Chiral version of the Burgess reagent and its reactions with epoxides

Article abstract of DOI:10.1055/s-2006-932450

A chiral auxiliary version of the Burgess reagent was prepared, and its reactions with epoxides were studied. Diastereomeric sulfamidates were converted to both enantiomers of protected trans-amino alcohols with ee of 84-98%. Georg Thieme Verlag Stuttgart

Full text of DOI:10.1055/s-2006-932450

LETTER
445
Chiral Version of the Burgess Reagent and its Reactions with Epoxides
C
hira
l
Versionof
t
a
he
B
urgess
n
R
eagent nes Leisch, Rachel Saxon, Bradford Sullivan, Tomas Hudlicky*
Department of Chemistry and Centre for Biotechnology, Brock University, 500 Glenridge Avenue, St. Catharines, Ontario,
L2S 3A1, Canada
E-mail: thudlicky@brocku.ca
Received 2 November 2005
ring sulfamidates,5b we have shown that styrene diol,
styrene oxide and other aryl-substituted oxiranes produce
rather the seven-membered sulfamidate of type 3 as major
products.4 These observations were subsequently
acknowledged in a recent paper by Nicolaou,5c who
showed that the production of seven-membered sulf-
amidates is a function of the electron density of the aro-
matic ring, which invites the reactivity of the resonance
form of the Burgess reagent 1b (Figure 1).
Abstract: A chiral auxiliary version of the Burgess reagent was
prepared, and its reactions with epoxides were studied. Diastereo-
meric sulfamidates were converted to both enantiomers of protected
trans-amino alcohols with ee of 84–98%.
Key words: chiral Burgess reagent, epoxides, menthol auxiliary
group, sulfamidate, trans-amino alcohol derivatives
There has been a recent revival of interest in the chemistry
of the Burgess reagent (1), originally designed and used
for dehydration of alcohols.1 Its reactivity with other func-
tional groups has been reinvestigated.2 Until recently it
has been generally accepted that epoxides and many other
functionalities are inert to treatment with the Burgess re-
agent.3 In 2003 we published the first disclosure of reac-
tions of epoxides with the Burgess reagent and
demonstrated their conversion to five- and seven-mem-
bered sulfamidates of type 2 and 3, respectively,4 as
shown in Scheme 1.
O
O
Et3NSO2N COMe
Et3NSO2NCOMe
1b
1a
Figure 1
The anion localized on oxygen, as in 1b, clearly prefers
the ‘harder’ benzylic site in aryl-substituted oxiranes, and
hence these reactions lead predominantly to seven-mem-
bered sulfamidates 3.
O
Since the reactive options of the Burgess reagent seem to
be subject to electronic control and can therefore be mod-
ulated, we have chosen to test several asymmetric ver-
sions of the reactions with oxiranes. Chiral catalysts were
tested with meso-epoxides and achiral Burgess reagent for
asymmetric induction. A chiral auxiliary version of the re-
agent was prepared with the expectation that both enantio-
mers of amino alcohols would be obtained, following
separation and removal of the auxiliary group. There are
many examples in the literature of asymmetric reactions
of meso-epoxides catalyzed by various C2-symmetric
Lewis acids.6 We tested two such catalysts: Jacobsen’s7
salen catalyst (4) and Bolm’s8 scandium triflate catalyst
(5, Figure 2). In both cases, racemic products were ob-
tained from cyclohexene oxide.
O
Et3NSO2NCO2Me
S
NCO2Me
H
OH H
R
R
(1)
R
R
O
R'
R'
R'
R'
R'
R'
MeO
O
O
S
N
O
O
R
O
MeO2CN
O
R
S
1
R
O
R
and/or
O
R
R
R = H, alkyl, aryl
2
3
Scheme 1
ranes.
Reactivity of the Burgess reagent with alcohols and oxi-
Nicolaou has demonstrated the conversion of diols and
other functionalities to sulfamidates, carbamates, and oth-
er compounds.5 We have proposed a common mechanism
and have indicated the possibility of degenerate pathways
to the sulfamidate from both epoxides and diols.4 Al-
though an earlier report suggested that aryl-substituted
diols provided a regioisomeric mixture of five-membered
H
H
N
N
Cr
Cl
t-Bu
O
O
t-Bu
N
N
Sc(OTf)3
OH
OH
t-Bu
t-Bu
4
5
Figure 2
SYNLETT 2006, No. 3, pp 0445–0449
Advanced online publication: 06.02.2006
DOI: 10.1055/s-2006-932450; Art ID: S11405ST
© Georg Thieme Verlag Stuttgart · New York
1
5.
