Two diastereomeric artificial enzymes with different catalytic activity

Article abstract of DOI:10.1002/ejoc.201200699

Two epimeric cyclodextrin-6-C-aldehydes were synthesised in 10 steps from β-cyclodextrin. The synthesis involved protection/partial deprotection, oxidation to a 6-aldehyde, olefination, dihydroxylation, selective protection of the secondary alcohol and ox

Full text of DOI:10.1002/ejoc.201200699

Job/Unit: O20699
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FULL PAPER
DOI: 10.1002/ejoc.201200699
Two Diastereomeric Artificial Enzymes with Different Catalytic Activity
[a]
[a]
[a]
[a]
Emil Lindbäck, You Zhou, Christian Marcus Pedersen, and Mikael Bols*
Keywords: Cyclodextrins / Glycosides / Enzyme mimics / Hydrolysis / Oxidation
Two epimeric cyclodextrin-6-C-aldehydes were synthesised
dominantly outside the cavity. Hydrolysis of aryl glycosides
in 10 steps from β-cyclodextrin. The synthesis involved pro- on the other hand was catalysed in a reaction following
tection/partial deprotection, oxidation to a 6-aldehyde, ole-
fination, dihydroxylation, selective protection of the second-
ary alcohol and oxidation. The two isomers catalysed the
oxidation of aromatic amines by hydrogen peroxide but pre-
Michaelis–Menten kinetics. The S isomer was a 5–20 times
better catalyst than the R isomer, which was explained from
models.
Introduction
Catalysis is a field of growing importance as the demand
for green and sustainable processes continues to increase.
The most sophisticated form of catalysis, enzyme catalysis,
is performed by naturally occurring proteins, and an ex-
[1]
tremely small number of small organic molecules, most of
which are cyclodextrin derivatives.[ Although these artifi-
cial enzymes are less efficient catalysts than natural enzymes
2]
4
at present, promising rate increases of over 6ϫ10 suggest
that this is a matter of proper adjustment of the artificial
[
3]
enzyme structure.
Recently, we found that cyclodextrin-6-aldehydes, such as
(Figure 1), were very good catalysts of the oxidation of
1
[
4]
aromatic amines and alcohols by hydrogen peroxide. The
reactions occur by the addition of H O to the aldehyde
2
2
followed by a more facile oxidation of the aromatic sub-
strate that is bound in the cyclodextrin cavity. The rate in-
3
4
creases obtained are 10 –10 times faster than the uncata-
[
5]
lysed reaction, which is better than some natural oxidases.
We wished to improve these promising catalysts and a
possible way of doing so would be to move the catalytic
group closer to the bound substrate by, for example, chain
extension at C-6. It is important that the aldehyde has little
conformational freedom, as a catalyst with many possible
conformers will be poor for the simple reason that only a
small fraction of the compound is in the catalytic confor-
mation. However, we have previously found that rigidity is
Figure 1. Cyclodextrin-6-aldehydes.
maintained when one extends the C chain at the 6-position
provided that the hydroxy group is retained.[
6,7]
Therefore,
extension with one carbon atom to the α-methoxy alde-
hydes 2R and 2S was an obvious choice (Figure 1) as the
methoxy group was expected to behave in a similar manner
to an OH group due to the similarity in electronic effects.
We report the synthesis of these two compounds and the
study of their performance as enzymatic catalysts of various
reactions.
[
a] Department of Chemistry, University of Copenhagen,
Universitetsparken 5, Denmark
Fax: +45-35320214
E-mail: bols@chem.ku.dk
Homepage: www.ki.ku.dk
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejoc.201200699
Eur. J. Org. Chem. 0000, 0–0
© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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E. Lindbäck, Y. Zhou, C. M. Pedersen, M. Bols
FULL PAPER
Results and Discussion
the other has the OH group pointing towards the outside.
The faster running R isomer was obtained in 58% yield,
and the slower running S isomer was obtained in 17% yield
Synthesis
(
Scheme 1).
The synthesis of the chain-extended aldehydes 2S and 2R
started from alcohol 3 (Scheme 1), which is readily obtained
from β-cyclodextrin using perbenzylation followed by selec-
tive debenzylation with diisobutylaluminum hydride
The major isomer 5R was then methylated with sodium
hydride and methyl iodide giving the O-methyl ether 6R in
7% yield. Zemplén-type transesterification of 6R removed
6
DIBAL).[8] This compound was subjected to a Swern
the benzoate to yield the primary alcohol 7R in 92%. Oxi-
dation of 7R using Dess–Martin periodinane gave the alde-
hyde 8S in modest yield (43%). Finally, deprotection by hy-
drogenolysis of the benzyl groups using palladium-on-car-
bon catalysis in 2-methoxyethanol gave 2S in 98% yield.
Similarly, the other epimeric monobenzoate 5S was O-
methylated to 6S, which was obtained in 85% yield
(
oxidation [(COCl) /dimethyl sulfoxide (DMSO)/Et N] to
2
3
give the corresponding aldehyde and was then reacted with
methyltriphenylphosphonium ylide to give the vinyl deriva-
tive 4. This compound was obtained in 81% yield from 3.
The alkene 4 was dihydroxylated with OsO /N-methyl-
4
morpholine N-oxide (NMO) to give two 1,2-glycol isomers
that were regioselectively benzoylated with benzoyl chloride
(Scheme 1). Removal of the benzoate gave alcohol 7S in
8
5% yield. Likewise, oxidation of the alcohol led to alde-
(1.2 equiv.) in cold pyridine. This gave two epimeric mono-
hyde 8R in 45% yield. Finally, deprotection of 8R gave 2R
in 95% yield.
benzoates 5R and 5S that, in line with earlier cases of a
[
6,7]
similar type,
could be separated by chromatography. The
reason for the comparatively large difference in polarity be-
tween these isomers is that they adopt the gg and gt (but
not the tg) conformers around the C5–C6 bond so that one
Catalysis Studies
Both 2R and 2S catalysed the oxidation of 2- and 4-hy-
isomer has the OH group pointing towards the cavity and droxyaniline (9 and 10) by hydrogen peroxide in a pH 7.0
Scheme 1. Synthesis of 2S and 2R.
2
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Diastereomeric Artificial Enzymes with Different Catalytic Activity
Table 1. Kinetic data for the hydrolysis of 11–13 (0.2–20 mm) catalysed by 2R and 2S (0.1 mm) in phosphate buffer pH 8.0.
