Tartrate- and imidazole-derived diketones and diols: Preparation and stability constants of their Cu2+ complexes

Article abstract of DOI:10.1007/s00706-011-0588-1

Overall, six tartrate- and imidazole-derived ketones and diols were synthesized in a stepwise manner as model compounds for the coordination of Cu²⁺ ions. The stability constants of copper(II) complexes were studied spectrophotometrically. It was found that the two model structures coordinate Cu²⁺ ions differentially. Graphical abstract: [Figure not available: see fulltext.]

Full text of DOI:10.1007/s00706-011-0588-1

Monatsh Chem (2011) 142:1131–1136
DOI 10.1007/s00706-011-0588-1
ORIGINAL PAPER
Tartrate- and imidazole-derived diketones and diols: preparation
and stability constants of their Cu2+ complexes
•
Michal Patak Oldrich Pytela Filip Bures
•
´
ˇ
ˇ
Received: 15 June 2010 / Accepted: 15 July 2011 / Published online: 24 August 2011
Ó Springer-Verlag 2011
Abstract Overall, six tartrate- and imidazole-derived
ketones and diols were synthesized in a stepwise manner as
model compounds for the coordination of Cu2? ions. The
stability constants of copper(II) complexes were studied
spectrophotometrically. It was found that the two model
structures coordinate Cu2? ions differentially.
as 1904. However, the modern renaissance and the original
name of TADDOL derivatives are ascribed to Seebach and
co-workers [11, 12]. Since then, TADDOL derivatives
evolved into easily accessible chiral ligands coordinating
various (transition) metals and, especially the titanium
TADDOL complexes, found applications in a variety of
reactions [13].
Keywords Heterocycles ꢀ Ligands ꢀ Stability constant ꢀ
Metal complexes ꢀ UV/vis spectroscopy
Within the course of our research focused on the
development of new optically active imidazole derivatives
and their application as ligands chelating mainly Cu2?
ions, we have synthesized several a-amino acid- [14–19]
and terpene-derived [20, 21] imidazoles. Hence, we report
herein a new family of imidazole-derived diketones and
diols featuring the tartaric acid motive and investigation of
their Cu2? complexes.
Introduction
Tartaric acid and its functional derivatives represent a
readily available, inexpensive, and optically active
C2-symmetric backbone [1]. Both (-)-(S,S)- and (?)-
(R,R)-tartaric acid derivatives have found application in
various areas of chemistry, such as: (i) the synthesis of
chiral ligands and auxiliaries—chiral pool [2]; (ii) bioactive
compounds [3]; (iii) resolution and fermentation processes
[4]; (iv) chiral derivatizing agents for NMR [5]; (v) food
additives [6]. Hence, tartaric acid derivatives have proven to
be among the most pervasive and versatile precursors for
the stereoselective elaboration and the construction of
optically pure privileged ligands, such as a,a,a0,a0,-tetra-
aryl-1,3-dioxolan-4,5-dimethanols (TADDOLs) and their
modifications [7–9] (Fig. 1).
Results and discussion
Synthesis
Our synthesis started with the preparation of dimethyl
(4R,5R)-2,2-dimethyl-1,3-dioxolan-4,5-dicarboxylate (1).
Dicarboxylate 1 was easily generated from the commer-
cially available (R,R)-tartaric acid by the reaction with 2,2-
dimethoxypropane and p-toluenesulfonic acid [22]. Three
basic imidazole derivatives, namely, 1-methylimidazole (2)
[23], 1,4,5-trimethylimidazole (3) [24], and 1-methyl-4,
5-diphenylimidazole (4) [23, 25], were chosen as the starting
heterocycles. The first attempted nucleophilic additions of
C2-lithiated imidazoles 2–4 to dicarboxylate 1 proved to be
difficult due to the unselective formation of several badly
separable products. Hence, we turned our attention towards
(4R,5R)-N,N,N0,N0,2,2-hexamethyl-1,3-dioxolan-4,5-dicarb-
oxamide (5), which undergoes the desired nucleophilic
The first parent TADDOL derivative (Ar = Ph,
R = CH3) has been synthesized by Frankland [10] as early
´
ˇ
M. Patak ꢀ O. Pytela ꢀ F. Bures (&)
Institute of Organic Chemistry and Technology,
Faculty of Chemical Technology, University of Pardubice,
´
Studentska 573, 53210 Pardubice, Czech Republic
e-mail: filip.bures@upce.cz
123

´
M. Patak et al.
1132
Fig. 1 The TADDOL structure
Table 1 Structure, yields, melting points, and optical rotations of the
synthesized diketones 6–8 and diols 9–11
Comp.
