H NMR spectrum with lit-
Ph-H), 7.68 (m, 2H, Ph-H), 7.58 (m, 1H, Ph-H), 6.37 (dd,
erature data (17).
1H, H2, J1,2 = 9.9 Hz, J2,3 = 4.9 Hz), 5.61 (dd, 1H, H1, J1,2
9.9 Hz, J1,6 = 4.4 Hz), 4.98 (m, 1H, H3, J2,3 = 4.9 Hz, J3,6
=
=
2-Iodo-3-(phenylsulfonyl)norbornanes (7a, 7b)
1.0 Hz, J1,3 = 1.0 Hz; J3,4a and J3,4b could not be deter-
mined), 3.95 (m, 1H, H6, J5,6a = 5.6 Hz, J5,6b = 3.5 Hz, J1,6
Yield: 307 mg (85% combined yield; ~1:1 molar ratio by
1H NMR). 1H NMR (300 MHz, CDCl3) for the 2-endo-iodo-
3-exo-(phenylsulfonyl) isomer 7a δ: 7.99 (m, 2H, Ph-H),
7.77 (m, 1H, Ph-H), 7.68 (m, 2H, Ph-H), 4.38 (cm, 1H, H2x,
J2x,3n = 5.9 Hz, J1,2x= 3.7 Hz, J2x,6x = 1.7 Hz, J2x,7s = ~0 Hz;
no COSY cross peak). A cross peak was observed for
H1-H2x, aiding confirmation of H3n, H2x), 3.05 (dd, 1H, H3n,
J2x,3n = 5.9 Hz, J3n,7a = 1.7 Hz, J3n,4 = ~0 Hz), 2.81 (m, 1H,
H4), 2.52 (m, 1H, H1), 2.08 (m, 1H, H7s), 1.67 (cms, 2H,
H5x, H6x) 1.34 (m, 1H, H7a), 1.27 (m,1H, H5n), 1.08 (m, 1H,
H6n). 13C NMR (75.4 MHz, CDCl3) phenyl δ: 138.5 (Ci),
133.9 (Cp), 129.4 (Cm), 128.7 (Co); norbornyl δ: 76.11 (C3),
45.31 (C1), 38.44 (C4), 34.64 (C7), 29.22 (C5), 27.46 (C6),
26.36 (C1).
=
4.4 Hz, J3,6 = 1.0 Hz), 2.17 (m, 2H, H5), 2.08, 1.96 (ms, 2H,
H4). 13C NMR (75.4 MHz, CDCl3) δ: 138.04 (C2), 118.32
(C1), 59.06 (C6), 26.14 (C4), 24.22 (C3), 19.39 (C5); Ph ab-
sorptions for 11a and 11b: 136.87, 135.72 (Ci), 128.92,
128.78 (Cm), 128.8, 128.42 (Co), 133.71 (Cp, both isomers).
1
For 11b: H NMR δ: 6.19 (dd, 1H, H2, J1,2 = 10.0 Hz, J2,3
=
5.1 Hz), 5.84 (dd, 1H, H1, J1,2 = 10.0 Hz, J1,6 = 2.6 Hz,
J1,3 = 1.3 Hz), 4.87 (m, 1H, H3, J2,3 = 5.1 Hz, J3,6 = 1.8 Hz,
J1,3 = 1.3 Hz; J3,4a and J3,4b could not be determined), 4.22
(m, 1H, H6, J5,6a = 10.7 Hz, J5,6b = 6.2 Hz, J1,6 = 2.6 Hz,
J3,6 = 1.8 Hz), 2.11, 2.02 (ms, 2H, H5), 2.11, 1.69 (ms, 2H,
H4). Ph absorptions overlapped those for 11a. 13C NMR
(75.4 MHz, CDCl3) δ: 136.81 (C2), 119.30 (C1), 61.65 (C6),
30.96 (C4), 23.68 (C3), 20.00 (C5). Anal. calcd. for
C12H13SO2I (%): C 41.25, H 3.75, S 9.18; found for 11a and
11b: C 40.83, H 3.68, S 8.66.