0
2.
2
0
0
6
One possible explanation of the complete lack of asym-
metric induction in this reaction may be that the Burgess
reagent itself may act as a Lewis acid and displace the ac-

446
H. Leisch et al.
LETTER
not favorable
CO2Me
N
O
O
S
O
8
x
intramolecular
CO2Me
N
O
S
NEt3
1
1
SO2
O
O
N CO2Me
O
O
7
intermolecular
6
1
1
MeO2C
SO2
N
NEt3
CO2Me
N
O
+ 1
S
O
NCO2Me
O
O
S
O2
2
9
Scheme 2 Possible mechanistic options for the formation of cis-sulfamidates from epoxides.
tual catalyst from the activated epoxide. As the reagent is that in this fashion both enantiomers of the products can
used in more than stoichiometric quantities (2.3 equiv) be obtained and converted to valuable amino alcohol de-
and the concentration of the catalyst is only 10 mol%, the rivatives (both cis and trans), whose use is common in
competition is unfavorable for the development of a chiral medicinal chemistry.11
transition state. This suspicion is supported by prelimi-
A menthol version of the Burgess reagent was prepared
nary calculations.9 At this stage of the project we have
and reacted with cyclohexene oxide producing a 1:1 mix-
also noted that the sulfamidates 2 are cis-, not trans-fused
ture of diastereomers of cis-fused sulfamidates as shown
in Scheme 3.
as we originally reported in our 2003 publication.4 The cis
stereochemistry is clearly a consequence of the mecha-
nism of this reaction and the requirement of two equiva-
lents of the reagent, one of which returns unchanged into
the reaction cycle.
The separation of diastereomers 11a and 11b was ardu-
ous, and the mixture was converted to benzoates 12a and
12b with ammonium benzoate. Because the sulfamidates
resemble cyclic sulfates in their reactivity with nucleo-
Possible mechanistic options are shown in Scheme 2.
Two different pathways of the reaction for oxiranes with
O
O
O
O
O
O
S
the Burgess reagent are possible. The activation of the ep-
oxide to give compound 6 is likely and supported by pre-
liminary calculations.9 Another option is the direct
nucleophilic attack of the Burgess reagent yielding com-
pound 7 although this process has a higher activation en-
ergy than the formation of 6.10 In either case, an
intramolecular closure to the sulfamidate is rather unlike-
ly; a more plausible mechanism invokes the reaction of ei-
ther 6 or 7 with a second equivalent of the Burgess
reagent. Rather than ejecting triethylamine by an intramo-
lecular sulfonation, alkoxide 7 reacts with the second
equivalent of the reagent to produce 9, also formed from
the opening of activated epoxide 6. Displacement of the
Burgess reagent then occurs from the site of initial oxirane
opening. A similar mechanism has also been proposed for
the reaction of (1) with diols and we have shown that ep-
oxides may be intermediates in these reactions.4,5c A study
of concentration- and stoichiometry-dependence indicat-
ed that indeed at least two equivalents are essential; with
one equivalent of the reagent yields were halved. Dilution
experiments did not change the product content.
S
O
*MO2CN
O
*MO2CN
i
+
O
NSO2NEt3
+
11b
11a
10
30%
ii, iii
NHCO2M*
OBz
NHCO2M*
NHCO2M*
OBz
M* =
+
+
~ 50%
12a
12b
13 (47%)
iv, v
iv, v
O
O
O
O
O
MeO
F3C
O
O
HN
HN
vi
vi
N
15b
Ph
~70%
(–)-14b
(+)-14a
15a
93% ee
98% ee
–
Scheme 3 Reagents and conditions: i. THF reflux, 1.5 h; ii. PhCO2
Surprised that the two C2-symmetric catalysts proved to
be completely ineffective in these reactions, we therefore
turned to the chiral-auxiliary-based approach, recognizing
+
NH4 , DMF, 45 °C, 12 h; iii. THF, H2O, concd H2SO4, r.t., 6 h; iv. 1
M NaOH in MeOH, 2 h; v. NaH, THF reflux, 18 h; vi. n-BuLi, 0 °C,
30 min, Mosher’s acid chloride, –78 °C to r.t.