R
Yield/%
m.p./°C
[a]D20a/deg cm2 g-1
6
H
58
54
83
67
66
48
96–97
-180.8
-130.3
?134.0
-206.8
-143.6
-85.6
7
Me
Ph
H
85–86
substitution more selectively [26]. Thus, the reaction of
dicarboxylate 1 with dimethylamine afforded smoothly
dicarboxamide 5 [27, 28]. Selective C2-lithiation of imi-
dazoles 2–4 and subsequent addition of the organolithium
intermediates to dicarboxamide 5 afforded the desired
diketones 6–8. However, the reaction conditions needed to
be optimized. We found that the highest yields and purity
of the desired diketones 6–8 can be achieved under the
following conditions: ratio of the lithiated imidazole and
the carboxamide 4:1, reaction temperature 0 °C, and
reaction time of 1.5 h followed by the reaction quench with
aqueous phosphate buffer should be used. Under these
conditions, diketones 6–8 were isolated in 54–83% yields
(Scheme 1, Table 1).
8
110–111
204–205
139–140
197–198
9
10
11
a
Me
Ph
Concentration c is 0.5 g/100 cm3 MeOH
mM þ nL ꢀ MmLn
where m is the number of metal ions and n means the
number of ligand molecules in the complex MmLn. The
particular equilibrium is described by the stability constant
of the complex defined by equation Eq. 1:
bMmLnc
bmn
¼
ð1Þ
m
n
½Mꢁ x½Lꢁ
Diketones 6–8 were in the next reaction step repeatedly
treated with the C2-lithiated imidazoles 2–4 under the
aforementioned conditions to afford target diols 9–11 in
yields of 48–67% (Scheme 1, Table 1). It should be noted
that direct fourfold addition of the C2-lithiated imidazoles
2–4 to dicarboxamide 5 yielded a mixture of several
inseparable products and, therefore, the stepwise addition
was necessary.
where bmn is the stability constant of the complex MmLn.
Spectrophotometric titration is a common technique used
for the determination of the stability constants bmn. Thus,
spectrophotometric titration of ligands 6–11 and Cu2? ions
in methanol has been employed to determine the stability
constants bmn (Fig. 2). Factor analysis of the matrix of
absorbancies (see ‘‘Experimental’’) during titration indi-
cated approximately 4–5 species with different absorption
spectra. This implies that, in the solution, two or three
complexes are being formed. The detailed analysis through
the EFA profiles [29, 30] modified for the factor analysis
Complexation
The formation of coordination compounds between metal
ions M and ligand L in the solution can be described by the
following reaction:
Fig. 2 The change in the UV/vis spectra of the ligand 7 in methanol
as a function of the copper(II) acetate addition during the titration
Scheme 1
123

Tartrate- and imidazole-derived diketones and diols
1133
which is most probably given by the sterically hindered
coordination of the acetate anions or molecules of solvent
as coligands to the two coordinated Cu2? ions. Hence, the
Cu2? ions were coordinated by ligand 8 in the most effi-
cient way. The formation of a 1:1 complex apparently
requires sterically more hindered coordination of both
imidazole rings. The appended substituents at imidazole
positions C4/C5 in ketones 7 and 8 hinder the access of
Cu2? ions and, therefore, the stability constants b11 are
generally smaller. However, the imidazole C4/C5 substi-
tution influences the stability constants b12 more
dramatically. The unsubstituted derivative 6 forms a stable
complex with two ligands coordinated to one Cu2? ion. In
contrast to this, the coordination of two ligands 8 with
bulky and rigid phenyl substituents is considerably hin-
dered and, therefore, the stability constant b12 is almost
negligible for ligand 8. From these relationships, we can
deduce that the coordination sites for Cu2? ions in dike-
tones 6–8 are most probably the carbonyl oxygens or the
imidazole nitrogens.
