Carbon-carbon double-bond formation from the reaction of organozinc reagents with aldehydes catalyzed by a nickel(II) complex

Article abstract of DOI:10.1002/1521-3773(20020802)41:15<2757::AID-ANIE2757>3.0.CO;2-Z

Stereoselective alkenylated compounds are formed from the reaction of organozinc halides and aldehydes (see scheme; FG = functional group). Under mild conditions, and in the presence of a silylating agent, the Ni-catalyzed procedure gives E-alkenes and E-

Full text of DOI:10.1002/1521-3773(20020802)41:15<2757::AID-ANIE2757>3.0.CO;2-Z

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2
000, 53, 15 ± 24; f) T. Matsumoto, H. Yamaguchi, M. Tanabe, Y.
of stilbenes have been reported, in which aldehyde tosylhy-
drazones were treated with benzotriazole-stabilized carban-
ions,[ trimethyl borate/lithium tert-butoxide, trialkylboranes,
and alkylboron chlorides.[
Yasui, K. Suzuki, Tetrahedron Lett. 2000, 41, 8393 ± 8396; g) G. B.
Caygill, D. S. Larsen, S. Brooker, J. Org. Chem. 2001, 66, 7427 ± 7431.
10] M. C. Carre nƒ o, A. Urbano, J. Fischer, Angew. Chem. 1997, 109, 1695 ±
5]
[
[
6]
1
697; Angew. Chem. Int. Ed. Engl. 1997, 36, 1621 ± 1623.
11] a) M. C. Carre nƒ o, A. Urbano, C. Di Vitta, Chem. Commun. 1999,
Organozinc complexes are powerful reagents for the
formation of carbon ± carbon bonds. Recently, transition-
8
2
17 ± 818; b) M. C. Carre nƒ o, A. Urbano, C. Di Vitta, Chem. Eur. J.
000, 6, 906 ± 913.
[7]
metal-catalyzed coupling reactions of halides with organozinc
complexes have been reported.[ In addition, we have
reported that the nitro group of 1-aryl-2-nitroethenes can be
[
12] Compound [(S)S]-3 was synthesized according to the procedure
reported for the (S)R enantiomer, by reaction of 4,4-dimethoxy-2,5-
cyclohexadienone with the lithium anion derived from [(S)S]-methyl-
p-tolylsulfoxide followed by acetal hydrolysis with aqueous oxalic
acid: M. C. Carre nƒ o, M. P e¬ rez Gonz a¬ lez, K. N. Houk, J. Org. Chem.
8]
substituted by organozinc halides, using [Ni(acac) ] (acac ˆ
2
acetylacetonato) as a catalyst in the presence of a tertiary
amine, to give 1-aryl-1-alkenes in excellent yields.[
1
997, 62, 9128 ± 9137.
9]
[
13] M. C. Carre nƒ o, M. P e¬ rez Gonz a¬ lez, M. Ribagorda, K. N. Houk, J. Org.
The reaction of alkylzinc reagents and carbonyl compounds
Chem. 1998, 63, 3687 ± 3693.
[
[
14] J. A. Dale, H. S. Mosher, J. Am. Chem. Soc. 1973, 95, 512± 519.
15] M. C. Carre nƒ o, J. L. GarcÌa Ruano, A. Urbano, Synthesis 1992, 651 ±
represents one of the most reliable methods to prepare
[10, 11]
optically active secondary alcohols.
. Herein we show that
6
53.
16] M. C. Carre nƒ o, A. Urbano, C. Di Vitta, J. Org. Chem. 1998, 63, 8320 ±
330.
E-stilbenes can be formed by the reaction of organozinc
halides with aryl aldehydes in the presence of a silylating
agent and using [NiCl (PPh ) ] as the catalyst. To our knowl-
[
8
[
17] K. Krohn, F. Ballwanz, W. Baltus, Liebigs Ann. Chem. 1993, 911 ± 913.
2
3 2
[
18] Different values of the optical rotation of the natural product are
edge, the formation of CˆC bonds by the reaction of
aldehydes and organozinc reagents, using this catalyst in the
presence of chlorotrimethylsilane, is yet to be reported.