–
5 –1
Substrate
Catalyst
Phosphate conc. [m]
K
m
[mm]
k
cat [10 s ]
kcat/kuncat
4-nitrophenyl α-d-glucopyranoside (11)
4-nitrophenyl α-d-glucopyranoside (11)
4-nitrophenyl α-d-glucopyranoside (11)
4-nitrophenyl α-d-glucopyranoside (11)
4-nitrophenyl β-d-glucopyranoside (12)
4-nitrophenyl β-d-glucopyranoside (12)
4-nitrophenyl α-d-galactopyranoside (13)
4-nitrophenyl α-d-galactopyranoside (13)
2R
2R
2S
2S
2R
2S
2S
2R
0.18
0.5
0.18
0.5
0.5
0.5
0.5
0.5
1.4Ϯ0.3
2.8Ϯ0.5
3.0Ϯ0.3
1.2Ϯ0.1
1.2Ϯ0.3
2.2Ϯ0.1
1.3Ϯ0.2
0.14Ϯ0.03
0.113Ϯ0.0069
0.361Ϯ0.038
1.05Ϯ0.052
1.93Ϯ0.053
0.229Ϯ0.023
2.30Ϯ0.034
2.77Ϯ0.097
0.191Ϯ0.017
101Ϯ6
201Ϯ21
934Ϯ46
1077Ϯ29
104Ϯ6
1044Ϯ16
956Ϯ33
65Ϯ6
phosphate buffer.[9] With concentrations of 5–10 mm hy- of reaction and a parallel line in the Hanes plot (Figure 3)
droxyaniline substrate and 64–72 mm hydrogen peroxide, showed competitive inhibition with a K value for cyclo-
i
adding just 0.1 mm of 2R or 2S led to a doubling of the rate pentanol of 56 mm.
of oxidation, which indicates that they are quite effective
catalysts of this reaction. However, in most cases the reac-
tion did not show saturation kinetics, which suggests that
part of the catalysis is occurring on an unbound substrate.
Only the catalysis by 2S on the oxidation of 4-aminoaniline
(
10) was found to follow Michaelis–Menten kinetics giving
–
4 –1
K = 1.4 mm, k = 1.1ϫ10
s
and kcat/kuncat = 154. This
m
cat
result is not an improvement over 6-aldehydes such as 1,
which on this substrate gave kcat/kuncat = 544.[ It is clear
4]
that neither 2S nor 2R is optimally placed to catalyse this
oxidation of an aromatic amine that is bound in the cavity. Figure 3. Hanes plot for the hydrolysis of 12 catalysed by 2S with
We have earlier observed that a cyclodextrin dialdehyde (o) and without (Δ) the presence of cyclopentanol. [S] is substrate
A
D
concentration. V is starting velocity and VЈ is starting velocity in
the presence of inhibitor. The plot shows that cyclopentanol is a
competitive inhibitor for 2S.
(
the 6 ,6 -analogue of 1) catalysed the hydrolysis of ni-
trophenyl glycosides, although with a modest rate increase
kcat/kuncat = 48).[
10,11]
Compounds 2R and 2S were there-
(
fore screened for catalysis of this reaction and were both
found to perform excellent catalysis that showed saturation
kinetics. The results are shown in Table 1.
The most plausible mode of catalysis in this reaction is
that the aldehyde in the catalyst is hydrated and acts as a
Interestingly, compound 2S is the better catalyst as it has general acid catalyst on a substrate that has the nitrophenyl
a 10 times higher k value than its epimer and gives rate group bound in the cavity of the cyclodextrin and with the
cat
3
increases of 10 over the uncatalysed reaction for all three carbohydrate moiety protruding from the primary face.
substrates 11–13 (Figure 2). For both catalysts, the Michae- However, it is puzzling that it is the 2S epimer that is the
lis–Menten constant, except for a single case, is in a narrow stronger catalyst because we normally would expect the al-
range (1.2–3 mm), which shows that the substrates and cata- dehyde to be pointing away from the cavity in that epimer.
lysts have fairly similar binding interactions. The change of This point and the simple fact that both 2R and 2S are
the substrate stereochemistry has no effect on the catalysis, catalysts suggests that the C5–C6 bond has more conforma-
which also fits an expected binding of the aromatic group tional freedom that initially supposed. An inspection of
into the cavity with the saccharide pointing out.
molecular models revealed that hydrogen bonding between
the oxygen atom of the OMe group in 2S and the 6-OH
group of the next glucose residue could be favourable and
the factor that would stabilise the conformation having the
hydrated aldehyde pointing towards the substrate (Figure 4,
top). Complex 2R (Figure 4, bottom) can also attain this
conformer but without stabilisation by hydrogen bonding.
Rather, hydrogen bonding between the OMe group and the
B
6
-OH group will in this case stabilise a conformer with the
aldehyde out of the ring.
We have presented a synthesis of two cyclodextrins where
one d-glucose residue has been replaced with a 6-O-methyl-
d- or l-heptodiulose. The new compounds catalyse the hy-
drolysis of aryl glycosides in an enzymatic manner and are,
Figure 2. Substrates for the enzyme-catalysed reactions.
To confirm the involvement of the cavity, an inhibition to the best of our knowledge, the first case where different
experiment was performed by adding cyclopentanol to the catalytic activity has been demonstrated in two epimeric
2S-catalysed hydrolysis of 11. A clear reduction in the rate cyclodextrin derivatives.
Eur. J. Org. Chem. 0000, 0–0
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E. Lindbäck, Y. Zhou, C. M. Pedersen, M. Bols
FULL PAPER
A
1
38.4, 138.2, 138.1 (Cipso), 137.2 (C-6 ), 128.4, 128.3, 128.2, 128.1,
1
28.0, 127.9, 127.8, 127.7, 127.6, 127.4, 127.2, 127.1, 127.0, 126.8
A
(
Ar-H), 118.5 (C-7 ), 98.9, 98.7, 98.5, 98.2, 98.0 (C-1), 81.3, 81.1,
8
7
7
6
1.0, 80.8, 80.6, 80.1, 79.9, 79.5, 79.3 79.1, 79.0, 78.9, 78.8, 78.5,
7.5 (CH), 76.2, 76.1, 76.0, 75.4, 75.3, 74.5, 73.6, 73.4, 73.3, 73.1,
2.9, 72.6, 72.3 (CH
9.6, 69.4, 69.3, 69.1, 69.0 (C-6) ppm. MALDI-TOF-MS: m/z
34Na 2955.3; found 2956.4.
