The (S)-proline/polyelectrolyte system: An efficient, heterogeneous, reusable catalyst for direct asymmetric aldol reactions

Article abstract of DOI:10.1002/ejoc.200500888

A direct asymmetric aldol reaction between unmodified aldehydes and ketones was achieved using the (S)-proline/poly-(diallyldimethylammonium) hexafluorophosphate heterogeneous catalytic system with enantioselectivities and yields comparable to those obtained in the (S)-proline-catalyzed reactions performed under homogeneous conditions. Recycling of the catalyst was possible at least six times without loss of activity and enantioselectivity. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.

Full text of DOI:10.1002/ejoc.200500888

FULL PAPER
DOI: 10.1002/ejoc.200500888
The (S)-Proline/Polyelectrolyte System: An Efficient, Heterogeneous, Reusable
Catalyst for Direct Asymmetric Aldol Reactions
Alexandr S. Kucherenko,[a] Marina I. Struchkova,[a] and Sergei G. Zlotin,*[a]
Keywords: Asymmetric aldol reactions / Organocatalysis / (S)-Proline / Polyelectrolytes / Heterogeneous catalysis
A direct asymmetric aldol reaction between unmodified alde-
hydes and ketones was achieved using the (S)-proline/poly-
(diallyldimethylammonium) hexafluorophosphate hetero-
geneous catalytic system with enantioselectivities and yields
actions performed under homogeneous conditions. Recycling
of the catalyst was possible at least six times without loss of
activity and enantioselectivity.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
comparable to those obtained in the (S)-proline-catalyzed re- Germany, 2006)
(S)-proline modified by 1,2,3-trimethylimidazolium cat-
Introduction
ions.[13] The modifier was covalently attached to the silica
–
Homogeneous asymmetric catalysis is widely used in or-
ganic chemistry for the synthesis of fine chemicals and nat-
ural compounds.[1] Yet, recovery of expensive chiral homo-
geneous catalysts from the reaction solution remains a diffi-
cult and so far unsolved problem.[2] To facilitate the separa-
tion of homogeneous catalysts from the reaction mixture,
they are immobilized on solid supports; however, reactions
catalyzed by the supported catalysts are usually less selec-
tive than the corresponding reactions in solutions.[3]
A direct asymmetric aldol reaction between unmodified
aldehydes and ketones is one of the most general and simple
methods of forming carbon–carbon bonds. This reaction
plays an important role in nature as a source of carbo-
hydrates[4] and is used for the synthesis of chiral β-hydroxy
carbonyl compounds, which are valuable intermediates in
organic synthesis.[5] Native amino acid (S)-proline[5] and its
amides[6,7] are efficient catalysts of the asymmetric aldol re-
action. The reaction was performed in acetone,[6b,6c,7a–7c]
DMSO,[5a,5b,7d,8] DMF,[7e] CH2Cl2,[7b,7d,9] CHCl3,[7f] tolu-
ene,[7d] PEG,[10] and ionic liquids.[6a,11] The catalyst solution
in anionic liquid can be recovered and reused. Yet, the ap-
plication of ionic liquids in the industrial syntheses of fine
chemicals is still problematic because of the relatively high
cost of these solvents.[12]
surface by the C–Si–O spacer. BF4 anions were used as
counteranions. Yet, according to our data, the thereby pre-
pared catalyst quickly lost its catalytic activity. The aldol
yield became 30–40% lower after the catalytic system was
used twice, possibly because of spacer cleavage.
Presumably, polymer supports in which ionic fragments
are linked with the polymer chain by hydrolytically stable
chemical bonds, in particular carbon-chained polyelectro-
lytes bearing the ionic moiety within each monomer unit,
should have higher supporting ability and chemical resis-
tance. It was reported that Rh and Ru chiral complexes
immobilized in a mixture of a 20% water (or methanol)
solution of poly(diallyldimethylammonium) chloride and
the ionic liquid could be used as recoverable catalysts for
enantioselective hydrogenation reactions of olefins and
ketones.[14] The polyelectrolyte prevented leaching of the
complexes and thus ensured the multiple use of the cata-
lysts.
Here we report the first example of a direct asymmetric
aldol reaction catalyzed by the heterogeneous, recoverable
catalytic system consisting of (S)-proline supported on solid
poly(diallyldimethylammonium) salts.