Herein, we report that a number of E-alkenes can be obtained
by this route. To investigate the scope and limitations of this
new reaction for the synthesis of E-alkenes, various aldehydes
and organozinc reagents, including some functionalized
species, have been utilized as substrates (Scheme 1). The
results are summarized in Table 1.
2
0
reported in the literature: (‡)-rubiginone A
2
: [a]
D
ˆ ‡92( c ˆ 0.5 in
[
2]
20
D
[3]
CHCl
3
), (‡)-fujianmycin B: [a]
ˆ ‡50 (c ˆ 0.176 in CHCl
3
), and
2
0
[4]
(
‡)-SNA-8073-B: [a]
D
ˆ ‡47 (c ˆ 0.141 in CHCl
3
). The enantio-
meric excess of our synthetic (‡)-14 was shown to be >95% after
transformation into the corresponding Mosher esters.[
14]
Carbon ± Carbon Double-Bond Formation
from the Reaction of Organozinc Reagents with
Aldehydes Catalyzed by a Nickel(ii) Complex**
Jin-Xian Wang,* Ying Fu, and Yulai Hu
Reactions that form carbon ± carbon bonds are of the
utmost importance in modern organic synthesis, and the
development of new methods to form such bonds is still a
formidable challenge for organic chemists. It is well known
that reactions forming CˆC bonds have been extensively used
in the synthesis of various polyfunctional unsaturated com-
pounds and natural products, while some applications in
combinatorial chemistry have also been described. Many
methods have been developed for CˆC bond formation such
Scheme 1.
[1]
as Wittig reactions, reductive coupling of carbonyl com-
pounds,[ self-coupling of a-lithiated benzylic sulfones,[3] and
condensation of aldehyde tosylhydrazones with stabilized
carbanions.[ More recently, new procedures for the synthesis
2]
We observed that certain organozinc reagents worked best
at particular reaction conditions. For the benzylic zinc halides,
reactions at room temperature gave the corresponding E-
stilbenes in good-to-excellent yields after 8 h (78 ± 92%,
entries 1 ± 8). However, when alkylzinc iodides were used,
yields of E-alkenes were optimized by carrying out reactions
at À188C, and then warming to room temperature (54 ± 89%,
entries 10 ± 15, 18 ± 21). Both electron-withdrawing and elec-
tron-donating substituents on the phenyl ring, such as methyl,
chloro, bromo, benzyloxy, hydroxy, and methoxy, are toler-
ated in these reactions and generally have little effect on
product yield, except for 2,4-dinitrobenzaldehyde which gave
no olefination product (entries 2± 11 and 17). Where organo-
4]
[
*] Prof. J.-X. Wang, Y. Fu, Dr. Y. Hu
Institute of Chemistry, Department of Chemistry
Northwest Normal University
Lanzhou 730070 (P. R. China)
Fax : (‡86)931-776-8159
E-mail: wangjx@nwnu.edu.cn
[
**] This work was supported by the National Natural Science Foundation
of China and the Northwest Normal University Science and Technol-
ogy Development Foundation of China.
Supporting information for this article is available on the WWW under
http://www.angewandte.org or from the author.
Angew. Chem. Int. Ed. 2002, 41, No. 15
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Table 1. Nickel(ii)-catalyzed alkenylation of functionalized organozinc reagents with aldehydes.[a]
Entry
1
Ar
Ph
FG-R or Aryl
Ph
X
Temp. [8C]
Time [h]
8
Product[b]
Yield[c] [%]
88
Cl
RT
-
MeOPh22
Ph
Cl
RT
8
79
3
4
4-HOPh
4-ClPh
Ph
Ph
Cl
RT
RT
8
8
78
87
Br
5
Ph
Ph
3-ClPh
Br
RT
8
81
6
7
3-BrPh
4-BrPh
Br
Br
RT
RT
8
8
63
85
Ph
8
9
0
4-MeOPh
Ph
Ph
Cl
Br
I
RT
8
8
92
0
2,4-(O
2
N)
2
Ph
RT
no reaction
1
1
4-MeOPh
4-MeOPh
n-C
7
H
15
-
À 18 ± RT
12
68
1
Cl(CH
2
)
3
-
I
I
À 18 ± RT
À 18 ± RT
12
12
63
61
1
1
2Ph
3
Ph
EtO
2
CCH
2
-
I
À 18 ± RT
12
66
1
1
1
4
5
6
Ph
Ph
Br(CH
2
)
3
-
I
À 18 ± RT
À 18 ± RT
RT
12
12
8
65
68
89
n-C
4
H
9
-
I
PhCHˆCH
PhCHˆCH
-
-
Ph
Cl
2
2
1
7
3-ClPh
Br
RT
8
74
1
1
8
9
PhCHˆCH
PhCHˆCH
2
2
-
-
n-C
n-C
6
7
H
H
13
-
-
I
I
À 18 ± RT
À 18 ± RT
12
12
62
60
15
2
2
0
1
PhCHˆCH
PhCHˆCH
2
2
-
-
I
I
À 18 ± RT
À 18 ± RT
12
12
54
n-C
5
H
11
-
65
[
[
a] All reactions were conducted on the following scale: 10 mmol aldehydes, 11 mmol organozinc reagents, 0.3 mmol catalyst [NiCl
b] All products were characterized by IR and H NMR spectroscopy, as well as mass spectrometry. [c] Yields of isolated products.
