Synthesis and structure of an air-stable hypervalent organobismuth (III) perfluorooctanesulfonate and its use as high-efficiency catalyst for Mannich-type reactions in water

Article abstract of DOI:10.1016/j.jorganchem.2009.07.018

An air-stable hypervalent organobismuth (III) perfluorooctanesulfonate was synthesized and characterized by spectroscopic and X-ray crystallographic techniques, and found to exhibit high catalytic efficiency towards one-pot Mannich-type reaction of ketones with aromatic aldehydes and aromatic amines in water. This catalyst also shows good recyclability and reusability. This catalytic system would provide a simple, efficient and 'green' avenue towards the synthesis of β-amino ketones.

Full text of DOI:10.1016/j.jorganchem.2009.07.018

Journal of Organometallic Chemistry 694 (2009) 3559–3564
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Synthesis and structure of an air-stable hypervalent organobismuth (III)
perfluorooctanesulfonate and its use as high-efficiency catalyst
for Mannich-type reactions in water
a
a
a
a
Xiaowen Zhang a,b, Shuangfeng Yin a, , Renhua Qiu , Jun Xia , Weili Dai , Zhenying Yu ,
*
Chak-Tong Au a,c, , Wai-Yeung Wong
d,
*
*
a College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, PR China
b Key Laboratory of Pollution Control and Resource Use of Hunan Province, University of South China, Hengyang 421001, PR China
c Department of Chemistry, Hong Kong Baptist University, Kowloon Tong, Hong Kong, PR China
d Department of Chemistry and Centre for Advanced Luminescence Materials, Hong Kong Baptist University, Kowloon Tong, Hong Kong, PR China
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 16 June 2009
Received in revised form 7 July 2009
Accepted 8 July 2009
Available online 5 August 2009
An air-stable hypervalent organobismuth (III) perfluorooctanesulfonate was synthesized and character-
ized by spectroscopic and X-ray crystallographic techniques, and found to exhibit high catalytic efficiency
towards one-pot Mannich-type reaction of ketones with aromatic aldehydes and aromatic amines in
water. This catalyst also shows good recyclability and reusability. This catalytic system would provide
a simple, efficient and ‘green’ avenue towards the synthesis of b-amino ketones.
Ó 2009 Published by Elsevier B.V.
Keywords:
Crystal structure
Mannich
Three-component reaction
Organobismuth
Perfluorooctanesulfonate
1. Introduction
synthesis of organobismuth derivatives and to exploit the
compounds for catalytic applications. On the other hand, Qiu
Bismuth is low in toxicity and relatively cheap. Being environ-
mentally friendly, bismuth compounds have been used in catalysis
and organic synthesis. In the past two decades, bismuth(III) com-
pounds (e.g., BiCl3, BiBr3, Bi(OTf)3, Bi(NO3)3) have been studied as
catalysts in a diversity of organic reactions, and review papers re-
lated to the catalysis of inorganic bismuth(III) compounds have
been published [1–8]. However, up till now, there are only several
reports on the use of organobismuth compounds as catalysts in or-
ganic synthesis, possibly due to the unstable nature of Bi–C bonds.
With ‘Green Chemistry’ and ‘Sustainable Development’ in mind, we
aim to synthesize stable organobismuth compounds and to inves-
tigate their potential uses. For example, organobismuth oxide,
hydroxide and methoxide bearing a stable cyclic framework were
synthesized and found to be good reagents and catalysts for CO2
chemical fixation [9–11]. Very recently we reported that organo-
bismuth complexes with equal or similar cyclic frameworks show
in vitro antiproliferative activity [12]. Due to the stability of the
cyclic frameworks, it is possible to conduct researches on the
et al. postulated that the incorporation of long-chain perflu-
oroalkylsulfonate and perfluoroarylsulfonate groups into organo-
metallic (e.g., Sn, Ti, Zr, Hf) complexes could result in enhanced
acidity and stability of materials [13–16]. Hence, we envision that
the incorporation of perfluorooctanesulfonate groups into organo-
bismuth species can result in the generation of organobismuth
compounds that are stable and have unique functionalities for
catalytic reactions.
