Molecular library obtained by allene insertion into the Pd-C bond of cyclopalladated complexes: Biological and pharmacological evaluation

Article abstract of DOI:10.1002/ejoc.200300776

A minilibrary of cationic N-heterocycles has been prepared and evaluated. The potential for the preparation was a result of the high versatility of palladium-mediated chemistry. The synthesis of the novel molecules was based on intramolecular quaternization of tertiary amine attached allylpalladium complexes. The steric and electronic factors of the reaction are discussed. The structures of the synthesized molecules made them candidates for precise biological and pharmacological evaluations. Of the various N-heterocyclic compounds, 2,2-dimethyl-3-methylenenaphtho[de/]quinolizinium showed antibacterial activity at micromolar concentrations. This compound also proved to be a nanomolar competitive antagonist for the channel site of the nicotinic acetylcholine receptor. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.

Full text of DOI:10.1002/ejoc.200300776

FULL PAPER
Molecular Library Obtained by Allene Insertion into the Pd؊C Bond of
Cyclopalladated Complexes: Biological and Pharmacological Evaluation
Claude Sirlin,*[a] Jaganaiden Chengebroyen,[a] Renato Konrath,[a] Günther Ebeling,[a]
Imad Raad,[a] Jairton Dupont,[b] Marie Paschaki,[c] Florence Kotzyba-Hibert,[c]
Colette Harf-Monteil,[d] and Michel Pfeffer*[a]
Dedicated to Prof. J. Vicente, University of Murcia, on the occasion of his 60th birthday
Keywords: Allenes / Antibiotics / N-heterocycles / Nicotinic receptor / Palladium
A minilibrary of cationic N-heterocycles has been prepared
and evaluated. The potential for the preparation was a result
of the high versatility of palladium-mediated chemistry. The
synthesis of the novel molecules was based on intramolecular
quaternization of tertiary amine attached allylpalladium
complexes. The steric and electronic factors of the reaction
are discussed. The structures of the synthesized molecules
logical evaluations. Of the various N-heterocyclic com-
pounds, 2,2-dimethyl-3-methylenenaphtho[def]quinolizin-
ium showed antibacterial activity at micromolar concentra-
tions. This compound also proved to be a nanomolar compet-
itive antagonist for the channel site of the nicotinic
acetylcholine receptor.
( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
made them candidates for precise biological and pharmaco- Germany, 2004)
Introduction
aration of a series of cationic N-heterocycles starting from
cyclopalladated tertiary amines.[3aϪ3d] We chose to investi-
Among palladium-mediated syntheses, reactions involv- gate the reactions between these organopalladium com-
ing cyclopalladated derivatives[1aϪ1c] open the route to mo- pounds and allenes, as such reactions seemed to afford the
lecular libraries that might be of interest to biologists or expected CϪC and CϪN bonds more readily than with
physicists. A huge number of cyclopalladated complexes other reactants. The palladium-mediated and -catalysed re-
have indeed been obtained by simple intramolecular CϪH actions of allenes have been reviewed recently.[4] Using a
bond activation. Moreover, the palladiumϪcarbon bond different strategy from ours, Larock and others[5aϪ5g] syn-
displays a richness of reactivity toward various substrates. thesized several N-heterocyclic compounds by means of a
The consequence is the potential for the synthesis of a wide Pd0-catalysed reaction between N-containing aryl units
range of novel organic or organometallic compounds. In with ortho-iodo substituents and a selection of allenes.
line with this strategy, we have previously described the
The series of N-heterocyclic compounds prepared were
preparation of some imine-allylpalladium complexes and evaluated as antibiotics and nicotinic acetylcholine receptor
their intramolecular reaction behaviour.[2aϪ2c] We now wish ligands. On the one hand, nosocomial infections[6] are a
to report on the application of the process to the prep- major problem in antibacterial therapy, and a problem only
likely to be solved by the discovery of new active molecules.
[a]
´
`
´
Universite Louis Pasteur, Laboratoire de Syntheses Metallo-
On the other hand, the finding of selective and powerful
agonists and antagonists of the nicotinic acetylcholine re-
ceptor (nAChR)[7] might be of considerable therapeutic im-
portance for the treatment of diseases such as congenital
myasthenia gravis,[8] Alzheimer’s syndrome and memory
impairment.[9]
´
induites, UMR CNRS 7513, Faculte de Chimie,
4 rue Blaise Pascal, 67070 Strasbourg, France
Fax: (internat.) ϩ33-3-90241526
E-mail: pfeffer@chimie.u-strasbg.fr
sirlin@chimie.u-strasbg.fr
[b]
[c]
Laboratorio de Sintese Assimetrica, IQ/UFRGS,
Av. Bento Gonc¸alves, 9500 Porto Alegre, Brazil
´
Universite Louis Pasteur, Laboratoire de Chimie Bioorganique,
UMR CNRS 7514,
Results and Discussion
´
Faculte de Pharmacie,
74 route du Rhin, 67401 Illkirch, France
[d]
´
Synthesis
Universite Louis Pasteur, Laboratoire de Toxinologie et
´
´
Antibiologie Bacteriennes, EA 1318, Institut de Bacteriologie
To perform an intramolecular reaction between the ter-
´
´
de la Faculte de Medecine,
tiary amines and the attached (η3-allyl)palladium com-
´
3 rue Koeberle, 67000 Strasbourg, France
1724
 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
DOI: 10.1002/ejoc.200300776
Eur. J. Org. Chem. 2004, 1724Ϫ1731

A Molecular Library Through Allene Insertion into a PdϪC Bond
FULL PAPER
plexes as depicted in Scheme 1, a series of cyclopalladated
For the preparation of the N-heterocycles, procedure A
complexes (see Figure 1) was treated with three different all- was used in general, the cyclopalladated complexes and the
enes [3-methyl-1,2-butadiene (1), 3-methoxy-1,2-propadiene allenes being allowed to react in CH2Cl2 or in MeOH. In
(2) and 1,2-heptadiene (3)].[2c]
some cases, however, this procedure failed or required
longer times to be complete. From previous results,[2c] we
also used procedure B: the reaction was performed in the
presence of triphenylphosphane in MeOH or in PhCl. The
yields of hexafluorophosphate salts were usually better, but
the isolation of halide salts was required for the bacterio-
logical assays. We thus selectively obtained the 3-alkylidene-
quinoliums 14؊16, benzo[c]azocinium 17 and 5-alkylidene-
aziniums 18؊23 (see Figure 2). Compound 24 has been de-
scribed previously.[2c] Such structures have hardly been en-
countered before in the literature.[13aϪ13g]
Regio- and Stereoisomerism
Scheme 1
Two reactions performed in CH2Cl2 were repeated in
MeOH. Whereas the cyclopalladated compound 10 had
given rise to the formation of the 5-isopropylideneazinium
20 in CH2Cl2, the same reaction in MeOH yielded a 2:3
mixture of 20 and its regioisomer, the 5-methyleneazinium
20Ј. From the organopalladium complex 9 in CH2Cl2 we
obtained only the 5-(isopropylidene)trimethylazinium 19,
while in MeOH a 1:1 mixture of the two regioisomers [19
and the 5-(methylene)pentamethylazinium 19Ј] was ob-
tained (see Scheme 2).
In MeOH the PdϪCl bond of the (π-allyl)palladium in-
termediate is more prone to dissociation, resulting in a cat-
ionic Pd complex. The consequence is an increase in the
positive charge at the more substituted terminus carbon of
the π-allyl moiety. As a consequence, nucleophilic attack of
the nitrogen atom at this carbon should be preferred. This
behaviour has often been observed in related reac-
tions.[5a][14a][14b] In the case of tertiary amine derivatives,
however, NϪC bond formation is hampered by the signifi-
cant hindrance resulting from the occurrence of an
NϩMe2ϪCMe2 unit, resulting in mixtures of regioisomers.