2
(PPh
3
)
2
] in THF (20 mL).
1
zinc halides were functionalized by chloro, bromo, and ester
moieties, the corresponding E-alkenes also contained these
groups (entries 11, 13, and 14). Interestingly, the unsaturated
double bond of phenylacrylic aldehyde could also be intro-
duced into the products in moderate-to-good yields (en-
tries 16 ± 21). We also found that these reactions tolerated
different molecular structures of RZnX; for example, under
the same conditions, the use of sterically hindered complexes
with branched functionalities gave the desired products in
moderate yields (entries 12and 20 ).
One advantage of this reaction, which makes it a partic-
ularly attractive synthetic procedure, is its regiospecificity.
The double bond is formed between the carbonyl carbon atom
of the aldehyde and the carbon atom of the organozinc
2758
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reagent. The reaction is also stereoselective; in all cases only
the E-alkenes were isolated after chromatography.
procedure, and excellent product yields, all under relatively
mild reaction conditions.
In the well-studied Wittig reaction, stilbenes are usually
formed in moderate-to-high yield as a mixture of E and
Z isomers, together with triphenylphosphine oxide as a by-
Experimental Section
product.[ Although the E:Z ratio can be changed by varying
1a]
Typical procedure: Method A: Benzylzinc halides (11 mmol) were pre-
pared following Knochel×s procedure. [NiCl (PPh ) ] (0.2g, 0.3 mmol) in
2 3 2
THF (2mL) was added to a solution of benzylzinc halides in THF at 0 8C.
After stirring the mixture for 2min, the temperature was allowed to reach
room temperature. A solution of benzaldehyde (1.06 g, 10 mmol) and
Me SiCl (2.18 g, 20 mmol) in THF (10 mL) was then added dropwise. The
3
reaction mixture was stirred at room temperature for 8 h. E-stilbenes were
obtained by column chromatography on silica gel using petroleum/ethyl
acetate as an eluent. All products were characterized by IR, H NMR, and
some of the reaction conditions,[
12, 13]
recent studies indicate
[19]
that the E:Z ratio is unchanged by varying the concentration,
mode of addition, or molar ratio of the aldehyde and ylide.[14]
Slight variations were seen by changing the substituents in the
aldehyde and aryl alkylidenetriphenylphosphorane precur-
sors. The use of an aldehyde as its enamine derivative can limit
1
possible side reactions to give E-stilbenes in high yields.[1a]
mass spectroscopy.
Our experimental results showed that this reaction is highly
stereoselective and only gives E-alkenes selectively.
