New chiral ionic liquids based on enantiopure sulfate and sulfonate anions for chiral recognition

Article abstract of DOI:10.1002/ejoc.201000801

The synthesis of new chiral ionic liquids with chiral anions is described. Chiral sulfate anions were prepared from alcohols of the "chiral pool" in good yields. Subsequent ion metathesis resulted in new salts with tetrabutylphosphonium and 1-butyl-3-meth

Full text of DOI:10.1002/ejoc.201000801

FULL PAPER
DOI: 10.1002/ejoc.201000801
New Chiral Ionic Liquids Based on Enantiopure Sulfate and Sulfonate Anions
for Chiral Recognition
Andreas Winkel[a] and René Wilhelm*[b][‡]
Keywords: Ionic liquids / Chirality / Anions / Green chemistry / Chiral recognition
The synthesis of new chiral ionic liquids with chiral anions is
described. Chiral sulfate anions were prepared from alcohols
of the “chiral pool” in good yields. Subsequent ion metathe-
sis resulted in new salts with tetrabutylphosphonium and 1-
butyl-3-methylimidazolium (BMIM) cations. In addition, the
synthesis of chiral sulfonate anions from (R)-phenylethyl-
amine and formaldehyde–sodium hydrogen sulfate, or so-
dium vinyl sulfonate is shown, giving new Brønsted basic
chiral ionic liquids. The potential of the new ionic liquids as
chiral shift reagents was explored. It was possible to use, in
addition to Mosher’s acid and the Brønsted basic ionic li-
quids, also 2,2,2-trifluoro-1-phenylethanol with the chiral
salts. The neutral alcohol was found to interact with the chi-
ral anions by hydrogen bonding.
in the NMR spectra was possible.[4b–4e,4g,4k,4l,4r,4w,4y] The
application of a neutral alcohol now allows a better explo-
ration of salts with chiral anions and, in addition, broadens
the scope of chiral ionic liquids that can be used in chiral
shift experiments.
Here, we show the synthesis of a series of new chiral ionic
liquids based on chiral sulfonates and sulfates and describe
their use as chiral shift reagents with 2,2,2-trifluoro-1-phen-
ylethanol.
Introduction
Ionic liquids have been the focus of increased attention
over the last two decades. These salts have, by definition, a
melting point below 100 °C and often contain organic ions.
Several of these salts constitute a promising class of organic
material due to their potential as novel solvents for reac-
tions and electrochemical processes.[1] In addition, a
number of these liquids could be regarded as potential
“green solvents” due to their negligible vapor pressure and
efficient recovery.[2]
When the ionic liquids are chiral, they can become inter-
esting for further applications, such as chiral solvents, chiral
chromatography, shift reagents, and catalysts.[3] Chiral ionic
liquids (CILs) are, in general, either based on chiral cat-
ions[3,4] or on chiral anions.[3,5]
Due to our efforts in the field of chiral ionic li-
quids[4k,4l,4t,4w] and because of our interest in exploring
their potential as chiral shift reagents, we have recently re-
ported a salt with a chiral anion that was able to interact
and provide stereodiscrimination in NMR experiments with
2,2,2-trifluoro-1-phenylethanol.[4w] This was the first time
that a chiral ionic liquid was used as a shift reagent with
a neutral compound. Normally, salts of racemic Mosher’s
carboxylates are used with chiral ionic liquids based on chiral
cations. Due to the formation of diastereomeric salt pairs, a
differentiation of the enantiomers of Mosher’s carboxylates
Results and Discussion
First, the desired sulfate and sulfonate based ionic liquids
were prepared. Synthesis of the organic sulfates from
alcohols as starting material is straightforward, and is most
often conducted by the use of an excess of readily available
pyridine sulfur trioxide complex in the presence of acetic
anhydride and an amine.[6] When the reaction is complete,
a mixture of the pyridinium sulfate and the remaining pyr-
idine sulfur trioxide complex is obtained, which is treated
with aqueous potassium hydroxide to gain the desired po-
tassium sulfate. The potassium hydroxide also destroys the
remaining pyridine sulfur trioxide complex. This method
was first applied to prepare potassium bornyl sulfate. We
planned to exchange the potassium cation with a more lipo-
philic cation in the next step through cation metathesis.
However, after the addition of potassium hydroxide to the
reaction mixture, the desired potassium bornyl sulfate could
not be obtained in either pure form or high yield, because
of its high water-solubility and its tendency to wash out
during workup.
[a] Institute of Organic Chemistry,
Clausthal University of Technology,
Leibnizstr. 6, 38678 Clausthal-Zellerfeld, Germany
[b] Faculty of Chemistry, Nicolaus Copernicus University,
7 Gagarin St., 87-100 Torun, Poland
Fax: +48-566114302
E-mail: rene.wilhelm@chem.uni.torun.pl
[‡] Address as of October 1, 2010: Department Chemie, Organische
Chemie, Universität Paderborn, Warburger Straße 100,
33098 Paderborn, Germany
Besides inorganic cations, such as sodium and potas-
sium, similar sized organic cations such as pyridinium could
also be employed in cation metathesis. Therefore, the prepa-
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A. Winkel, R. Wilhelm
FULL PAPER
Scheme 1. Preparation of CIL sulfates.
ration of pure pyridinium sulfate seemed beneficial. The removal of all liquids by distillation under high vacuum, a
previously used method was slightly changed and an excess solid was obtained that was successively washed with di-
of enantiopure alcohol (1.0 equiv.) and pyridinium sulfur ethyl ether. NMR analysis indicated that the pure triethyl-
trioxide complex (0.9 equiv.) were used (Scheme 1). The de- ammonium sulfates 1c and 4c were obtained. The salts were
sired pyridinium bornyl sulfate 2a could be obtained in up subsequently used in the metathesis with BMIM chloride
to 92% yield. In addition, the salts could be successfully in a water/ethyl acetate mixture.
applied in the ion metathesis with tetrabutylphosphonium
chloride.
Salts 1d and 4d were thereafter successfully obtained in
90 and 99% yield, respectively, by using a water/ethyl acet-
When an aqueous solution of the phosphonium chloride ate mixture for the metathesis reaction.
and the pyridinium bornyl sulfate were mixed, the phospho-
nium sulfate precipitated and could be filtered off. However, pared. Amines can be transformed into sulfonates by means
because further addition of water redissolved the desired
product, the application of a dichloromethane/water mix-
ture was found to be more beneficial for the isolation of the
desired phosphonium sulfate 2e in good yield.
Next, two salts with chiral sulfonate anions were pre-
In addition, sulfates were also prepared from the
enantiopure alcohols menthol, fenchol, and α-isopinocam-
pheol. Along with the phosphonium chloride, 1-butyl-3-
methylimidazolium (BMIM) chloride was also applied for
the cation metathesis.
Unfortunately, when the ion metathesis was conducted
with BMIM chloride, the obtained solids proved to be mix-
tures of BMIM and pyridinium salts, as shown by NMR
analysis. Further washing with water caused a reduction in
the yield and led, in only a few cases, to pure products.
Because BMIM and pyridinium cations seem to exhibit
comparable hydrophilicities, a cation exchange was neces-
sary. To this end, the pyridinium salts were dissolved in a
minimum amount of water and excess aqueous ammonia
was added. After evaporating the water, ammonia and pyr-
idine, the pure ammonium fenchoyl- and bornyl sulfates 3b
and 2b could be obtained. This method unfortunately failed
with pyridinium menthyl- and α-isopinocampheoyl sulfates
1a and 4a. These two salts were therfore dissolved in dichlo-
romethane and an excess of triethylamine was added. After Scheme 2. Preparation of CIL sulfonates.