Synlett 2006, No. 3, 445–449 © Thieme Stuttgart · New York

LETTER
Chiral Version of the Burgess Reagent
447
NH
O
HO
O
N
S
O
*MO
O
H
O
O
N
O
O
O
*MO2CN
S
O
PhCO2 NH4
18a
S
(10)
O
+
O
or
NH2
17
16
O
S
HO
O
N
O
O
18b
50% KOH
Scheme 4 Formation of sulfonyl urea derivative 18.
Table 1 Reactions of Oxirane with Menthyl Version of the Burgess Reagent
Oxirane
Sulfamidates (%)a
Benzoates (%)
ee (%)b or de (%)c
O
O
O
O
O
O
S
S
NHCO2M*
OBz
NHCO2M*
OBz
*MO2CN
*MO2CN
O
(+) 98 and (–) 93b
11a
11b
12a
12b
30%
O
49%
O
O
O
S
S
*MO2CN
O
NHCO2M*
OBz
*MO2CN
O
NHCO2M*
OBz
O
98 and 93c
19a
19b
20a
20b
37%
O
52%
O
O
O
S
S
NHCO2M*
OBz
*MO2CN
O
*MO2CN
O
NHCO2M*
OBz
O
93 and 92c
21a
21b
22a
22b
35%
75%
NCO2M*
O
O
BzO
BzO
NCO2M*
O
O
S
S
O
O
C4H9
NCO2M*
NCO2M*
–
C4H9
C4H9
C4H9
C4H9
O
24a/24bd
23a
23b
22%
36%
O
O
O
O
O
S
S
NHCO2M*
OBz
NHCO2M*
OBz
*MO2CN
*MO2CN
O
O
(+) 94 and (–) 84e
25a
25b
26a
26b
36%
51%
a Yields are isolated and unoptimized.
b Enantiomeric excess determined by Mosher’s amide formation of cyclic carbamates, derived from the corresponding benzoates by hydrolysis
and cyclization.
c Diastereomeric excess determined by GC/MS of benzoates after separation by flash column chromatography.
d Not separable by flash column chromatography.
e Diastereomeric excess determined by GC/MS of separated benzoates after hydrogenation.
Synlett 2006, No. 3, 445–449 © Thieme Stuttgart · New York

448
H. Leisch et al.
LETTER
philes this process also allows for the synthesis of trans- These initial results provide for the first example of the
amino alcohols. Separation of the benzoates and conver- chiral version of the Burgess reagent and demonstrate that
sion to the known cyclic carbamates 14a and 14b provid- chiral derivatives of both cis- and trans-amino alcohols
ed evidence of excellent enantiomeric excess in both can be obtained from epoxides in an enantiodivergent
amino alcohol products {optical rotations of 14a and 14b fashion through resolution methodology. Future work will
were higher than reported literature values: Compound focus on the detailed mechanistic study of this reaction,
22
14a: [a]D +7.5 (c 1.0, EtOH), lit.12 +6.0 (c 1.0, EtOH); reinvestigation of C2-symmetric catalysts under stoichio-
22
compound 14b: [a]D –7.4 (c 1.0, EtOH), lit.12 –5.9 (c metric or Lewis acid catalyzed conditions, and synthesis
1.0, EtOH)}. Accurate determinations of enantiomeric and exploration of other more rigid, chiral auxiliary
purity were made by 19F NMR evaluation of Mosher groups, which will permit easier separation of diastereo-
amides 15a and 15b and comparison with Mosher amide meric sulfamidates. Application of this reaction will be
data obtained on the racemate of 14. A moderate yield of extended to other reactive systems such as aziridines, and
the allylic amine derivative 12 was obtained from the these results will be reported in due course.
reaction of sulfamidates 11a and 11b with ammonium
Experimental Procedures
Determination of diastereomeric excess was performed on a Perkin
benzoate. A more detailed study of this reaction revealed
that treatment of 11a and 11b under strongly acidic con-
ditions (6 N HCl–dioxane, 1:1) led to the isolation of
racemic 13 in nearly quantitative yield. Simply heating a
mixture of 11a and 11b in DMF at 45 °C for 18 hours pro-
vided 13 in moderate yield (55%) along with recovered
starting material. This is another useful result as it allows
for the direct conversion of epoxides to derivatives of
allylic amines. In cases where the diastereomers are more
easily separated, both enantiomers of allylic amine
carbamates will therefore become available.