When the same reactions were performed in CH2Cl2, the
previous electronic factors were much less important. The
NϪC bond formation between the tertiary amines and the
allylpalladium units was mainly governed by steric repul-
sions between the more substituted allylic carbon and the
dimethylamine fragment. This resulted in the selective for-
mation of compounds 19 and 20.
Figure 1. Structures of the various cyclopalladated starting com-
plexes
As depicted in Table 1, 3-methyl-1,2-butadiene (1) gave
The cyclopalladated benzyl- and naphthylamines 4؊7 higher yields than 3-methoxy-1,2-propadiene (2) and 1,2-
were prepared by described procedures,[10aϪ10e] while the heptadiene (3). With these last two allenes an (E)/(Z) mix-
cyclic [(dimethylamino)propene]palladium complexes 8؊13 ture of compounds was obtained, with the (E) isomer al-
were synthesized by chloro- or bromopalladation of the ways predominant.
corresponding propargylamines,[11] these in turn being pre-
This result may be explained by the nature of the interac-
pared by standard procedures. Although the Mannich reac- tions between the fragment attached to the central allylic
tion was a good synthetic route to acetylenic amines, acety- carbon atom and the substituents located at the terminus
lenes bearing aryl-substituted groups were difficult to pre- carbon atom of the allylic fragment (see Scheme 3). Indeed,
pare. Sonogashira coupling[12aϪ12c] (providing complexes 12 it is well known that the allylpalladium complexes exist as
and 13) proved to be a useful alternative for the preparation equilibrium mixtures of both the syn and anti compounds.
of such propargylamines.
The thermodynamically favoured isomer is that with the R
Eur. J. Org. Chem. 2004, 1724Ϫ1731
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C. Sirlin, M. Pfeffer et al.
FULL PAPER
Figure 2. Structures of the various cationic N-heterocyclic compounds obtained
Scheme 3
Scheme 2
In Vitro Susceptibility of Aerobic Bacteria
Table 1. Influence of the nature of the allene on the yield and on
the stereochemistry
According to NCCLS guidelines, four reference strains
were used: Escherichia coli ATCC 25922, Staphylococcus
aureus ATCC 2913, Bacillus subtilis ATCC 6633 and Enter-
ococcus faecalis ATCC 29212. In addition, two clinical
strains were selected: Micrococcus sp. and Corynebacterium
sp. With the cationic N-heterocycles prepared, no growth
inhibition was observed by the diffusion[15a][15b] or di-
Compound 14 14a 14b 15 15a 19 19a 20 20a
Yield (%)
(E)/(Z)
85 41
49
91 55
15:2
78 70
2:1
76 65
E
11:1 20:1
fragment in the syn position. Despite this preference, the lution[16a,16b] methods with E. coli, E. faecalis or B. subtilis
reaction usually takes place, for steric reasons, on the minor at any tested concentration. Growth inhibition was only ob-
anti isomer; the (E) configuration is then obtained. Similar served for compound 24 at 150 mg with Micrococcus sp and
selectivities, though less clear-cut, have been observed by Corynebacterium sp. The N-heterocycle 24 had a MIC[17] of
Larock.[5c]
120 µ with Micrococcus sp, 240µ with Corynebacterium
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Eur. J. Org. Chem. 2004, 1724Ϫ1731

A Molecular Library Through Allene Insertion into a PdϪC Bond
FULL PAPER
sp and 1 m with S. aureus. The compound was bacteri- (Ki) were determined from [3H]-PCP binding inhibition at
cidal[18] for S. aureus at 1 m, while a decrease of 3 log equilibrium by the three best ligands (10 nM to 0.5 m) for
units was achieved with Corynebacterium sp.
the NBC binding site[22] (see Table 3).
The affinities for the NCB binding site were in the micro-
molar range, while the affinity for the ACh binding site was
50 times lower (ca. 50 µ). Compound 24 showed a high
affinity for the NCB site (0.5 µ). Moreover, its affinity for
the NCB binding site was two orders of magnitude (ratio
of 144) higher than for the ACh site. All the N-heterocycles
tested have a quaternary ammonium moiety, which may ex-
plain why they all show affinity for the two ACh and NCB
binding sites. In the case of the ACh binding site, steric
hindrance might explain the moderate affinity (ca. 50 µ).
In the case of the NCB binding site, the more hydrophobic
the molecule, the better the affinity, as well as the selectivity
for this site in relation to that for the ACh site. This is es-
pecially true for compound 24.
Nicotinic Receptor Binding Properties
The nicotinic acetylcholine receptor (nAChR)[19] con-
tains a cation-selective ion channel, the opening of which is
regulated by the binding of acetylcholine (ACh). In ad-
dition to that binding site for ACh and competitive antag-
onists such as tubocurare, nAChRs contain a distinct allos-
teric antagonist site located within the ion channel. The new
N-heterocycles were tested on the two binding sites located
on the nAChR from the Torpedo marmarata electric organ:
the ACh and the NCB binding sites. Inhibition properties
of the ACh binding site were derived from [125I]-α-bungaro-
toxin initial rate binding inhibition with the tested ligands
at 10 µ. Inhibition properties of the NBC binding site were
determined from [3H]-PCP binding inhibition at equilib-
rium with the tested ligands at 1 µ. The results are col-
lected in Table 2.
Conclusion
Table 2. Inhibition of the ACh-binding site derived from [125I]-α-
bungarotoxin initial rate binding inhibition; inhibition of the NBC-
binding site derived from [3H]-PCP binding inhibition at equilib-
rium
A series of quaternized N-heterocycles has been prepared
by insertion of allenes into the PdϪC bonds of various
cyclopalladated tertiary amines. Depending on the solvent
and reactants, the C2 unit insertion reaction was regio- and
stereoselective. These selectivities were functions of both
steric and electronic factors. The potential of the molecular
library was examined in the field of life sciences; 2,2-di-
Compound
ACh Binding site (%)
NBC Binding site (%)
14
15
16
17
19
20
21
22
23
24
33
49
24
7
26
28
18
48
33
54
37
72
75
63
39
55
60
57
63
79
methyl-3-methylenenaphto[def]quinolizinium
displayed
antibacterial activity, though at higher than usual antibiotic
concentrations. Pharmacological measurements were more
encouraging. Selective binding to the distinct binding sites
of the nicotinic receptor was obtained with two molecules
from the library, 2,2-dimethyl-3-methylenenaphto[def]quin-
olizinium showing an affinity (500 nM) similar to that of
PCP, the reference ligand used in this study. This cationic
N-heterocycle might be used as a lead for the design of new
drugs in the future.
At 10 µ, three compounds inhibited about 50% of the
ACh binding, while the other inhibited 30%. The eight-
membered ring heterocycle 17 was the poorest inhibitor.[20]
At 1 µ, most of the compounds inhibited more than 50%
of the binding to NCB. Three compounds inhibited more
than 70% of this binding. Protection constants (Kp) (see
Experimental Section
General Remarks: Solvents (CH2Cl2, MeOH, Et2O and hexane)
were dried beforehand and distilled under argon. The different all-
enes were prepared as described previously.[2c] 1H (300.13 or
200.13 MHz) and 13C (75.47 or 50.32 MHz) NMR spectra were
recorded with AC 300 or AC 200 Bruker instruments. The spectra
were externally referenced to tetramethylsilane. The coupling con-
stants are expressed in Hz. Abbreviations: Ar aromatic, br. broad,
quat. quaternary. The amounts of crystallization solvent were de-
Table 3. Protection constants (Kp) derived from [125I]-α-bungaro-
toxin initial rate binding inhibition by the tested ligands (10 nM to
0.5 m) for the ACh-binding site; inhibition constants (Ki) from
[3H]-PCP binding inhibition at equilibrium by the tested ligands
(10 nM to 0.5 m) for the NBC-binding site
Compound ACh-Binding site Kp (µ) NBC-Binding site Ki (µ)
1
termined by H NMR spectroscopy. IR spectra were recorded on
an IRFT Bruker instrument. Melting points were measured with a
Köfler bank (melting points of hexafluorophosphate salts exceeded
250 °C). Combustion analyses were performed by the Service cen-
15
16
22
24
55
Ϫ
59
72
1.6
1.5
Ϫ
0.5
´
tral de microanalyses du CNRS, Universite Louis Pasteur, Stras-
bourg. The mass spectra were carried out by the Laboratoire de
´
spectroscopie de masse de l’Universite Louis Pasteur, Strasbourg.