Fig. 3 The indication of the ratio of metal:ligand (2:1 and 1:2) in the
Cu2? complexes with 11 in dependence on the ratio of the analytical
concentrations of ligand cL and metal ions cM
In comparison to diketones 6–8, the absence of an ML
complex for alcohols 9–11 reflects a different structure of
the coordination site. It seems that diketones 6–8 coordi-
nate Cu2? ions in ML complexes via carbonyl oxygens and
less through the imidazole nitrogen N3. However, a
cumulation of bulky groups that hinder efficient coordi-
nation in the ML type of complexes can be the second
explanation. The relationship of the stability constants b21
(M2L) in dependence on the imidazole C4/C5 substitution
is similar to for diketones 6–8. This implies that the same
coordination site is employed in both types of compounds,
most probably imidazole N3. A weak dependence of the
stability constant b12 on the imidazole C4/C5 substitution
reveals that imidazole N3 is not a coordination site in the
ML2 complexes of diols 9–11. A coordination of two
ligands through four hydroxy groups seems to be more
probable. A small increase of the stability constant b12 as a
consequence of imidazole C4/C5 substituents can be rela-
ted to the sterically hindered coordination of the acetate
anions or the molecules of solvent as coligands.
[29] revealed that, whereas diketones 6–8 form 2:1, 1:1,
and 1:2 complexes (metal:ligand) with Cu2? ions, diols
9–11 give only 2:1 and 1:2 complexes. A representative
output of such analysis for ligand 11 is shown in Fig. 3.
This observation was also verified by the calculation of
various models comprising different types of complexes.
The calculation using the general model, which comprises
the formation of M2L, ML, and ML2 complexes, provided
the corresponding stability constants of ketones 6–8. In the
case of diols 9–11, the stability constant b11 was statisti-
cally not significant and, therefore, a simplified model
comprising only the formation of M2L and ML2 complexes
was used. The stability constant values for compounds
6–11 and Cu2? ions in methanol are summarized in Table 2.
The data in Table 2 show that the stability constants b21
and b11 for diketones 6–8 in dependence on the imidazole
C4/C5 substitution differ only slightly. The highest value
of b21 was obtained for the phenyl-disubstituted diketone 8,
Table 2 The calculated stability constants b for diketones 6–8 and diols 9–11, their standard deviations, and residual standard deviations of the
nonlinear regression s
Comp.
R
log b21 (M2L)
log b11 (ML)
log b12 (ML2)
s
6
H
10.29 0.010
10.03 0.013
11.38 0.042
7.323 0.001
6.888 0.004
8.449 0.003
7.100 0.010
5.991 0.005
12.76 0.009
9.587 0.001
3.302 0.086
9.014 0.001
9.534 0.006
10.13 0.01
1.08 9 10-3
6.89 9 10-3
4.24 9 10-3
2.89 9 10-3
5.51 9 10-3
5.67 9 10-3
7
Me
Ph
H
8
6.164 0.036
a
9
a
a
10
11
a
Me
Ph
This type of complex was not observed
123

´
M. Patak et al.
1134
Conclusion
hexane) was added at 0 °C under argon. The yellow or
orange reaction mixture was stirred for 15 min, whereupon
0.98 g of 5 (4.0 mmol) dissolved in 30 cm3 THF was
added. The reaction mixture was stirred for 1.5 h at 0 °C
and poured into a vigorously stirred biphasic system of
200 cm3 aqueous KH2PO4 (10%) and 200 cm3 CH2Cl2.
The organic phase was separated, the aqueous layer was
extracted with 2 9 150 cm3 CH2Cl2, the combined organic
layers were dried (Na2SO4), and the solvents were evapo-
rated at reduced pressure. The resulting crude product was
purified on column chromatography using the indicated
solvent system.
Starting from dicarboxamide 5, diketones 6–8 and diols
9–11 were prepared by the nucleophilic addition of
C2-lithiated imidazole species. The direct fourfold addition
proved to be difficult and, therefore, the stepwise addition
was necessary. Both diketones 6–8 and TADDOL-like
diols 9–11 were examined as model compounds for the
complexation of Cu2? ions. Whereas diketones 6–8 formed
the expected M2L, ML, and ML2 complex species, diols
9–11 provided only M2L and ML2 types of complexes.