The Mannich reaction is one of the most useful reactions for the
synthesis of nitrogen-containing compounds and is an effective
method for the construction of C–C bonds [17–19]. The conven-
tional catalysts for classical three-component Mannich reactions
of aldehydes, ketones and amines are mineral and organic acids,
and drawbacks such as long reaction time, harsh reaction condi-
tion, toxicity and difficulty in product separation are inevitable. It
is hence desirable to develop synthetic routes that are free from
such shortcomings.
It has been pointed out that organic synthesis using catalysts
that are not based on transition metals is an important, interesting
and challenging research topic in catalytic synthesis [3]. With the
aim of developing new catalysts suitable for one-pot Mannich-type
reaction and as an extension of our work on bismuth chemistry
* Corresponding authors. Tel./fax: +86 731 85118161.
E-mail addresses: sf_yin@hnu.cn (S. Yin), pctau@hkbu.edu.hk (C.-T. Au),
rwywong@hkbu.edu.hk (W.-Y. Wong).
0022-328X/$ - see front matter Ó 2009 Published by Elsevier B.V.
doi:10.1016/j.jorganchem.2009.07.018

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X. Zhang et al. / Journal of Organometallic Chemistry 694 (2009) 3559–3564
[9–12,20], we synthesized an organobismuth (III) perfluorooctane-
sulfonate (C6H11N(CH2C6H4)2 Bi(OSO2C8F17)) 1. The compound is
air-stable and shows high efficiency for the Mannich-type reaction
under relatively mild conditions.
changes in response to the electronic nature of bismuth [6,21–
24]. The Bi–N(1) distance (2.397(5) Å) is shorter than that
(2.631(4) Å) of precursor 2 [11]. As expected, the Bi–O(1) distance
(2.497(5) Å) is longer than the covalent Bi–O bond (2.077 Å) and
shorter than the Bi–O bond distance of tBuN(CH2C6H4)2BiOH
t
(2.691(4) Å) and BuN(CH2C6H4)2BiOCOOMe (2.730(4) Å) [10].
2. Results and discussion
2.2. Physiochemical property
2.1. Molecular structure
We found that the organobismuth perfluorooctanesulfonate 1
remained as dry crystals or a powder and suffered no color change
in a test of one month in air. Therefore, it is air-stable. Its Lewis
acidity is weak, showing strength of 4.8 < H0 6 6.8. The thermal
stability of compound 1 was investigated by TG–DSC analysis un-
der N2 atmosphere (Fig. 2). Apparently there are two stages of
weight loss. The plateau in the range of 29–246 °C suggests that
1 is thermally stable up to 246 °C. The weight loss in the 246–
356 °C range should be due to the loss of –OSO2C8F17 (weight loss
50.8%, theoretical loss 50.6%). The stage in the 356–631 °C range
can be ascribed to the loss of organic ligand entities. The endother-
mic peak that appears at 187 °C reflects a step of fusion rather than
desorption as there is no weight loss. The material is stable up to
about 246 °C, and an exothermic peak appears at 246 °C followed
by a significant decline in weight. It is suggested that the oxidation
of –OSO2C8F17 occurs at this stage. When the temperature is up to
about 356 °C, another exothermic signal appears, plausibly due to
The quality of the crystals of compound 1 was verified by sin-
gle-crystal X-ray diffraction. Listed in Table 1 are the crystal data,
data collection and structure refinement details.
An ORTEP representation of the structure of compound 1, as
well as selected bonds and angles are shown in Fig. 1. One can
see that the central bismuth-containing part of the compound
exhibits a pseudo-trigonal bipyramidal (TBP) structure, where both
the C(1) and C(8) atoms exist in the equatorial position of the TBP
structure along with a lone electron pair of bismuth, and the N(1)
and O(1) atoms are at the apical positions; the N(1)–Bi–O(1) bond
angle is 156.49(19)o. The Bi–C(1) and Bi–C(8) distance is 2.215(6) Å
and 2.234(6) Å, respectively, while the C(1)–Bi–C(8) angle is
93.9(2)o. As previously reported, the Bi–N coordination distance
in
5,6,7,12-tetrahydrodibenz[c,f][1,5]-azabismocines
flexibly
Table 1
Crystal data, data collection and structure refinement details for compound
C6H11N(C6H4)2Bi(OSO2C8F17) 1.