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Novel Chiral Ionic Liquids
of nucleophilic attack, and two readily available reaction probably due to enhanced hydrogen bonding because of the
partners for amines are sodium formaldehyde bisulfite and decreased polarity of the solvent and, thus, salt 1e showed a
sodium vinyl sulfonate (Scheme 2). The reaction of (R)- splitting of 3.5 Hz, whereas the 19F NMR spectra in CDCl3
phenylethylamine with these sodium salts in water yielded showed no splitting. Furthermore, in the case of salt 3e,
the corresponding sodium sulfonates 5a and 6a in 95 and changing the solvent to [D8]toluene caused an increased
25%, respectively.
splitting of the 19F NMR signal of the alcohol (7.0 Hz in
The basic sulfonates thus obtained were used in a subse- [D8]toluene compared to 3.4 Hz in CDCl3). Table 1 summa-
quent cation metathesis with tetrabutylphosphonium chlo- rizes the results; Figure 1 shows the 19F NMR signals ob-
ride, which gave the resulting room temperature ionic li- served for 2,2,2-trifluoro-1-phenylethanol in the presence of
quids 5b and 6b in 88 and 87% yield, respectively. The cat- salt 3e in the two solvents.
ion metathesis with BMIM chloride failed to give any of
Furthermore, when the basic phosphonium salts 5b and
the desired salts. Differential scanning calorimetry (DSC) 6b were submitted to 19F NMR analysis with alcohol 7
measurements documented the therml stability of the phos- (Table 2), 5b caused no splitting of the CF3-group of the
phonium salts up to 220 °C (5b) and 345 °C (6b).
alcohol in CDCl3, whereas use of [D8]toluene as solvent
To explore the potential of the new chiral ionic liquids resulted in a splitting of 6.7 Hz. Regardless of the solvent,
for chiral recognition, the prepared ionic liquids were tested salt 6b caused a splitting of the 19F NMR signal of alcohol
as chiral shift reagents with 2,2,2-trifluoro-1-phenylethanol 7; in CDCl3 a splitting of J = 6.3 Hz was observed wheras
(7). In addition, the basic ionic liquids 5b and 6b were also in [D8]toluene a splitting of J = 6.8 Hz was found.
explored with Mosher’s carboxylic acid 8 (Scheme 3).
In addition, racemic Mosher’s acid 8 was also applied as
a substrate with the basic salts 5b and 6b; the results are
shown in Table 2. In this case, the splitting of the 19F NMR
signal varied from J = 19.2 Hz in deuterated chloroform to
J = 40.6 Hz in deuterated toluene for salt 5b; salt 6b gave
comparable results (J = 18.8 Hz and 40.6 Hz, respectively).
For comparison, salt 3e was also used under the same
conditions with racemic Mosher’s acid (8), because it gave
the best results with alcohol 7. However, Mosher’s acid
showed no splitting in the presence of 3e in deuterated chlo-
roform..
Scheme 3. Alcohol 7 and Mosher’s acid 8.
Because it was expected that the racemic alcohol 7 would
interact with the enantiopure anions of the ionic liquids
through hydrogen bonding, the polarity of the solvent
should have a strong influence on the formation of a dia-
stereomeric adduct. Hence, it was decided to perform the
19F NMR experiments in deuterated chloroform and in tol-
uene. However, because the solubility of salts incorporating
Conclusions
The synthesis of new chiral ionic liquids with chiral
BMIM as the cation was often very low in toluene, not all anions has been developed. The chiral sulfate and sulfonate
salts could be investigated in both solvents. anions were prepared from compounds derived from the
In most cases, when chloroform was used, no splitting of chiral pool in a straightforward manner in good yields.
the 19F NMR doublet signal for alcohol 7 was observed. During the preparation of the desired ionic liquids it was
The fenchol-based salts 3e and 3d, however, showed a split- also possible to circumvent problems associated with ion
ting of the doublet in CDCl3 by around 3.4 and 1.9 Hz, metathesis with pyridinium salts. Whereas salts 1c, 4c, 1d,
respectively. Better results were obtained in [D8]toluene, and 4d had melting points below 100 °C, salts 5b and 6b
Table 1. 19F NMR (375 MHz) chemical shifts of 2,2,2-trifluoro-1-phenylethanol (7) with sulfate salts.
Entry
Salt
Solvent
19F NMR δ [ppm]
19F NMR ∆δ [Hz][a]
1
2
3
4
5
6
–
[D8]toluene
[D8]toluene
[D8]toluene
[D8]toluene
[D8]toluene
CDCl3
–78.27 (d, J = 6.9 Hz)
–
3.5
–
7.0
–
1e
2e
3e
4e
–
–77.41 (d, J = 7.2 Hz) –77.42 (d, J = 7.3 Hz)
–77.40 (d, J = 7.3 Hz)
–77.37 (d, J = 7.0 Hz) –77.39 (d, J = 6.9 Hz)[b]
–77.41 (d, J = 7.4 Hz)
–78.84 (d, J = 6.6 Hz)
–
7
8
9
10
11
12
13
14
1e
1d
2e
2d
3e
3d
4e
4d
CDCl3
CDCl3
CDCl3
CDCl3
CDCl3
CDCl3
CDCl3
CDCl3
–78.34 (d, J = 6.9 Hz)
–78.45 (d, J = 7.1 Hz)
–78.34 (d, J = 7.2 Hz)
–78.48 (d, J = 7.2 Hz)
–78.28 (d, J = 7.2 Hz) –78.29 (d, J = 7.1 Hz)
–78.41 (d, J = 7.1 Hz) –78.42 (d, J = 7.0 Hz)
–78.32 (d, J = 7.1 Hz)
–
–
–
–
3.4
1.9
–
–78.47 (d, J = 7.1 Hz)
–
[a] Distance between the two doublets. [b] The two doublets actually appear as a triplet at δ = –77.38 ppm with J = 7.0 Hz. This signal
is divided into its two overlaying doublets for better comparison.
Eur. J. Org. Chem. 2010, 5817–5824
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A. Winkel, R. Wilhelm
FULL PAPER
Figure 1. 19F NMR spectra of alcohol 7 with salt 3e in [D8]toluene (left) and in CDCl3 (right).
Table 2. 19F NMR (375 MHz) chemical shifts of 2,2,2-trifluoro-1-
phenylethanol (7) and Mosher’s acid (8).
Experimental Section
Pyridinium (1R,2S,5R)-2-Isopropyl-5-methylcyclohexyl Sulfate (1a):
The preparation of pyridinium sulfates was based on a modified
method described by Natelson:[6] (–)-Menthol (5.47 g, 35 mmol)
was dissolved in toluene (50 mL) and a mixture of pyridine (5 mL)
and acetic anhydride (5 mL) was added. Pyridine-sulfur trioxide
complex (5 g, 31.4 mmol) was added and the mixture was heated
to 50 °C for 30 min. After cooling, petroleum ether (50 mL) was
added and the precipitated solid was filtered off, washed with pe-
troleum ether and dried in vacuo to give a white solid (9.41 g,
92%); m.p. 169.8 °C. [α]2D5 = –48.8 (c = 1.23, CHCl3). MS (ES, 0 V,
neg. scan): m/z (%) = 234.9 (32) [Manion], 471.1 (71) [2Manion + H+],
Entry
Salt
Solvent
19F NMR δ [ppm]
19F NMR
∆δ [Hz][a]
7 or 8
5b/7
1
2
[D8]toluene –82.25 (d, J = 6.7 Hz)
–82.27 (d, J = 6.7 Hz)[b]
[D8]toluene –82.22 (d, J = 6.8 Hz)
6.7
6.8
6b/7
–82.24 (d, J = 6.8 Hz)[c]
–78.25 (d, J = 7.1 Hz)
–78.20 (d, J = 6.3 Hz)
–78.22 (d, J = 6.3 Hz)[d]
4
5
5b/7
6b/7
CDCl3
CDCl3
–
6.3
6
7
–/8
5b/8
[D8]toluene –71.67
[D8]toluene –75.03
–75.14
CDCl3
CDCl3
–
40.6
751.0 (7) [3Manion + 2Na+]. IR (KBr): ν = 2958, 1491, 1247, 1193,
˜
1
1053, 973, 800 cm–1. H NMR (400 MHz): δ = 14.06 (br. s, 1 H,
8
9
–/8
5b/8
–71.78
–70.84
–70.89
–70.65
–70.70
–72.22
–
19.2
NH), 9.01 (dd, J = 6.6, 1.5 Hz, 2 H, ArH), 8.57 (tt, J = 7.9, 1.5 Hz,
1 H, ArH), 8.10 (dd, J = 7.8, 6.7 Hz, 2 H, ArH), 4.27 (td, J = 10.8,
4.4 Hz, 1 H, HCOSO3), 2.49 (ddd, J = 9.4, 7.4, 4.8 Hz, 1 H, HCH),
2.22 (dtd, J = 13.9, 7.0, 2.4 Hz, 1 H, CH), 1.73–1.57 (m, 2 H,
2ϫHCH), 1.52–1.35 (m, 1 H, CH), 1.35–1.24 (m, 1 H, CH), 1.10
(dd, J = 23.3, 12.1 Hz, 1 H, HCH), 1.06–0.97 (m, 1 H, HCH), 0.89
(d, J = 6.5 Hz, 3 H, CH3), 0.85 (d, J = 7.1 Hz, 3 H, CH3), 0.84–
0.78 (m, 4 H, HCH, CH3) ppm. 13C NMR (100 MHz): δ = 146.3,
142.2, 127.5, 79.6, 48.0, 42.0, 34.3, 31.6, 25.6, 23.2, 22.2, 21.1, 16.1
ppm. HRMS (ESI): calcd. for C10H19O4S [Manion] 235.1004; found
235.0995.