2
Ph), 72.1, 71.8, 71.7, 71.6, 71.4, 70.0 (CH),
190
calcd. for C183H O
6AR-C-Methyl Benzoate-2A–G,3A–G,6B,C,D.E,F,G-eiocosakis-O-benzyl-
A
A–G A–G
β-cyclodextrin (5R) and 6 S-C-Methyl Benzoate-2
6
,3
,
B,C,D.E,F,G
-eiocosakis -O-benzyl-β-cyclodextrin (5S): To a solution
of 4 (3.1 g, 1.06 mmol) and NMO (742.8 mg, 6.34 mmol) in ace-
tone/H O (300:17, 32 mL) was added OsO (0.4 mL, 2.5 wt.-% in
2
4
methyl-2-propanol). The reaction mixture was stirred at room tem-
perature for 24 h. The reaction was quenched by adding aqueous
Na S O (30 mL, 10 wt.-%). Then EtOAc (30 mL) was added and
2 2 3
the two phases were separated. The aqueous layer was extracted
with EtOAc (2 ϫ 30 mL). The combined organic extracts were
washed with NH
100 mL). The organic layer was dried (MgSO
centrated in vacuo.
4
Cl (50 mL) and saturated aqueous NaCl
(
4
), filtered and con-
Figure 4. Proposed reaction complexes in the hydrolysis of aryl
glycosides catalysed by 2S and 2R.
The crude glycol isomers and pyridine (0.51 mL, 6.36 mmol) were
dissolved in DCM (35 mL). The solution was cooled too 0 °C and
BzCl (0.15 mL, 1.3 mmol) was slowly added. The reaction mixture
was then allowed to reach room temperature and was stirred for
5 h. The temperature was adjusted to 0 °C, and additional amounts
of pyridine (0.51 mL, 1.3 mmol) and BzCl (0.15 mL, 1.3 mmol)
were added, after which the reaction mixture was stirred at room
Experimental Section
5A-C-Vinyl-2A–G,3A–G,6B,C,D,E,F,G-eiocosakis-O-benzyl-β-cyclo-
dextrin (4): To a solution of oxalyl chloride (1.5 mL, 17.7 mmol) in
dichloromethane (DCM, 15 mL) at –78 °C DMSO (2.5 mL,
temperature for 5 h. The reaction was quenched by adding H
2
O
(
30 mL). Then the phases were separated and the aqueous layer
35.4 mmol) in DCM (5 mL) was slowly added. The mixture was
was extracted with DCM (2 ϫ 30 mL). The combined organic
phases were concentrated under reduced pressure. Purification of
the concentrate by column chromatography (EtOAc/n-heptane,
stirred at –78 °C for 30 min. Then a solution of 3 (5.2 g, 1.8 mmol)
in DCM (40 mL) was added. The reaction mixture was stirred for
1
.5 h. Then NEt
warming to room temperature and stirring for 30 min. H
30 mL) was added and the phases were separated. The aqueous
layer was extracted with DCM (2ϫ30 mL). The combined organic
3
(6.1 mL, 44.3 mmol) was added at –78 °C before
7
:33) furnished 5R (1.9 g, 58 %) and 5S (0.52 g, 17%) as white
2
O
foams.
(
Data for 5R: R
0.52, EtOAc). H NMR (500 MHz, CDCl
3
f
1
= 0.32 (EtOAc/cyclohexane, 1:4). [α]
D
= +49 (c =
): δ = 7.97–7.95 (m, 2
H, Ar-H), 7.46–7.43 (m, 1 H, Ar-H), 7.31–7.27 (m, 2 H, Ar-H),
.24–6.96 (m, 100 H, Ar-H), 5.32 (d, J = 3.1 Hz, 1 H, 1-H), 5.10
d, J = 3.8 Hz, 1 H, 1-H), 5.07 (d, J = 3.2 Hz, 1 H, 1-H), 5.05 (d,
J = 11.3 Hz, 1 H, CHPh), 5.02–5.01 (m, 3 H, 2ϫ1-H, CHPh),
.98–4.96 (m, 2 H, 1-H, CHPh), 4.92–4.87 (m, 2 H, 2 CHPh), 4.85
d, J = 3.4 Hz, 1 H, 1-H), 4.73–4.64 (m, 6 H, 6 CHPh), 4.56–4.22
layers were dried (MgSO
duced pressure.
4
), filtered and concentrated under re-
7
(
PPh
THF, 15 mL) at –40 °C and nBuLi (13.6 mL, 1.3 n in n-hexane)
was slowly added. The mixture was stirred at this temperature for
5 min, then warmed to 0 °C and stirred for 5 min. A solution of
3 3
CH Br (8.2 g, 23.0 mmol) was suspended in tetrahydrofuran
(
4
1
(
(
the crude aldehyde in THF (35 mL) was added. The mixture was
warmed to room temperature and was stirred for 4 h. The reaction
A
A
A
m, 33 H, 6 -H, 7 a-H, 31 CHPh), 4.18–4.14 (m, 2 H, 7 b-H,
CHPh), 4.07–4.02 (m, 2 H, 5-H, 6-H), 3.99–3.82 (m, 19 H), 3.71–
was quenched by adding H
and the water phase was extracted with DCM (2ϫ40 mL). The
combined organic extracts were dried (MgSO ), filtered and con-
2
O (30 mL). The phases were separated
3
=
CDCl
.66 (m, 2 H), 3.49–3.35 (m, 11 H, 6ϫ2-H, 5ϫ6-H), 3.26 (dd, J
1
3
3.3, J = 9.1 Hz, 1 H, 2-H) ppm. C NMR (APT, 125 MHz,
): δ = 167.0 (C=O), 139.5, 139.4, 139.3, 139.2, 138.7, 138.6,
38.5, 138.3, 138.0, 137.8 (Cipso), 133.2 (Ar-H), 130.4 (Cipso), 129.8,
4
3
centrated under reduced pressure. Purification of the concentrate
by column chromatography (EtOAc/n-heptane, 1:19Ǟ3:17) fur-
1
1
1
9
7
28.6, 128.5, 128.4, 128.3, 128.2, 128.1, 128.0, 127.9, 127.8, 127.7,
27.6, 127.5, 127.4, 127.3, 127.2, 127.1, 127.0 (Ar-H), 99.2, 99.0,
8.9, 98.6, 98.4, 97.3 (C-1), 81.4, 81.2, 81.1, 80.7, 80.5, 80.2, 79.7,
9.6, 79.4, 79.2, 79.0, 78.9, 78.6, 78.4, 78.2 (CH), 76.0, 75.8
nished the title compound (4.2 g, 81%) as a white foam, R
f
= 0.38
= +50 (c = 0.52, EtOAc). H NMR
): δ = 7.22–6.95 (m, 100 H, Ar-H), 5.85–5.78 (m,
1
(
(
EtOAc/cyclohexane, 7:13). [α]
500 MHz, CDCl
D
3
A
A
1
H, 6 -H), 5.42 (d, J = 3.7 Hz, 1 H, 1-H), 5.25–5.20 (m, 4 H, 7 a-
H, 1-H, 2 CHPh), 5.09 (d, J = 10.7 Hz, 1 H, CHPh), 5.08 (d, J =
1.0 Hz, 1 H, CHPh), 4.99 (d, J = 11.0 Hz, 1 H, CHPh), 4.97–4.95
(
CH
2
Ph), 75.7 (C-5), 75.6, 75.3, 75.2, 75.1, 75.0, 73.6, 73.4, 73.3,
3.2, 73.0, 72.8, 72.7, 72.6 (CH Ph), 71.8, 71.7, 71.6, 71.5, 71.3,
1.2 (CH), 69.5, 69.4, 69.3 (C-6), 69.0 (C-6 ), 68.9 (C-6), 66.2 (C-
7
7
7
2
1
A
A
(
4
(
m, 2 H, 1-H, CHPh), 4.92–4.87 (m, 5 H, 3ϫ1-H, 7 b-H, CHPh),
.86 (d, J = 3.3 Hz, 1 H, 1-H), 4.76–4.63 (m, 9 H, 9 CHPh), 4.62
d, J = 10.8 Hz, 1 H, CHPh), 4.55 (d, J = 12.0 Hz, 1 H, CHPh),
A
196
) ppm. MALDI-TOF-MS: m/z calcd. for C190H O37Na 3094.3;
found 3093.6.