Table 3) were obtained from [125I]-α-bungarotoxin initial
rate binding inhibition by the three best ligands (10 nM to
(2-Butynyl)dimethylamine: The apparatus used to generate pro-
0.5 m) for the ACh binding site.[21] Inhibition constants pyne[23] consists of a two-necked, round-bottomed, 500 mL flask
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C. Sirlin, M. Pfeffer et al.
FULL PAPER
fitted with a magnetic stirring bar, a dropping funnel and a reflux
condenser. The flask was charged with 1-butanol (180 mL) and
potassium hydroxide (75 g), a gentle reflux being maintained. 1,2-
Dibromopropane (67 g, 0.33 mol) was placed in the dropping fu-
nnel. In a second two-necked, round-bottomed flask, fitted with a
magnetic stirring bar and a cold finger condenser, was placed a
mixture of paraformaldehyde (6.3 g, 0.21 mol), dimethylamine
(40% aqueous solution, 26 mL, 0.21 mol) and cuprous iodide
(500 mg) in diglyme (35 mL). The temperature was maintained be-
tween 70 and 75 °C. The dibromide was added to the refluxing
BuOH/KOH and the resulting propyne was bubbled under the sur-
face of the second reaction mixture. The rate of addition of the
dibromide was adjusted according to the rate of reflux of the pro-
pyne (b.p. Ϫ23 °C) at the cold finger (filled with dry-ice/acetone).
The addition was complete in 3 hours. The material from the se-
cond flask was distilled, and the fraction boiling between 80 and
125 °C was collected. This distillate was treated with KOH, filtered
and distilled again. A colourless liquid was obtained (10 g, yield
122.9, 118.9, 118.5 (Ar ϩ olefinic), 65.8 (CH2), 55.3 (NCH3), 23.1
and 21.8 [C(CH3)2] ppm.
Hexafluorophosphate 15a: The compound was obtained from 3-
methoxy-1,2-propadiene (2); recrystallization from CH2Cl2/diethyl
ether, yield 55 mg, 55%. C16H18F6NOP ϩ 1/2CH2Cl2: calcd. C
46.32, H 4.44, N 3.27; found C 45.99, H 4.21, N 2.89. 15:2 Mixture
1
1
of (E) and (Z) isomers as measured by H NMR spectroscopy. H
NMR ([D6]acetone, (E) isomer, characteristic signals): δ ϭ 8.41
3
4
3
(dd, J ϭ 7.5, J ϭ 0.9, 1 H, Ar), 8.21 (t, J ϭ 7.3, 1 H, Ar), 8.05
(d, 3J ϭ 8.3, 1 H, Ar), 7.08 (s, 1 H, CHOCH3), 4.69 (s, 2 H, NCH2),
4.06 (s, 3 H, OCH3), 3.83 (s, 6 H, NCH3) ppm; [(Z) isomer, charac-
teristic signals]: δ ϭ 7.91 (d, 3J ϭ 8.8, 1 H, Ar), 4.88 (s, 2 H,
NCH2), 4.03 (s, 3 H, OCH3); 3.90 (s, 6 H, NCH3) ppm.
Compound 16PF6: Yield 84 mg, 83%. C17H24F6NP: calcd. C 52.71,
H 6.20, N 3.62; found C 52.75, H 6.16, N 3.50. 1H NMR ([D6]ace-
tone): δ ϭ 7.41Ϫ7.37 (m, 2 H, Ar), 7.20 (t, 3J ϭ 4.4, 1 H, Ar), 4.90
3
(dd, J ϭ 10.7, 6.2, 1 H, NCH), 4.62 (s, 2 H, NCH2), 3.57 (s, 3 H,
1
5
52%). B.p. 116Ϫ125 °C. H NMR (CDCl3): δ ϭ 3.13 (q, J ϭ 2.4,
2 H, CH2), 2.25 (s, 6 H, 2 NCH3), 1.81 (t, 5J ϭ 2.4, 3 H, CH3) ppm.
NCH3), 2.84 (s, 3 H, NCH3), 2.95Ϫ2.71 (m, 2 H, CH2Ar),
2.70Ϫ2.55 (m, 1 H, α CH2), 2.25Ϫ1.78 (m, 3 H, αϩβ CH2), 2.11
[s, 3 H, C(CH3)2] and 1.96 [s, 3 H, C(CH3)2] ppm. 13C NMR ([D6]a-
cetone): δ ϭ 138.8, 136.6, 133.4, 128.7, 128.5, 127.4, 127.3, 119.6
(Ar ϩ olefinic), 69.7 (NCH), 66.7 (NCH2), 52.6, 44.7 and 28.6
(CH2), 23.2 and 23.1 (NCH3), 21.2 and 20.9 [C(CH3)2] ppm.
Dimethyl(3-phenyl-2-propynyl)amine: Anhydrous dimethylamine
(13.4 g, 0.3 mol) was added to a stirred mixture of phenylacetylene
(20.4 g; 0.2 mol), paraformaldehyde (6.6 g, 0.22 mol) and cuprous
iodide (200 mg) in dioxane (40 mL, exothermic reaction). The reac-
tion mixture was heated at reflux for 3 h, and the solvent was re-
moved in vacuo. Distillation of the residue afforded a colourless
liquid (28 g, yield 88%). B.p.5 114 °C. 1H NMR (CDCl3): δ ϭ
7.46Ϫ7.38 (m, 2 H, Ar), 7.33Ϫ7.23 (m, 3 H, Ar), 3.45 (s, 2 H,
NCH2), 2.35 (s, 6 H, 2 NCH3) ppm.
Compound 17PF6: Yield 83 mg, 65%. C20H26F6NO4P ϩ H2O: calcd.
C 47.34, H 5.52, N, 2.76; found C 47.26, H 5.12, N 2.69. 1H NMR
([D6]acetone): δ ϭ 7.84 (dd, 3J ϭ 7.6, 4J ϭ 1.7, 1 H, Ar), 7.67Ϫ7.54
2
2
(m, 3 H, Ar), 4.91 (d, J ϭ 13.5, 1 H, NCH), 4.72 (t, J ϭ 14.0, 2
2
H, NCH2), 4.22 (d, J ϭ 13.5, 1 H, NCH), 3.83 (s, 3 H, OCH3),
3.80 (s, 3 H, OCH3), 3.70 (s, 3 H, NCH3), 3.12 (s, 3 H, NCH3),
1.83 [s, 3 H, C(CH3)2], 1.59 [s, 3 H, C(CH3)2] ppm. 13C NMR
([D6]acetone): δ ϭ 167.8 and 165.5 (CO), 147.7, 142.1, 137.4, 136.5,
136.0, 131.6, 130.5, 128.8, 128.2, 117.4 (Ar ϩ olefinic), 66.1 and
63.5 (NCH2), 56.8 and 49.2 (OCH3), 53.2 and 53.0 (NCH3), 22.1
and 21.2 [C(CH3)2] ppm. IR (KBr pellet): ν˜ ϭ 1723, 1706 (CO)
Dimethyl[3-(3,4-diethoxycarbonylphenyl)-2-propynyl]amine: A mix-
ture of diethyl 4-bromophthalate[24] (8.1 g, 27 mmol), propargyldi-
methylamine (2.7 g, 32 mmol), bis(triphenylphosphane)palladium
dichloride (18 mg), cuprous iodide (36 mg) and triphenylphos-
phane (36 mg) in triethylamine (30 mL) was heated under reflux
for 4 hours.[12aϪ12c] Diethyl ether (50 mL) was then added, and the
resulting solution was washed twice with aqueous sodium hydrox-
ide solution (20%, 40 mL). Drying with MgSO4 and evaporation
cmϪ1
.
b) A solution of 3-methyl-1,2-butadiene (1, 53 mg, 0.78 mmol) in
CH2Cl2 (3 mL) was added to a stirred solution of 10 (250 mg,
0.37 mmol) in CH2Cl2 (10 mL). The colour of the solution changed
rapidly from yellow to black. Stirring was continued at room temp.
for an additional 2 h to ensure complete reaction. The mixture was
filtered through a Celite pad and the solvent was removed in vacuo.