110
100
90
80
70
60
50
40
30
20
2.0
Entry
C6H11N(C6H4)2Bi(OSO2C8F17)
(1)
DSC
....... TG
246.3 oC
1.5
Chemical formula, formula weight
Cryst. habit
Cryst. size (mm)
Cryst. syst, space group
a, b, c (Å)
C28H23BiF17NO3S, 985.51
Prismatic, colorless
0.39 Â 0.34 Â 0.17
1.0
ꢀ
Triclinic, P1
0.5
10.3897(12), 11.1263(13),
14.1172(16)
92.681(2), 100.123(2),
95.441(2)
1595.9(3), 2, 2.051
948
20, 52.0
5.72
8797, 6163
0 0
356.43 oC
a
, b, c (°)
V (Å), Z, Dc (g cmÀ3
F (0 0 0)
T (°C), 2hmax (°)
)
-0.5
-1.0
-1 5
-2.0
187.3 oC
l(Mo K
a
) (mmÀ1
)
Number of reflections measured, number of
unique reflections
Number of observed reflections (Rint), R (I > 2
r
(I)) 5226 (0.035), 0.042
wR2 (F2, all reflections)
0.094
497
0.96
0
100 200 300 400 500 600 700 800
Number of parameters
Temperature /o
Goodness of fit (GOF) on F2
C
2
w = 1/[r
2(Fo2) + (0.0489P) ] where P = (Fo + 2Fc2)/3.
2
Fig. 2. TG–DSC curves of compound 1.
Fig. 1. Thermal ellipsoid plot of C6H11N(C6H4)2Bi(OSO2C8F17) (50% probability level). Hydrogen atoms on the carbon atoms are omitted for clarity. Selected bond lengths (Å)
and angles (°): Bi–C(1) 2.215(6); Bi–C(8) 2.234(6); Bi–N(1) 2.397(5); Bi–O(1) 2.497(5); N(1)–C(14) 1.487(7); N(1)–C(7) 1.491(8); N(1)–C(15) 1.521(8); S(1)–O(1) 1.455(5);
C(1)–Bi–C(8) 93.9(2); C(1)–Bi–N(1) 77.97(19); C(8)–Bi–N(1) 75.3(2); C(1)–Bi–O(1) 90.1(2); C(8)–Bi–O(1) 85.5(2); N(1)–Bi–O(1) 156.49(19); S(1)–O(1)–Bi 150.2(4); O(1)–
S(1)–C(21) 99.4(3).

X. Zhang et al. / Journal of Organometallic Chemistry 694 (2009) 3559–3564
3561
Table 2
the oxidation of the organic entities. The final substance that left
behind after heating to 700 °C as identified by XRD analysis is
BiF3 [25] (overall weight loss 73.0%, theoretical loss 73.0%).
C6H11N(CH2C6H4)2Bi(OSO2CF3)-catalyzed three-component Mannich-type reactions
of benzaldehyde, aniline and cyclohexanone in different solvents.a
Ph
O
NH
O
2.3. C6H11N(C6H4)2Bi(OSO2C8F17)-catalyzed Mannich reaction
CHO
+
NH2
5 mol%, Cat.
H2O, 25OC
+
We adopted the one-pot three-component Mannich reaction for
the study of catalytic activity of compound 1 (Tables 2–4). One can
see that the reaction that involves benzaldehyde, aniline and cyclo-
hexanone occurs smoothly in MeOH, EtOH, THF, H2O, and CH3C6H5
(Table 2, entries 1–5), but slowly in CH3CN and CH2Cl2 (Table 2, en-
tries 6–7). The yield of the target product (i.e., b-amino ketone) is
above 96% in 2 h when water, methanol or ethanol was used as
the solvent. It is apparent that a polar solvent benefits this reaction.
Since the use of water as a medium for organic synthesis is known
to be environmentally friendly [26], we selected water as the sol-
vent for further investigations.