The asymmetric aldol reaction was performed under the
action of (S)-proline adsorbed on silica gel.[5b] The authors
managed to recover the catalyst, though the ee of the prod-
ucts were lower. Good yields and ee values, compared to
those obtained using nonsupported proline, were obtained
when the aldol reaction was catalyzed by silica-supported
Results and Discussion
We investigated poly(diallyldimethylammonium) salts of
different molecular mass [100.000–200.000 Da (a) and
–
400.000–500.000 Da (b)] containing Cl– (1), BF4 (2), and
–
PF6 (3) anions. Solid poly(diallyldimethylammonium)
chloride 1b was obtained from a commercially available (Al-
drich) 20% aqueous solution of the corresponding polymer.
Poly(diallyldimethylammonium) tetrafluoroborate 2b and
hexafluorophosphates 3a,b were prepared by mixing poly-
mer 1a or 1b (20%) with HBF4 (50%) or HPF6 (60%).
[a] N. D. Zelinsky Institute of Organic Chemistry, Russian Acad-
emy of Sciences,
Leninsky prospect 47, 119991, Moscow, Russia
Fax: +7-095-1355328
E-mail: zlotin@ioc.ac.ru
2000
© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2006, 2000–2004

(S)-Proline/Polyelectrolyte: Catalyst for Direct Asymmetric Aldol Reactions
FULL PAPER
Polyelectrolytes 2b, 3a, and 3b, which were poorly soluble were filtered off, and a mixture of aldol 9a and elimination
in water, precipitated from the reaction mixture. They were product 10a was isolated from the filtrate. According to 1H
identified by 31P- and 19F NMR spectroscopy and microa- NMR spectroscopic data, the aldol 9a content in the mix-
nalysis data. We were not able to detect the tetrafluorobo- ture was 83–96% depending on the catalyst. Aldol 9a was
rate 2b by 19F NMR spectroscopy because of its poor solu- isolated from the mixture in a pure state by column
bility in [D6]DMSO.
chromatography on silica gel. The yield of product 9a was
(S)-Proline was supported on polyelectrolytes 1b, 2b, 3a, 55–59%, ee 66–69%, [α]2D0 = +48
and 3b by mixing each polymer solution (suspension) in (Table 1).
2 (c = 1.41, CHCl3)
CH3OH with the organocatalyst solution in the same sol-
Next we investigated the recoverability of catalytic sys-
vent. To achieve better (S)-proline adsorption, the amino tems 4b, 5b, 6a, and 6b in the aldol reaction between com-
acid/polymer ratio was chosen in such a way that each (S)- pounds 7a and 8. Each catalyst was used twice without re-
proline molecule would interact with two pyrrolidine moie- duction of the ee values of aldol 9a. The yield of aldol 9a
ties. Evaporation of the solvent under reduced pressure af- was found to decrease significantly in the second cycle in
forded the corresponding supported catalysts 4b, 5b, 6a, the reactions catalyzed by systems 4b and 5b bearing the
and 6b as colorless solids in quantitative yield (Scheme 1). anions Cl– and BF4– (25% and 36%, respectively). Doubled
IR spectra of the prepared catalysts contained signals at reaction time (30 h) was required to obtain 9a in the yield
1556–1564, 1624, and 2400–3000 cm–1, which could be at- (50%) comparable with that in the first cycle (Table 1, en-
tributed to the C=O, NH, and OH groups of the proline try 2). In the case of chloride 4b, the amount of elimination
molecules immobilized on the polymer surface.
product 10a increased by a factor of 3.5 when the catalyst
First we studied the catalytic activities of the hetero- was used repeatedly. On the other hand, in the reactions
geneous catalysts 4b, 5b, 6a, and 6b in the asymmetric aldol catalyzed by hexafluorophosphates 6a, and 6b, the yield of
reaction between benzaldehyde (7a) and acetone (8). The aldol 9a and the ratio 9a/10a remained nearly the same
reaction was carried out in a 30-fold excess of acetone at when the recovered catalyst was used.
25 °C for 15 h. The (S)-proline amount in the added cata-
System 6b was further studied in asymmetric aldol reac-
lyst was 15 mol-% with respect to the aldehyde. After com- tions between substituted aromatic aldehydes 7b–g and ace-
pletion of the reaction, the solid catalysts 4b, 5b, 6a, and 6b tone (8). The reactions were carried out under the same
Scheme 1. (S)-Proline-supported poly(diallyldimethylammonium) salts.