After the addition of water (5 mL), the resulting solution was fil-
tered and KPF6 (180 mg, 1 mmol) was added, affording 20 as a
pale yellow solid. This was filtered, washed with Et2O and dried
in vacuo.
1
of the solvent afforded a yellow oil (7.62 g, yield 95%). H NMR
(CDCl3): δ ϭ 7.82Ϫ7.50 (m, 3 H, Ar), 4.37 (q, 3J ϭ 7.1, 2 H,
3
OCH2), 4.35 (q, J ϭ 7.1, 2 H, OCH2), 3.48 (s, 2 H, NCH2), 2.36
3
3
(s, 6 H, 2 NCH3), 1.37 (t, J ϭ 7.1, 3 H, CH3), 1.36 (t, J ϭ 7.1, 3
H, CH3) ppm.
Dimethyl[3-(4-nitrophenyl)-2-propynyl]amine: The ligand was pre-
pared as above.[12aϪ12c] Quantitative yield. 1H NMR (CDCl3): δ ϭ
3
3
8.18 (d, J ϭ 8.9, 2 H, Ar), 7.56 (d, J ϭ 8.9, 2 H, Ar), 3.51 (s, 2
H, NCH2), 2.39 (s, 6 H, 2 NCH3) ppm.
Compound 20PF6: Yield 230 mg, 76%. C16H21ClF6NP: calcd. C
47.13, H 5.19, N 3.43; found C 47.13, H 5.26, N 3.39. 1H NMR
([D6]acetone): δ ϭ 7.53Ϫ7.22 (m, 5 H, Ar), 4.49 (s, 4 H, NCH2),
3.43 (s, 6 H, NCH3), 1.93 [s, 3 H, C(CH3)2], 1.22 [s, 3 H, C(CH3)2]
ppm. 13C NMR ([D6]acetone): δ ϭ 145.9, 138.9, 137.0, 122.2, 119.8
(Cquat.), 130.1, 129.4, 128.9 (CHAr), 65.8 and 63.6 (NCH2), 52.9
(NCH3), 24.0 and 23.4 [C(CH3)2] ppm.
Cationic Heterocycles Synthesis. General Procedure A: a) A solution
of 5 (82 mg, 0.13 mmol) and 3-methyl-1,2-butadiene 1 (23 mg,
0.33 mmol) in CH2Cl2 (10 mL) was stirred for 16 h at room temp.
After filtration through a Celite pad, the filtrate was evaporated to
dryness, leaving a brownish yellow residue. Extraction with water
and addition of 1 equivalent of KPF6 (49 mg, 0.26 mmol) yielded
a white precipitate. This was dried in vacuo.
When the reaction was performed in MeOH, the result was a 2:3
mixture of 20 and its regioisomer 20Ј; total yield 80%. 20Ј: 1H
NMR ([D6]acetone): δ ϭ 7.53Ϫ7.22 (m, 5 H, Ar), 5.73 and 4.99
(2s, 2 H, ϭCH2), 4.79 (s, 2 H, NCH2), 3.39 (s, 6 H, NCH3), 1.83
(s, 6 H, CH3) ppm.
Compound 15PF6: Yield 91 mg, 91%. C17H20F6NP: calcd. C 53.26,
H 5.22, N 3.66; found C 53.59, H 5.22, N 3.59. 1H NMR ([D6]ace-
3
3
tone): δ ϭ 8.26 (d, J ϭ 7.8, 1 H, Ar), 8.21 (d, J ϭ 8.3, 1 H, Ar),
3
3
8.08 (d, J ϭ 8.2, 1 H, Ar), 7.87 (d, J ϭ 7.2, 1 H, Ar), 7.80Ϫ7.74
(m, 2 H, Ar), 4.97 (s, 2 H, ϭCH2), 3.92 (s, 6 H, NCH3), 2.32 [s, 3
H, C(CH3)2], 2.29 [s, 3 H, C(CH3)2] ppm. 13C NMR ([D6]acetone):
δ ϭ 143.2, 141.4, 134.8, 131.4, 130.0, 128.1, 127.6, 127.2, 126.1,
Compound 20a: The compound was obtained from the 3-methoxy-
1,2-propadiene (2); yield 195 mg, 65%. C15H19ClF6NOP: calcd. C
1728
 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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Eur. J. Org. Chem. 2004, 1724Ϫ1731

A Molecular Library Through Allene Insertion into a PdϪC Bond
FULL PAPER
43.97, H 4.67, N 3.42; found C 43.84, H 4.68, N 3.51. 1H NMR NMR (CDCl3): δ ϭ 8.36 (d, J ϭ 7.9, 1 H, Ar), 7.97 (d, J ϭ 8.2,
([D6]acetone): δ ϭ 7.49Ϫ7.45 (m, 3 H, Ar), 7.37Ϫ7.28 (m, 2 H,
3
3
3
4
1 H, Ar), 7.85 (dd, J ϭ 7.8, J ϭ 1.4, 1 H, Ar), 7.69Ϫ7.60 (m, 3
Ar), 6.22 (s, 1 H, CHOCH3), 4.56 (s, 2 H, NCH2), 4.52 (s, 2 H, H, Ar), 5.00 (s, 2 H, NCH2), 4.13 (s, 6 H, NCH3), 2.43 [s, 3 H,
NCH2), 3.72 (s, 3 H, OCH3), 3.55 (s, 6 H, NCH3) ppm. 13C NMR C(CH3)2], 2.23 [s, 3 H, C(CH3)2] ppm. 13C NMR (CDCl3): δ ϭ
([D6]acetone): δ ϭ 154.4 (CHOCH3), 153.1, 134.8, 128.5, 115.2
(Cquat.), 130.2, 129.5, 129.4 (CHAr), 65.4 and 58.7 (NCH2), 61.7 126.5, 126.2, 119.5 (CHAr), 65.5 (NCH2), 55.4 (NCH3), 23.7 and
(OCH3), 52.6 (NCH3) ppm.
143.7, 141.1, 134.1, 129.7, 122.4, 118.1 (Cquat.), 130.7, 127.6, 126.9,
23.6 [C(CH3)2] ppm. IR (KBr pellet): ν˜ ϭ 1638 (CϭC) cmϪ1
.
Compound 19PF6: Yield 200 mg, 78%. C11H19ClF6NP: calcd. C
38.22, H 5.54, N 4.05; found C 37.08, H 5.41, N 3.91. 1H NMR
([D6]acetone): δ ϭ 4.36 (s, 2 H, NCH2), 4.32 (br. s, 2 H, NCH2),
Compound 17Cl: Yield 468 mg, 77%. M.p. 160Ϫ161 °C.
C20H26ClNO4 ϩ 2H2O: calcd. C 57.75, H 7.27, N 3.36; found C
1
3
57.90, H, 6.97, N 2.76. H NMR (CDCl3): δ ϭ 8.16 (dd, J ϭ 5.9,
5
2
3.35 (s, 6 H, NCH3), 2.18 (t, J ϭ 2.0, 3 H, CCH3), 2.06 [s, 3 H,
1 H, Ar), 7.60Ϫ7.48 (m, 3 H, Ar), 5.10 (d, J ϭ 13, 1 H, NCH),
C(CH3)2], 1.98 [s, 3 H, C(CH3)2] ppm. 13C NMR ([D6]acetone):
δ ϭ 143.9, 132.2, 121.7, 120.7 (Cquat.), 65.7 and 63.5 (NCH2), 52.9
(NCH3), 24.2, 23.2 and 20.1 (CH3) ppm.