1
1
(
1
b: H NMR (400 MHz, CDCl
3
): d ˆ 7.62± 7.50 (m, 4H; Ar-H), 7.39 ± 7.19
3
3
m, 4H; Ar-H), 7.10 (d, J(H,H) ˆ 16.6 Hz, 1H; ˆCH), 6.94 (dd, J(H,H) ˆ
Based on our experimental results and other related
3
8.6 Hz, J(H,H) ˆ 7.0 Hz, 2H; ˆCH, Ar-H), 3.88 ppm (s, 3H; OCH
3
); IR
studies,[
15]
,
[16]
we propose the general reaction mechanism
shown in Scheme 2. The first step of this mechanism is the
reaction of [NiCl (PPh ) ] (1) with the functionalized organo-
(KBr): nÄ ˆ 3017, 2969, 2841, 1600, 1591, 1569, 1483, 1466, 1241, 1030, 965,
À1
‡
‡
7
1
53, 691 cm ; MS (70 eV): m/z (%): 210 (100) [M ], 195 (4) [M À CH
3
],
‡
‡
‡
79 (13) [M À OCH
3
], 165 (40) [M À OCH
3
À CH
2
], 152(1 )2 [ M À
2
3
2
‡
‡
OCH
3
À C
2
H
3
], 139 (4) [M À OCH
3
À C
3
H
4
], 128 (2) [M À OCH
3
À
zinc reagent 2, to form [FG-ArCH NiCl(PPh ) ] (3). The
‡
‡
2
3 2
C
4
H
3
], 115 (3) [M À OCH
3
À C
‡
5
5
H
].
4
], 104 (17) [M À OCH
3
À C
6 4
H ], 91
second step is 1,2-addition of 3 to an aromatic aldehyde 4,
which is activated by chlorotrimethylsilane,[ to give nickel
complex 6. The loss of 1 from 6, in the presence of
chlorotrimethylsilane, yields secondary silyl ethers 7, which
(24) [C H CH
‡
‡1], 77 (3) [C H
6
5
6
17]
1
3
4
2
a: H NMR (400 MHz, CDCl
3
): d ˆ 7.32(dt, J(H,H) ˆ 8.2Hz, J(H,H) ˆ
3
4
2.0 Hz, 2H; Ar-H), 6.80 (dt, J(H,H) ˆ 8.8 Hz, J(H,H) ˆ 1.8 Hz, 2H; Ar-
3
3
H), 6.28 (d, J(H,H) ˆ 15.8 Hz, 1H; H-1), 6.02(dt, J(H,H) ˆ 15.8 Hz,
4
3
have been isolated.[18] Compounds 7 can also be detected in
J(H,H) ˆ 7.2Hz, 1H; H-2), 3.77 (s, 3H, OCH
.6 Hz), 1.41 ± 1.08 (m, 10H, CH
CH
64, 831, 725 cm ; MS (70 eV): m/z (%): 232 (M , 17.5), 147(100), 134
3
), 2.17 (q, 2H, J(H,H) ˆ
3
6
2
), 0.88 ppm (t, J(H,H) ˆ 6.4 Hz, 3H;
the reaction by GC-MS. Loss of Me SiOH from 7 gives the
3
3
); IR (neat): nÄ ˆ 2927, 2855, 1610, 1511, 1465, 1370, 1301, 1241, 1098,
À1 ‡
final E-alkenes product 8.
9
In conclusion, we have developed a new and convenient
method for the efficient and highly stereoselective synthesis
of E-alkenes from the corresponding aldehydes and function-
alized organozinc reagents in the presence of a silylating agent
and a catalytic quantity of [NiCl (PPh ) ]. The main advan-
(22.5), 121, (46.8), 91 (24), 77 (7.0).
1
3
4
2b: H NMR (400 MHz, CDCl ): d ˆ 7.27 (dt, J(H,H) ˆ 8.8 Hz, J(H,H) ˆ
3
3
2
.2 Hz, 2H; Ar-H), 6.84 (m, 2H; Ar-H), 6.37 (d, J(H,H) ˆ 16.0 Hz, 1H;
3 4
H-1), 6.01 (dt, J(H,H) ˆ 15.8 Hz, J(H,H) ˆ 7.0 Hz, 1H; H-2), 3.77 (s, 3H,
3
3
OCH
CH
3
), 3.55 (t, J(H,H) ˆ 6.6 Hz, 2H; CH
2
), 2.35 (q, J(H,H) ˆ 6.8 Hz, 2H;
2
3 2
2
), 1.95 ± 1.74 ppm (m, 2H, CH
2
); IR (neat): nÄ ˆ 2996, 2934, 2861, 1610,
À1
tages of this new method are high stereoselectivity, tolerance
to unsaturated and polyfunctional groups, simple operation
1
512, 1461, 1240. 1170, 1037, 960, 800, 725, 685, 651 cm ; MS (70 eV): m/z
(%): 214 (1) [M ‡4], 213 (3) [M ‡3], 212 (3) [M ‡2], 211 (9) [M ‡1], 210
‡
‡
‡
‡
‡
(
(
21) [M ], 175 (2), 161 (2), 147 (100), 121
51), 91 (35), 77 (14).