[(4R,5R)-2,2-dimethyl-1,3-dioxolane-4,5-diyl]bis-
[(1-methyl-1H-imidazol-2-yl)methanone]
(6, C15H18N4O4)
Experimental
The reagents and solvents were reagent-grade and were pur-
chased from Penta, Aldrich, and Acros, and used as received.
The starting dicarboxylate 1 [22], imidazoles 2–4 [23–25],
and dicarboxamide 5 [27, 28] were synthesized according to
literature procedures. All reactions were performed in flame-
dried flasks under inert argon atmosphere. Tetrahydrofuran
(THF) was distilled from sodium benzophenone ketyl radical.
Column chromatography was carried out with silica gel 60
(particle size 0.040–0.063 mm, 230–400 mesh; Merck) and
commercially available solvents. Thin-layer chromatography
(TLC) was conducted on aluminum sheets coated with silica
gel 60 F254 obtained from Merck, with visualization by UV
lamp (254 or 360 nm). 1H and 13C NMR spectra were
recorded at 400 and 100 MHz, respectively, with a Bruker
Avance 400 instrument at 25 °C. Chemical shifts are reported
in ppm relative to the signal of Me4Si. The residual solvent
signal in the 1H and 13C NMR spectra was used as an internal
reference (CDCl3—7.25 and 77.23 ppm). Apparent reso-
nance multiplicities are described as s (singlet), br s (broad
singlet), d (doublet), and m (multiplet). Mass spectra were
measured on a GC/MS configuration comprised of an Agilent
Technologies 6890N gas chromatograph equipped with a
5973 Network MS detector (EI 70 eV, mass range
33–550 Da) or on an LC–MS Micromass Quattro Micro API
(Waters) instrument with a direct input (ESI? , CH3OH,
mass range 200–800 Da). IR spectra were recorded on a
Perkin Elmer FT-IR Spectrum BX spectrometer. Optical
rotations were measured on a Perkin Elmer 341 polarimeter
using the sodium D line (589 nm), specific rotations [a] are
given in units of deg cm2 g-1, and concentration c is 0.5 g/
100 cm3 MeOH. Elemental analyses were performed on an
EA 1108 Fisons instrument, and their results were found to be
in good agreement with the calculated values.
Off-white solid. Yield 0.74 g (58%); m.p.: 96–97 °C;
Rf = 0.38 (SiO2; EtOAc); [a]2D0 = -180.8° cm2 g-1
(c = 0.5, MeOH); 1H NMR (400 MHz, CDCl3):
d = 1.54 (s, 6H, 2 9 CH3), 4.00 (s, 6H, 2 9 NCH3),
5.87 (s, 2H, 2 9 CH), 6.84 (s, 2H, 2 9 CHim), 6.94 (s, 2H,
2 9 CHim) ppm; 13C NMR (100 MHz, CDCl3): d = 26.78,
35.95, 79.17, 113.33, 127.21, 129.60, 142.09, 186.63 ppm;
ꢀ
IR (neat): m = 3,132, 2,985, 2,926, 1,682 (C=O), 1,403,
1,260, 1,206, 1,160, 1,043, 978, 881, 862, 780, 754,
700 cm-1; EI-MS (70 eV): m/z = 318 (M?, 1), 260 (24),
209 (61), 181 (57), 151 (100), 109 (94).
[(4R,5R)-2,2-dimethyl-1,3-dioxolane-4,5-diyl]bis
[(1,4,5-trimethyl-1H-imidazol-2-yl)methanone]
(7, C19H26N4O4)
Off-white solid. Yield 0.81 g (54%); m.p.: 85–86 °C;
Rf = 0.49 (SiO2; EtOAc); [a]2D0 = -130.3° cm2 g-1
(c = 0.5, MeOH); 1H NMR (400 MHz, CDCl3):
d = 1.55 (s, 6H, 2 9 CH3), 1.85 (s, 6H, 2 9 CimCH3),
2.09 (s, 6H, 2 9 CimCH3), 3.89 (s, 6H, 2 9 NCH3), 5.78
(s, 2H, 2 9 CH) ppm; 13C NMR (100 MHz, CDCl3):
d = 8.93, 12.69, 26.77, 32.72, 79.39, 112.82, 130.93,
ꢀ
136.03, 140.38, 185.92 ppm; IR (neat): m = 3,434, 2,983,
2,921, 1,669 (C=O), 1,560, 1,463, 1,373, 1,293, 1,180,
1,104, 1,013, 942, 900, 779, 727 cm-1; EI-MS (70 eV): m/
z = 374 (M?, 2), 316 (27), 237 (19), 179 (100), 137 (99),
110 (22), 56 (23).