2
2
5.03 (d, J ϭ 13, 1 H, NCH), 4.39 (d, J ϭ 13.4, 1 H, NCH), 3.97
(s, 3 H, NCH3), 3.87 (s, 6 H, OCH3), 3.65 (d, 2J ϭ 13.4, 1 H,
NCH), 3.36 (s, 3 H, NCH3), 1.84 (1s, 3 H, C(CH3)2], 1.60 [s, 3 H,
C(CH3)2] ppm. 13C NMR (D2O): δ ϭ 169.3 and 167.1 (CO), 149.2,
140.8, 136.9, 135.3, 127.6, 114.6 (Cquat.), 135.2, 130.9, 130.1, 127.6
(CHAr) 65.4 and 62.7 (NCH2), 56.2 and 48.5 (OCH3), 53.7 and
53.6 (NCH3), 21.3 and 20.5 [C(CH3)2] ppm. IR (KBr pellet): ν˜ ϭ
When the reaction was performed in MeOH, a 1:1 mixture of 19
and its regioisomer 19Ј was obtained in a total yield of 80%. 19Ј:
1H NMR ([D6]acetone): δ ϭ 5.78 and 5.77 (2s, 2 H, ϭCH2), 4.52
(br. s, 2 H, NCH2), 3.34 (s, 6 H, NCH3), 2.15 (t, 5J ϭ 1.8, 3 H,
CCH3), 1.78 (s, 6 H, CH3) ppm.
1734 and 1706 (CO), 1631 (CϭC) cmϪ1
·
Chloride 18: Yield 335 mg, 82%. C15H27ClN ϩ 2H2O: calcd. C
54.87, H 9.52, N 4.27; found C 54.81, H 9.46, N 4.14. 1H NMR
([D6]acetone): δ ϭ 4.43 (q, 3J ϭ 6.1, 1 H, NCH), 4.38 (d, 2J ϭ
13.0, 1 H, NCH), 4.20 (d, 2J ϭ 13.0, 1 H, NCH), 3.36 (s, 3 H,
NCH), 3.13 (s, 3 H, NCH3), 2.68 (t, 2 H, α CH2), 2.04 [s, 3 H,
C(CH3)2], 1.98 [s, 3 H, C(CH3)2], 1.70 (d, 3 H, NCHCH3),
Compound 19a: This compound was obtained from 3-methoxy-1,2-
propadiene (2). Yield 180 mg, 70%. C10H17ClF6NOP: calcd. C
34.55, H 4.93, N 4.03; found C 34.29, H 4.80, N 3.90. 2:1 mixture
1
1
of (E) and (Z) isomers as measured by H NMR spectroscopy. H
NMR ([D6]acetone); (E) isomer: δ ϭ 6.56 (s, 1 H, CHOCH3), 4.34
(m, 4 H, NCH2), 3.84 (s, 3 H, OCH3), 3.31 (s, 6 H, NCH3), 2.23
(t, 5J ϭ 2.0, 3 H, CCH3) ppm; (Z) isomer: δ ϭ 7.01 (s, 1 H,
CHOCH3), 4.36 (m, 4 H, NCH2), 3.86 (s, 3 H, OCH3); 3.39 (s, 6
3
1.56Ϫ1.28 (m, 4 H, β and γ CH2), 0.89 (t, J ϭ 7.0, 3 H, δ CH3)
ppm. 13C NMR ([D6]acetone): δ ϭ 137.7, 132.1, 121.7 114.0
(Cquat.), 65.7 (NCH), 57.9 (NCH2), 48.7 and 43.9 (NCH3), 27.4,
25.4 and 18.2 (CH2), 20.1 and 19.4 [C(CH3)2], 10.1 (NCHCH3),
9.28 (CH3) ppm.
5
H, NCH3), 2.05 (t, J ϭ 1.8, 3 H, CCH3) ppm.
c) The cyclopalladated complex 6 (500 mg, 0.8 mmol) and 3-
methyl-1,2-butadiene (1, 2.5 equiv., 134 mg, 2 mmol) in dichloro-
methane (20 mL) were stirred overnight at room temp. A black,
heterogeneous mixture was obtained. The black metallic palladium
produced was filtered off, and the yellow filtrate was concentrated
and treated with water. After filtration of the resulting solution,
water was evaporated, and the residue was dried in vacuo. The
cationic heterocycle was recrystallized as a chloride salt from
chloroform/diethyl ether.
General Procedure B
a) Under argon, the cyclopalladated complex
4 (70 mg,
0.13 mmol), 3-methyl-1,2-butadiene (1) (22 mg, 0.32 mmol) and tri-
phenylphosphane (240 mg, 0.9 mmol) in methanol (15 mL) were
stirred at room temp. for 2 hours. A fine yellow precipitate of
[Pd(PPh3)4] was obtained. After filtration, the remaining solution
was evaporated to dryness, leaving a yellow, oily residue. The ad-
dition of one equivalent of KPF6 to a water solution of this oil
yielded the expected heterocyclic compound as a solid.
Compound 16Cl: Yield 288 mg, 65%. M.p. 144Ϫ145 °C. C17H23ClN
ϩ 2H2O: calcd. C 65.05, H 9.00, N 4.46; found C 65.70, H 8.33,
1
N 4.38. H NMR (CDCl3): δ ϭ 7.39Ϫ7.28 (m, 2 H, Ar), 7.14 (dd,
2
3
3J ϭ 6.9, 1 H, Ar), 4.94 (d, J ϭ 14.6, 1 H, NCH), 4.74 (dd, J ϭ
Compound 14PF6: 77 mg, 85%. C14H20F6NP: calcd. C 48.41, H 5.76,
3
2
N 4.03; found C 48.66, H 5.73, N 3.94. 1H NMR ([D6]acetone):
9.5, J ϭ 6.7, 1 H, NCH), 4.62 (d, J ϭ 14.6, 1 H, NCH), 3.80 (s,
3 H, NCH3), 2.88 (s, 5 H, NCH3 and ArCH2), 2.63 (m, 1 H, α
CH), 2.21 (m, 1 H, α CH), 2.10 [s, 3 H, C(CH3)2], 2.02 [s, 3 H,
C(CH3)2], 1.83 (m, 2 H, β CH2) ppm. 13C NMR (CD3OD): δ ϭ
138.0, 136.7, 133.0, 126.6, 118.9 (Cquat.), 128.2, 126.9 (CHAr), 69.3
(NCH), 66.5 (NCH2), 52.8 and 44.6 (NCH3), 28.6 (ArCH2), 23.6
and 22.3 [C(CH3)2], 23.4 and 20.6 (CH2) ppm. IR (KBr pellet): ν˜ ϭ
3
3
4
δ ϭ 7.48 (d, J ϭ 7.5, 1 H, Ar), 7.42 (td, J ϭ 6.5, J ϭ 1.8, 1 H,
Ar), 7.37Ϫ7.26 (m, 2 H, Ar), 4.67 (s, 2 H, NCH2), 4.36 (s, 2 H,
NCH2), 3.39 (s, 6 H, NCH3), 2.14 [s, 3 H, C(CH3)2], 2.04 [s, 3 H,
C(CH3)2] ppm. 13C NMR ([D6]acetone): δ ϭ 140.1, 133.0, 129.8,
128.8, 128.6, 128.0, 119.8 (Ar ϩ olefinic), 65.1 and 64.4 (NCH2),
53.0 (NCH3), 23.8 and 22.5 [C(CH3)2] ppm.
1637 (CϭC) cmϪ1
.