3
b: 1H NMR (400 MHz, CDCl
3
): d ˆ
3
7
.46 (t, J(H,H) ˆ 7.6 Hz, 3H; Ar-H),
3
7.36 (t, J(H,H) ˆ 7.6 Hz, 2H; Ar-H),
7.32± 7.20 (m, 4H; Ar-H), 6.98 (ddd,
3
4
3
4
3
4
4
J(H,H) ˆ 19.8 Hz,
J(H,H) ˆ 10.6 Hz,
J(H,H) ˆ 4.1 Hz; 1H), 6.94 (ddd,
4
J(H,H) ˆ 19.8 Hz,
J(H,H) ˆ 10.6 Hz,
J(H,H) ˆ 4.1 Hz, 1H; CHˆ), 6.72(ddd,
4
J(H,H) ˆ 20.5 Hz,
J(H,H) ˆ 11.4 Hz,
J(H,H) ˆ 5.3 Hz, 1H; CHˆ), 6.61 ppm
3
4
(
ddd,
J(H,H) ˆ 21.2 Hz,
J(H,H) ˆ
1.5 Hz, 4J(H,H) ˆ 4.6 Hz, 1H; CHˆ);
1
‡
MS (70 eV): m/z (%): 243 (3.4) [M ‡3],
‡
‡
2
2
42 (19.8) [M ‡2], 241 (13.1) [M ‡1],
‡
40 (62.1) [M ], 205 (100) [MÀCl].
1
4
c: H NMR (400 MHz, CDCl
3
): d ˆ
7
.45 ± 7.19 (m, 5H; Ar-H), 6.82(dd,
3
4
J(H,H) ˆ 16.8 Hz, J(H,H) ˆ 10.2Hz,
3
1
H; H-1), 6.53 (t, J(H,H) ˆ 16.8 Hz,
3
1
H; H-2), 6.25 (dd, J(H,H) ˆ 15.2Hz,
4
J(H,H) ˆ 10.2Hz, 1H; H-3), 5.80 (dt,
3
4
J(H,H) ˆ 15.0 Hz,
J(H,H) ˆ 7.0 Hz,
3
1
2
0
H; H-4), 2.10 (q, J(H,H) ˆ 7.0 Hz,
H; CH ), 1.46 ± 1.25 (m, 10H, CH ),
.88 ppm (t, J(H,H) ˆ 6.2Hz, 3H;
2
2
3
CH
3
); IR (neat): nÄ ˆ 2926, 2855, 1636,
Scheme 2. General mechanism for a nickel(ii)-catalyzed alkenylation of aldehydes with functionalized
organozinc reagents.
1606, 1511, 1465, 1370, 1250, 1037, 962,
838, 765 cm ; MS (70 eV): m/z (%): 243
À1
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1433-7851/02/4115-2759 $ 20.00+.50/0
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COMMUNICATIONS
‡
‡
(
(
1) [M ‡1], 242 (5) [M ], 197 (2), 183 (1), 169 (1), 157, (1), 143 (47), 128
Mechanistic Features, Cooperativity, and
Robustness in the Self-Assembly of
Multicomponent Silver(i) Grid-Type
Metalloarchitectures
28), 117 (7), 104 (2), 91 (13), 77 (5), 57 (100), 41 (57).