For 2-exo-iodo-3-endo-(phenylsulfonyl)norbornane (7b):
1H NMR (300 MHz, CDCl3) δ: 4.11 (dd, 1H, H2n), 3.27 (dd,
1H, H3x), 2.89 (bs, 1H, H4), 2.50 (bs, 1H, H1), 2.41 (d, 1H,
H7s), ~1.7–1.0 (ms, 5H, H5,6, H7a).
A mixture of cis/trans-3-iodo-6-p-tosylcyclohexenes was
previously obtained from reaction of 1,3-cyclohexadiene wth
iodine/sodium p-toluenesulfinate (20).
4-Iodo-5-(phenylsulfonyl)octane (9a, 9b)
Yield: 316 mg (83% combined yield); single component
by TLC on silica gel (hexane – ethylacetate (1:1 v/v as
1
eluent); however, H NMR revealed the formation of 9a and
1
General procedure for dehydroiodination of
iodo(phenylsulfonyl) compounds 1, 3, 5, 7, 9, and 11
9b in 67:33 molar ratio. For the major isomer 9a: H NMR
(300 MHz, CDCl3) δ: 7.88 (m, 2H, Ph-H), 7.62 (m, 1H, Ph-
H), 7.59 (m, 2H, Ph-H), 4.61 (ddd, 1H, H4, J3a,4 = 10.8 Hz,
To a solution of the iodosulfonyl compound (1.0 mmol) in
CH2Cl2 (50 mL) under nitrogen, neutral alumina (60–200
mesh, 100 cc) was added, and the resulting slurry was stirred
for 1 day at rt, filtered, and the alumina was extracted with
CH2Cl2 (50 mL). The combined extract was evaporated to
give the crude α,β-unsaturated sulfone, which was purified
by flash column chromatography on silica gel (toluene
eluent, unless noted otherwise). Products were oily liquids,
unless noted otherwise.
J3b,4 = 3.3 Hz, J4,5 = 2.4 Hz), 3.54 (ddd, 1H, H5, J5,6a
7.7 Hz, J5,6b = 3.7 Hz, J4,5 = 2.4 Hz), 2.11, 1.99 (ms, 2H,
6a,6b), 1.77, 1.67 (ms, 2H, H3a,3b), 1.41 (m, 2H, H7), 1.55,
1.25 (ms, 2H, H2a,2b), 0.91 (t, 3H, H1, J1,2 = 7.3 Hz), 0.88 (t,
3H, H8, J7,8 = 7.3 Hz); J2,3 and J6,7 were not determined. 13
=
H
C
NMR (75.4 MHz, CDCl3) δ: 139.3 (s, Ci), 134.4 (d, Cp),
129.8 (d, Cm) 128.7 (d, Co), 72.53 (d, C5), 36.52 (t, C3),
31.84 (d, C4), 28.21 (t, C6), 23.89 (t, C2), 22.46 (t, C7), 14.18
(q, C8), 13.23 (q, C1). Anal. calcd. for C14H21SO2I (%): C
44.08, H 5.55, S 8.41; found (mixture of 9a and 9b): C
44.24, H 5.29, S 8.01.
1-(Phenylsulfonyl)cyclopentene (2)
1
Flash chromatography on silica gel with hexane – ethyl
For the minor isomer 9b: H NMR δ: 7.94 (m, 2H, Ph),
1
acetate (1:1 v/v) as eluent (192 mg, 92%); mp 20–25 °C. H
7.62 (m, 1H, Ph), 7.59 (m, 2H, Ph), 4.51 (ddd, 1H, H4,
J3a,4 = 9.2 Hz, J3b,4 = 5.4 Hz, J4,5 = 2.2 Hz), 2.70 (ddd, 1H,
H5, J5,6a = 5.9 Hz, J5,6b = 5.2 Hz, J4,5 = 2.2 Hz), 2.02, 1.73
(ms, 2H H6a,6b), 1.99, 1.70 (ms, 2H, H3a,3b), 1.43 (m, 2H,
NMR (300 MHz, CDCl3) δ: 7.9 (m, 2H, Ph), 7.6 (m, 3H,
Ph), 6.81 (dd, 1H, H2, J2,3a = 3.8 Hz, J2,3b = 3.1 Hz) 3.1 (m,
1
4H, H3, H5), 2.1 (m, 2H, H4); the H shifts are consistent
with literature (34) data. 13C NMR (75.4 MHz, CDCl3)
phenyl δ: 140.1 (Ci), 133.65 (Cp), 129.46 (Cm), 128.21 (Co);
cyclopentenyl δ: 145.52, 140.51, 33.29, 31.19, 23.97.