[(4R,5R)-2,2-dimethyl-1,3-dioxolane-4,5-diyl)bis-
[(1-methyl-4,5-diphenyl-1H-imidazol-2-yl)methanone]
(8, C39H34N4O4)
Off-white solid. Yield 2.07 g (83%); m.p.: 110–111 °C; Rf =
0.63 (SiO2; EtOAc/hexane 1:1); [a]2D0 = ?134.0° cm2 g-1
1
(c = 0.5, MeOH); H NMR (400 MHz, CDCl3): d = 1.73
(s, 6H, 2 9 CH3), 3.62 (s, 6H, 2 9 NCH3), 6.14 (s, 2H,
2 9 CH), 6.70 (d, 4H, J = 7.2 Hz, Ph), 7.11–7.14 (m, 6H,
Ph), 7.24–7.30 (m, 8H, Ph), 7.35–7.39 (m, 2H, Ph) ppm;
13C NMR (100 MHz, CDCl3): d = 26.89, 33.53, 79.93,
General procedure for the synthesis of diketones 6–8
To imidazole 2–4 (16.0 mmol) dissolved in 50 cm3 THF,
10.25 cm3 of nBuLi (16.4 mmol, 1.6 M solution in
123

Tartrate- and imidazole-derived diketones and diols
1135
112.90, 126.45, 127.20, 128.29, 129.15, 129.27, 129.45,
130.49, 133.33, 135.33, 138.27, 141.36, 186.50 ppm; IR
870, 781, 698 cm-1; ESI–MS: m/z = 595 (M ? 1)?, 1211
(2M ? 23)?.
ꢀ
(neat): m = 3,053, 2,985, 2,934, 1,684 (C=O), 1,446, 1,379,
[(4R,5R)-2,2-dimethyl-1,3-dioxolane-4,5-diyl]bis-
[bis(1-methyl-4,5-diphenyl-1H-imidazol-2-yl)methanol]
(11, C71H62N8O4)
1,202, 1,112, 1,025, 989, 954, 902, 770, 694 cm-1; EI-MS
(70 eV): m/z = 234 (100), 218 (14), 165 (48); ESI–MS: m/
z = 623 (M ? 1)?, 645 (M ? 23)?, 1,267 (2M ? 23)?.
Off-white solid. Yield 262 mg (48%); m.p.: 197–198 °C;
Rf = 0.63 (SiO2; EtOAc/hexane 1:2); [a]2D0 = -85.6°
General procedure for the synthesis of diols 9–11
1
cm2 g-1 (c = 0.5, MeOH); H NMR (400 MHz, CDCl3):
d = 1.59 (s, 6H, 2 9 CH3), 2.73 (s, 6H, 2 9 NCH3), 3.93 (s,
6H, 2 9 NCH3), 5.86 (s, 2H, 2 9 CH), 7.05–7.53 (m, 40H,
Ph), 9.60 (br s, 2H, OH) ppm; 13C NMR (100 MHz, CDCl3):
d = 27.13, 31.84, 34.10, 74.59, 81.58, 106.69, 125.85,
126.25, 126.54, 126.66, 127.99, 128.14, 128.52, 128.59,
128.89, 128.94, 130.24, 130.46, 130.96, 131.10, 131.43,
131.83, 133.26, 134.03, 135.24, 135.76, 146.44, 149.28 ppm;
To imidazole 2–4 (2.0 mmol) dissolved in 20 cm3 THF,
1.28 cm3 of nBuLi (2.05 mmol, 1.6 M solution in hexane)
was added at 0 °C under argon. The yellow or orange
reaction mixture was stirred for 15 min, whereupon dike-
tone 6–8 (0.5 mmol) dissolved in 15 cm3 THF was added.