Elmer Claurus 500 GC/MS using a Perkin Elmer Elite-5MS col-
umn, 10 m, 0.25 mmID, 2 mL/min helium flow. For the separation
of diastereomers following temperature program was used 50 °C (2
min), 15 °C/min to 160 °C, 1 °C/min to 240 °C, 15 °C/min to
300 °C (3 min).
Menthol Burgess Reagent 10
A solution of menthol (5 g, 32 mmol) in dry benzene (15 mL) was
added dropwise to a solution of chlorosulfonyl isocyanate (5.21 g,
36.8 mmol) in dry benzene (15 mL) over 20 min. The reaction tem-
perature was kept between 25–30 °C using an ice-water bath. After
complete addition, the reaction mixture was stirred at r.t. for an ad-
ditional 30 min. The solvent was removed under reduced pressure
and the residue was purified by crystallization (hexane, 40 mL) to
give the menthol sulfamoyl chloride intermediate as colorless crys-
tals (87%); mp 86–88 °C (hexane); [a]D23 –64.5 (c 0.8, CHCl3). To
a solution of Et3N (4.76 g, 47 mmol) in benzene (20 mL) was added
dropwise a solution of menthol sulfamoyl chloride (7 g, 23.5 mmol)
in dry benzene (40 mL) keeping the reaction temperature between
10–15 °C. After stirring at r.t. for 1 h, the reaction mixture was fil-
tered. The solvent was evaporated and the residue was crystallized
from THF–hexanes to give 7.24 g of menthol Burgess reagent 10 as
colorless solid (85%); mp 87–89 °C (THF–hexanes); [a]D23 –48.7 (c
0.475, CHCl3). IR (film): n = 3426, 3020, 2958, 2872, 1682, 1457,
1389, 1369, 1340, 1285, 1253, 1216, 1105, 982, 922, 891 cm–1. 1H
NMR (300 MHz, CDCl3): d = 4.51 (td, J = 11.0, 4.6 Hz, 1 H), 3.45
(q, J = 7.7 Hz, 6 H), 3.14–3.26 (m, 1 H), 1.93–2.08 (m, 2 H), 1.65
(d, J = 11.9 Hz, 2 H), 1.30–1.44 (m, 11 H), 0.92–1.03 (m, 2 H), 0.87
(t, J = 7.7 Hz, 6 H), 0.76 (d, J = 6.6 Hz, 3 H). 13C NMR (75 MHz,
CDCl3): d = 157.7, 76.4, 50.7, 47.3, 46.7. 41.3, 34.6, 31.8, 26.4,
23.7, 21.2, 16.6, 9.8, 8.8.
The results from the reactions of other oxiranes with men-
thyl Burgess reagent 10 are summarized in Table 1. The
moderate isolated yields of cis-sulfamidates reflect the
difficulty of isolation and separation of the diastereomers,
not an uncommon problem in auxiliary group-mediated
resolutions.13 These issues will eventually be addressed
and solved by employing more rigid, bulkier auxiliary
groups, such as those derived from pinene, sparteine, or
quinine. We anticipate that the cis-fused sulfamidates will
then be more easily separated and lead to optically active
cis-amino alcohols through hydrolysis.
The cis-sulfamidates were converted to trans-benzoates
via inversion with ammonium benzoate at the oxygenated
carbon and the enantiomeric or diastereomeric excess was
determined after separation by column chromatography.
Benzoates 26a and 26b were hydrogenated to 12a and
12b, respectively, and their identity as well as their optical
purity evaluated by direct comparison, establishing also
that no allylic mode of the oxirane opening occurred. The
products from the reactions of n-butyl oxirane proved un-
separable.
General Procedure for the Reaction of Oxiranes with Menthyl
Burgess Reagent
To a solution of oxirane (2.0 mmol) in THF (5 mL) was added men-
thol Burgess reagent 10 (4.69 mmol). And the resulting reaction
mixture was stirred at 70 °C until complete consumption of the ox-
irane (TLC). The reaction mixture was cooled to r.t. and filtered
through a plug of silica to remove salts formed during the reaction.