H7), 1.50, 1.39 (ms, 2H, H2a,2b), 0.88 (t, 3H, H1, J1,2
=
7.1 Hz), 0.875 (t, 3H, H8, J7,8 = 7.3 Hz). 1H shifts for 9a and
9b were determined using COSY, HETCOR, and 1D de-
© 2006 NRC Canada

672
Can. J. Chem. Vol. 84, 2006
127.67 (Co); cyclohexadiene δ: 136.05 (C1), 133.21
1-(Phenylsulfonyl)cyclohexene (4)
1
Yield: 198 mg (95%); mp 39–43 °C. IR (KBr, cm–1) νmax
:
(C4),131.59 (C2),122.5 (C3), 22.9 (C5), 19.9 (C6). The H
1
1620 (C=C), 1300 (SO2, νasym), 1140, (SO2, νsym). H NMR
shifts are similar to published (34) data.
(300 MHz, CDCl3) δ: 7.11 (dd, 1H, H2, J2,3a = 4.3 Hz, J2,3b
=
3.1 Hz), 2.35 (m, 2H, H3, H6), 1.8–1.5 (m, 4H, H4, H5); the
shifts and splitting pattern for Ph were similar to those for 2.
The 1H shifts are consistent with published (17, 34) values.
General procedure for the synthesis of ␥-oxygenated,
␣,␤-unsaturated sulfones
Allylic alcohols or their tert-butyldimethylsilyl ethers
were treated with 1 equiv. each of benzensulfinic acid and
N-iodosuccinimide in anhydrous dichloromethane at room
termperature. Progress of reactions was monitored by TLC
using mixtures of ethyl acetate – hexanes as noted with each
example shown in the following. The reaction mixture was
diluted with dichloromethane (10 mL), then washed with 5%
aqueous sodium thiosulfate solution, water, and brine, dried
(sodium sulfate), and concentrated. Crude iodophenylsul-
fones were redissolved in dichloromethane and stirred over-
night at room temperature with neutral alumina (10× excess
by weight). The reaction mixture was filtered, solids were
washed with ethyl acetate, and the filtrate was concentrated
to give the vinyl sulfones that were purified further in some
cases as noted. In the case of iodophenylsulfones 19, 20, and
23, elimination was carried out by stirring overnight in car-
bon tetrachloride containing 1.3 equiv. of DABCO.
2-(Phenylsulfonyl)norbornene (8) (ref. 34)
1
Yield: 209 mg (89%). H NMR (300 MHz, CDCl3) δ:
6.93 (d, 1H, H3, J3,4 = 3.8 Hz), 3.14 (cm, 1H, H1), 3.01 (cm,
1H, H4), 1.79 (cm, 1H, H6-exo), 1.67 (cm, 1H, H5-exo), 1.52
(m, 1H, H7-syn), 1.24 (m, 1H, H7-anti), 1.10 (cm, 1H, H6-endo),
0.96 (cm, 1H, H5-endo); the Ph shifts and splitting patterns
were similar to those for 7. 13C NMR (75.4 MHz, CDCl3)
phenyl δ: 140.22 (Ci), 133,59 (Cp), 129.50 (Cm), 128.09
(Co); norbornenyl δ: 147.80 (C2), 146.39 (C3), 49.73 (C7),
44.03 (C4), 43.38 (C1), 25.18 (C5), 25.07 (C6). Anal. calcd.
for C13H14SO2 (%): C 66.63, H 6.02, S 13.68; found: C
66.50, H 6.29, S 13.58.