The reaction mixture was stirred for 1.5 h at 0 °C and
poured into a vigorously stirred biphasic system of 50 cm3
aqueous KH2PO4 (10%) and 50 cm3 CH2Cl2. The organic
phase was separated, the aqueous layer was extracted with
2 9 50 cm3 CH2Cl2, the combined organic layers were
dried (Na2SO4), and the solvents were evaporated at
reduced pressure. The resulting crude product was purified
on column chromatography using the indicated solvent
system.
ꢀ
IR (neat): m = 2,887 (OH), 1,600, 1,504, 1,441, 1,370, 1,230,
1,133, 1,053, 1,024, 908, 771, 693 cm-1
m/z = 1,113 (M ? 23)?.
; ESI–MS:
Stability constant b determination
The stability constants of the complexes prepared from
ligands 6–11 and Cu2? ions were determined by spectro-
photometric titration at 25 °C. A 1-cm-wide quartz cuvette
was filled with 3 cm3 of ligand solution in methanol
(c = 2 9 10-5 mol/dm3) and the absorption spectrum was
measured in the range of wavelengths k from 280 to
350 nm. A 745 mm3 quantity of solution of copper(II)
acetate in methanol (c = 2 9 10-3 mol/dm3, the accurate
concentration was determined by ICP) was added gradually
in 2–50-mm3 portions. The additions were optimized with
respect to the molar ratio of ligand:metal (15:1 at the
beginning, 1:25 at the end, 45 additions overall). The
absorption spectra were recorded upon each Cu2? addition.
The absorption spectrum of 745 mm3 of the aforemen-
tioned copper(II)acetate solution in 3 cm3 of methanol was
measured at the end. The stability constants b and their
molar absorption coefficients e (k) were calculated from the
matrix of measured absorbancies (row—concentrations,
columns—wavelengths) employing the program OPchem
[31]. The same program was used for the determination of
the number of particles in the solution and for the indica-
tion of the complexes with the given ratio of metal:ligand.
[(4R,5R)-2,2-dimethyl-1,3-dioxolane-4,5-diyl]bis[bis(1-
methyl-1H-imidazol-2-yl)methanol] (9, C23H30N8O4)
Off-white solid. Yield 161 mg (67%); m.p.: 204–205 °C;
Rf = 0.25
(SiO2;
EtOAc/MeOH
5:1);
[a]2D0
=
-206.8° cm2 g-1 (c = 0.5, MeOH); H NMR (400 MHz,
CDCl3): d = 1.32 (s, 6H, 2 9 CH3), 3.24 (s, 6H,
2 9 NCH3), 3.98 (s, 6H, 2 9 NCH3), 5.33 (s, 2H,
2 9 CH), 6.47 (s, 4H, 4 9 CHim), 6.77 (s, 2H, 2 9 CHim),
6.82 (s, 2H, 2 9 CHim), 9.26 (br s, 2H, OH) ppm; 13C
NMR (100 MHz, CDCl3): d = 26.79, 33.93, 35.62, 73.74,
81.21, 106.27, 122.35, 122.54, 123.69, 126.92, 146.78,
1
ꢀ
149.03 ppm; IR (neat): m = 2,981 (OH), 1,461, 1,388,
1,280, 1,239, 1,118, 1,070, 985, 896, 728, 717, 685 cm-1
ESI–MS: m/z = 505 (M ? 23)?, 987 (2M ? 23)?.