A
4
3
.44–4.20 (m, 23 H, 5 -H, 22 CHPh), 4.04–3.82 (m, 20 H), 3.79– Data for 5S: R
f
1
= 0.29 (EtOAc/cyclohexane, 1:4). [α]
D
= +52 (c =
): δ = 8.10–8.09 (m, 2
H, Ar-H), 7.50–7.47 (m, 1 H, Ar-H), 7.36–7.11 (m, 2 H, Ar-H),
3
25 MHz, CDCl ]: δ = 139.6, 139.5, 139.4, 139.3, 138.7, 138.6, 7.22–6.96 (m, 100 H, Ar-H), 5.50 (d, J = 3.0 Hz, 1 H, 1-H), 5.36
.77 (m, 5 H), 3.52 (d, J = 10.7 Hz, 1 H, 6-H), 3.50–3.30 (m, 13 0.25, EtOAc). H NMR (500 MHz, CDCl
3
13
H, 7ϫ2-H, 6ϫ6-H) ppm. C NMR [attached proton test (APT),
1
4
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Diastereomeric Artificial Enzymes with Different Catalytic Activity
(
(
d, J = 3.6 Hz, 1 H, 1-H), 5.21 (d, J = 10.7 Hz, 1 H, CHPh), 5.17 H, Ar-H), 7.18–6.95 (m, 100 H, Ar-H), 5.22 (d, J = 3.2 Hz, 1 H,
d, J = 10.7 Hz, 1 H, CHPh), 5.12 (d, J = 10.7 Hz, 1 H, CHPh), 1-H), 5.17 (d, J = 3.4 Hz, 1 H, 1-H), 5.14 (d, J = 3.5 Hz, 1 H, 1-
.10 (d, J = 3.5 Hz, 1 H, 1-H), 5.00 (d, J = 11.0 Hz, 1 H, CHPh), H), 5.07–5.04 (m, 3 H, 1-H, 2 CHPh), 5.02–4.96 (m, 7 H, 3ϫ1H,
.93 (d, J = 3.6 Hz, 1 H, 1-H), 4.90 (d, J = 11.1 Hz, 1 H, CHPh), 4 CHPh), 4.92–4.87, (m, 2 H, 2 CHPh), 4.73 (d, J = 10.9 Hz, 1 H,
5
4
4
4
4
4
2
1
3
2
.83 (d, J = 3.4 Hz, 1 H, 1-H), 4.82 (d, J = 3.2 Hz, 1 H, 1-H), 4.79–
.76 (m, 2 H, 1-H, CHPh), 4.71 (d, J = 11.1 Hz, 1 H, CHPh), 4.68–
.62 (m, 4 H, CHPh), 4.63 (d, J = 11.1 Hz, 2 H, 2 CHPh), 5.57–
CHPh), 4.68–4.61 (m, 5 H, 5 CHPh), 4.50 (d, J = 12.1 Hz, 1 H,
CHPh), 4.46 (d, J = 11.0 Hz, 1 H, CHPh), 4.45–4.19 (m, 26 H,
A
A
A
7 a-H, 7 b-H, 24 CHPh), 4.12–4.05 (m, 3 H, 5-H, 6-H, 6 -H),
4.03–3.72 (m, 28 H), 3.67 (br. d, J = 9.7 Hz, 1 H, 6-H), 3.56 (d, J
= 10.2 Hz, 1 H, 6-H), 3.52–3.50 (m, 2 H, 2ϫ6-H), 3.47 (d, J =
11.2 Hz, 1 H, 6-H), 3.44–3.30 (m, 8 H, 7ϫ2-H, 6-H), 3.26 (s, 3 H,
A
A
.51 (m, 2 H, 2 CHPh), 4.46–4.16 (m, 26 H, 6 -H, 7 a-H,
4 CHPh), 4.15–4.07 (m, 2 H), 3.97–3.60 (m, 28 H), 3.57 (d, J =
0.7 Hz, 1 H, 6-H), 3.50 (dd, J = 3.6, J = 9.3 Hz, 1 H, 2-H), 3.46–
.35 (m, 7 H, 3ϫ2-H, 4ϫ6-H), 3.30 (dd, J = 3.5, J = 9.4 Hz, 1 H,
-H), 3.27 (dd, J = 3.2, J = 10.1 Hz, 1 H, 2-H), 3.25 (dd, J = 3.3,
1
3
3 3
OCH ) ppm. C NMR (APT, 125 MHz, CDCl ): δ = 166.2 (C=O),
139.5, 139.4, 139.3, 139.2, 138.6, 138.5, 138.4, 138.3, 138.2 (Cipso),
13
J = 9.1 Hz, 1 H, 2-H) ppm. C NMR (APT, 125 MHz, CDCl
3
): δ 128.9, 128.4, 128.3, 128.2, 128.1, 128.0, 127.9, 127.8, 127.7, 127.5,
=
166.5 (C=O), 139.7, 139.5, 139.4, 139.3, 139.2, 138.7, 138.6, 127.4, 127.3, 127.1, 127.0 (Ar-H), 99.3, 99.2, 98.9, 98.8, 98.2, 98.0
1
1
1
38.5, 138.4, 138.3, 138.2, 138.0, 137.8 (Cipso), 133.5, 130.2 (Ar-H),
29.8 (Cipso), 129.1, 128.5, 128.4, 128.3, 128.2, 128.1, 128.0, 127.9,
27.8, 127.7 127.6, 127.5, 127.3, 127.2, 127.1, 127.0, 126.9, 126.8 72.8, 72.7 (CH
69.2, 69.1 (C-6), 66.3 (C-7 ), 58.6 (OCH
MS: m/z calcd. for C191 37Na 3108.3; found 3108.3.