Table 1. Asymmetric aldol reaction between benzaldehyde (7a) and acetone (8) catalyzed by the (S)-proline/polyelectrolyte systems 4b,
5b, 6a,and 6b.[a]
Entry
Catalyst
Cycle
9a/10a[b]
Yield 9a [%][c]
ee 9a [%][d]
1
2
3
4
5
6
7
8
4b
4b
5b
5b
6a
6a
6b
6b
1
2
1
2
1
2
1
2
10:2
55 (62[5b], 51[13], 58[11a]
)
67 (60[5b], 64[13], 71[11a]
)
10:7(11:7[e])
9:1
25 (50[e])
67
66
67
69
67
69
67
59
36
53
52
55
54
9:1
15:1
12:1
10:1
10:1
[a] Reagents and conditions: i 7a (0.5 mmol), 8 (1 mL), 4b (33.6 mg) or 5b (40.6 mg) or 6a,b (49.2 mg), 25 °C, 15 h. [b] Determined by
1H NMR spectroscopy. [c] Isolated yield. [d] Determined by 1H NMR spectroscopy in CDCl3 by using Eu(facam)3 and by comparing
the specific optical rotation [α]2D0 of reaction product 9a with literature data.[6b] [e] T = 30 h.
Eur. J. Org. Chem. 2006, 2000–2004
© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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2001

A. S. Kucherenko, M. I. Struchkova, S. G. Zlotin
FULL PAPER
conditions. Addition products (AP) 9b–g were obtained in the product-specific optical rotations with the literature
58–98% yields. A small amount (4%) of the elimination by- data.[6b] The values obtained were comparable to those
product (EP) formed along with the major compound 9e reported for the reactions catalyzed by modified silica-
(1H NMR spectroscopy) only in the case of p-chlorobenzal- supported (S)-proline[13] and by (S)-proline–solvent
dehyde (7e). The reaction of aldehyde 7g with acetone (8) {DMSO,[5b] PEG,[10] and ionic liquid (bmim)[PF6][11a,11b]
}
proceeded with participation of one of the two aldehyde systems. The advantage of the (S)-proline/polyelectrolyte
groups, despite the donor excess, affording aldol 9g system 6b was its better recoverability. The catalyst that is
(Table 2). 4-Methoxybenzaldehyde reacted sluggishly with filtered off and washed with acetone can be used in the
acetone (8) under the studied conditions to give the corre- aldol reaction at least six times without a decrease in prod-
sponding aldol in only 10% yield (1H NMR spectroscopic uct yields and enantioselectivities.
data).
The extent of the catalytic system 6b was estimated in
The ee values for aldols 9b–e were determined by 1H asymmetric aldol reactions between aromatic aldehydes
NMR spectroscopy by using Eu(facam)3 and by comparing 7a–c and cyclic ketones 11 and 12. The reactions were per-
Table 2. Asymmetric aldol reaction between substituted aromatic aldehydes 7b–g and acetone (8) catalyzed by the (S)-proline/poly(diallyl-
dimethylammonium) hexafluorophosphate system 6b.[a]
Entry ST/AP/EP[b]
9
Yield [%][c] (cycle)
ee [%][d] (cycle)
[α]2D0,
c = 1.00, CHCl3
[e]
1
2
Ͻ1:98:Ͻ1
Ͻ1:98:Ͻ1
b
c
97 (1), 98 (2), 95(3), 96(4), 97(5),
72 (1), 73 (2), 72 (3), 70 (4),72(5),
+51.4 (+62.1; c 0.35)
96(6) (88[10], 94[11b]
)
71 (6) (70[10],[11b]
)
98 (1), 97 (2), 95 (3), 94(4), 97 (5), 70 (1), 68 (2), 71 (3), 72 (4),70 (5),
+46.4 (+61.6; c 0.51)
97 (6) (68[5b],[11b], 85[13] 69 (6) (76[5b], 65[11b], 66[13]
)
)
3
4
5
6
Ͻ1:98:Ͻ1
19:77:4
Ͻ1:98:Ͻ1
Ͻ1:98:Ͻ1
d
e
f
97 (94[5b], 88[10]
)
65 (69[5b], 60[10]
)