The solvent was removed under reduced pressure, and the residue
was purified by flash column chromatography (hexanes–EtOAc,
8:1) affording two diastereomers in a ratio of 1:1.
As expected, the reaction of styrene oxide with the chiral
Burgess reagent yielded predominately the seven-mem-
bered sulfimidate 16, which was treated with ammonium
benzoate to yield a mixture of diastereomers identified by
2D-NMR (gDQCOSY, gHMQC and gHMBC at –20 °C)
tentatively as 18a or 18b,14,15 apparently produced by the
protonation of sulfimidate 16 and displacement with am-
monia (Scheme 4). Attempts to hydrolyze the sulfonyl
group under basic conditions resulted in the formation of
racemic styrene oxide, in agreement with previous re-
sults.4
trans-1-(N-Carbomenthyloxy)-2-benzoylcyclohexane 12a and
12b
To a solution of diastereomers 11a and 11b (170 mg, 0.47 mmol) in
dry DMF (1 mL) was added ammonium benzoate (120 mg, 0.85
mmol). The solution was heated to 45 °C until TLC analysis indi-
cated full conversion of the starting material (18 h). The solvent was
evaporated and the residue was dissolved in THF (3 mL). Three
Synlett 2006, No. 3, 445–449 © Thieme Stuttgart · New York

LETTER
Chiral Version of the Burgess Reagent
449
drops of H2O and concentrated H2SO4 were added and the reaction
mixture was stirred at r.t. for 12 h, before the pH was set to 8 (sat.
NaHCO3). The layers were separated and the aqueous layer was ex-
tracted three times with CH2Cl2. The combined organic layers were
washed with H2O and brine and the solvent was evaporated under
reduced pressure. The residue was purified by flash column chro-
matography (CH2Cl2–MeOH, 400:1) affording 47 mg of 12a (25%)
and 46 mg of 12b (24%).
(4) Rinner, U.; Adams, D. R.; dos Santos, M. L.; Abboud, K. A.;
Hudlicky, T. Synlett 2003, 1247.
(5) (a) Nicolaou, K. C.; Snyder, S. A.; Nalbandian, A. Z.;
Longbottom, D. A. J. Am. Chem. Soc. 2004, 126, 6234.
(b) Nicolaou, K. C.; Huang, X.; Snyder, S. A.; Rao, P. B.;
Bella, M.; Reddy, M. V. Angew. Chem. Int. Ed. 2002, 41,
834. (c) Nicolaou, K. C.; Snyder, S. A.; Longbottom, D. A.;
Nalbandian, A. Z.; Huang, X. Chem. Eur. J. 2004, 10, 5581.
(d) Nicolaou, K. C.; Longbottom, D. A.; Snyder, S. A.;
Nalbandian, A. Z.; Huang, X. Angew. Chem. Int. Ed. 2002,
41, 3866.
(6) (a) Schneider, C.; Sreekanth, A. R.; Mai, E. Angew. Chem.
Int. Ed. 2004, 43, 5691. (b) Yang, M.; Zhu, C.; Yuan, F.;
Huang, Y.; Pan, Y. Org. Lett. 2005, 7, 1927. (c) Schaus, S.
E.; Larrow, J. F.; Jacobsen, E. N. J. Org. Chem. 1997, 62,
4197. (d) Sagawa, S.; Abe, H.; Hase, Y.; Inaba, T. J. Org.
Chem. 1999, 64, 4962. (e) Iida, T.; Yamamoto, N.;
Matsunaga, S.; Woo, H.-G.; Shibasaki, M. Angew. Chem.
Int. Ed. 1998, 37, 2223. (f) Carrée, F.; Gil, R.; Collin, J.
Org. Lett. 2005, 7, 1023. (g) Bartoli, G.; Bosco, M.;
Carlone, A.; Locatelli, M.; Melchiorre, P.; Sembri, L. Org.
Lett. 2004, 6, 3973. (h) Bartoli, G.; Bosco, M.; Carlone, A.;
Locatelli, M.; Massaccesi, M.; Melchiorre, P.; Sembri, L.
Org. Lett. 2004, 6, 2173. (i) Bandini, M.; Cozzi, P. G.;
Melchiorre, P.; Umani-Ronchi, A. Angew. Chem. Int. Ed.
2004, 43, 84.