10
6b/8
CDCl3
18.8
11
3e/8
CDCl3
–
[a] Distance between the two doublets or singlets. [b] The two dou-
blets appear as a triplet at δ = –82.26 ppm (J = 6.7 Hz). This signal
is divided into its two overlaying doublets for better comparison.
[c] The two doublets appear as a triplet at δ = –82.23 ppm (J =
6.8 Hz). This signal is divided into its two overlaying doublets for
better comparison. [d] The two doublets appear as a triplet at δ =
–78.21 ppm (J = 6.3 Hz). This signal is divided into its two overlay-
ing doublets for better comparison.
The other pyridinium salts were prepared in the same manner as
described for (–)-menthol.
Pyridinium
(1S,2R,4S)-1,7,7-Trimethylbicyclo[2.2.1]heptan-2-yl
Sulfate (2a): White solid (9.05 g, 92%); m.p. 182.2–184.1 °C. [α]2D5
were room-temperature ionic liquids. The potential of these
new ionic liquids as chiral shift reagents was explored and = –15.7 (c = 1.08, CHCl3). MS (ES, 0 V, neg. scan): m/z (%) =
233.1 (16) [Manion], 467.0 (100) [2Manion + H+]. IR (KBr): ν = 2952,
˜
it was possible to use 2,2,2-trifluoro-1-phenylethanol with
some of the chiral salts in NMR experiments. The neutral
alcohol interacts with the chiral anions through hydrogen
bonding. In addition, Mosher’s acid could also be used with
the Brønsted basic ionic liquids 5b and 6b. This work
should enable an expansion of the applications of chiral
ionic liquids in chiral recognition. Currently, further ana-
logues of the presented chiral anions are being prepared
and will be investigated for the chiral recognition of a
broader set of alcohols.
1
1629, 1548, 1484, 1280, 1208, 1008 cm–1. H NMR (400 MHz): δ
= 12.40 (s, 1 H, NH), 9.04 (dd, J = 5.1, 1.5 Hz, 2 H, ArH), 8.57
(tt, J = 7.9, 1.5 Hz, 1 H, ArH), 8.21–8.03 (m, 2 H, ArH), 4.73–4.54
(m, 1 H, HCOSO3), 2.37–2.25 (m, 1 H, HCH), 1.97–1.86 (m, 1 H,
HCH), 1.77–1.61 (m, 2 H, CH, HCH), 1.39 (dd, J = 13.8, 3.3 Hz,
1 H, HCH), 1.28–1.16 (m, 2 H, 2ϫHCH), 0.90 (d, J = 1.8 Hz, 3
H, CH3), 0.87 (s, 3 H, CH3), 0.85 (s, 3 H, CH3) ppm. 13C NMR
(100 MHz): δ = 146.2, 142.3, 127.5, 84.2, 49.3, 47.5, 44.9, 36.7,
28.1, 26.7, 19.8, 18.9, 13.5 ppm. HRMS (ESI): calcd. for
C10H17O4S [Manion] 233.0848; found 233.0840.
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Novel Chiral Ionic Liquids
Pyridinium
(1S,2R,4S)-1,3,3-Trimethylbicyclo[2.2.1]heptan-2-yl
off and the remaining solid was washed with diethyl ether to re-
move traces of pyridine and dried in vacuo.
Sulfate (3a): White solid (8.66 g, 88%); m.p. 200.1 °C. [α]2D5 = +11.3
(c = 1.06, CHCl3). MS (ES, 0 V, neg. scan): m/z (%) = 233.1 (14)
Triethylammonium
(1R,2S,5R)-2-Isopropyl-5-methylcyclohexyl
[Manion], 467.0 (100) [2Manion + H+]. IR (KBr): ν = 2962, 1634,
˜
Sulfate (1c): White solid (8.39 g, 86%); m.p. 78.2 °C. [α]2D5 = –54.2
(c = 1.00, CHCl3). MS (ES, 0 V, pos. scan): m/z (%) = 102.1169
(100) [Mcation]. MS (ES, 0 V, neg. scan): m/z (%) = 235.0800 (100)
1486, 1258, 1187, 1025, 992 cm–1. H NMR (400 MHz): δ = 12.58
1
(br. s, 1 H, NH), 9.03 (dd, J = 6.6, 1.5 Hz, 2 H, ArH), 8.55 (tt, J
= 7.9, 1.5 Hz, 1 H, ArH), 8.09 (dd, J = 7.8, 6.7 Hz, 2 H, ArH),
4.03 (d, J = 1.8 Hz, 1 H, HCOSO3), 1.76–1.62 (m, 3 H, CH, CH2),
1.51 (dd, J = 10.3, 1.6 Hz, 1 H, HCH), 1.40 (ddt, J = 11.1, 8.6,
4.2 Hz, 1 H, HCH), 1.20–1.11 (m, 4 H, Me, HCH), 1.09 (s, 3 H,
CH3), 1.07–0.98 (m, 1 H, HCH), 0.96 (s, 3 H, CH3) ppm. 13C NMR
(100 MHz): δ = 146.2, 142.3, 127.5, 90.6, 49.0, 48.2, 41.3, 39.2,
30.1, 26.1, 26.0, 20.8, 19.5 ppm. HRMS (ESI): calcd. for
C10H17O4S [Manion] 233.0848; found 233.0849.
[Manion]. IR (KBr): ν = 2958, 2935, 1476, 1251, 1209, 972, 791
˜
cm–1. 1H NMR (400 MHz): δ = 9.77 (s, 1 H, NH), 4.19 (td, J =
10.8, 4.4 Hz, 1 H, HCOSO3), 3.18 (qd, J = 7.3, 4.7 Hz, 6 H,
3ϫNCH2), 2.54–2.44 (m, 1 H, HCH), 2.28 (dtd, J = 13.9, 7.0,
2.4 Hz, 1 H, CH), 1.71–1.59 (m, 2 H, 2ϫHCH), 1.49–1.34 (m, 10
H, 3ϫCH3, CH), 1.33–1.23 (m, 1 H, CH), 1.07 (dd, J = 23.3,
12.3 Hz, 2 H, 2ϫHCH), 0.89 (q, J = 6.8, 5.5 Hz, 6 H, 2ϫCH3),
0.84 (d, J = 6.9 Hz, 4 H, CH3, HCH) ppm. 13C NMR (100 MHz):
δ = 79.0, 48.0, 46.6, 42.0, 34.4, 31.6, 25.4, 23.2, 22.2, 21.2, 16.0, 8.8
ppm. HRMS (ESI): calcd. for C6H16N [Mcation] 102.1283; found
102.1284; calcd. for C10H19O4S [Manion] 235.1004; found 235.1002.