Hexafluorophosphate 14a: The heterocycle was obtained from 3-
methoxy-1,2-propadiene (2); yield 31 mg, 41%. C13H18F6NOP ϩ 1/
2CH2Cl2: calcd. C 41.39, H 4.89, N 3.58; found C 40.90, H 4.56,
N 3.34. 11:1 mixture of (E) and (Z) isomers as measured by 1H
Compound 14Cl: Yield 250 mg, 54%. M.p. Ͼ 250 °C. C14H20ClN ϩ
H2O: calcd. C 65.70, H 8.67, N 5.47; found C 64.30, H 8.57, N
1
3
5.39. H NMR (CDCl3): δ ϭ 7.47 (d, J ϭ 7.8, 1 H, Ar), 7.36 (td,
3J ϭ 7.8, J ϭ 1.5, 1 H, Ar), 7.30Ϫ7.24 (m, 2 H, Ar), 4.88 (s, 2 H,
4
1
NMR spectroscopy. H NMR ([D6]acetone, (E) isomer, character-
NCH2), 4.54 (s, 2 H, NCH2), 3.64 (s, 6 H, NCH3), 2.18 [s, 3 H,
C(CH3)2], 2.12 [s, 3 H, C(CH3)2] ppm. 13C NMR (CDCl3): δ ϭ
139.7, 132.0 (Cquat.), 128.9, 128.3, 128.0, 127.5 (CHAr), 64.9 and
64.3 (NCH2), 52.9 (NCH3), 23.8 and 22.8 [C(CH3)2] ppm. IR (KBr
3
3
istic signals): δ ϭ 8.25 (d, J ϭ 7.9, 1 H, Ar), 7.42 (td, J ϭ 7.6,
4J ϭ 1.6, 1 H, Ar), 7.33 (td, 3J ϭ 7.6, 4J ϭ 1.3, 1 H, Ar), 7.26 (dd,
3J ϭ 7.6, J ϭ 0.8, 1 H, Ar), 6.78 (s, 1 H, CHOCH3), 4.88 (s, 2 H,
4
NCH2), 4.34 (s, 2 H, NCH2), 3.96 (s, 3 H, OCH3), 3.38 (s, 6 H,
pellet): ν˜ ϭ 1637 (CϭC) cmϪ1
.
3
NCH3) ppm; [(Z) isomer, characteristic signals]: δ ϭ 7.75 (d, J ϭ
Compound 15I: Yield 445 mg, 76%. M.p. 214Ϫ215 °C. C17H20IN:
calcd. C 55.90, H 5.52, N 3.83; found C 56.03, H 5.50, N 3.63. H
8.8, 1 H, Ar), 7.51 (t, 1 H, Ar), 4.84 and 4.52 (2s, 4 H, NCH2),
3.93 (s, 3 H, OCH3), 3.43 (s, 6 H, NCH3) ppm.
1
Eur. J. Org. Chem. 2004, 1724Ϫ1731
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 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
1729

C. Sirlin, M. Pfeffer et al.
FULL PAPER
Hexafluorophosphate 14b: This compound was obtained from 1,2-
3J ϭ 8.0, 4J ϭ 1.5, 1 H, Ar), 4.77 (s, 2 H, NCH2), 4.64 (s, 2 H,
heptadiene (3). Yield 48 mg, 49%. C16H24F6NP: calcd. C 51.20, H NCH2), 4.35 (q, 3J ϭ 7.0, 2 H, OCH2), 4.34 (q, 3J ϭ 7.0, 2 H,
6.40, N 3.73; found C 50.26, H 6.09, N 3.59. 20:1 mixture of (E)
OCH2), 3.70 (s, 6 H, NCH3), 2.02 [s, 3 H, C(CH3)2], 1.35 (t, 6 H,
and (Z) isomers as measured by H NMR spectroscopy. H NMR 2 CH3), 1.21 [s, 3 H, C(CH3)2] ppm. 13C NMR (CDCl3): δ ϭ 167.0
1
1
3
([D6]acetone, (E) isomer, characteristic signals): δ ϭ 7.93 (d, J ϭ
(CO), 145.6, 140.5, 134.2, 132.8, 131.6, 123.3, 118.2 (Cquat.), 131.8,
129.4, 129.3 (CHAr), 65.0 and 62.6 (NCH2), 61.9 and 61.8 (OCH2),
3
7.6, 1 H, Ar), 7.50Ϫ7.37 (m, 2 H, Ar), 7.30 (d, J ϭ 6.4, 1 H, Ar),
4
6.81 (t, J ϭ 7.6, 1 H, CH), 4.92 (br. s, 2 H, NCH2), 4.66 (br. s, 2 52.2 (NCH3), 24.7 and 24.1 [C(CH3)2], 14.1 (CH3) ppm.
H, NCH2), 3.45 (s, 6 H, NCH3), 2.43Ϫ2.36 (m, 2 H, α CH2),
c) 3-Methyl-1,2-butadiene (1, 0.105 g, 1.5 mmol) was added to a
3
1.59Ϫ1.36 (m, 4 H, β and γ CH2), 0.94 (t, J ϭ 7.2, 3 H, δ CH3)
stirred suspension of the cyclopalladated complex 10 (0.336 g,
ppm; [(Z) isomer, characteristic signals]: δ ϭ 7.78 (br. d, 1 H, Ar),
0.5 mmol) in 5 mL of PhCl. A brown precipitate appeared. After
6.13 (br. t, 1 H, CH), 4.94 (br. s, 2 H, NCH2), 4.43 (br. s, 2 H,
3 min, triphenylphosphane (1.04 g, 4 mmol) was added, and the
NCH2), 3.43 (s, 6 H, NCH3) ppm.
precipitate dissolved, giving a dark solution. This slowly deposited
a new precipitate. Filtration after 30 min and washing with chloro-
benzene and hexane afforded a colourless solid after drying. It was
recrystallized from chloroform/diethyl ether.
Hexafluorophosphate 16a: The compound was obtained from 3-
methoxy-1,2-propadiene (2); yield 54 mg, 53%. C16H22F6NOP:
calcd. C 49.36, H 5.66, N 3.60; found C 49.61, H 5.63, N 3.44. 1:1
mixture of (E) and (Z) isomers as measured by 1H NMR spec-
troscopy. 1H NMR ([D6]acetone, (E) isomer, characteristic signals):
Compound 20Cl: Yield 215 mg, 72%. M.p. 230 °C (dec.).
C16H21Cl2N: calcd. C 64.43, H 7.10, N 4.70; found C 64.46, H
3
δ ϭ 8.11 (d, J ϭ 8.0, 1 H, Ar), 6.70 (s, 1 H, CHOCH3), 4.56 (d,
1
7.36, N 4.68. H NMR (D2O): δ ϭ 7.67Ϫ7.35 (m, 5 H, Ar), 4.33
2
2J ϭ 13.2, 1 H, NCH), 4.22 (d, J ϭ 13.2, 1 H, NCH), 3.94 (s, 3
(s, 2 H, NCH2), 4.28 (s, 2 H, NCH2), 3.25 (s, 6 H, NCH3), 1.91 [s,
H, OCH3), 3.02 (s, 3 H, NCH3), 3.01 (s, 3 H, NCH3) ppm; [(Z)
3
H, C(CH3)2], 1.23 [s, 3
H, C(CH3)2] ppm. 13C NMR
isomer, characteristic signals]: δ ϭ 7.54 (d, 3J ϭ 7.9, 1 H, Ar), 7.43
([D6]DMSO): δ ϭ 143.4, 137.7, 135.2, 121.4, 118.2 (Cquat.), 129.0,
128.4, 127.9 (CHAr), 63.8 and 61.3 (NCH2), 51.2 (NCH3), 23.4 and
23.2 [C(CH3)2] ppm.