Compound 12a: mp 111–113 °C; Rf = 0.5 (CH2Cl2–MeOH, 100:1);
[a]D20 –77.8 (c 1.05, CHCl3). IR: n = 3434, 3368, 3019, 2954, 2868,
1711, 1603, 1585, 1513, 1452, 1370, 1318, 1279, 1216, 1115, 1038,
1028, 757, 712, 668 cm–1. 1H NMR (300 MHz, CDCl3): d = 8.07 (d,
J = 7.7 Hz, 2 H), 7.55 (t, J = 7.2 Hz, 1 H), 7.43 (t, J = 7.7 Hz, 2 H),
4.83 (dt, J = 10.6, 4.5 Hz, 1 H), 4.59 (d, J = 9.3 Hz, 1 H), 4.34–4.46
(m, 1 H), 3.76–3.90 (m, 1 H), 2.07–2.19 (m, 2 H), 1.73–1.93 (m, 3
H), 1.13–1.69 (m, 10 H), 0.91–1.06 (m, 1 H), 0.86 (d, J = 10.0 Hz,
3 H), 0.75 (d, J = 6.6 Hz, 3 H), 0.46–0.68 (m, 4 H). 13C NMR (75
MHz, CDCl3): d = 167.2, 156.5, 133.4, 130.6, 130.2, 128.7, 76.6,
74.7, 54.3, 47.5, 41.2, 34.6, 32.8, 31.5, 26.6, 25.0, 24.5, 23.8, 22.2,
21.1, 16.8. HRMS: m/z calcd for C24H35NO4: 401.2566; found:
401.2579.
Compound 12b: mp 138–141 °C; Rf = 0.45 (CH2Cl2–MeOH,
20
100:1); [a]D –15.8 (c 1.05, CHCl3). IR (film): n = 3685, 3435,
3020, 2956, 2869, 1711, 1515, 1452, 1318, 1279, 1216, 1115, 1039,
929, 759, 714, 669 cm–1. 1H NMR (300 MHz, CDCl3): d = 8.05 (d,
J = 7.7 Hz, 2 H), 7.55 (t, J = 7.1 Hz, 1 H), 7.43 (t, J = 7.7 Hz, 2 H),
4.86 (dt, J = 10.6, 4.5 Hz, 1 H), 4.69 (d, J = 9.3 Hz, 1 H), 4.35–4.49
(m, 1 H), 3.73–3.90 (m, 1 H), 2.12 (d, J = 12.5 Hz, 2 H), 1.98 (d,
J = 11.9 Hz, 1 H), 1.73–1.88 (m, 2 H), 1.08–1.68 (m, 10 H), 0.79–
0.97 (m, 5 H), 0.55 (d, J = 6.4 Hz, 3 H), 0.30 (d, J = 6.4 Hz, 3 H).
13C NMR (75 MHz, CDCl3): d = 167.2, 156.3, 133.3, 130.4, 130.1,
128.7, 76.0, 74.6, 54.4, 47.6, 41.8, 34.6, 33.2, 31.7, 31.6, 26.5, 24.9,
24.5, 23.9, 22.4, 20.7, 16.3. HRMS: m/z calcd for C24H35NO4:
401.2566; found: 401.2575.
(7) Martinez, L. E.; Leighton, J. L.; Carsten, D. H.; Jacobsen, E.
N. J. Am. Chem. Soc. 1995, 117, 5897.
(8) Bolm, C.; Ewald, M.; Felder, M.; Schlingloff, G. Chem. Ber.
1992, 125, 1169.
(9) We thank Prof. Travis Dudding (Brock University) for
performing transition state optimization calculations
(Gaussian 03) for the C2 catalysts as well as for the menthol
auxiliary. Full details of these calculations will be disclosed
in an upcoming full paper.
(10) We thank one of the referees for suggesting this explanation.
(11) For reviews on the synthesis and utility of 1,2-amino-
alcohols see: (a) Shaw, G. In Comprehensive Heterocyclic
Chemistry II; Katritzky, A. R.; Rees, C. W.; Scriven, E. F.
V., Eds.; Pergamon Press: New York, 1996, 397.
(b) Wallbaum, S.; Martens, J. Tetrahedron: Asymmetry
1992, 3, 1475. (c) Noyori, R.; Kitamura, M. Angew. Chem.,
Int. Ed. Engl. 1991, 193, 34. (d) Singh, V. K. Synthesis
1991, 605.