Pyridinium (1S,2S,3S,5R)-2,6,6-Trimethylbicyclo[3.1.1]heptan-3-yl
Sulfate (4a): White solid (8.46 g, 86%); m.p. 114.3 °C. [α]2D5 = +25.7
(c = 1.00, CHCl3). MS (ES, 0 V, neg. scan): m/z (%) = 233.1 (12)
[Manion], 467.0 (100) [2Manion + H+]. IR (KBr): ν = 2871, 1629,
˜
Triethylammonium
(1S,2S,3S,5R)-2,6,6-Trimethylbicyclo[3.1.1]-
1547, 1485, 1276, 1208, 1185 cm–1. 1H NMR (400 MHz): δ = 11.54
(br. s, 1 H, NH), 9.02 (dd, J = 6.7, 1.5 Hz, 2 H, ArH), 8.53 (tt, J
= 7.8, 1.5 Hz, 1 H, ArH), 8.07 (dd, J = 7.8, 6.7 Hz, 2 H, ArH),
4.75 (ddd, J = 9.7, 5.2, 4.5 Hz, 1 H, HCOSO3), 2.63–2.55 (m, 1 H,
HCH), 2.34–2.26 (m, 1 H, HCH), 2.20–2.13 (m, 1 H, CH), 2.05
(ddd, J = 14.5, 4.5, 2.8 Hz, 1 H, HCH), 1.88 (tt, J = 5.9, 3.1 Hz, 1
H, CH), 1.76 (td, J = 5.9, 2.1 Hz, 1 H, CH), 1.17 (s, 3 H, CH3),
1.13 (d, J = 7.4 Hz, 3 H, CH3), 1.02 (d, J = 9.8 Hz, 1 H, HCH),
0.89 (s, 3 H, CH3) ppm. 13C NMR (100 MHz): δ = 146.3, 142.3,
127.5, 79.1, 47.6, 44.7, 41.6, 38.4, 36.5, 33.8, 27.5, 23.9, 20.4 ppm.
HRMS (ESI): calcd. for C10H17O4S [Manion] 233.0848; found
233.0842.
heptan-3-yl Sulfate (4c): White solid (8.25 g, 91%); m.p. 72.7 °C.
[α]2D5 = +26.7 (c = 1.03, CHCl3). MS (ES, 0 V, pos. scan): m/z (%)
= 102.1169 (100) [Mcation]. MS (ES, 0 V, neg. scan): m/z (%) =
233.0531 (100) [Manion], 467.1701 (12) [2Manion + H+]. IR (KBr): ν
˜
= 2941, 1478, 1248, 1211, 978, 779, 615 cm–1. 1H NMR (400 MHz):
δ = 9.76 (s, 1 H, NH), 4.72 (dt, J = 9.7, 4.9 Hz, 1 H, HCOSO3),
3.29–3.11 (m, 6 H, 3ϫNCH2), 2.68–2.56 (m, 1 H, HCH), 2.41–
2.28 (m, 1 H, HCH), 2.27–2.14 (m, 1 H, CH), 2.08 (ddd, J = 14.5,
4.2, 2.7 Hz, 1 H, HCH), 1.92 (ddd, J = 8.6, 5.7, 3.1 Hz, 1 H, CH),
1.80 (td, J = 5.8, 1.8 Hz, 1 H, CH), 1.39 (t, J = 7.3 Hz, 9 H,
3ϫCH3), 1.21 (s, 3 H, CH3), 1.18 (d, J = 7.4 Hz, 3 H, CH3), 1.07
(d, J = 9.7 Hz, 1 H, HCH), 0.94 (s, 3 H, CH3) ppm. 13C NMR
(100 MHz): δ = 78.4, 47.7, 46.6, 44.7, 41.6, 38.4, 36.5, 33.8, 27.6,
Ammonium Sulfates 2b and 3b: Pyridinium sulfates 2a or 3a were
dissolved in a minimum amount of water. Ammonia (10 equiv. in
water) was added and the solution was stirred for 15 min. Excess
water, ammonia and pyridine were distilled off and the remaining
solid was further dried in vacuo, washed with diethyl ether to re-
move traces of pyridine and dried in vacuo.
23.8, 20.3, 8.8 ppm. HRMS (ESI): calcd. for C6H16N [Mcation
]
102.1283; found 102.1284; calcd. for C10H17O4S [Manion] 233.0848;
found 233.0856.
3-Butyl-1-methyl-1H-imidazol-3-ium Sulfates 1d, 2d, 3d, and 4d:
Prepared using standard cation metathesis in a CH2Cl2/water or
Ammonium
(1S,2R,4S)-1,7,7-Trimethylbicyclo[2.2.1]heptan-2-yl ethyl acetate/water mixture from BMIM chloride and ammonium
Sulfate (2b): White solid (6.32 g, 87%); m.p. 216.2 °C. [α]2D5 = –20.3
(c = 1.08, MeOH). MS (ES, 0 V, neg. scan): m/z (%) = 233.0587
or triethylammonium sulfates.
1-Butyl-3-methyl-1H-imidazolium (1R,2S,5R)-2-Isopropyl-5-methyl-
cyclohexyl Sulfate (1d): Slightly yellow solid (8.37 g, 90%); m.p.
88.4 °C. [α]2D5 = –45.1 (c = 1.02, CHCl3). MS (ES, 0 V, pos. scan):
m/z (%) = 139.1022 (100) [Mcation]. MS (ES, 0 V, neg. scan): m/z
(100) [Manion], 467.1701 (18) [2Manion + H+]. IR (KBr): ν = 2956,
˜
1456, 1264, 1200, 1065, 1009, 864 cm–1. H NMR (400 MHz): δ =
1
4.67–4.55 (m, 1 H, HCOSO3), 2.47–2.32 (m, 1 H, HCH), 1.97–1.73
(m, 3 H, CH, 2ϫHCH), 1.45–1.29 (m, 3 H, 3ϫHCH), 1.05–0.90
(m, 9 H, 3ϫCH3) ppm. 13C NMR (100 MHz): δ = 85.8, 48.9, 47.2,
44.6, 36.1, 27.7, 26.3, 19.5, 18.4, 12.8 ppm. HRMS (ESI): calcd.
for C10H21O4S [Manion] 233.0848; found 233.0858.
(%) = 235.0800 (100) [Manion], 493.1810 (5) [2Manion + Na+]. IR
1
(KBr): ν = 2960, 1577, 1463, 1166, 977, 798, 605 cm–1. H NMR
˜
(400 MHz): δ = 9.68 (s, 1 H, N=CHN), 7.53 (s, 1 H, CH), 7.40 (s,
1 H, CH), 4.26 (t, J = 7.3 Hz, 2 H, NCH2), 4.24–4.16 (m, 1 H,
Ammonium
(1S,2R,4S)-1,3,3-Trimethylbicyclo[2.2.1]heptan-2-yl HCOSO3), 4.03 (s, 3 H, NCH3), 2.53 (br. d, J = 12.2 Hz, 1 H,
Sulfate (3b): White solid (3.75 g, 54%); m.p. 218.3 °C. [α]2D5 = +14.8
(c = 1.08, MeOH). MS (ES, 0 V, neg. scan): m/z (%) = 233.0587
HCH), 2.32 (dtd, J = 13.9, 6.9, 2.2 Hz, 1 H, CH), 1.95–1.81 (m, 2
H, CH2), 1.72–1.61 (m, 2 H, 2ϫHCH), 1.52–1.42 (m, 1 H, CH),
1.43–1.33 (m, 2 H, CH2), 1.32–1.23 (m, 1 H, CH), 1.13–0.99 (m, 2
(100) [Manion], 467.1781 (10) [2Manion + H+]. IR (KBr): ν = 2963,
˜
1472, 1243, 1174, 1067, 975, 873 cm–1. H NMR (400 MHz): δ = H, 2ϫHCH), 0.96 (t, J = 7.4 Hz, 3 H, CH3), 0.93–0.81 (m, 10 H,
1
3.97 (d, J = 1.8 Hz, 1 H, HCOSO3), 1.82–1.72 (m, 2 H, CH, HCH), 3ϫCH3, HCH) ppm. 13C NMR (100 MHz): δ = 138.0, 123.8,
1.70–1.59 (m, 2 H, 2ϫHCH), 1.56–1.45 (m, 1 H, HCH), 1.26 (dd,
J = 10.4, 1.4 Hz, 1 H, HCH), 1.16 (s, 3 H, CH3), 1.16–1.08 (m, 4
122.1, 78.3, 49.8, 48.2, 42.3, 36.5, 34.5, 32.2, 31.7, 25.5, 23.3, 22.3,
21.3, 19.5, 16.2, 13.5 ppm. HRMS (ESI): calcd. for C8H15N2
H, CH3, HCH), 0.98 (s, 3 H, CH3) ppm. 13C NMR (100 MHz): δ [Mcation] 139.1235; found 139.1232; calcd. for C10H19O4S [Manion
]
= 92.2, 48.5, 47.9, 40.7, 38.8, 29.4, 25.6, 25.5, 20.2, 18.7 ppm.