(C-1), 81.2, 80.9, 80.8, 79.6, 79.5, 79.3, 79.2, 79.1, 78.9, 78.8, 78.7,
78.4 (CH), 75.8 (C-6 ), 75.7, 75.5, 75.2, 73.5, 73.4, 73.3, 73.1, 72.9,
A
2
Ph), 72.3, 71.9, 71.8, 71.5, 71.2 (CH), 69.5, 69.4,
A
(Ar-H), 100.1, 99.6, 99.1, 98.3, 98.0, 97.9, 98.8 (C-1), 81.5, 81.4,
3
) ppm. MALDI-TOF-
8
7
7
6
1.3, 81.1, 81.0, 80.9, 80.7, 80.5, 80.3, 79.8, 79.7, 79.3, 79.0, 78.9,
8.6, (CH), 76.2, 75.9, 75.4, 74.8, 74.6, 73.7 73.6, 73.5, 73.3, 73.1,
3.0, 72.8, 72.7, (CH
9.4, 69.0, 68.3, (C-6), 66.5 (C-7 ), 66.3 (C-6 ) ppm. MALDI-
37Na 3094.3; found 3095.3.
198
H O
General Procedure for Debenzoylation of 6R and 6S: The benzoyl-
ated CD 6R or 6S (1.2 g, 0.389 mmol) was dissolved in MeOH/
THF (1:4, 25 mL). Then MeONa (0.6 mL, 25 wt.-% in MeOH) was
added. The reaction mixture was stirred overnight at room tem-
2
Ph), 72.4, 71.8, 71.6, 71.5, 71.1, 70.8, 69.6,
A
A
196
TOF-MS: m/z calcd. for C190H O
General Procedure for Methylation of Monobenzoylated Cyclodex-
2
perature. The reaction was quenched by adding H O (15 mL), and
trins (CDs) 5R and 5S: The monobenzoylated CD 5R or 5S (1.8 g,
the organic solvent was removed under reduced pressure. The aque-
0
.586 mmol) was dissolved in N,N-dimethlyformamide (DMF)/
ous phase was extracted with DCM (4ϫ15 mL). The combined
MeI (7:10, 17 mL), and the temperature was adjusted to 0 °C. To organic extracts were dried (MgSO4), filtered and concentrated un-
the solution was added NaH (60%, 117.2 mg, 2.93 mmol) in por-
tions over 2 h. The reaction mixture was then allowed to reach
room temperature over 2 h. It was quenched by adding saturated
der reduced pressure. Purification of the concentrate by column
chromatography (EtOAc/n-heptane, 7:33Ǟ31:9) furnished the CD
monol 7R or 7S.
4
aqueous NH Cl (20 mL), the aqueous layer was extracted with
6AR-C-Hydroxymethyl-2 -G,3A–G,6B,C,D,E,F,G-eiocosakis-O-benzyl-
A
EtOAc (3ϫ25 mL), and the combined extracts were concentrated
under reduced pressure. Purification of the concentrate by column
chromatography (EtOAc/n-heptane, 4:1) furnished the methylated
CD 6R or 6S, respectively.
A
6
0
f
-O-methyl-β-cyclodextrin (7R): 1.1 g, 92 % (white foam); R =
.26 (EtOAc/n-heptane, 7:13). [α]
1
D 2 2
= +49 (c = 0.31, CH Cl ). H
NMR (500 MHz, CDCl
(
3
): δ = 7.24–6.89 (m, 100 H, Ar-H), 5.58
d, J = 3.3 Hz, 1 H, 1-H), 5.33 (d, J = 3.0 Hz, 1 H, 1-H), 5.26 (d,
6AR-C-Methyl Benzoate-2A–G,3A–G,6B,C,D,E,F,G-eiocosakis-O-benzyl- J = 10.8 Hz, 1 H, CHPh), 5.21 (d, J = 10.6 Hz, 2 H, 2 CHPh),
A
6
0
-O-methyl-β-cyclodextrin (6R): 1.2 g, 67 % (white foam); R
f
1
=
H
5.16–5.13 (m, 3 H, 1-H, 2 CHPh), 5.06 (d, J = 10.6 Hz, 1 H,
CHPh), 4.92 (d, J = 3.4 Hz, 1 H, 1-H), 4.89 (d, J = 11.1 Hz, 1 H,
.26 (EtOAc/n-heptane, 1:4). [α]
D
= +37 (c = 0.36, EtOAc).