Acknowledgment
The authors are indebted to Natural Sciences and Engineering
Research Council (NSERC) of Canada, Canadian Foundation for
Innovation (CFI), Ontario Innovation Trust (OIT), Petroleum Re-
search Fund administered by the American Chemical Society (PRF-
AC), and Brock University for financial support of this work. TDC
Research Inc. and TDC Research Foundation are acknowledged for
summer research fellowships for R.S. and B.S.
(12) de Parrodi, C. A.; Juaristi, E.; Quinterno, L.; Clara-Sosa, A.
Tetrahedron: Asymmetry 1997, 8, 1075.
(13) Pelphrey, P. M.; Abboud, K. A.; Wright, D. L. J. Org. Chem.
2004, 69, 6931.
References and Notes
(14) Compound 18: colorless oil; [a]D23 –48.5 (c 0.275, CHCl3).
IR (film): n = 3448, 3340, 2956, 2926, 2871, 1631, 1548,
1496, 1446, 1372, 1322, 1173, 1097, 986, 954, 917, 863,
815, 759, 700, 661, 609, 541 cm–1. 1H NMR (499 MHz,
CDCl3): d = 7.28–7.46 (m, 5 H), 7.06 (br s, 1 H), 5.76 (br s,
1 H), 5.06 (dt, J = 9.3, 2.2 Hz, 1 H), 4.80 (td, J = 11.0, 4.6
Hz, 1 H), 4.24 (ddd, J = 10.6, 8.8, 2.8 Hz, 1 H), 4.13 (ddd,
J = 18.2, 10.3, 9.2 Hz, 1 H), 2.68 (br s, 1 H), 2.08 (d, J = 12.5
Hz, 1 H), 1.83–1.91 (m, 1 H), 1.67 (d, J = 12.1 Hz, 2 H),
1.32–1.51 (m, 2 H), 0.99 (q, J = 11.6 Hz, 1 H), 0.91 (d,
J = 5.8 Hz, 3 H), 0.89 (dd, J = 6.8, 1.0 Hz, 3 H), 0.85 (m, 1
H), 0.76 (t, J = 6.5 Hz, 3 H). 13C NMR (126 MHz, CDCl3):
d = 160.3, 138.5, 129.1, 128.7, 126.5, 79.5, 75.0, 72.1, 47.1,
40.7, 34.1, 31.5, 26.4, 23.3, 22.4, 21.2, 16.8. HRMS: m/z
calcd for C19H30N2O5S: 398.1875; found: 398.1855.
(15) We thank Dr. Ion Ghiviriga (NMR) and Dr. David Powell
(mass spectrometry) from the University of Florida for their
assistance with the structure assignment of 18. The details of
these assignments will be reported in an upcoming full paper.
(1) (a) Atkins, G. M.; Burgess, E. M. J. Am. Chem. Soc. 1968,
90, 4744. (b) Burgess, E. M.; Penton, H. R.; Taylor, E. A. J.
Am. Chem. Soc. 1970, 92, 5224. (c) Atkins, G. M.; Burgess,
E. M. J. Am. Chem. Soc. 1972, 94, 6135. (d) Burgess, E.
M.; Penton, H. R.; Taylor, E. A. J. Org. Chem. 1973, 38, 26.
(2) For reviews of Burgess Reagent see: (a) Burckhardt, S.
Synlett 2000, 559. (b) Lamberth, C. J. Prakt. Chem. 2000,
342, 518. (c) Taibe, P.; Mobashery, S. In Encyclopedia of
Reagents in Organic Synthesis, Vol. 5; Paquette, L. A., Ed.;
Wiley: Chichester, 1995, 3345. (d) Khapli, S.; Dey, S.; Mal,
D. J. Ind. Inst. Sci. 2001, 81, 461.
(3) The following statement appeared in a review by Lamberth
(ref. 2b) published in 2000: ‘The compatibility of the
Burgess reagent with many functionalities, e.g. halogens,
epoxides, alkenes, alkynes, aldehydes, ketones, acetals,
esters, secondary amides, makes it an attractive technique
for the introduction of C–C double bonds into highly
functionalized molecules.’
Synlett 2006, No. 3, 445–449 © Thieme Stuttgart · New York