HRMS (ESI): calcd. for C10H21O4S [Manion] 233.0848; found
233.0847.
235.1004; found 235.1002.
1-Butyl-3-methyl-1H-imidazolium
(1S,2R,4S)-1,7,7-Trimethylbi-
cyclo[2.2.1]heptan-2-yl Sulfate (2d): Slightly yellow solid (8.24 g,
88%); m.p. 107.3 °C. [α]2D5 = –14.1 (c = 1.09, CHCl3). MS (ES, 0 V,
pos. scan): m/z (%) = 139.1022 (100) [Mcation]. MS (ES, 0 V, neg.
Triethylammonium Sulfates 1c and 4c: Pyridinium sulfates 1a and
4a were dissolved in a minimum amount of dichloromethane. Tri-
ethylamine (10 equiv.) was added and the solution was stirred for
15 min. Excess CH2Cl2, triethylamine and pyridine were distilled
scan): m/z (%) = 233.0591 (100) [Manion], 489.1416 (5) [2Manion
+
Na+]. IR (KBr): ν = 3101, 2957, 1639, 1260, 1212, 1010, 854 cm–1.
˜
Eur. J. Org. Chem. 2010, 5817–5824
© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
5821

A. Winkel, R. Wilhelm
1H NMR (400 MHz): δ = 9.59 (s, 1 H, N=CHN), 7.60 (t, J = 0.76 (m, 10 H, 3ϫCH3, HCH) ppm. 13C NMR (100 MHz): δ =
FULL PAPER
1.7 Hz, 1 H, CH), 7.47 (t, J = 1.7 Hz, 1 H, CH), 4.58 (ddd, J =
9.8, 3.3, 1.9 Hz, 1 H, HCOSO3), 4.26 (t, J = 7.3 Hz, 2 H, NCH2),
4.03 (s, 3 H, NCH3), 2.36–2.22 (m, 1 H, HCH), 2.00–1.91 (m, 1 H,
HCH), 1.91–1.82 (m, 2 H, CH2), 1.75–1.65 (m, 1 H, HCH), 1.63
(t, J = 4.5 Hz, 1 H, HCH), 1.42–1.31 (m, 3 H, 3 HCH), 1.27–1.15
(m, 2 H, CH2), 0.95 (t, J = 7.4 Hz, 3 H, CH3), 0.89 (s, 3 H, CH3),
0.87 (s, 3 H, CH3), 0.85 (s, 3 H, CH3) ppm. 13C NMR (100 MHz):
δ = 137.5, 124.0, 122.2, 82.8, 49.7, 49.1, 47.4, 44.9, 36.9, 36.4, 32.1,
28.1, 26.7, 19.8, 19.4, 18.9, 13.4 ppm. HRMS (ESI): calcd. for
C8H15N2 [Mcation] 139.1235; found 139.1232; calcd. for C10H17O4S
[Manion] 233.0848; found 233.0839.
77.5, 48.2, 42.3, 34.6, 31.6, 25.3, 24.0 (d, JPC = 15 Hz), 23.8 (d, JPC
= 5 Hz), 23.2, 22.2, 21.3, 18.7 (d, JPC = 47 Hz), 16.13, 13.5 ppm.
HRMS (ESI): calcd. for C16H36P [Mcation
] 259.2555; found
259.2550; calcd. for C10H19O4S [Manion] 235.1004; found 235.0996.
Tetrabutylphosphonium (1S,2R,4S)-1,7,7-Trimethylbicyclo[2.2.1]-
heptan-2-yl Sulfate (2e): White solid (10.77 g, 87%); m.p. 148.2–
150.4 °C. [α]2D5 = –12.4 (c = 1.05, CHCl3). MS (ES, 0 V, pos. scan):
m/z (%) = 259.2119 (100) [Mcation]. MS (ES, 0 V, neg. scan): m/z
(%) = 233.0535 (100) [Manion], 489.1416 (5) [2Manion + Na]. IR
(KBr): ν = 2958, 2875, 1467, 1248, 1221, 1011, 784 cm–1. 1H NMR
˜
(400 MHz): δ = 4.56 (ddd, J = 9.9, 3.3, 2.0 Hz, 1 H, HCOSO3),
1-Butyl-3-methyl-1H-imidazolium
(1S,2R,4S)-1,3,3-Trimethylbi- 2.40–2.21 (m, 9 H, 4ϫPCH2, HCH), 2.11–1.99 (m, 1 H, HCH),
cyclo[2.2.1]heptan-2-yl Sulfate (3d): Slightly yellow solid (4.78 g,
86%); m.p. 104.7 °C. [α]2D5 = +11.1 (c = 1.06, CHCl3). MS (ES, 0 V,
pos. scan): m/z (%) = 139.1022 (100) [Mcation]. MS (ES, 0 V, neg.
1.73–1.58 (m, 2 H, CH, HCH), 1.58–1.46 (m, 16 H, 8ϫCH2), 1.39
(dd, J = 13.7, 3.4 Hz, 1 H, HCH), 1.31–1.14 (m, 2 H, 2ϫHCH),
0.97 (t , J = 7.0 Hz, 12 H, 4ϫCH3), 0.92 (s, 3 H, CH3), 0.87 (s, 3
H, CH3), 0.84 (s, 3 H, CH3) ppm. 13C NMR (100 MHz): δ = 82.1,
49.1, 47.3, 45.0, 36.9, 28.1, 26.8, 24.0 (d, JPC = 15 Hz), 23.8 (d, JPC
scan): m/z (%) = 233.0648 (100) [Manion], 489.1497 (5) [2Manion
+
Na+]. IR (KBr): ν = 2960, 1574, 1468, 1244, 992, 849, 619 cm–1.
˜
1H NMR (600 MHz): δ = 9.58 (s, 1 H, N=CHN), 7.54 (t, J = = 5 Hz), 19.9, 19.0, 18.7 (d, JPC = 47 Hz), 13.5, 13.4 ppm. HRMS
1.8 Hz, 1 H, CH), 7.40 (t, J = 1.8 Hz, 1 H, CH), 4.21 (t, J = 7.4 Hz,
2 H, NCH2), 3.99 (s, 3 H, NCH3), 3.94 (d, J = 1.8 Hz, 1 H,
HCOSO3), 1.88–1.79 (m, 2 H, CH2), 1.72–1.60 (m, 3 H, CH, CH2),
1.51–1.44 (m, 1 H, HCH), 1.41–1.35 (m, 1 H, HCH), 1.35–1.29 (m,
2 H, CH2), 1.14–1.07 (m, 4 H, CH3, HCH), 1.05 (s, 3 H, CH3),
0.96–0.93 (m, 4 H, CH3, HCH), 0.91 (t, J = 7.4 Hz, 3 H, CH3)
ppm. 13C NMR (150 MHz): δ = 137.7, 123.9, 122.2, 89.4, 49.8,
48.9, 48.2, 41.3, 39.1, 36.4, 32.2, 30.1, 26.2, 26.1, 20.8, 19.52, 19.49,
13.5 ppm. HRMS (ESI): calcd. for C8H15N2 [Mcation] 139.1235;
found 139.1230; calcd. for C10H17O4S [Manion] 233.0848; found
233.0841.