NMR (500 MHz, CDCl
m, 1 H, Ar-H), 7.30–7.27 (m, 2 H, Ar-H), 7.19–6.90 (m, 100 H, CHPh), 4.77 (d, J = 3.6 Hz, 1 H, 1-H), 4.74–4.61 (m, 8 H, 8 CHPh),
Ar-H), 5.26 (d, J = 3.6 Hz, 1 H, 1-H), 5.25 (d, J = 3.6 Hz, 1 H, 1- 4.54 (d, J = 11.3 Hz, 1 H, CHPh), 4.50 (d, J = 12.1 Hz, 1 H,
H), 5.11 (d, J = 3.3 Hz, 1 H, 1-H), 5.08–4.99 (m, 8 H, 3ϫ1-H, CHPh), 4.47–4.21 (m, 23 H, 6-H, 22 CHPh), 4.17 (br. d, J =
CHPh), 4.89 (d, J = 10.8 Hz, 1 H, CHPh), 4.83 (d, J = 3.0 Hz, 1 10.2 Hz, 1 H, 5-H), 4.01–3.65 (m, 26 H), 3.58–3.54 (m, 2 H, 2ϫ6-
3
): δ = 7.96–7.94 (m, 2 H, Ar-H), 7.45–7.42 CHPh), 4.85 (d, J = 3.2 Hz, 1 H, 1-H), 4.81–4.78 (m, 2 H, 1-H,
(
5
A
A
A
H, 1-H), 4.71–4.55 (m, 8 H, 8 CHPh), 4.45–4.22 (m, 28 H, 7 a-H, H), 3.52–3.36 (m, 11 H, 4ϫ2-H, 3-H, 4ϫ6-H, 7 a-H, 7 b-H),
A
7
3
b-H, 26 CHPh), 4.04 (dd, J = 2.0, J = 11.0 Hz, 1 H, 6-H), 3.99–
.77 (m, 21 H), 3.65 (dd, J = 7.7, J = 9.7 Hz, 1 H, 4-H), 3.51 (d,
3.34 (dd, J = 3.5, J = 9.4 Hz, 1 H, 2-H), 3.32 (dd, J = 3.2, J =
1
3
9.4 Hz, 1 H, 2-H), 3.26–3.23 (m, 4 H, 2-H, OCH
(APT, 125 MHz, CDCl ): δ = 139.6, 139.5, 139.4, 139.1, 139.0,
) ppm. 138.7, 138.6, 138.5, 138.4, 138.3, 138.2, 138.1, (Cipso), 128.5, 128.4,
): δ = 166.5 (C=O), 139.5, 139.4, 128.3, 128.2, 128.1, 128.0, 127.9, 127.8, 127.7, 127.6, 127.5, 127.2,
39.3, 138.6, 138.5, 138.4, 138.3, 138.2 (Cipso), 133.2 (Ar-H), 130.3 127.1, 127.0, 126.7 (Ar-H), 99.3, 99.1, 98.7, 98.3, 98.2, 97.9, 97.7
ipso), 129.8, 128.6, 128.4, 128.3, 128.2, 128.1, 128.0, 127.9, 127.8, (C-1), 81.8, 81.3, 81.2, 81.0, 80.5, 80.3, 80.1, 79.6, 79.2, 78.9, 78.8,
27.7, 127.6, 127.5, 127.4, 127.2, 127.1, 127.0, 126.8 (Ar-H), 99.1, 78.6, 77.7 (CH), 76.4, 76.1, 75.5, 74.6, 74.2, 73.8, 73.5, 73.4, 73.3,
8.9, 98.7, 98.6, 98.4, 98.1 (C-1), 81.3, 81.1, 81.0, 80.8, 79.7, 79.1, 73.0, 72.7, 72.4, 72.2 (CH Ph), 72.1, 71.8, 71.7, 71.6, 71.4, 70.3
9.0, 78.9, 78.8, 78.7, 78.3 (CH), 76.0, 75.9, 75.6, 75.5, 75.2, 74.5, (CH), 69.7, 69.6, 69.4, 69.3, 69.0 (C-6), 60.9 (C-7 ), 58.0 (OCH
3.6, 73.4, 73.3, 73.1, 72.9, 72.7, 72.3 (CH Ph), 72.3, 72.0, 71.8, ppm. MALDI-TOF-MS: m/z calcd. for C184 36Na 3003.3;
1.6, 71.5 (CH), 69.5, 69.3, 69.0, 68.8 (C-6), 64.8 (C-7 ), 57.9 found 3004.0.
3
) ppm. C NMR
J = 11.0 Hz, 2 H, 2ϫ6-H), 3.48–3.33 (m, 11 H, 6ϫ2-H, 5ϫ6-H),
3
3
.25 (dd, J = 3.1, J = 9.2 Hz, 1 H, 2-H), 3.18 (s, 3 H, OCH
3
13
C NMR (APT, 125 MHz, CDCl
3
1
(C
1
9
7
7
7
2
A
3
)
2
194
H O
A
(
3
3 198
OCH ) ppm. MALDI-TOF-MS: m/z calcd. for C191H O37Na
108.4; found 3108.0.
A
6
6
AS-C-Hydroxymethyl-2A–G,3 -G,6B,C,D,E,F,G-eiocosakis-O-benzyl-
A
-O-methyl-β-cyclodextrin (7S): 980 mg, 85% (white foam); R
f
1
=
H
A
S-C-Methyl Benzoate-2A–G,3A–G,6B,C,D,E,F,G-eiocosakis-O-benzyl-
6
6
0.38 (EtOAc/n-heptane, 9:11). [α]
NMR (500 MHz, CDCl
D
= +46 (c = 0.28, DCM).
A
-O-methyl-β-cyclodextrin (6S): 1.1 g, 85% (white foam); R
f
= 0.42
= +48 (c = 0.36, EtOAc). H NMR
): δ = 8.00–7.98 (m, 2 H, Ar-H), 7.38–7.37 (m, 3
3
): δ = 7.19–6.91 (m, 100 H, Ar-H), 5.24
1
(
(
EtOAc/n-heptane, 2:3). [α]
500 MHz, CDCl
D
(d, J = 2.2 Hz, 1 H, 1-H), 5.12–5.04 (m, 6 H, 4ϫ1-H, 2 CHPh),
4.97–4.95 (m, 3 H, 1-H, 2 CHPh), 4.90 (d, J = 10.5 Hz, 1 H,
3
Eur. J. Org. Chem. 0000, 0–0
© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
5

Job/Unit: O20699
/KAP1
Date: 13-08-12 11:47:03
Pages: 8
E. Lindbäck, Y. Zhou, C. M. Pedersen, M. Bols
CHPh), 4.84 (d, J = 11.1 Hz, 1 H, CHPh), 4.81 (d, J = 3.0 Hz, 1 128.1, 127.8, 127.7, 127.6, 127.5, 127.4, 127.3, 127.2, 127.1, 127.0
FULL PAPER
A
H, 1-H), 4.69–4.64 (m, 6 H, 6 CHPh), 4.62 (d, J = 10.8 Hz, 1 H,
CHPh), 4.56 (d, J = 10.9 Hz, 1 H, CHPh), 4.50–4.26 (m, 25 H,
(Ar-H), 99.5, 99.1, 98.9, 98.4, 98.1, (C-1), 83.2 (C-6 ), 81.3, 81.1,
80.8, 80.4, 79.9, 79.8, 79.6, 79.5, 79.3, 79.1, 78.9, 78.8, 78.7, 78.1,
2
3
7
5 CHPh), 4.22 (d, J = 12.4 Hz, 1 H, CHPh), 4.00–3.75 (m, 26 H), (CH), 76.0, 75.9, 75.4, 74.9, 73.4, 73.3, 73.1, 72.9, 72.7, 72.6
A
.71–3.67 (m, 2 H), 3.56–3.36 (m, 14 H, 6ϫ2-H, 6ϫ6-H, 7 a-H,
(CH2Ph), 72.4, 71.8, 71.5, 71.4, 71.2 (CH), 69.9, 69.6, 69.4, 69.2,
68.9 (C-6), 58.4 (OCH ) ppm. MALDI-TOF-MS: m/z calcd. for
36Na 3001.3; found 3002.8.