+66.2 (+97.0; c 0.34)
+41.2 (+62.7; c 0.48)
+30.5
65 (75[f], 74[g], 72[h]
)
62 (70[f], 65[g], 67[h]
)
96
58
62
62
g
+49.9
[a] Reagents and conditions: i 7b–g (0.5 mmol), 8 (1 mL), 6b (49.2 mg), 25 °C, 15 h. [b] Determined by 1H NMR spectroscopy. [c] Isolated
1
yield. [d] Determined by H NMR spectroscopy in CDCl3 by using Eu(facam)3. [e] Literature data[6b] for the corresponding compounds
(ee 85–93%) are given in parentheses. [f] Data for the reaction of p-bromobenzaldehyde with acetone in the catalytic system (S)-proline-
modified silica gel.[13] [g] Data for the reaction of p-bromobenzaldehyde with acetone in DMSO.[5b] [h] Data for the reaction of p-bro-
mobenzaldehyde with acetone in (bmim)[PF6].[11a]
Table 3. Asymmetric aldol reaction between aldehydes 7a–c and cycloalkanones 11, 12 catalyzed by the catalytic system 6b.[a]
Reagents
X
H
n
AP
Yield [%][b]
ee [%][c]
7a, 11
2
13a syn
13a anti
13b syn
13b anti
13c syn
13c anti
14b syn
14b anti
14c syn
14c anti
50 (51[11a]
)
)
20 (n.d.[11a]
)
)
20 (32[11a]
71 (n.d.[11a]
7b, 11
7c, 11
7b, 12
7c, 12
m-NO2
p-NO2
m-NO2
p-NO2
2
2
3
3
65 (47[d]
25 (47[d]
)
)
31 (86[d]
69 (32[d]
)
)
70 (27[5b]
28 (46[5b]
)
)
52 (63[5b]
)
n.d. (69[5b]
78
)
23 (4[d]
)
67 (87[d]
)
91 (93[d]
)
18(24[5b]
)
)
n.d (67[5b]
)
80(41[5b]
78 (89[5b]
)
[a] Reagents and conditions: i 7a–c (0.5 mmol), 11 or 12 (1 mL), 6b (49.2 mg), 20 °C, 15 h. [b] Determined by 1H NMR spectroscopy.
[c] Determined by 1H NMR spectroscopy by using Eu(facam)3. [d] Data for reactions of p-(trifluoromethyl)benzaldehyde with cyclopenta-
none and cyclohexanone in (bmim)[PF6].[11b]
2002
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Eur. J. Org. Chem. 2006, 2000–2004

(S)-Proline/Polyelectrolyte: Catalyst for Direct Asymmetric Aldol Reactions
FULL PAPER
due was thoroughly washed with distilled water until washings had
pH 7 and dried with P2O5 in vacuo (3 Torr) at 60 °C for 2 h to
afford the corresponding polymers 2b, 3a, and 3b as colorless pow-
ders.
formed in excess ketone. Aldehydes 7a–c were found to re-
act with cycloalkanones 11 and 12 under the above-men-
tioned conditions to yield aldols 13a–c and 14b,c, respec-
tively, as a mixture of syn- and anti isomers (Table 3).
The syn/anti isomer ratio in the reaction products was
determined on the basis of integral ratios of protons located
at the α-position with respect to the hydroxy group in the
1H NMR spectra of each isomer. α-Protons were assigned
to particular isomers on the basis of their chemical shifts δ
Poly(diallyldimethylammonium) Tetrafluoroborate (2b): Yield 2.48 g
(94%). (C8H16BF4N)2n (213.02)2n: calcd. C 45.11, H 7.57, N 6.58;
found C 45.19, H 7.47, N 6.63.
Poly(diallyldimethyl ammonium) Hexafluorophosphate (3a): Yield
1
3.18 g (95%). 19F NMR ([D6]DMSO): δ = –68.60 (d, JP,F
=
713 Hz) ppm. 31P NMR: δ = –41.21 (sept, JP,F = 714 Hz) ppm.
(C8H16F6NP)2n (271.18)2n: calcd. C 35.43, H 5.95, N 5.17; found C
35.37, H 5.84, N 5.21.
3
1
1
and coupling constants J1
with the vicinal cycloalk-
H– H
anone proton (δ = 5.31–5.48 ppm, J = 2–3 Hz in syn iso-
mers, δ = 4.71–4.91 ppm, J = 8–9 Hz in anti isomers).