(Z,E)-4-(Phenylsulfonyl)-4-octene (10a, 10b)
Flash chromatography (hexane – ethyl acetate, 1:1 v/v),
187 mg (80% combined yield); E:Z = 67:33 determined by
1H NMR. For the Z isomer (10a): 1H NMR (300 MHz,
CDCl3) δ: 7.884 (m, 2H, Co), 7.60 (m, 1H, Hp), 7.53 (m, 2H,
Hm), 6.008 (dd, 1H, H5, J5,6 = 7.9 Hz, J3,5 = 1.2 Hz), 2.604
(m, 2H, H6, J5,6 = 7.9 Hz, J6,7 = 7.4 Hz, J3,6 = 1.2 Hz), 2.284
(ddd, 2H, H3, J2,3 = 7.5 Hz, J3,5 = 1.2 Hz, J3,6 = 1.2 Hz),
1.522 (m, 2H, H2, J2,3 = 7.5 Hz, J1,2 = 7.4 Hz), 1.393 (m,
(E)-3-Phenylsulfonyl-2-propen-1-ol (14)
Allyl alcohol was converted to the iodophenylsulfonyl de-
rivative 13 in 60% yield as described in the previous para-
graph. Rf 0.17 (40% ethyl acetate – hexanes). IR (ATR, cm–1)
ν
max: 3495 (OH), 3064, 2934, 1447, 1300 (S=O), 1142
(S=O), 1082. 1H NMR (CDCl3) δ: 7.9 (m, 2H, PhH), 7.7 (m,
3H, PhH), 4.57 (sextet, 1H, J = 4.5 Hz, CHI), 4.04 (dd, 1H,
J = 4.5, 12.6 Hz, CHOH), 3.93 (dd, 1H, J = 4.5, 12.6 Hz,
CHOH), 3.93 (dd, 1H, J = 9.6 Hz, PhSO2CH2), 3.67 (dd,
1H, J = 4.5 Hz, PhSO2CH2), 2.43 (bs, 1H, OH). 13C NMR
(CDCl3) δ: 139.0, 134.6, 129.8, 128.2, 67.4 (CHOH), 62.3
(CH2SO2Ph), 22.0 (CHI). HRMS calcd. for C9H12O3SI:
325.9552 (M + H); found: 325.9561.
2H, H7, J6,7 = 7.4 Hz, J7,8 = 7.4 Hz), 0.889 (t, 3H, H8, J7,8
=
1
7.4 Hz) 0.877 (t, 3H, H1, J1,2 = 7.4 Hz); the H shifts are
consistent with literature (35) data. 13C NMR (75.4 MHz,
CDCl3) phenyl δ: 141.53 (s, Ci), 132.82 (d, Cp), 128.78 (d,
Cm), 126.90 (d, Co); octene chain δ: 142.99 (d, C5), 140.20
(s, C4), 34.80 (t, C3), 30.21 (t, C6), 22.19 (t, C7), 22.10 (t,
1
C2), 13.39 (q, C1), 13.11 (q, C8). For the E isomer (10b): H
NMR δ: 7.857 (m, 2H, Co), 7.60 (m, 1H, Hp), 7.53 (m, 2H,
Hm), 6.927 (dd, 1H, H5, J5,6 = 7.5 Hz, J3,5 = 0.5 Hz), 2.185
(m, 2H, H6, J5,6 = 7.5 Hz, J6,7 = 7.5 Hz; J3,6 could not be de-
termined), 2.189 (m, 2H, H3, J2,3 = 6.5 Hz, J3,5 = 0.5 Hz),
1.522 (m, 2H, H7, J6,7 = 7.5 Hz, J7,8 = 7.5 Hz), 1.359 (m,
Elimination as described in the general procedure gave
crystalline vinyl sulfone 14 (202 mg, 95%); mp 134–136 °C
(lit. value (27) mp 139 to 140 °C). Rf 0.18 (ethyl acetate –
1
hexanes, 1:1). H NMR (CDCl3) δ: 7.9 (m, 2H, PhH), 7.6
(m, 3H, PhH), 7.06 (m, 1H, J = 18 Hz, C=CH), 6.66 (m, 1H,
J = 18 Hz, C=CH), 4.42 (m, 2H, CH2OH), 1.6, (bs, 1H,
2H, H2, J1,2 = 7.5 Hz, J2,3 = 6.5 Hz), 0.947 (t, 3H, H8, J7,8
=
1
1
7.5 Hz) 0.826 (t, 3H, H1, J1,2 = 7.5 Hz); the H shifts agree
with published (35) data. 13C NMR phenyl δ: 140.83 (s, Ci),
132.79 (d, Cp), 128.80 (d, Cm), 127.65 (d, Co); octene chain
δ: 142.06 (d, C5), 139.89 (s, C4), 30.08 (t, C3), 28.22 (t, C6),
21.54 (t, C7), 22.10 (t, C2), 13.71 (q, C1), 13.51 (q, C8). The
chemical shift and coupling assignments for 10a and 10b
were made using a combination of correlated COSY,
HETCOR, and 1-D decoupling. Anal. calcd. for C14H20SO2
(%): C 66.33, H 7.99, S 12.71; found (10a and 10b): C
65.92, H 7.81, S 12.35.