A
b-H), 3.33 (dd, J = 3.2, J = 9.5 Hz, 1 H, 2-H), 3.14 (s, 3 H,
3
OCH
3
) ppm. 13C NMR (APT, 125 MHz, CDCl
3
): δ = 139.6, 139.4,
184 192
C H O
1
1
1
39.3, 139.2, 138.6, 138.5, 138.4, 138.3, 137.9 (Cipso), 128.5, 128.4,
28.3, 128.2, 128.1, 128.0, 127.9, 127.7, 127.6, 127.5, 127.4, 127.3,
27.2, 127.1, 127.0, 126.9 (Ar-H), 99.2, 99.0, 98.8, 98.5, 98.2, 97.9
General Procedure for Debenzylation of 8R and 8S: A solution of
R or 8S (80 mg, 0.027 mmol), Pd/C (10%, 30 mg) and trifluora-
8
cetic acid (TFA, 1 drop) in 2-methoxyethanol (15 mL) was intro-
duced to a hydrogen atmosphere (balloon pressure). The mixture
was stirred for 24 h. After this time the MALDI-TOF spectra indi-
cated the formation of the hemiacetal with 2-methoxyethanol.
Then the mixture was filtered through a Millipore filter. Evapora-
tion of the solvent gave the debenzylated CD monoaldehyde.
(
7
(
C-1), 81.3, 81.1, 80.9, 79.8, 79.7, 79.2, 79.1, 78.9, 78.8, 78.6 (CH),
5.8, 75.7, 75.6, 75.3, 75.0, 73.5, 73.4, 73.0, 72.9, 72.8 72.7, 72.5
CH Ph), 71.9, 71.7, 71.6, 71.5, 71.1, 70.9 (CH), 70.1, 69.7, 69.5,
2
A
69.1 (C-6), 59.2 (C-7 ), 57.5 (OCH
3
) ppm. MALDI-TOF-MS: m/z
36Na 3003.3; found 3004.3.
194
calcd. for C184H O
A
1
General Procedure for Oxidation of CD Monols 7R and 7S: Dess– 6 S-C-Formyl-β-cyclodextrin (2S): 31 mg, 97 % (white solid). H
A-H
Martin periodinane (758 mg, 1.79 mmol) was added to a stirred
6
NMR (500 MHz, [D ]DMSO): δ = 9.66 (s, 1 H, 7 ), 5.88–5.69
solution of 7R or 7S (1.06 g, 0.357 mmol) in DCM (50 mL) at (m, 16 H, 16OH), 4.92 (d, J = 3.1 Hz, 1 H, 1-H), 4.84–4.81 (m, 6
A
room temperature under nitrogen. The mixture was stirred for 5 h.
The reaction was quenched by adding 15 wt.-% of Na in satu-
rated aqueous NaHCO (50 mL) and Et O (50 mL). The mixture
was left stirring for 2 h. Then the phases were separated and the
organic layer was washed with saturated aqueous NaHCO
2ϫ50 mL). The organic phase was concentrated in vacuo. Purifi-
H, 6ϫ1-H), 4.61–4.39 (m, 4 H, 4OH), 4.09–4.03 (m, 2 H, 6 -H),
1
3
2
S
2
O
3
6
3.63–3.24 (m, 42 H) ppm. C NMR (APT, 125 MHz, [D ]DMSO):
δ = 204.5 (C-7 ), 102.2, 102.1, 101.7 (C-1), 82.8 (C-6 ), 81.9, 81.7,
81.5, 73.2, 73.1, 72.9, 72.5, 72.1 (CH), 60.3, 60.0, 59.7 (C-6), 57.6
(OCH ) ppm. MALDI-TOF-MS: m/z calcd. for C44H72O36Na
A
A
3
2
3
3
(
1199.37; found 1199.37.
cation of the concentrate by column chromatography (EtOAc/n-
heptane, 1:6) furnished the CD aldehyde.
6AR-C-Formyl-β-cyclodextrin (2R): 46 mg, 95% (white solid). 1H
A
NMR (300 MHz, D
2
O): δ = 9.54 (s, 1 H, 7 -H), 5.00 (d, J = 3.3 Hz,
6AS-C-Formyl-2A–G,3A–G,6B,C,D,E,F,G-eiocosakis-O-benzyl-6 -O-
A
1 H, 1-H), 4.96–4.91 (m, 5 H, 5ϫ1-H), 4.86 (d, J = 2.9 Hz, 1 H,
3
1-H), 3.84–3.67 (m, 24 H), 3.55–3.42 (m, 17 H), 3.23 (s, 3 H, OCH )
methyl-β-cyclodextrin (8S): 457 mg, 43% (white foam); R
f
= 0.25
): δ = 9.39 (s,
H, 7 -H), 7.19–6.97 (m, 100 H, Ar-H), 5.30 (d, J = 3.7 Hz, 1 H, 101.8, 101.5 (C-1), 89.8 (C-6 ), 73.1, 73.0, 72.7, 72.0, 71.9, 71.8,
-H), 5.26 (d, J = 3.5 Hz, 1 H, 1-H), 5.12 (d, J = 3.4 Hz, 1 H, 1-
71.7, 71.4, 70.8 (CH), 60.4, 60.2, 60.1, 59.6 (C-6), 58.0 (OCH
1
13
A
(
EtOAc/n-heptane, 2:3). H NMR (500 MHz, CDCl
3
2
ppm. C NMR (125 MHz, D O): δ = 204.9 (C-7 ), 102.2, 102.0,
A
A
1
1
3
)
H), 5.05–4.95 (m, 9 H, 3ϫ1-H, 6 CHPh), 4.86 (d, J = 11.0 Hz, 1 ppm. MALDI-TOF-MS: m/z calcd. for C44
H, CHPh), 4.79 (d, J = 3.4 Hz, 1 H, 1-H), 4.76 (d, J = 11.3 Hz, 1 found 1199.6.