2
2
(s, 1 H, CHOCH3), 4.73 (d, J ϭ 13.8, 1 H, NCH), 4.37 (d, J ϭ
13.8, 1 H, NCH), 3.91 (s, 3 H, OCH3), 3.59 (s, 3 H, NCH3), 3.54
(s, 3 H, NCH3) ppm.
Bacteriological Tests
b) 3-Methyl-1,2-butadiene (1, 0.105 g, 1.5 mmol) was added to the
palladacycle 12 (0.484 g, 0.5 mmol) dissolved in chlorobenzene
(5 mL). After 15 min, triphenylphosphane (1.04 g, 4 mmol) was ad-
ded, and the mixture was stirred overnight. Addition of hexane
(15 mL) afforded a yellow precipitate, which was filtered and ex-
tracted with water (2 ϫ 5 mL). After filtration, the water extract
was evaporated in vacuo, leaving an almost colourless solid.
Recrystallization from acetone/MeOH gave colourless crystals.
Stock solutions were obtained by dissolving the N-heterocycles in
water at concentrations of 200 mg/L and 2 mg/L. The solutions
were subsequently sterilized by membrane filtration (Millex 0.22
µm Millipore), and stored in sterile sealed glass vials at 4 °C. Sterile
disks were soaked with the different molecule solutions and dried
at 20 °C for 24 h. Antibacterial activity was tested by the diffusion
method[15a][15b] with soaked disks on Mueller-Hinton agar inocu-
lated with different bacteria strains (according to CA-SFM guide-
lines)[25a][25b] and by the dilution method[16a][16b] in Mueller-Hinton
broth in order to determine the minimum inhibitory concentration
(MIC)[17] and the minimal bactericidal concentration (MBC).[18]
Plates and tubes were incubated in air at 35 °C for 18 to 20 hours.
Bacterial inoculum was standardized by using direct suspensions of
colonies from overnight growth in saline adjusted to a turbidity
matching the 0.5 McFarland standard, and diluted to obtain a den-
sity of 104 CFU/mL for the diffusion method and 105 CFU/mL for
the dilution method. Purity and inoculum density as well as per-
centage of viable bacteria in limpid tubes were checked by plate
counting on sheep blood agar. Broth containing no molecule solu-
tion was inoculated with each selected bacterial strain as a control
for organism viability (growth control) in the dilution method.
Disks soaked with sterile water were used as control in the dif-
fusion method.
Chloride 22: Yield 150 mg, 44%. M.p. Ͼ 250 °C. C16H20Cl2N2O2:
1
calcd. C 55.99, H 5.87, N 8.16; found C 55.70, H 6.14, N 8.12. H
3
3
NMR (D2O): δ ϭ 8.31 (d, J ϭ 8.9, 2 H, Ar), 7.61 (d, J ϭ 8.9, 2
H, Ar), 4.40 (s, 2 H, NCH2), 4.34 (s, 2 H, NCH2), 3.29 (s, 6 H,
NCH3), 1.89 [s, 3 H, C(CH3)2], 1.24 [s, 3 H, C(CH3)2] ppm. 13C
NMR ([D6]DMSOo): δ ϭ 146.7, 144.6, 143.7, 133.6, 123.2, 118.5
(Cquat.), 130.6, 123.6 (CHAr), 63.8 and 61.2 (NCH2), 51.3 (NCH3),
23.9 and 23.1 [C(CH3)2] ppm.
Compound 19Cl: The heterocycle was directly crystallized from
water; yield 85 mg, 36%. M.p. 235 °C (dec.). C11H19Cl2N: calcd. C
55.94, H 8.11, N 5.93; found C 55.95, H 8.20, N 5.97. 1H NMR
(D2O): δ ϭ 4.15 (br. s, 2 H, NCH2), 4.07 (s, 2 H, NCH2), 3.14 (s,
6 H, NCH3), 2.16 (t, 5J ϭ 1.9, 3 H, CCH3), 2.01 [s, 3 H, C(CH3)2],
1.91 [s, 3 H, C(CH3)2] ppm. 13C NMR ([D6]DMSO): δ ϭ 141.6,
130.1, 121.0, 119.7 (Cquat.), 63.6 and 61.1 (NCH2), 51.0 (NCH3),
23.8 and 23.2 [C(CH3)2], 19.5 (CH3) ppm.
Binding Properties to the Nicotinic Receptor
Materials: [3H]-Phencyclidine ([3H]-PCP) and [125I]-α-bungarotoxin
([125I]-BgTx) were purchased from New England Nuclear. Live Tor-
pedo marmorata were obtained from the Biological Station of Ros-
coff (France). Pepstatine, aprotinine, PMSF, proadifen, carbamyl-
choline (Carb), and d-tubocurarine chloride were purchased from
Sigma.
Bromide 21: Direct crystallization from water; yield 160 mg, 41%.
M.p. Ͼ 250 °C. C16H21Br2N: calcd. C 49.64, H 5.47, N 3.62; found
C 49.40, H 5.66, N 3.60. 1H NMR (D2O): δ ϭ 7.51Ϫ7.33 (m, 5 H,
Ar), 4.43 (s, 2 H, NCH2), 4.29 (s, 2 H, NCH2), 3.23 (s, 6 H, NCH3),
1.88 [s, 3 H, C(CH3)2], 1.20 [s, 3 H, C(CH3)2] ppm. 13C NMR
([D6]DMSO): δ ϭ 143.3, 139.7, 137.7, 119.4, 113.7 (Cquat.), 129.0,
128.4, 127.9 (CHAr), 65.2 and 61.3 (NCH2), 51.1 (NCH3), 23.4 and
23.2 [C(CH3)2] ppm.
Membrane preparation: AChR-rich membrane fragments were
purified from frozen T. marmorata electric organ.[26] Specific [125I]-
α-bungarotoxin binding activities were determined by the DEAE
filter disc procedure and typically ranged from 1.5 to 2 nmol of
Chloride 23: Recrystallization from acetone/CH2Cl2; yield 200 mg,
45%. M.p. 220 °C (dec.). C22H29Cl2NO4: calcd. C 59.73, H 6.61,
N 3.17; found C 59.62, H 6.51, N 3.16. 1H NMR (CDCl3): δ ϭ
[
125I]-α-bungarotoxin bound per mg of protein.[27] Protein determi-
3
4
7.73 (d, J ϭ 8.0, 1 H, Ar), 7.51 (d, J ϭ 1.5, 1 H, Ar), 7.39 (dd, nation was achieved by a modified Lowry method.[28]
1730
 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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Eur. J. Org. Chem. 2004, 1724Ϫ1731

A Molecular Library Through Allene Insertion into a PdϪC Bond
FULL PAPER
6585. [5g] K. Hiroi, Y. Hiratsuka, K. Watanabe, I. Abe, F. Kato,
M. Hiroi, Tetrahedron Assym. 2002, 13, 1351.
R. N. Jones, Chest 2001, 119, 397S.
Agonist-Binding Site: Ligand inhibition constants at the agonist-
binding site were determined from the decrease in initial binding
rate of [125I]-α-BgTx to nAChR-rich membranes (2 nM α-BgTx
binding sites). After preincubation of Torpedo membrane with li-
gand in PBS pH 7.2 for 30 min, [125I]-αBgTx (2 nM) was added and
the suspension was incubated for 6 min at 25 °C, filtered through
Millipore HAWP and counted. Competing ligands were tested at
10 µ  and at a range of concentrations (10 nM to 0.5 m) for the
best ligands.
[6]
[7]
[8]
[9]
F. Hucho, C. Weise, Angew. Chem. Int. Ed. 2001, 40, 3100.
A. G. Engel, K. Ohno, S. M. Sine, Muscle Nerve 2003, 27, 4.
M. W. M. Holladay, M. J. Dart, J. K. Lynch, J. Med. Chem.
1997, 40, 4169.