Method B: Under an argon atmosphere, a mixture of zinc dust (0.85 g,
3 mmol), 1,2-dibromoethane (0.19 g, 1.0 mmol), and THF (2 mL) was
heated in a three-necked flask to 60 ± 708C for 2± 3 min and then cooled to
room temperature. Chlorotrimethylsilane (0.1 mL) was added, and the
mixture was stirred at room temperature for 15 min. A solution of RI
12mmol) in THF (10 mL) was then added, and the mixture was stirred for
2h at 35 8C. The resulting RZnI solution was then added to another three-
necked flask, in which [NiCl (PPh ] (0.2g, 0.3 mmol) and THF (2mL)
had been previously heated at 608C for 2min. The resulting mixture was
cooled to À188C. A solution of aldehyde (10 mmol) and chlorotrimethyl-
silane (20 mmol) in THF (10 mL) was added over a few minutes and the
mixture was allowed to warm to room temperature. After stirring the
mixture for 12h, saturated aqueous solution of NH
10 mL) were added and the mixture was stirred for 10 min. The organic
4
layer was separated, dried over anhydrous MgSO , and concentrated. The
product was isolated from the crude reaction mixture by column
chromatography on silica gel using petroleum ether/ethyl acetate as the
1
Annie Marquis, Jean-Pierre Kintzinger, Roland Graff,
Paul N. W. Baxter, and Jean-Marie Lehn*
(
1
2
3 2
)
Self-organization processes allow the spontaneous but
controlled generation of complex organic or inorganic archi-
tecture on the basis of the molecular information stored in the
components, and its processing through the interactional
4
Cl (10 mL) and Et
2
O
algorithms defined by specific molecular recognition
(
[1, 2]
events.
Such processes connect input components with
output entity(ies), with a fidelity/reliability depending on the
robustness of the program, that is, its ability to resist
interference from factors other than the directing/dominant
coding interactions.
eluent.
Received: December 28, 2001
Revised: April 11, 2002 [Z18460]
While in equilibrium conditions, the process ideally leads to
the preferential formation of a given entity under thermody-
namic control/pressure; input and output species may be
linked by complex mechanistic pathways and involve the
generation of kinetic species that may or may not be direct
intermediates. Such is the case, for instance, in the final
formation of the thermodynamically favored circular heli-
[
1] a) K. B. Becker, Synthesis 1983, 341 ± 368; b) O. H. Wheeler, H. N.
Batlle de Pabon, J. Org. Chem. 1965, 30, 1473 ± 1477; c) A. R.
Macquire in Comprehensive Organic Functional Group Transforma-
tions (Eds.: A. R. Katristzky, O. Meth-Cohn, C. W. Rees) Pergamon,
New York, 1995.
[
[
[
2] J. E. McMurry, M. P. Fleming, J. Am. Chem. Soc. 1974, 96, 4708 ± 4709.
3] L. Engman, J. Org. Chem. 1984, 49, 3559 ± 3563.
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[3]
cates following kinetically favored triple-helical complexes.
Although it is crucial to gain insight into the mechanistic,
thermodynamic, and kinetic features of the self-organization
process, only few such studies have been reported.[ Whereas
the preferential, ideally exclusive, formation of a given entity
is usually pursued, various factors may interfere with the
dominant code and complicate the issue. Thus, considering the
self-assembly of inorganic grid architectures, which makes use
of specifically designed ligands and of strong metal-ion
2
49 ± 251.
5] A. R. Katritzky, D. O. Tymoshenko, S. A. Belyakov, J. Org. Chem.
999, 64, 3332± 3334.
6] a) G. W. Kabalka, J. T. Maddox, E. Bogas, J. Org. Chem. 1994, 59,
[
[
4]
1
5
1
530 ± 5531; b) G. W. Kabalka, Z. Wu, Y. Ju, Tetrahedron 2001, 1663 ±
670.
[
7] P. Knochel, J. J. Almena Perea, P. Jones, Tetrahedron, 1998, 54, 8275 ±
319.
8
[
8] a) R. Giovannini, T. Studemann, A. Devasa-Gayaraj, G. Dussin, P.
Knochel, J. Org. Chem. 1999, 64, 3544 ± 3553; b) B. H. Lipshutz, P. A.
Blomgren, S.-K. Kim, Tetrahedron Lett. 1999, 40, 197 ± 200; c) H.
Avedissian, L. Berinllon, G. Cahiez, P. Knochel, Tetrahedron Lett.
[5]
[6]
[7]
coordination interactions, [2 Â 2]-, [3 Â 3]-, and [4 Â 4]-
type entities form exclusively. However, with a pentadentate
‡
ligand, both an incomplete [4 Â 5]Ag grid and a quadruple
1
998, 39, 6163 ± 6166.
20
[
9] Y. Hu, J. Yu, S. Yang, J.-X. Wang, Y. Yin, Synlett. 1998, 1213 ± 1214.
helicate are simultaneously generated in place of the full
[
[
10] a) K. Soai, S. Niwa, Chem. Rev. 1992, 92, 833 ± 856; b) R. Noyori, M.