Entry
Solvent
Time (h)
Yield (%)b
1
2
3
4
5
6
7
H2O
2
2
2
2
2
6
3
96
99
98
90
95
87
85
CH3OH
C2H5OH
THF
Toluene
CH3CN
CH2Cl2
a
Reaction conditions: benzaldehyde (1.0 mmol), aniline (1.0 mmol), cyclohexa-
none (1.0 mmol), cat. (0.05 mmol), H2O (2.0 ml), 25 °C.
In order to show the generality and scope of the new protocol,
we selected aldehydes, aromatic amines and ketones of various
b
Isolated yield.
Table 3
The one-pot three-component Mannich-type reaction in water.a
R2
O
5 mol%, Cat.
H2O, 25OC
NH
O
R1CHO
R2NH2
+
+
R3
R1
R3
R4
R4
Entry
Aldehyde
Amine
Ketone
Time (h)
Yield (%)b
1
2
3
4
5
6
7
8
PhCHO
PhNH2
PhNH2
PhNH2
PhNH2
PhNH2
PhNH2
PhNH2
o-CH3C6H4NH2
p-NO2C6H4NH2
PhNH2
Cyclohexanone
15
16
12
16
17
18
14
16
17
19
36
15
99
98
95
99
99
99
95
30
50
60
30
88
p-ClC6H4CHO
p-CF3C6H4CHO
p-O2NC6H4CHO
p-CH3OC6H4CHO
p-CH3C6H4CHO
C7H15CHO
PhCHO
PhCHO
PhCHO
PhCHO
PhCHO
Cyclohexanone
Cyclohexanone
Cyclohexanone
Cyclohexanone
Cyclohexanone
Cyclohexanone
Cyclohexanone
Cyclohexanone
Acetone
9
10
11
12
PhNH2
PhNH2
Acetophenone
1-(3-nitrophenyl)ethanone
a
Reaction conditions: aldehyde (1.0 mmol), amine (1.0 mmol), ketone (1.0 mmol), cat. (0.05 mmol), H2O (2.0 ml), 25 °C.
Isolated yield.
b
Table 4
Catalytic activity of different bismuth compounds in Mannich reaction of benzaldehyde, aniline and cyclohexanone.a
Ph
O
NH
O
CHO
+
NH2
5 mol%, Cat.
H2O, 25OC
+
Entry
Catalyst (5 mol%)
Solvent
Time (h)
Yield (%)b
1
2
3
4
5
6
7
8
9
10
no catalyst added
C6H11N(CH2C6H4)2BiCl
C6H11N(CH2C6H4)2Bi(OSO2C8F17) (1)
tBuN(CH2C6H4)2Bi+[B(C6F5)4]À
Bi(OSO2CF3)3
Bi(O2CCF3)3
S(CH2C6H4)2BiCl
C6H11N(CH2C6H4)2Bi[OCO2(CH2)2GePh3]
C6H5N(CH2C6H4)2Bi[OCO2(CH2)2GePh3]
tBuN(CH2C6H4)2Bi[OCO2(CH2)2GePh3]
H2O
H2O
H2O
H2O
H2O
H2O
H2O
H2O
H2O
H2O
5
3
2
2
2
5
2
3
3
3
8
50
95
92
84c
77c
20
80
75
55
a
Reaction conditions: benzaldehyde (1.0 mmol), aniline (1.0 mmol), cyclohexanone (1.0 mmol), cat. (0.05 mol), H2O (2.0 ml), 25 °C.
Isolated yield.
See Ref. [40].
b
c

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X. Zhang et al. / Journal of Organometallic Chemistry 694 (2009) 3559–3564
kinds. Table 3 demonstrates that excellent yields of b-amino ke-
tones are obtained across the selected aldehydes including those
that bear an electron-withdrawing group (Table 3, entries 2–4).
The use of electron-rich aromatic aldehydes also leads to good
yields of products (Table 3, entries 5–6). However, a change of
substituted groups in phenyl plane of aromatic amines results in
a poor reaction rate (Table 3, entries 8–9). Three other ketones
are also examined (Table 2, entries 10–12). As expected, m-
NO2PhCOCH3 exhibits higher activity than PhCOCH3 due to the
electron-withdrawing ability of –NO2.