72
H O36Na 1199.4;
H, CHPh), 4.70–4.60 (m, 8 H, 8 CHPh), 4.51 (d, J = 12.1 Hz, 1 H,
CHPh), 4.44 (d, J = 12.0 Hz, 2 H, CHPh), 4.41–4.23 (m, 21 H,
Enzymatic Oxidation Assays: Each assay was performed on 7–8
samples (2 mL each) of the appropriate substrate at different con-
centrations in 90–190 mm phosphate buffer, pH 7 containing 64–
A
2
1
1
1 CHPh), 4.16 (br. d, J = 10.3 Hz, 1 H, 5 -H), 4.12 (d, J =
A
0.9 Hz, 1 H, 6-H) 3.99–3.75 (m, 19 H, 6 -H), 3.54 (d, J = 11.0 Hz,
2 2
72 mm H O , and either the catalyst (0.17–0.30 mm) or nothing as
H, 6-H), 3.50–3.35 (m, 11 H, 6ϫ2-H, 5ϫ6-H), 3.18 (dd, J = 3.3,
control. The reactions were followed at 25 °C by moitoring UV
absorption at 400 nm and were typically monitored for 30 min. Ve-
locities were determined as the slope of the progress curve of each
reaction. Uncatalysed velocities were obtained from a series of
separate experiments. Catalysed velocities were calculated by sub-
tracting the uncatalysed rate from the total rate of the appropriate
cyclodextrin containing sample. The catalysed velocities were used
to construct Hanes plots ([S]/V vs. [S]) to check if the reaction
J = 9.4 Hz, 1 H, 2-H), 3.08 (s, 3 H, OCH
3
) ppm. 13C NMR (APT,
1
1
1
9
7
7
3
25 MHz, CDCl ): δ = 139.3, 139.2, 139.1, 138.4, 138.3, 138.2,
38.1 (Cipso), 128.3, 128.2, 128.0, 127.9, 127.8, 127.7, 127.6, 127.5,
27.4, 127.3, 127.2, 127.1, 127.0, 126.9 (Ar-H), 98.9, 98.6, 98.4,
A
8.2, 98.1 (C-1), 83.8 (C-6 ), 81.2, 80.9, 80.8, 80.6, 80.5, 80.4, 79.7,
9.3, 79.2, 78.9, 78.8, 78.7, 78.6, 78.1, 77.9 (CH), 75.9, 75.7, 75.3,
A
5.1 (CH
2
Ph), 73.5 (C-5 ), 73.3, 73.2, 72.8, 72.7, 72.6, 72.5
(
(
C
CH
C-6), 58.2 (OCH
36Na 3001.3; found 3002.1.
6AR-C-Formyl-2A–G,3A–G,6B,C,D,E,F,G-eiocosakis-O-benzyl-6 -O-
methyl-β-cyclodextrin (8R): 450 mg, 45% (white foam); R = 0.35
): δ = 9.41 (s,
H, 7 -H), 7.21–6.94 (m, 100 H, Ar-H), 5.23 (d, J = 3.1 Hz, 1 H,
-H), 5.18–5.16 (m, 2 H, 2 ϫ 1-H), 5.10 (d, J = 10.5 Hz, 1 H,
2
Ph), 71.8, 71.7, 71.5, 71.4 (CH), 69.5, 69.4, 69.3, 69.1, 68.9
followed Michaelis–Menten kinetics. In that case K
determined using least square non-linear regression fitting to the
max vs. [S] curve. kcat was calculated as Vmax/[cyclodextrin]. kuncat
m
and Vmax were
3
) ppm. MALDI-TOF-MS: m/z calcd. for
184 192
H O
V
A
was determined as the slope from a plot of Vuncat vs. [S]. The fol-
lowing extinction coefficients (25 °C, pH 7) and wavelengths
f
–
1
–1
1
were used: 2-aminophenoxazin-3-one, 0.42 mm cm at 400 nm;
N,NЈ-bis(p-hydroxyphenyl)-2-hydroxy-5-amino-1,4-benzoquinone
(
1
1
EtOAc/n-heptane, 2:3). H NMR (500 MHz, CDCl
3
A
–
1
–1
diimine, 1.59 mm cm at 400 nm.
CHPh), 5.09 (d, J = 10.9 Hz, 1 H, CHPh), 5.03–4.98 (m, 2 H, 1-
H, CHPh), 4.95 (d, J = 3.2 Hz, 2 H, 2ϫ1-H), 4.88 (d, J = 11.0 Hz,
Enzymatic Glycoside Hydrolysis Assays: Each assay was performed
on 2 mL samples prepared from 1 mL aqueous solutions of the
appropriate aryl glycoside at different concentrations mixed with
1 mL of phosphate or other buffer containing either cyclodextrin
1
H, CHPh), 4.87 (d, J = 11.0 Hz, 1 H, CHPh), 4.69–4.60 (m, 10
H, 1-H, 9 CHPh), 4.49 (d, J = 12.4 Hz, 1 H, CHPh), 4.46–4.19 (m,
A
2
5 H, 6 -H, 24 CHPh), 4.03–3.85 (m, 20 H), 3.80–3.64 (m, 7 H), derivative (0.47 mg) or nothing as control. The reactions were fol-
3.56 (d, J = 10.2 Hz, 2 H, 2ϫ6-H), 3.52 (d, J = 10.5 Hz, 1 H, 6- lowed continuously at 59 °C by monitoring UV absorption at
H), 3.46–3.34 (m, 11 H, 7ϫ2-H, 4 CHPh), 3.21 (s, 3 H, OCH
3
)
400 nm. The reactions were monitored for 3–18 h. Velocities were
determined as the slope of the progress curve of each reaction.
Uncatalysed velocities were obtained directly from the control sam-
ppm. 13C NMR (APT, 125 MHz, CDCl
): δ = 203.1 (C-7 ), 138.6,
A
3
138.5, 138.4, 138.3, 138.2, 137.9 (Cipso), 128.5, 128.4, 128.3, 128.2,
6
www.eurjoc.org
© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 0000, 0–0

Job/Unit: O20699
/KAP1
Date: 13-08-12 11:47:03
Pages: 8
Diastereomeric Artificial Enzymes with Different Catalytic Activity
ples. Catalysed velocities were calculated by subtracting the uncata-
lysed velocity from the velocity of the appropriate cyclodextrin con-
taining sample. The catalysed velocities were used to construct
J. Xu, J. Liu, J. Shen, Catal. Lett. 2008, 124, 413–417; f) K.
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m
and Vmax were deter-
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mined as the slope from a plot of Vuncat vs. [S]. The inhibition
experiments were performed by adding cyclopentanol (4 μL) to a
catalysed sample.
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Acknowledgments
We thank the Danish Research Council for Nature and Universe
(FNU) and the Lundbeck foundation for financial support.
4
-hydroxyaniline is N,NЈ-bis(p-hydroxyphenyl)-2-hydroxy-5-
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Received: May 24, 2012
Published Online: ᭿
Eur. J. Org. Chem. 0000, 0–0
© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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7

Job/Unit: O20699
/KAP1
Date: 13-08-12 11:47:03
Pages: 8
E. Lindbäck, Y. Zhou, C. M. Pedersen, M. Bols
FULL PAPER
Enzyme Models
E. Lindbäck, Y. Zhou, C. M. Pedersen,
M. Bols* ........................................... 1–8
Two Diastereomeric Artificial Enzymes
with Different Catalytic Activity
Two epimeric cyclodextrin aldehyde hy-
drates catalyse the hydrolysis of aryl glycos-
ides, but with widely different effectiveness:
for one epimer the rate is 1000 times faster,
whereas it is only 100 times faster for the
other.
Keywords: Cyclodextrins / Glycosides /
Enzyme mimics / Hydrolysis / Oxidation
8
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Eur. J. Org. Chem. 0000, 0–0