;
[(4R,5R)-2,2-dimethyl-1,3-dioxolane-4,5-diyl]bis-
[bis(1,4,5-trimethyl-1H-imidazol-2-yl)methanol]
(10, C31H46N8O4)
Off-white solid. Yield 196 mg (66%); m.p.: 139–140 °C;
Rf = 0.30 (SiO2; EtOAc/MeOH 5:1); [a]2D0 = -
143.6° cm2 g-1 (c = 0.5, MeOH); 1H NMR (400 MHz,
CDCl3): d = 1.35 (s, 6H, 2 9 CH3), 1.81 (s, 6H,
2 9 CimCH3), 1.89 (s, 6H, 2 9 CimCH3), 2.04 (s, 6H,
2 9 CimCH3), 2.12 (s, 6H, 2 9 CimCH3), 3.10 (s, 6H,
2 9 NCH3), 3.84 (s, 6H, 2 9 NCH3), 5.26 (s, 2H,
2 9 CH), 9.53 (br s, 2H, OH) ppm; 13C NMR
(100 MHz, CDCl3): d = 8.62, 9.35, 11.92, 13.03, 26.97,
31.20, 33.08, 73.77, 81.58, 105.99, 123.15, 123.77, 128.20,
131.13, 144.98, 147.24 ppm; IR (neat): ꢀm = 2,918 (OH),
1,721, 1,440, 1,396, 1,369, 1,222, 1,128, 1,069, 1,004, 911,
Acknowledgments This research was supported by the Czech
Science Foundation (203/08/0208) and the Ministry of Education,
Youth, and Sport of the Czech Republic (MSM 002167501).
References
´
´
1. Gawronski J, Gawronska K (1999) Tartaric and malic acids in
synthesis. Wiley, New York
123

´
M. Patak et al.
1136
´ ˇ
18. Sıvek R, Pytela O, Bures F (2008) J Heterocycl Chem 45:1621
´
2. Blaser H-U (1992) Chem Rev 92:935
ˇ ´
19. Sıvek R, Bures F, Pytela O, Kulhanek J (2008) Molecules
3. Ghosh AK, Koltun ES, Bilcer G (2001) Synthesis 9:1281
4. Gal J (2008) Chirality 20:5
5. Parker D (1991) Chem Rev 91:1441
6. Horn HJ, Holland EG, Hazleton LW (1957) J Agric Food Chem
5:759
7. Yoon TP, Jacobsen EN (2003) Science 299:1691
8. Benessere V, Del Litto R, De Roma A, Ruffo F (2010) Coord
Chem Rev 254:390
13:2326
ˇ
20. Kulhanek J, Bures F, Simon P, Schweizer WB (2008) Tetrahe-
´
dron Asymmetry 19:2426
ˇ
ˇ
´
˚
ˇ ˇ
21. Bures F, Kulhanek J, Ruzicka A (2009) Tetrahedron Lett 50:3042
22. Mash EA, Nelson KA, Van Deusen S, Hemperly SS (1990) Org
Synth 68:92
23. Kikugawa Y (1981) Synthesis 2:124
9. Kagan HB, Dang TP (1972) J Am Chem Soc 94:6429
10. Frankland PF, Twiss DF (1904) J Chem Soc 85:1666
11. Seebach D, Beck AK, Heckel A (2001) Angew Chem Int Ed
40:92
12. Weidmann B, Wilder L, Olivero AG, Maycock CD, Seebach D
(1981) Helv Chim Acta 64:357
13. Duthaler RO, Hafner A (1992) Chem Rev 92:807
24. Arduengo AJ, Rasika Dias HV, Dixon DA, Harlow RL, Klooster
WT, Koetzle TF (1994) J Am Chem Soc 116:6812
25. Bredereck H, Gompper R, Hayer D (1959) Chem Ber 92:338
26. Prasad KR, Chandrakumar A (2007) Tetrahedron 63:1798
27. Ohshima T, Shibuguchi T, Fukuta Y, Shibasaki M (2004) Tet-
rahedron 60:7743
28. Zinchenko AA, Sergeyev VG, Kabanov VA, Murata S, Yoshik-
awa K (2004) Angew Chem Int Ed 43:2378
29. Maeder M (1987) Anal Chem 59:527
ˇ
14. Bures F, Kulhanek J (2005) Tetrahedron Asymmetry 16:1347
15. Marek A, Kulhanek J, Ludwig M, Bures F (2007) Molecules
´
´
ˇ
12:1183
ˇ
capek M (2006) Tetrahedron Asymmetry 17:900
30. Tauler R, Kowalski B, Fleming S (1993) Anal Chem 65:2040
31. OPchem, O. Pytela, Version 5.02, webpage: http://webak.upce.
cz/_koch/cz/veda/OPgm.htm
´
16. Bures F, Szotkowski T, Kulhanek J, Pytela O, Ludwig M, Hol-
ˇ
´ ˇ
17. Marek A, Kulhanek J, Bures F (2009) Synthesis 2:325
123