OH). The H NMR spectrum of 14 reported in the literature
lists the vinylic hydrogens as a multiplet at δ 7.1–6.6, the
CH2OH methylene hydrogens as a multiplet at δ 5.55–4.20,
and the hydroxyl proton resonance as a broad singlet at δ
3.90 (28).
(E)-4-Phenylsulfonyl-3-buten-2-ol (16)
3-Butene-2-ol (72 mg, 1 mmol) was converted to
diastereomeric 3-iodo-4-phenylsulfonyl-2-butanols (15).
Yield: 216 mg (63%). Rf 0.23 (40% ethyl acetate – hexanes).
IR (ATR, cm–1) νma1x: 3531 (OH), 2960, 1447, 1280 (S=O),
1142 (S=O), 1082. H NMR δ: 7.90 (m, 2H, PhH), 7.62 (m,
3H, PhH), 4.60 (ddd, 1H, J = 9.8, 4.2, 2.0 Hz, CHI), 4.53
(td, 1H, J = 6.6, 4.2 Hz, CHI), 4.06 (dd, 1H, J = 14.2,
9.8 Hz, PhSO2CH), 3.74 (d, 2H, J = 6.6 Hz, PhSO2CH2),
3.70 (dd, 1H, J = 14.2, 4.4 Hz, PhSO2CH), 3.62, (bs or dq if
OH is decoupled, 1H, J = 4.2, 6.1 Hz, CHOH), 3.43 (bs or
dq if OH is decoupled, 1H, J = 5.9, 2.0 Hz, CHOH), 2.20
1-(Phenylsulfonyl)-1,3-cyclohexadiene (12) (refs. 3a, 34)
1
Yield: 203 mg (92%). H NMR (300 MHz, CDCl3) δ: 7.9
(m, 2H, Ph-H), 7.5 (m, 2H, Ph-H), 7.04 (dd, 1H, H2, J2,3
=
4.5 Hz, J2,4 = 2.0 Hz), 7.61 (m, 1H, Ph-H), 6.11 (dd, 1H, H3,
J3,4 = 9.4 Hz, J2,3 = 4.5 Hz) Hz, 6.07 (cm, 1H, H4) 2.35 (cm,
2H, H6), and 2.27 (cm, 2H, H5). 13C NMR (75.4 MHz,
CDCl3) phenyl δ: 139.50 (Ci), 133.08 (Cp), 129.01 (Cm),
© 2006 NRC Canada

Wolff et al.
673
(bs, OH), 1.29 (d, 3H, J = 6.1 Hz, CH3), 1.27 (d, 3H, J =
5.9 Hz, CH3). 13C NMR (CDCl3) δ: 134.1, 134.0, 128.4,
128.4, 128.0, 127.7, 69.7 (CHOH), 67.7 (CHOH), 62.5
(PhSO2CH2), 62.0 (PhSO2CH2), 32.6 (CHI), 30.7 (CHI),
25.0 (CH3), 20.9 (CH3). HRMS calcd. for C10H14O3SI:
340.9708 (M + H); found: 340.9705.