(ESI): calcd. for C16H36P [Mcation] 259.2555; found 259.2547; calcd.
for C10H17O4S [Manion] 233.0848; found 233.0840.
Tetrabutylphosphonium
(1S,2R,4S)-1,3,3-Trimethylbicyclo[2.2.1]-
heptan-2-yl Sulfate (3e): White solid (6.25 g, 85%); m.p. 161.6–
163.5 °C. [α]2D5 = +7.0 (c = 0.58, CHCl3). MS (ES, 0 V, pos. scan):
m/z (%) = 259.2119 (100) [Mcation]. MS (ES, 0 V, neg. scan): m/z
(%) = 233.0591 (100) [Manion], 489.1416 (5) [2Manion + Na]. IR
(KBr): ν = 2962, 2934, 2873, 1468, 1247, 1220, 1005 cm–1. 1H NMR
˜
(400 MHz): δ = 3.95 (d, J = 1.8 Hz, 1 H, HCOSO3), 2.41–2.23 (m,
8 H, 4ϫPCH2), 1.85–1.74 (m, 1 H, HCH), 1.70 (dt, J = 12.1,
2.7 Hz, 1 H, HCH), 1.67–1.60 (m, 1 H, CH), 1.60–1.46 (m, 17 H,
8ϫCH2, HCH), 1.43–1.32 (m, 1 H, HCH), 1.16 (s, 3 H, CH3),
1.14–1.06 (m, 4 H, CH3, HCH), 1.04–0.88 (m, 16 H, 5ϫCH3,
HCH) ppm. 13C NMR (100 MHz): δ = 88.6, 48.9, 48.3, 41.4, 39.1,
30.1, 26.2, 26.1, 24.0 (d, JPC = 15 Hz), 23.8 (d, JPC = 5 Hz), 20.8,
19.5, 18.7 (d, JPC = 47 Hz), 13.5 ppm. HRMS (ESI): calcd. for
C16H36P [Mcation] 259.2555; found 259.2547; calcd. for C10H17O4S
[Manion] 233.0848; found 233.0838.
1-Butyl-3-methyl-1H-imidazolium (1S,2S,3S,5R)-2,6,6-Trimethylbi-
cyclo[3.1.1]-heptan-3-yl Sulfate (4d): White solid (9.06 g, 99%); m.p.
51.9 °C. [α]2D5 = +19.0 (c = 1.74, CHCl3). MS (ES, 0 V, pos. scan):
m/z (%) = 139.1032 (100) [Mcation]. MS (ES, 0 V, neg. scan): m/z
(%) = 233.0587 (100) [Manion], 467.1781 (10), [Manion + H]. IR
1
(KBr): ν = 2961, 1573, 1469, 1222, 1057, 976, 928 cm–1. H NMR
˜
(400 MHz): δ = 9.63 (s, 1 H, N=CHN), 7.55 (t, J = 1.6 Hz, 1 H,
CH), 7.43 (t, J = 1.7 Hz, 1 H, CH), 4.72 (ddd, J = 9.7, 5.1, 4.6 Hz,
1 H, HCOSO3), 4.26 (t, J = 7.4 Hz, 2 H, NCH2), 4.04 (s, 3 H,
NCH3), 2.67–2.56 (m, 1 H, HCH), 2.37–2.27 (m, 1 H, HCH), 2.23–
2.12 (m, 1 H, CH), 2.07 (ddd, J = 14.6, 4.5, 2.6 Hz, 1 H, HCH),
1.94–1.82 (m, 3 H, CH, CH2), 1.79 (td, J = 5.9, 2.0 Hz, 1 H, CH),
1.43–1.30 (m, 2 H, CH2), 1.20 (s, 3 H, CH3), 1.17 (d, J = 7.4 Hz,
3 H, CH3), 1.05 (d, J = 9.7 Hz, 1 H, HCH), 0.98–0.91 (m, 6 H,
2ϫCH3) ppm. 13C NMR (100 MHz): δ = 137.7, 123.9, 122.2, 77.8,
49.8, 47.7, 44.8, 41.7, 38.4, 36.8, 36.5, 33.8, 32.2, 27.6, 23.9, 20.4,
Tetrabutylphosphonium (1S,2S,3S,5R)-2,6,6-Trimethylbicyclo[3.1.1]-
heptan-3-yl Sulfate (4e): White solid (10.66 g, 88%); m.p. 116.3 °C.
[α]2D5 = +17.7 (c = 1.16, CHCl3). MS (ES, 0 V, pos. scan): m/z (%)
= 259.3 (35) [Mcation], 751.5 (100) [2Mcation + Manion]. MS (ES, 0 V,
neg. scan): m/z (%) = 725.3 (100) [2Manion + Mcation]. IR (KBr): ν
˜
= 2961, 2934, 1467, 1246, 1219, 978, 616 cm–1. 1H NMR
(400 MHz): δ = 4.69 (ddd, J = 9.7, 5.3, 4.6 Hz, 1 H, HCOSO3),
2.68–2.56 (m, 1 H, HCH), 2.39–2.24 (m, 9 H, 4ϫPCH2, HCH),
2.24–2.14 (m, 1 H, CH), 2.09 (ddd, J = 14.5, 4.4, 2.7 Hz, 1 H,
HCH), 1.89 (tt, J = 5.9, 3.1 Hz, 1 H, CH), 1.77 (td, J = 5.9, 2.0 Hz,
1 H, CH), 1.63–1.45 (m, 16 H, 8ϫCH2), 1.20 (s, 3 H, CH3), 1.18
(d, J = 7.4 Hz, 3 H, CH3), 1.10 (d, J = 9.6 Hz, 1 H, HCH), 0.97
(t, J = 7.0 Hz, 12 H, 4ϫCH3), 0.94 (s, 3 H, CH3) ppm. 13C NMR
(100 MHz): δ = 77.0, 47.7, 44.8, 41.7, 38.4, 36.7, 33.7, 27.6, 24.0
19.5, 13.5 ppm. HRMS (ESI): calcd. for C8H15N2 [Mcation
]
139.1235; found 139.1240; calcd. for C10H17O4S [Manion] 233.0848;
found 233.0852.
Tetrabutylphosphonium Sulfates 1e, 2e, 3e, and 4e: Prepared by
standard ion metathesis in a CH2Cl2/water mixture from tetrabu-
tylphosphonium chloride and pyridinium sulfates.
(d, JPC = 15 Hz), 23.8 (d, JPC = 5 Hz), 23.8, 20.4, 18.7 (d, JPC
=
47 Hz), 13.5 ppm. HRMS (ESI): calcd. for C16H36P [Mcation
259.2555; found 259.2549; calcd. for C10H17O4S [Manion] 233.0848;
found 233.0841.