In Table 4, the catalytic performance of compound 1 is com-
pared with that of other bismuth compounds. One can see that
in a blank run the isolated yield of b-amino carbonyl compound
is only 8%. Over C6H11N(CH2C6H4)2BiCl, tBuN(CH2C6H4)2–
Bi+[B(C6F5)4]À, Bi(OSO2CF3)3, Bi(O2CCF3)3, C6H11N(CH2C6H4)2 Bi[O-
CO2(CH2)2GePh3], and C6H5N(CH2C6H4)2Bi[OCO2(CH2)2GePh3], the
yields are above 70%. The catalytic activity can be ranked in the
order of C6H11N(CH2C6H4)2Bi(OSO2C8F17
> tBuN(CH2C6H4)2-
Bi+[B(C6F5)4]À > Bi(OSO2CF3)3 > C6H11N(CH2C6H4)2Bi[OCO2(CH2)2
GePh3] > Bi(O2CCF3)3 > C6H5N(CH2C6H4)2Bi[OCO2(CH2)2GePh3]
)
> tBuN(CH2C6H4)2 Bi[OCO2(CH2)2GePh3]. As reported in the litera-
ture, HCl [27], HBF4 [28], InCl3 [29], Y(OTf)3 [30], Yb(OPf)3 (Ytter-
bium perfluorooctanoate)[31], Zn(BF4)2 [32], ZrOCl2Á8H2O [33],
SiO2–OAlCl2 [34], PS–SO3H (polystyrene-supported sulfonic acid)
[35], heteropoly acid (H3PW12O40) [36], NbCl5 [37], HClO4–SiO2
[38] and Bi(OTf)3 [39] were used as catalysts in the Mannich-type
reactions. Despite individual feature(s) and/or merit(s) of the
catalysts, drawbacks such as difficulty of product separation,
impossible recycling and reuse of catalyst caused much concerns.
Despite the low solubility of aldehydes, ketones, and amines in
water, Mannich reactions proceed efficiently at ambient tempera-
ture in the presence of compound 1. The catalyst remains in solid
100
90
80
70
60
50
Fresh
1
2
3
4
5
6
7
8
9
Recycle number
Fig. 3. Catalyst recycling. (For each cycle: PhCHO 1.06 g, 10.0 mmol, PhNH2 0.93 g, 10.0 mmol, cyclohexanone 0.98 g, 10.0 mmol, and H2O 20.0 ml.)
X
O
O
S
O
Bi
PhCHO
PhNH2
N
X
O
O
S
O
H
O
H2N
Bi
N
X
O
O
S
O
II
HO
H
N
Bi
N
I
III
H2O
H
N
X
O
X
S
O
O
O
S
O
O
O
Bi
O
Bi
N
N
N
OH
N
X=C8F17
IV
V
Scheme 1. Proposed mechanism on the direct Mannich reaction catalyzed by organobismuth perfluorooctanesulfonate 1.

X. Zhang et al. / Journal of Organometallic Chemistry 694 (2009) 3559–3564
3563
form throughout the reaction, suggesting the catalysis is heteroge-
neous. Compared the results in Table 2, when some organic sol-
vents (e.g., THF) was used as the solvent, the catalytic process
was homogeneous, while the isolated yield of Mannich product
was lower in THF than that in water. We deduced that the differ-
ence in yield could be explained by dynamical equilibrium. As is
well known that the Mannich product is insoluble in water but
has good solubility in THF. Thus the use of water as solvent is ben-
eficial for the formation of the desired product.