4.66 (CHOSi). HRMS calcd. for C18H29O3SiS: 353.1607
(M + H); found: 353.1612.
3-(tert-Butyldimethylsiloxy)-2-methyl-1-(phenylsulfonyl)-
cyclohexene (24)
The TBDMS ether of 2-methylcyclohexenol gave
diastereomeric 2-iodo-3-phenylsulfonyl derivatives (23) and
a small amount of a side product that was not identified;
from 266 mg (1.18 mmol) of alkene there was obtained
334 mg (57%) of iodophenylsulfonyl adducts as an oil.
Treatment with alumina (2.1 g) gave 122 mg (92%) of vi-
nyl sulfone 16; mp 74 to 75 °C (lit. value (29) mp 64–66 °C.
1
Rf 0.19 (40% ethyl acetate – hexanes). The H NMR spec-
trum of 16 matched that reported (29).
1
Rf 0.30 (10% ethyl acetate – hexanes). H NMR δ: 7.89 (m,
2H, PhH), 7.51 (m, 3H, PhH), 3.83 (m, 1H), 3.12 (m, 1H),
2.75 (m, 1H), 2.47–1.41 (m, 6H), 1.29 (s, 3H, CH3), 1.26 (s,
3H, CH3), 0.85 (s, t-Bu), 0.83 (s, t-Bu), 0.06 (s, CH3), 0.04
(s, CH3).
(E)-1-(Phenylsulfonyl)hex-1-en-3-ol (18)
1-Hexen-3-ol (100 mg, 1 mmol) was converted to
diastereomeric 2-iodo-1-(phenylsulfonyl)hex-1-en-3-ols (17).
Yield: 305 mg (83%). Rf 0.36 (40% ethyl acetate – hexanes).
IR (ATR, cm–1) νm1ax: 3497, 2959, 2933, 1447, 1304 (S=O),
1142 (S=O) 1083. H NMR δ: 7.90 (m, 2H, PhH), 7.60 (m,
3H, PhH), 4.62 (ddd, 1H, J = 10.0, 4.3, 2.0 Hz, CHI), 4.49
(td, 1H, J = 6.9, 6.3, 4.1 Hz, CHI), 4.09 (dd, 1H, J = 14.2,
10.0 Hz, PhSO2CH), 3.79 (dd, 1H, J = 15.4, 6.3 Hz,
PhSO2CH2), 3.71 (dd, 1, J = 15.4, 6.9 Hz, PhSO2CH), 3.70
(dd, 1, J = 14.2, 4.3 Hz, PhSO2CH), 3.54 (cm, 1H, J =
4.1 Hz, CHOH), 3.11 (cm, 1H, J = 2.0 Hz, CHOH), 2.10
(bs, OH), 1.64–1.32 (m, 2 × 4H, CH2), 0.96 (m, 3H, J =
6.9 Hz, CH3), 0.94 (m, 3H, J = 6.7 Hz, CH3). 13C NMR
(CDCl3) δ: 138.7, 138.5, 134.0, 134.0, 129.4, 129.3, 129.3,
128.0, 127.7, 74.3 (CHOH), 71.0 (CHOH), 62.6
(PhSO2CH2), 61.5 (PhSO2CH2), 41.3, 36.5, 31.6, 28.6, 18.7,
18.5, 13.9, 13.9. HRMS calcd. for C12H18O3SI: 369.0021
(M + H); found: 369.0021.