]
Tetrabutylphosphonium (1R,2S,5R)-2-Isopropyl-5-methylcyclohexyl
Sulfate (1e): White solid (11.43 g, 93%); m.p. 127.7 °C. [α]2D5 = –36.7
(c = 1.02, CHCl3). MS (ES, 0 V, pos. scan): m/z (%) = 259.2060
(100) [Mcation]. MS (ES, 0 V, neg. scan): m/z (%) = 235.0800 (100)
Sodium (R)-(1-Phenylethylamino)methanesulfonate (5a): Sodium
[Manion], 493.1810 (5) [2Manion + Na]. IR (KBr): ν = 2958, 2932,
hydroxymethanesulfonate (10 g, 74.6 mmol) was dissolved in water
˜
1466, 1249, 1222, 981, 783 cm–1. 1H NMR (400 MHz): δ = 4.15 (100 mL) and (R)-1-phenylethylamine (14.3 mL, 111.9 mmol) was
(td, J = 10.7, 4.4 Hz, 1 H, HCOSO3), 2.60–2.50 (m, 1 H, HCH),
2.42–2.20 (m, 9 H, 4ϫPCH2, CH), 1.66–1.58 (m, 2 H, 2ϫHCH),
1.58–1.46 (m, 16 H, 8ϫCH2), 1.46–1.34 (m, 1 H, CH), 1.30–1.19
added. The mixture was refluxed for 15 h then the solvent was dis-
tilled off and the remaining white solid was successively washed
with diethyl ether to remove traces of amine. The solid obtained
(m, 1 H, CH), 1.10–0.91 (m, 15 H, 4ϫCH3, HCH, CH2), 0.91– was dried in vacuo to give the product as a white solid (16.81 g,
5822 Eur. J. Org. Chem. 2010, 5817–5824
www.eurjoc.org
© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Novel Chiral Ionic Liquids
95%); m.p. 211.8 °C. [α]2D5 = +63.7 (c = 1.48, H2O). MS (ES, 0 V,
126.5, 57.9, 51.1, 43.9, 24.3, 23.8 (d, J = 15 Hz), 23.6 (d, J = 5 Hz),
neg. scan): m/z (%) = 214.0417 (100) [Manion], 429.1015 (30) 18.5 (d, J = 47 Hz), 13.4 ppm. HRMS (ESI): calcd. for C16H36P
[2Manion + H], 644.1714 (7) [3Manion + 2H], 859.2197 (15) [4Manion [Mcation] 259.2555; found 259.2563; calcd. for C10H14NO3S [Manion
]
+ 3H]. IR (KBr): ν = 3509, 2965, 1454, 1211, 1052, 762, 700 cm–1.
228.0694; found 228.0699.
˜
1H NMR (400 MHz): δ = 7.38–7.30 (m, 4 H, ArH), 7.31–7.24 (m,
1 H, ArH), 4.22 (q, J = 6.6 Hz, 1 H, CH), 3.62 (d, J = 14.0 Hz, 1
H, HCH), 3.50 (d, J = 14.0 Hz, 1 H, HCH), 1.29 (d, J = 6.6 Hz, 3
H, CH3) ppm. 13C NMR (100 MHz): δ = 143.5, 128.8, 127.6, 127.1,
Acknowledgments
The authors would like to thank Dr. Namyslo for performing the
19F NMR measurements and Dr. G. Dräger from the University
of Hannover, Germany for HRMS measurements.
62.8, 55.3, 22.2 ppm. HRMS (ESI): calcd. for C9H12NO3S [Manion
214.0538; found 214.0535.
]
Sodium (R)-2-(1-Phenylethylamino)ethanesulfonate (6a): An
aqueous solution (25%) of sodium vinylsulfonate (77 mmol) and
(R)-phenylethylamine (15 mL, 111.5 mmol) was mixed and heated
at reflux temperature for 5 d. The mixture was filtered and the sol-
vent was removed from the filtrate by distillation under vacuum.
The remaining solid was washed with THF and dried in vacuo to
give the product as a white solid (4.84 g, 25%); m.p. 345.0 °C.
[α]2D5 = +33.0 (c = 1.22, MeOH). MS (ES, 0 V, neg. scan): m/z (%)
= 228.0558 (100) [Manion], 457.1284 (55) [2Manion + H], 686.2181
[1] P. Wasserscheid, T. Welton, Ionic Liquids in Synthesis, 2nd ed.,
Wiley-VCH, Weinheim, 2008, vol. 1–2.
[2] R. D. Rogers, K. R. Seddon, in: ACS Symposium Series 856,
American Chemical Society, Washington DC, 2003, pp. 2.
[3] For reviews on chiral ionic liquids, see: a) C. Baudequin, J.
Baudoux, J. Levillain, D. Cahard, A. C. Gaumont, J. C. Pla-
quevent, Tetrahedron: Asymmetry 2003, 14, 3081; b) J. Ding,
D. W. Armstrong, Chirality 2005, 17, 281; c) C. Baudequin, D.
Bregeon, J. Levillain, F. Guillen, J. C. Plaquevent, A. C. Gau-
mont, Tetrahedron: Asymmetry 2005, 16, 3921; d) A. D. Head-
ley, B. Ni, Aldrichimica Acta 2007, 40, 107; e) H. Ohno, K.
Fukumoto, Acc. Chem. Res. 2007, 40, 1122; f) X. Chen, X. Li,
A. Hu, F. Wang, Tetrahedron: Asymmetry 2008, 19, 1; g) A.
Winkel, P. V. G. Reddy, R. Wilhelm, Synthesis 2008, 999; h)
K. Bica, P. Gaertner, Eur. J. Org. Chem. 2008, 3235; i) J.-C.
Plaquevent, J. Levillain, F. Guillen, C. Malhiac, A.-C. Gau-
mont, Chem. Rev. 2008, 108, 5035; j) S. Z. Luo, L. Zhang, J. P.
Cheng, Chem. Asian J. 2009, 4, 1184; k) B. Ni, A. D. Headley,
Chem. Eur. J. 2010, 16, 4426.
[4] For a few selected examples, see: a) J. Howarth, K. Hanlon, D.
Fayne, P. McCormac, Tetrahedron Lett. 1997, 38, 3097; b) Y.
Ishida, H. Miyauchi, K. Saigo, Chem. Commun. 2002, 2240; c)
P. Wasserscheid, A. Bösmann, C. Bolm, Chem. Commun. 2002,
200; d) J. Levillain, G. Dubant, I. Abrunhosa, M. Gulea, A.-
C. Gaumont, Chem. Commun. 2003, 2914; e) H. Clavier, L.
Boulanger, N. Audic, L. Toupet, M. Mauduit, J. C. Guillemin,
Chem. Commun. 2004, 1224; f) B. Pégot, G. Vo-Thanh, D.
Gori, A. Loupy, Tetrahedron Lett. 2004, 45, 6425; g) Y. Ishida,
D. Sasaki, H. Miyauchi, K. Saigo, Tetrahedron Lett. 2004, 45,
9455; h) J. Baudoux, P. Judeinstein, D. Cahard, J.-C. Plaquev-
ent, Tetrahedron Lett. 2005, 46, 1137; i) Y. Génisson, N. Lauth-
de Viguerie, C. André, M. Baltas, L. Gorrichon, Tetrahedron:
Asymmetry 2005, 16, 1017; j) J. Ding, V. Desikan, X. Han, T. L.
Xiao, R. Ding, W. S. Jenks, D. W. Armstrong, Org. Lett. 2005,
7, 335; k) V. Jurcˇík, M. Gilani, R. Wilhelm, Eur. J. Org. Chem.
2006, 5103; l) V. Jurcˇík, R. Wilhelm, Tetrahedron: Asymmetry
2006, 17, 801; m) S.-P. Luo, D.-Q. Xu, H.-D. Yue, L.-P. Wang,
W.-L. Yang, Z.-Y. Xu, Tetrahedron: Asymmetry 2006, 17, 2028;
n) V. Kumar, C. E. Olsen, S. J. C. Schäffer, V. S. Parmar, S. V.
Malhotra, Org. Lett. 2007, 9, 3905; o) M. L. Patil, C. V. L. Rao,
S. Takizawa, K. Takenaka, K. Onitsuka, H. Sasai, Tetrahedron
2007, 63, 12702; p) L. Zhang, S. Luo, X. Mi, S. Liu, Y. Qiao,
H. Xu, J.-P. Cheng, Org. Biomol. Chem. 2008, 6, 567; q) P. G. J.
Plaza, B. A. Bhongade, G. Singh, Synlett 2008, 2973; r) D. K.
Bwambok, H. M. Marwani, V. E. Fernand, S. O. Fakayode, M.