It is worth mentioning that the syn isomers of aldols 13a–
c predominated in the reactions of aldehydes 7a–c with cy-
clopentanone (11). However, the anti isomers of aldols
14b,c were the major products of the corresponding reac-
tions with cyclohexanone (12). The syn/anti isomer ratio
was not influenced by the reaction time (15–48 h) or the
structure of the aldehyde.
Poly(diallyldimethylammonium) Hexafluorophosphate (3b): Yield
1
3.22 g (96%). 19F NMR ([D6]DMSO): δ = –69.00 (d, JP,F
=
712 Hz) ppm. 31P NMR: δ = –41.30 (sept, JP,F = 713 Hz) ppm.
(C8H16F6NP)2n (271.18)2n: calcd. C 35.43, H 5.95, N 5.17; found C
35.39, H 5.98, N 5.12.
1
S-Proline/Poly(diallyldimethylammonium) Salt Catalysts 4b, 5b, 6a,
6b. General Procedure:
A solution of (S)-proline (8.6 mg,
0.075 mmol) in CH3OH (5 mL) was added to stirred solution (sus-
pension) of polymer 1b (24 mg), 2b (32 mg), or 3a,b (40 mg) in the
same solvent (10 mL). The mixture was stirred at 20 °C for 0.5 h,
the solvent was evaporated under reduced pressure, and the residue
was dried in vacuo (3 Torr) at 25 °C for 1 h to afford the corre-
sponding supported catalysts 4b, 5b, 6a,b as colorless powders.
Conclusions
A new stable and recoverable heterogeneous catalytic sys-
tem, (S)-proline/poly(diallyldimethylammonium) hexafluo-
rophosphate, was developed for the direct asymmetric aldol
reaction between unmodified aldehydes and ketones. A
range of this and other supported polyelectrolyte systems
as chiral catalysts for enantioselective reactions of organic
compounds is now being studied.
Catalyst 4b: Yield 33 mg (100%). IR (KBr): ν = 644, 796, 852, 916,
˜
948, 984, 1036, 1084, 1172, 1256, 1296, 1320, 1380, 1408, 1452,
1564, 1624, 2348, 2956, 3056 (br), 3420 (br) cm–1.
Catalyst 5b: Yield 41 mg (100%). IR (KBr): ν = 644, 796, 852, 916,
˜
948, 1036, 1084, 1168, 1256, 1296, 1320, 1380, 1408, 1452, 1564,
1624, 2400, 2984, 3008, 3048 (br), 3430 (br) cm–1.
Catalyst 6a: Yield 49 mg (100%). IR (KBr): ν = 644, 796, 852, 948,
˜
Experimental Section
984, 1036, 1088, 1168, 1256, 1296, 1320, 1380, 1408, 1452, 1556,
General Remarks: 1H NMR spectra were recorded with Bruker AM
300 (300.13 MHz {1H}) and Bruker DRX 500 (500.13 {1H}, 125.76
{13C}, 470.4 {19F}, 202.4 MHz {31P}) instruments in CDCI3 and
1624, 2348, 2984, 3048 (br), 3420 (br) cm–1.
Catalyst 6b: Yield 49 mg, (100%). The IR spectrum was identical
to that of the compound 6a.
1
[D6]DMSO. H-, 13C-, 19F-, and 31P chemical shifts were recorded
relative to Me4Si, CDCl3, CFCl3, and H3PO4, respectively. IR spec-
tra (KBr pellets) were recorded with a Specord M82 instrument.
Specific optical rotations [α]2D0 were measured with a Jasco DIP-
360 instrument at 589 nm. Silica gel 0.060–0.200 nm (Acros) was
used for column chromatography. Solvents were purified by stan-
dard methods.