The crude mixture was taken up in carbon tetrachloride
(3 mL), DABCO was added (88 mg, 1.3 equiv.), and the
mixture was stirred overnight at room temperature. The mix-
ture was diluted with dichloromethane, extracted with water
and brine, dried (Na2SO4), and concentrated to give 196 mg
of a mixture of products that was purified using a Waters
vacuum manifold with a 20 Sep-Pak silica gel cartridge and
5%–20% ethyl acetate – hexanes as eluant to give 95 mg
(38%) of vinyl sulfone 24 as an oil. Rf 028 (10% ethyl ace-
1
tate – hexanes). H NMR δ: 7.86 (m, 2H, PhH), 7.60 (m,
3H, PhH), 3.87 (m, 1H, CHOSi), 3.12 (m, 1H), 2.45 (s, 3H,
CH3), 2.36–1.24 (m, 6H), 1.29 (s, CH3), 0.93 (s, t-Bu), 0.13
(s, CH3), 0.12 (s, CH3). HRMS calcd. for C19H31O3SiS:
366.1763 (M + H); found: 366.1772
Phenylsulfonyl 4-O-acetyl-2,3,6-trideoxy-␣,␤-L-threo-hex-
2-enopyranoside (27)
Treatment with alumina (3 g) gave 211 mg (88%) of vinyl
sulfone 18; mp 54–57 °C (lit. value (30) mp 56–58 °C). Rf
Benzenesulfinic acid (560 mg, 4 equiv.) was added to a
stirring solution of 3,4-di-O-acetyl-6-deoxy-L-glucal (214 mg,
1 mmol) in 5 mL of anhydrous dichloromethane at 0 °C.
The reaction was allowed to warm to room temperature and
stirred for 1 h, after which TLC (20% ethyl acetate –
hexane) showed that starting material was consumed. The
mixture was then diluted with 40 mL of dichloromethane
and washed with 10% NaHCO3 (40 mL) and brine (40 mL),
dried (Na2SO4), and concentrated to an oil that was purified
on a Waters vacuum manifold using a 20 cc Sep-Pak silica
gel cartridge and 20% ethyl acetate – hexane as eluant to
give a 3:1 mixture of α and β anomers that were not sepa-
rated. Yield: 255 mg (86%). Rf 0.4 (40% ethyl acetate – hex-
0.25 (40% ethyl acetate – hexanes). The H and 13C NMR
1
spectra of 18 matched those reported (30).
3-(tert-Butyldimethylsiloxy)-1-(phenylsulfonyl)cyclo-
hexene (21) and 3-(tert-butyldimethylsiloxy)-2-
(phenylsulfonyl)cyclohexene (22)
Iodophenylsulfonation of the TBDMS ether of cyclohex-
enol gave a mixture of regioisomeric 2-iodo-1-phenyl-
sulfonyl and 1-iodo-2-phenylsulfonyl derivatives (19, 20);
from 214 mg (1 mmol) of alkene there was obtained 371 mg
(77%) of iodophenylsulfonyl adducts as an oil. Rf 0.36 (10%
1
ethyl acetate – hexanes). H NMR δ: 7.90 (m, 2H, PhH),
1
anes). H NMR (300 MHz, CDCl3): see Table 2. 13C NMR
7.60 (m, 3H, PhH), 5.15 (m, 1H), 4.90 (m, 1H), 4.40 (m,
1H), 3.61 (m, 1H), 3.51 (m, 1H), 3.19 (m, 1H), 2.14–1.90
(m, 4H), 1.66–1.48 (m, 2H), 0.90 (s, t-Bu), 0.82 (s, t-Bu),
0.06 (s, CH3), 0.04 (s, CH3).
(75.4 MHz, CDCl3) δ: 169.8, 169.4, 136.6, 134.0, 133.7
(C2/C3), 132.9 (C2/C3), 129.6, 128.7, 128.6, 128.1, 120.9
(C2/C3), 119.0 (C2/C3), 89.3 (C1, α), 88.1 (C1, β), 72.4, 68.7,
68.4, 20.7, 20.6, 17.8, 17.5. Analytical MW calcd. for
C14H16O5S: 296; found by ESIMS: 314.3 (38%) (M +
NH4)+, 155.3 (100%). HRMS calcd. for C14H17O5S:
296.0797 (M + H); found: 297.0787.