[10] [10a]
M. Pfeffer, Inorg. Synth. 1989, 26, 211. [10b] A. C. Cope, E.
C. Friedrich, J. Am. Chem. Soc. 1968, 90, 909. [10c] T. Komatsu,
M. Nonoyama, J. Inorg. Nucl. Chem. 1977, 39, 1161.
Beydoun, PhD thesis, Louis Pasteur University, Strasbourg,
France, 1990.
Organometallics 1987, 6, 2029.
[10d]
N.
[10e]
NCB-Binding Site: Association constants of ligands for the non-
competitive blocking of the (NCB) binding site were determined
by competition experiments at equilibrium (45 min preincubation)
with [3H]-PCP (1 nM) and ligand on desensitized AChRs (68 nM
F. Maassarani, M. Pfeffer, G. Le Borgne,
[11]
J. Dupont, N. R. Basso, M. R. Meneghetti, R. A. Konrath, R.
Burrow, M. Horner, Organometallics 1997, 16, 2386.
[12] [12a]
[
125I]-αBgTx binding sites, 30 min preincubation with 0.1 m Carb
K. Sonogashira, Y. Tohda, N. Hagihara, Tetrahedron Lett.
1975, 4467. [12b] A. Arcadi, S. Cacchi, F. Marinelli, Tetrahedron
at 25 °C). The suspensions were filtered through GF-B (Whatman)
and counted. Competing ligands were tested at 1 µ and in the
10 nM to 500 nM concentration range for the three best ligands.
[12c]
Lett. 1989, 30, 2581.
Chem. 1992, 57, 6998.
A. P. Melissaris, M. H. Litt, J. Org.
[13] [13a] Hoffman-La Roche, US Patent 2470109, 1947. [13b] L. Wit-
[13c]
tig, Justus Liebig Ann. Chem. 1954, 589, 55, 71.
Brown, M. Sainsbury, S. F. Dyke, W. G. D. Lagton, Tetrahedron
D. W.
[13d]
1971, 27, 4519.
F. Eiden, U. Rehse, Chem. Ber. 1974, 107,
[13e]
1057.
F. Eiden, C. Herdeis, Arch. Pharm. 1976, 309, 425.
Acknowledgments
Prof. Henri Monteil and Prof. Maurice Goeldner are gratefully
acknowledged for their contributions. Financial supports of this
[13f]
S. M. Makin, A. I. Pomoaev, J. Org. Chem. USSR (Engl.
Transl.) 1981, 17, 2020. [13g]T. Lorand, J. Deli, D. Szabo, A.
Foeldesi, A. Zschunke, Pharmazie 1985, 40, 536.
[14] [14a] B. Akermark, S. Hansson, B. Krakenberger, A. Vitagliano,
`
work has been provided by the CNRS, the Ministere de la Recher-
[14b]
K. Zetterberg, Organometallics 1984, 3, 679.
T. Cuvigny,
che et de la Technologie (fellowship to J. C.), COFECUB (Brazil,
project 188/96, fellowship to R. K.) and CAPES (Brazil, fellowship
to G. E.).
M. Julia, C. Rolando, J. Organomet. Chem. 1985, 285, 395.
[15] [15a] Performance standards for antimicrobial disk susceptibility
[15b]
tests, 6th ed. in Approved Standard 1997, 17, 7.
F. Renaud, W. Hansen, C. Bollet, Precis de bacteriologie cli-
nique (Ed.: ESKA), 2000, 565, 575.
[16] [16a]
J. Freney,
´
´
[1] [1a]
J. Spencer, M. Pfeffer, Advances in Metallo-organic Chemis-
Methods for dilution antimicrobial susceptibility tests for
[1b]
try 1998, 6, 103.
1992, 64, 335.
109, 567.
M. Pfeffer, Pure and Applied Chemistry
M. Pfeffer, Recl. Trav. Chim. Pays-Bas 1990,
bacteria that grow aerobically, 4th ed. in Approved Standard
[1c]
[16b]
1997, 17, 9.
P. Courvalin, F. Goldstein, A. Philippon, J.
Sirot, LЈantibiogramme 1985, 191.
[2] [2a]
[17]
J. Chengebroyen, M. Pfeffer, C. Sirlin, Tetrahedron Lett.
1996, 37, 7263. [2b] J. J. H. Diederen, H. W. Frühauf, H. Hiem-
stra, K. Vrieze, M. Pfeffer, Tetrahedron Lett. 1998, 39, 4111. [2c]
J. Chengebroyen, M. Linke, M. Robitzer, C. Sirlin, M. Pfeffer,
J. Organomet. Chem. 2003, 687, 313.
MIC is the lowest concentration of antimicrobial agent that
completely inhibits growth of the organism in the tubes as de-
tected by the unaided eye.
MBC is obtained for a decrease of at least 4 log units of the
inoculum percentage of viable bacteria.
K. Brejc, W. J. van Dijk, R. V. Klaassen, M. Schuurmans, J.
van der Dost, A. B. Smit, T. K. Sixma, Nature 2001, 411, 269.
C. E. Spivak, J. A. Waters, R. S. Aronstam, Mol. Pharmacol.
1989, 36, 177.
T. Grutter, M. Goeldner, F. Kotzyba-Hibert, Biochemistry
1999, 38, 7476.
[18]
[19]
[20]
[21]
[22]
[3] [3a]
P. A. van der Schaaf, J.-P. Sutter, M. Grellier, G. P. M. van
Mier, A. L. Spek, G. van Koten, M. Pfeffer, J. Am. Chem. Soc.
[3b]
1994, 116, 5134.
M. Grellier, M. Pfeffer, G. van Koten,
[3c]
Tetrahedron Lett. 1994, 35, 2877.
De Cian, J. Fischer, Inorg. Chim. Acta 1994, 220, 115.
Grellier, M. Pfeffer, J. Organomet. Chem. 1997, 548, 301.
M. Pfeffer, J.-P. Sutter, A.
[3d]
M.
[4]
R. Zimmer, C. U. Dinesh, E. Nandanan, F. Kahn, Chem. Rev.
2000, 100, 3067.
A. T. Eldefrawi, E. R. Miller, D. L. Murphy, M. E. Eldefrawi,
Mol. Pharmacol. 1982, 22, 72.
[5] [5a]
[23]
[24]
R. C. Larock, N. G. Berrios-Pena, C. A. Fried, J. Org.
G. B. Heisig, H. M. Davis, J. Am. Chem. Soc. 1935, 57, 339.
B. D. Hosangadi, R. H. Dave, Tetrahedron Lett. 1996, 37, 6375.
[5b]
Chem. 1991, 56, 2615.
R. C. Larock, Y. He, W. W. Leong,
X. Han, M. D. Refvik, J. M. Zenner, J. Org. Chem. 1998, 63,
[25] [25a] General technical conditions for dilution methods in Com-
[5c]
[25b]
´
2154.
R. C. Larock, C. Tu, P. Pace, J. Org. Chem. 1998, 63,
munique 2000؊01, 3.
Microbiological titration of anti-
6859. [5d] E. Desarbre, J.-Y. Merour, Tetrahedron Lett. 1996, 37,
biotics in Pharmacopee Franc¸aise 1984, V.2.2.1.
T. Saitoh, J.-P. Changeux, Eur. J. Biochem. 1980, 105, 51.
J. Schmidt, M. A. Raftery, Anal. Biochem. 1973, 52, 349.
G. L. Paterson, Anal. Biochem. 1977, 83, 346.
Received December 11, 2003
´
´
[5e]
[26]
[27]
[28]
43.
J. J. H. Diederen, R. W. Sinkeldam, H. W. Frühauf, H.
Hiemstra, K. Vrieze, Tetrahedron Lett. 1999, 40, 4255.
[5f]
R
Grigg, W. S. MacLachlan, D. T. MacPherson, V. Sridharan, S.
Suganthan, M. Thorton-Pett, J. Zhang, Tetrahedron 2000, 56,
Eur. J. Org. Chem. 2004, 1724Ϫ1731
www.eurjoc.org
 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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