Aldol Reaction between Unmodified Aldehydes 7a-g and Ketones 8,
11, and 12 Catalyzed by S-Proline/Poly(diallyldimethylammonium)
Salt Catalysts 4b, 5b, 6a,b. General Procedure: A mixture of alde-
hyde 7a–g (0.5 mmol), the corresponding ketone 8, 11, or 12
(1 mL), and catalyst 4b (33.6 mg), 5b (40.6 mg) or 6a,b (49.2 mg)
was stirred at 25 °C for 15 h. The catalyst was filtered off, washed
with acetone (2×0.5 mL), dried in vacuo (3 Torr) at 25 °C for 1 h
and used in the reaction between fresh portions of the aldehyde and
the ketone. The combined filtrates were evaporated under reduced
pressure. The corresponding aldols 9a–g, 13a–c, and 14b,c were
isolated from the residue by column chromatography on silica gel
(eluent: n-hexane/ethylacetate, 3:1). 1H NMR spectra of known
compounds 9a–e, 13a–c, and 14b were in accordance with litera-
ture.[6b]
Poly(diallyldimethylammonium) Chloride (1b): Methanol (40 mL)
was added to a water solution of poly(diallyldimethylammonium)
chloride (MM 400.000–500.000 Da) (4.00 g, 20%). The mixture ob-
tained was poured into stirred diethyl ether (100 mL). The solvents
were decanted; the residue was washed with diethyl ether
(3×25 mL) and refluxed with anhydrous benzene (50 mL) in a
Dean-Stark apparatus until the remaining water was completely
removed (1 h). The solvent was evaporated, and the residue was
dried in vacuo (3 Torr) at 25 °C for 1 h to afford 1b (0.56 g, 70%)
as a colorless powder. (C8H16ClN)2n (161.67)2n: calcd. C 59.43, H
9.98, N 8.66; found C 59.20, H 9.76, N 8.79.
4-Hydroxy-4-(4Ј-methoxycarbonylphenyl)-butan-2-one
(9f):
M.p. 65–66 °C. [α]2D0 = +30.5 (c = 1.00, CHCl3). 1H NMR (CDCl3):
δ = 2.12 (s, 3 H, CH3), 2.80 (m, 2 H, CH2), 3.60 (br. s, 1 H, OH),
3.85 (s, 3 H, OCH3), 5.16 (dd, J1 = 8.5 Hz, J2 = 4.0 Hz, 1 H, CH),
7.36 (d, 8.1 Hz, 2 H, H-Ar), 7.92 (d, 8.1 Hz, 2 H, H-Ar) ppm. 13C
NMR (CDCl3): δ = 30.7 (C–CH3), 51.7 (CH2), 52.1 (OCH3), 69.4
(CH–OH), 125.5 (CH-Ar), 129.3 (C-Ar), 129.8 (CH-Ar), 148.0 (C-
Ar), 166.8 (CO2Me), 208.7 (C=O) ppm. C12H14O4 (222.24): calcd.
C 64.85, H 6.35; found C 64.86, H 6.58.
Poly(diallyldimethylammonium) Tetrafluoroborate (2b) and Hexaflu-
orophosphates (3a,b). General Procedure: HBF4 (3.20 g, 50%) [for
2b] or HPF4 (4.40 g, 60%) [for 3a,b] was gradually added to a
stirred water solution of poly(diallyldimethylammonium) chloride
(MM 100.000–200.000 Da for 3a, 400.000–500.000 Da for 2b and
3b) (10.0 g, 20%). The upper aqueous layer was decanted, the resi-
Eur. J. Org. Chem. 2006, 2000–2004
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2003

A. S. Kucherenko, M. I. Struchkova, S. G. Zlotin
FULL PAPER
[6] a) H.-M. Guo, L.-F. Cun, L.-Z. Gong, A.-Q. Mi, Y.-Z. Jiang,
Chem. Commun. 2005, 1450–1452; b) Z. Tang, F. Jiang, L.-T.
Yu, X. Cui, L.-Z. Gong, A.-Q. Mi, Y.-Z. Jiang, Y.-D. Wu, J.
Am. Chem. Soc. 2003, 125, 5262–5263; c) Tanimori, T. Naka,
M. Kirihata, Synth. Commun. 2004, 34, 4043–4048.
[7] a) P. Krattiger, R. Kovasy, J. D. Revell, S. Ivan, H. Wennemers,
Org. Lett. 2005, 7, 1101–1103; b) Z. Tang, Z.-H. Yang, X.-H.
Chen, L.-F. Cun, A.-Q. Mi, Y.-Z. Jiang, L.-Z. Gong, J. Am.
Chem. Soc. 2005, 127, 9285–9289; c) S. Samanta, J. Liu, R.
Dodda, C.-G. Zhao, Org. Lett. 2005, 7, 5321–5323; d) A. Bøge-
vig, N. Kumaragurubaran, K. A. Jørgensen, Chem. Commun.