Lowry, I. Negulescu, R. M. Strongin, I. M. Warner, Chirality
2008, 20, 151; s) D. Chen, M. Schmitkamp, G. Franciò, J.
Klankermayer, W. Leitner, Angew. Chem. Int. Ed. 2008, 47,
7339; t) A. Blanrue, R. Wilhelm, Synthesis 2009, 583; u) O. N.
Van Buu, A. Aupoix, G. Vo-Thanh, Tetrahedron 2009, 65,
2260; v) M. Bonanni, G. Soldaini, C. Faggi, A. Goti, F. Car-
bona, Synlett 2009, 747; w) A. Winkel, R. Wilhelm, Tetrahe-
dron: Asymmetry 2009, 20, 2344; x) M. Li, S. L. De Rooy, D. K.
Bwambok, B. El-Zahab, J. F. DiTusa, I. M. Warner, Chem.
Commun. 2009, 6922; y) B. Altava, D. S. Barosa, M. I. Burg-
uete, J. Escorihuela, S. V. Luis, Tetrahedron: Asymmetry 2009,
20, 999; z) N. Rios-Lombardia, E. Busto, V. Gotor-Fernandez,
(12) [3Manion + 2H], 915.2859 (8) [4Manion + 3H]. IR (KBr): ν =
˜
2967, 1416, 1219, 1205, 1056, 761, 700 cm–1. 1H NMR (200 MHz):
δ = 7.49–7.31 (m, 5 H, ArH), 3.91–3.81 (m, 1 H, CH), 3.09–3.01
(m, 2 H, CH2SO3), 2.87–2.79 (m, 2 H, NCH2), 1.37 (d, J = 6.6 Hz,
3 H, CH3) ppm. 13C NMR (50 MHz): δ = 146.4, 131.3, 130.0,
129.4, 59.5, 52.4, 44.1, 24.5 ppm. HRMS (ESI): calcd. for
C10H14NO3S [Manion] 228.0694; found 228.0701.
Preparation of Tetrabutylphosphonium (R)-(1-Phenylethylamino)
Alkanesulfonates: Tetrabutylphosphonium chloride (500 mg,
1.7 mmol) was dissolved in CH2Cl2 (10 mL) and a solution of 5a
or 6a (4 equiv., 6.8 mmol) in a minimum amount of water was
added. The mixture was stirred vigorously for 3 h, then the phases
were separated and the organic phase was washed with a minimum
amount of water. The organic phase was dried with sodium sulfate
and the solvent was removed under vacuum.
Tetrabutylphosphonium (R)-(1-Phenylethylamino)methanesulfonate
(5b): Yellow liquid (709 mg, 88%). [α]2D5 = +28.7 (c = 1.16, CHCl3).
MS (ES, 0 V, pos. scan): m/z (%) = 259.6197 (100) [Mcation]. MS
(ES, 0 V, neg. scan): m/z (%) = 214.0471 (100) [Manion], 429.1167
(24) [2Manion + H], 644.1807 (4) [3Manion + 2H], 859.2413 (10)
[4Manion + 3H]. IR (NaCl): ν = 2960, 2933, 2873, 1493, 1194, 1031,
˜
441 cm–1. 1H NMR (400 MHz): δ = 7.43–7.38 (m, 2 H, ArH), 7.32–
7.24 (m, 2 H, ArH), 7.19 (tt, J = 7.2, 1.4 Hz, 1 H, ArH), 4.52 (q,
J = 6.5 Hz, 1 H, HCOSO3), 3.65 (d, J = 13.3 Hz, 1 H, HCH), 3.53
(d, J = 13.3 Hz, 1 H, HCH), 2.48 (br. s, 1 H, NH), 2.40–2.25 (m,
8 H, 4ϫPCH2), 1.61–1.44 (m, 16 H, 8ϫCH2), 1.35 (d, J = 6.6 Hz,
3 H, CH3), 0.96 (t, J = 7.0 Hz, 12 H, 4ϫCH3) ppm. 13C NMR
(100 MHz): δ = 145.7, 128.1, 127.3, 126.6, 64.0, 55.3, 24.11, 24.0
(d, J = 15 Hz), 23.8 (d, J = 5 Hz), 18.76 (d, J = 47 Hz), 13.5 ppm.
HRMS (ESI): calcd. for C16H36P [Mcation
] 259.2555; found
259.2568; calcd. for C9H12NO3S [Manion] 214.0538; found 214.0548.
Tetrabutylphosphonium (R)-2-(1-Phenylethylamino)ethanesulfonate
(6b): Yellow liquid (721 mg, 87%). [α]2D5 = +20.2 (c = 1.10, CHCl3).
MS (ES, 0 V, pos. scan): m/z (%) = 259.6197 (100) [Mcation]. MS
(ES, 0 V, neg. scan): m/z (%) = 228.0558 (100) [Manion], 457.1364
(50) [2Manion + H], 686.2181 (10) [3Manion + 2H], 915.3082 (6)
[4Manion + 3H]. IR (NaCl): ν = 2961, 2933, 2873, 1493, 1205, 1035,
˜
414 cm–1. 1H NMR (400 MHz): δ = 7.38–7.32 (m, 2 H, ArH), 7.32–
7.25 (m, 2 H, ArH), 7.19 (tt, J = 7.2, 1.4 Hz, 1 H, ArH), 3.82 (q,
J = 6.6 Hz, 1 H, CH), 3.04–2.84 (m, 4 H, 2ϫCH2), 2.72 (br. s, 1
H, NH), 2.40–2.18 (m, 8 H, 4ϫPCH2), 1.63–1.41 (m, 16 H,
8ϫCH2), 1.33 (d, J = 6.6 Hz, 3 H, CH3), 0.97 (t, J = 7.0 Hz, 12
H, 4ϫCH3) ppm. 13C NMR (100 MHz): δ = 145.7, 128.1, 126.7,
Eur. J. Org. Chem. 2010, 5817–5824
© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
5823

A. Winkel, R. Wilhelm
FULL PAPER
V. Gotor, R. Porcar, E. Garcia-Verdugo, S. V. Luis, I. Alfonso,
S. Garcia-Granda, A. Menendez-Velazquez, Chem. Eur. J.
2010, 16, 836.
mann, C. W. Lehmann, J. Klankermayer, W. Leitner, Angew.
Chem. Int. Ed. 2006, 45, 3689; f) M. Bian, F. Xu, C. Ma, Syn-
lett 2007, 2951; g) S. Hu, T. Jiang, Z. Zhang, A. Zhu, B. Han,
J. Song, Y. Xie, W. Li, Tetrahedron Lett. 2007, 48, 5613; h) W.
Zhou, L.-W. Xu, H.-Y. Qiu, G.-Q. Lai, C.-G. Xia, J.-X. Jiang,
Helv. Chim. Acta 2008, 91, 53; i) Y. Qian, S. Xiao, L. Liu, Y.
Wang, Tetrahedron: Asymmetry 2008, 19, 1515.
[5] For a few selected examples, see: a) M. J. Earle, P. B. McCor-
mac, K. R. Seddon, Green Chem. 1999, 1, 23; b) J. Pernak, I.
Goc, I. Mirska, Green Chem. 2004, 6, 323; K. Fukumoto, M.
Yoshizawa, H. Ohno, J. Am. Chem. Soc. 2005, 127, 2398; c)
L. C. Branco, P. M. P. Gois, N. M. T. Lurenco, V. B. Kurteva,
C. A. M. Afonso, Chem. Commun. 2006, 2371; d) H. Zhao, L.
Jackson, Z. Song, O. Olubajo, Tetrahedron: Asymmetry 2006,
17, 1549; e) R. Gausepohl, P. Buskens, J. Kleinen, A. Bruck-
[6]
S. Natelson, S. P. Gottfried, J. Am. Chem. Soc. 1939, 61, 971.
Received: June 4, 2010
Published Online: September 1, 2010
5824
www.eurjoc.org
© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2010, 5817–5824