400 MHz for proton and at 100 MHz for carbon nuclei (in CDCl3)
using a INOVA-400 M (Varian) spectrometer. The chemical shifts
of 1H (d ppm) were examined using tetramethylsilane as the inter-
nal standard (d 0.0) while those of 13C NMR were recorded using
CDCl3 as the internal standard (d 77.0). Melting points of com-
pounds were determined over a XT-4 micro apparatus (Beijing
Tech Instrument Co. Ltd.). Elemental analysis was conducted over
a VARIO EL III (Elementar) instrument. Single-crystal X-ray diffrac-
tion analysis was performed in Shanghai Institute of Organic
To examine the reusability and applicability of the catalyst,
compound 1 was subject to cycles of the Mannich reaction. When
(E)-N-benzylideneaniline was consumed completely, the mixture
was subject to methylene chloride extraction and the residue after
vacuum evaporation was analyzed by column chromatograph
(petroleum ether/ethyl acetate = 5/1). The recovered catalyst was
reused directly. In a test of 10 cycles, the change of product yield
is minimal (isolated yield only slightly declined from 95% to
94%), indicating that the catalyst is stable and reusable (Fig. 3).
Chemistry, Chinese Academy of Sciences using a SMART-APEX instru-
ment. TG–DSC analysis was performed on a NETZSCH-STA-449C
equipment (operation condition: N2, 5 °C/min heating rate). The
acidity was measured by the Hammett indicator method [41,42].
The employed indicators were crystal violet (pKa = 0.8), dimethyl
yellow (pKa = 3.3), methyl red (pKa = 4.8), and neutral red
(pKa = 6.8). Acid strength was expressed by the Hammett acidity
function (H0) as scaled by pKa value of the indicators.
4.2. Synthesis of compound 1
2.4. Proposed mechanism
The precursor C6H11N(CH2C6H4)2BiCl 2 of 1 was prepared
according to the procedure described elsewhere [11]. The synthetic
process of compound 1 is shown in Scheme 2. C6H11N(CH2-
C6H4)2BiCl 2 (2.61 g, 5.0 mmol) was dissolved in 90.0 ml THF, then
a solution of Ag(OSO2C8F17) (3.04 g, 5.0 mmol) in 60.0 ml THF was
added. After the mixture was stirred in the dark at room tempera-
ture for 3 h, it was filtered. The filtrate mixed with 10.0 ml hexane
was refrigerated for 24 h, giving colorless crystals (4.93 g, 98.0%).
Good crystals qualified for single-crystal X-ray diffraction analysis
were obtained by the recrystallization of compound 1 in a mixed
solvent of THF/hexane (volume ratio: 10/1). Compound 1: 1H
NMR(D6 acetone, 400 MHz, TMS): d 1.14 (1H, td, J = 7.0), 1.24–
1.33(4H, m), 1.63 (1H, d, J = 14.0), 1.84 (2H, d, J = 13.0), 1.98 (2H,
d, J = 11.5), 2.94 (1H, td, J = 11.5), 4.33 (2H, d, J = 15.5), 4.53 (2H,
d, J = 15.0), 7.31 (2H, td, J = 8.0, ArH), 7.49 (2H, d, J = 7.5, ArH)
7.55 (2H, t, J = 7.5 ArH), and 8.29 (2H, d, J = 7.5, ArH). 13C NMR
(D6 acetone, 100 MHz): d 25.88, 26.318, 31.99, 64.95, 67.71,
129.24, 129.43, 131.59, 137.98, 154.32 and 206.21. 19F NMR (D6
acetone, 376 MHz): À121.16 (2F, m), À117.70 (2F, s), À116.88
(4F, b), À116.54 (2F, s), À115.31 (2F, s), À109.01 (2F, t), À76.05
(3F, t). Melting point: 184–185 °C. Anal. Calc. for C28H23BiF17NO3S
(985.09): C, 34.12; H, 2.35; Bi, 21.21; F, 32.77; N, 1.42; O, 4.87; S,
3.25. Found: C, 34.07; H, 2.39; Bi, 21.24; F, 32.71; N, 1.46; O,
4.90; S, 3.21%.