Kitamura, Angew. Chem. 1991, 103, 34 ± 48; Angew. Chem. Int. Ed.
Engl. 1991, 30, 49 ± 69.
11] a) P. I. Dosa, G. C. Fu, J. Am. Chem. Soc. 1998, 120, 445 ± 446; b) C.
Lutz, P. Jones, P. Knochel, Synthesis 1999, 312± 316.
12] G. Drefahl, D. Lorenz, G. Schnitt, J. Prakt. Chem. 1964, 23, 143 ± 148.
13] A. W. Johnson, V. L. Kyllingstad, J. Org. Chem. 1966, 31, 334 ± 336.
14] H. Yamataka, K. Nagareda, K. Ando, T. Hanafusa, J. Org. Chem.
‡
[
5 Â 5]Ag entity, because of the interplay of various struc-
2
5
[8]
tural factors. On the other hand, such cases also stress that
when different ™Boltzmann species∫ are thus formed, pro-
vided they are well defined, diversity ensues, an attractive
[
[
[
[9]
feature of multiple outputs in a self-assembly process. To
gain understanding of the self-organization pathways, it is first
necessary to identify the species that may form and then try to
define their role in the process. In particular, features such as
1
992, 57, 2865 ± 2869.
[
[
[
15] C. Alvisi, S. Casolari, A. L. Costa, M. Ritani, E. Tagliavini, J. Org.
Chem. 1998, 63, 1330 ± 1333.
16] R. Latouche, F. Texier-Boullet, J. Hamelin, Tetrahedron Lett. 1991, 32,
[
*] Prof. Dr. J.-M. Lehn, Dr. A. Marquis, Dr. P. N. W. Baxter
Laboratoire de Chimie Supramol e¬ culaire
ISIS-Universit e¬ Louis Pasteur
1
179 ± 1182.
17] a) E. Nakamura, S. Aoki, K. Sekiya, H. Oshino, I. Kuwajima, J. Am.
Chem. Soc. 1987, 109, 8056 ± 8066; b) C. R. Johnson, T. G. Marren,
4
, rue Blaise Pascal, 67000 Strasbourg (France)
Tetrahedron Lett. 1987, 28, 27 ± 30.
Fax : (‡33)390-241-117
1
[
18] Spectroscopic data for 7: H NMR (400 MHz, CDCl
3
): d ˆ 7.42(dd,
E-mail: lehn@chimie.u-strasbg.fr
3
3
3
J(H,H) ˆ 8.2Hz, J(H,H) ˆ 1.8 Hz; 1H), 6.89 (t, J(H,H) ˆ 7.4 Hz ;
3
3
Dr. J.-P. Kintzinger
Laboratoire de RMN de la Mati e¡ re Condens e¬ e
CNRS-Universit e¬ Louis Pasteur
1
3
0
1
H), 6.77 (d, J(H,H) ˆ 8.2Hz; 1H), 5.09 (t, J(H,H) ˆ 6.0 Hz; 1H),
3
.77 (s, 3H), 1.58 (s, 2H), 1.24 (s, 8H), 0.84 (t, J(H,H) ˆ 6.6 Hz; 3H),
.06 ppm (s, 9H); 13C NMR (100 MHz, CDCl
3
): d ˆ 155.4, 134.3, 127.4,
4
, rue Blaise Pascal, 67000 Strasbourg (France)
26.7, 120.4, 109.8, 68.3, 39.0, 31.8, 29.2, 26.0, 22.7, 14.1, 0.0 ppm; MS
70 eV): m/z (%): 296 (M ‡2, 0.5), 281 (5), 211 (100), 181 (5), 136 (4),
‡
(
Dr. R. Graff
Service Commun de RMN
Universit e¬ Louis Pasteur
1
22 (4), 92 (4), 74 (16).
19] S. C. Berk, M. C. P. Yeh, N. Jeong, P. Knochel, Organometallics 1990,
, 3053 ± 3064.
[
9
1, rue Blaise Pascal, 67000 Strasbourg (France)
2760
¹ WILEY-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002
1433-7851/02/4115-2760 $ 20.00+.50/0
Angew. Chem. Int. Ed. 2002, 41, No. 15