The crude mixture was taken up in carbon tetrachloride
(3 mL), DABCO was added (112 mg, 1.3 equiv.), and the
mixture was stirred overnight at room temperature. The mix-
ture was diluted with dichloromethane, extracted with water
and brine, dried (Na2SO4), and concentrated to give 262 mg
(92%) of a mixture of vinyl sulfone 21 and its regioisomer
22, which were not separated. Rf 0.27 (10% ethyl acetate –
Iodophenylsulfonation of dihydropyran
Dihydropyran (252 mg, 3 mmol) was dissolved in a mix-
ture of 3 mL each of anhydrous acetonitrile and anhydrous
dichloromethane. Tetra-N-butylammonium benzenesulfinate
(36) (3 mmol, 1.15 g) and 4 Å molecular sieves (100 mg)
were added and the reaction mixture was stirred for 30 min,
then N-iodosuccinimide (675 mg, 3 mmol) was added and
1
hexanes). The H NMR spectrum of the mixture of vinyl
sulfones showed a 2.2:1 ratio of vinyl sulfone 21 (the reso-
nances of which matched those reported in the literature,
ref. 27) and another product, assigned as the regioisomeric
vinyl sulfone 22, which showed peaks at δ 7.17 (C=CH) and
© 2006 NRC Canada

674
Can. J. Chem. Vol. 84, 2006
Table 2.
ments that revealed the formation of benzenesulfonyl iodide
from benzenesulfinic acid and N-iodosuccinimide. We also
thank Villanova University for financial support of this re-
search.
α Anomer
β Anomer
δH, J
δH
δH
5.075
6.234
6.234
5.017
4.390
1.196
5.226
5.943a,b
6.120a
4.520
3.588
1.220
H1
H2
H3
H4
H5
H6
References
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York. 1999. Chap. 11.
OAc
Ho
2.092
7.937
2.031
7.879
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Hm
Hp
7.594
7.544
7.693
2.1
7.702c
d
J1,2
J1,3
J1,4
J1,5
J2,3
J2,4
J3,4
J4,5
J5,6
d
2.2
2.5
0.7
2.7
-0
-10.5
10.5
1.7
d
d
2.2
8.4
6.3
8.4
6.1
aH2 and H3 shifts, including related coupling con-
stants, may need to be exchanged.
bBroadened dt multiplet.
cShifts determined with the help of COSY.
dThe coupling constants could not be determined
because of the small ∆δ between H2 and H3, generat-
ing high order multiplets.
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the reaction was allowed to stir for 8 h at –78 °C. The reac-
tion was diluted with dichloromethane (50 mL), washed with
10% NaHSO3 (50 mL), water (50 mL), and brine (50 mL),
dried over Na2SO4, and concentrated to give a yellow oily
product that was then purified by flash chromatography over
silica gel using 40% ethyl acetate in hexanes as the eluant.
One of the products separated as a waxy solid (101 mg,
11%) was determined to be the trans-3-iodo-2-succinimide
adduct of dihydropyran. The other fractions contained a
mixture (211 mg) of the 3-iodo-2-phenylsulfonyl adducts
and other side products that were not identified. The trans-3-
iodo-2-succinimide 26 adduct had: Rf 0.28 (40% ethyl ace-
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1
tate – hexane). IR (film, cm–1) νmax: 2950, 1716, 1371. H
NMR δ: 5.24 (d, 1H, J = 11.2 Hz, CHN), 5.16 (ddd, 1H, J =
2.8, 11.2 Hz, CHI), 4.15 (m, 1H), 3.68 (m, 1H), 2.74 (s, 4H,
CH2CH2), 2.60 (m, 1H), 2.13 (m, 1H), 1.78 (m, 1H), 1.40
(m, 1H). 13C NMR δ: 178.2, 86.2, 71.6, 39.9, 31.2, 30.4,
26.7. HRMS calcd. for C9H13NO3I: 309.9940; found: 309.9942.
The 3-iodo-2-phenylsulfonyl adducts 27 had: Rf 0.5 (40%
ethyl acetate – hexane). IR (film, (cm–1) νmax: 2950, 1625,
1439, 1320 (S=O), 1139 (S=O). 1H NMR δ: 5.01 (d, 1H, J =
5.6 Hz, CHS) 4.86 (d, 1H, J = 6.7 Hz, CHS), 4.21–3.98 (m,
2H), 3.72 (m, 1H), 3.62 (m, 1H), 2.2–1.6 (m, 10H). HRMS
calcd. for C11H12O3SI: 350.9548 (M – H); found: 350.9582.
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© 2006 NRC Canada

Wolff et al.
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© 2006 NRC Canada