A possible mechanism of the Mannich-type reaction that in-
volves the use of compound 1 as catalyst in water is proposed
(Scheme 1). When compound 1 (I) is added to the reaction solu-
tion, the carbonyl oxygen atom of benzaldehyde coordinates with
the bismuth atom and is activated; and this results in the forma-
tion of an intermediate II. Then aniline (a nucleophile) attacks
the activated carbonyl group of benzaldehyde and forms a hydro-
gen-bond (between H and O) with OSO2C8F17, producing the inter-
mediate imine IV. With the release of a water molecule, there is an
intramolecular rearrangement. Meanwhile, the carbonyl oxygen
atom of cyclohexanone coordinates with the bismuth atom and
is activated, forming a 1-cyclohexen-1-ol intermediate V. Then
the p-electrons of the activated (or unstabilized) imine delocalize
towards the activated 1-cyclohexen-1-ol, forming a new carbon–
carbon bond through the re-face of the double bond plane. Then
the
p-electrons of the activated 1-cyclohex-1-enol redistribute to
form cyclohexanone (accompanied by the transfer of hydrogen
atom to nitrogen atom). It is worth pointing out that all of the elec-
tron-transfer processes occur simultaneously and it is impossible
for the substrates to adjust into positions that would cause side
reactions (such as aldol addition and condensation). Finally, the
Mannich adduct is formed and catalyst 1 renewed.
3. Conclusion
4.3. X-ray crystallography
In summary, we synthesized and characterized for the first time
a stable hypervalent organobismuth (III) perfluorooctanesulfonate
of Lewis acidity. The compound shows good catalytic efficiency in
three-component Mannich reactions of aldehydes, amines, and ke-
tones in water under mild reaction conditions. Moreover, the cat-
alyst can be easily recycled and reused. The adoption of this
catalytic system would afford a simple, efficient and ‘green’ ap-
proach for the synthesis of b-amino ketones.
Crystals suitable for X-ray diffraction study were grown by slow
evaporation of the solution (compound dissolved in THF/hexane)
at room temperature. Geometric and intensity data were collected
at 293 K using graphite-monochromated Mo
Ka radiation
(k = 0.71073 Å) on a Bruker Axs SMART 1000 CCD diffractometer.
The crystallinity, orientation matrix, and accurate unit-cell param-
eters were determined according to standard procedures. The col-
lected frames were processed with the software SAINT [43], and
absorption correction (SADABS) [44] was applied to the acquired
4. Experimental
4.1. General
All manipulations of air-sensitive materials were conducted in a
glovebox filled with argon or under the protection of N2 atmo-
sphere according to the standard Schlenk tube techniques. The
commercially available chemicals were purchased from Aldrich
or Sinopharm Chemical Reagent Co. Ltd., and were used as received
without further purification. NMR spectra were recorded at
THF, dark
N
N
Bi
Cl
+ AgOSO C F
8 17
2
rt, 3 h
Bi
OSO C F
8 17
2
Scheme 2. Synthesis of organobismuth perfluorooctanesulfonate 1.

3564
X. Zhang et al. / Journal of Organometallic Chemistry 694 (2009) 3559–3564
reflection peaks. The structure was solved by the Direct or Patter-
son method (SHELXS97, Sheldrick, 1990) [45] in conjunction with
standard difference Fourier techniques, and subsequently refined
by full-matrix least-squares analyses on F2. Hydrogen atoms were
generated in their idealized positions and all non-hydrogen atoms
were assigned with anisotropic displacement parameters.
Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/
data_request/cif.
Supplementary data associated with this article can be found, in
the online version, at doi:10.1016/j.jorganchem.2009.07.018.
References
4.4. Mannich reaction
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This work was financially supported by the National Science
Foundation of China (Nos. 20507005, 20873038, E50725825).
X.W. Zhang thanks the municipal engineering key project of
‘11th Five-Year Plan’ of Hunan Province for financial support. C.T.
Au and W.Y. Wong thank the Hong Kong Baptist University for
financial support (FRG/08-09/II-09). C.T. Au thanks the Hunan Uni-
versity for an adjunct professorship. S.F. Yin thanks Dr. S. Shimada
of AIST, Japan for helpful advices.
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Appendix A. Supplementary material
[45] G.M. Sheldrick, SHELXTLTM, Reference Manual, ver. 5.1, Madison, WI, 1997.
CCDC 733861 contains the supplementary crystallographic data
for this paper. These data can be obtained free of charge from The