2002, 620–621; e) A. B. Northrup, D. W. C. Mac Millan, J. Am.
Chem. Soc. 2002, 124, 6798–6799; f) J.-R. Chen, H.-H. Lu, X.-
Y. Li, L. Cheng, J. Wan, W.-J. Xiao, Org. Lett. 2005, 7, 4543–
4545.
4-Hydroxy-4-(4Ј-formylphenyl)-butan-2-one (9g): Colorless oil.
1
[α]2D0 = +49.9 (c = 1, CHCl3). H NMR (CDCl3): δ = 2.21 (s, 3 H,
CH3), 2.84 (m, 2 H, CH2), 3.55 (br. s, 1 H, OH), 5.21 (dd, J1
=
7.5 Hz, J2 = 4.8 Hz, 1 H, CH), 7.49 (d, 8.0 Hz, 2 H, H-Ar), 7.81
(d, 8.0 Hz, 2 H, H-Ar), 9.96 (s, 1 H, CH=O) ppm. 13C NMR
(CDCl3): δ = 30.8 (C–CH3), 51.7 (CH2), 69.3 (CH–OH), 126.2
(CH-Ar), 130.0 (C-Ar), 135.7 (CH-Ar), 149.7 (C-Ar), 192.0
(CH=O), 208.7 (C=O) ppm. C11H12O3 (192.21): calcd. C 68.74, H
6.29; found C 68.82, H 6.44.
Acknowledgments
[8] a) Y. Hayashi, W. Tsuboi, M. Shoji, N. Suzuki, Tetrahedron
Lett. 2004, 45, 4353–4356; b) M. Amedjkouh, Tetrahedron:
Asymmetry 2005, 16, 1411–1414; c) I. Izquierdo, M. T. Plaza,
R. Robles, A. J. Mota, F. Franco, Tetrahedron: Asymmetry
2001, 12, 2749–2754.
We are grateful for the financial support of the Russian Foundation
of Basic Researches (grant 03–03–32659) and the Basic Research
Program of the Russian Academy of Sciences.
[9] A. Bøgevir, N. Kumaragurubaran, K. A. Jørgensen, Chem.
Commun. 2002, 620–621.
[10] S. Chandrasekhar, Ch. Narsihmulu, N. R. Reddy, S. S. Sultana,
Tetrahedron Lett. 2004, 45, 4581–4582.
[1]
[2]
R. Noyori, Asymmetric Catalysis in Organic Synthesis, Wiley,
New York, 1994.
a) C. E. Song, S. Lee, Chem. Rev. 2002, 102, 3495–3524; b) Q.-
H. Fan, Y.-M. Li, A. S. C. Chan, Chem. Rev. 2002, 102, 3385–
3466.
[11] a) T.-P. Loh, L.-C. Feng, H.-Y. Yang, J.-Y. Yang, Tetrahedron
Lett. 2002, 43, 8741–8743; b) P. Kotrusz, I. Kmentová, B. Go-
ˇ
[3] D. E. De Vos, I. F. J. Vankelecom, P. A. Jacobs (Eds.), Chiral
Catalyst Immobilization and Recycling, Wiley-VCH, Weinheim,
2000.
tov, S. Toma, Chem. Commun. 2002, 2510–2511; c) A. Córdova,
Tetrahedron Lett. 2004, 45, 3949–3952.
[12] H.-U. Blaser, M. Studer, Green Chem. 2003, 5, 112–117.
[13] M. Gruttadauria, S. Riela, P. L. Meo, F. D’Anna, R. Noto,
Tetrahedron Lett. 2004, 45, 6113–6116.
[4] T. D. Machajewski, C.-H. Wong, Angew. Chem. Int. Ed. 2000,
39, 1352–1374.
[5] a) B. List, R. A. Lerner, C. F. Barbas III, J. Am. Chem. Soc.
2000, 122, 2395–2396; b) K. Sakthivel, W. Notz, T. Bui, C. F.
Barbas III, J. Am. Chem. Soc. 2001, 123, 5260–5267; c) B. List,
Tetrahedron 2002, 58, 5573–5590.
[14] A. Wolfson, I. F. J. Vankelecom, P. A. Jacobs, Tetrahedron Lett.
2003, 44, 1195–1198.
Received: November 11, 2005
Published Online: February 23, 2006
2004
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