Nitrogen functionalities in palladium-catalyzed reactions on solid supports: A case study

Article abstract of DOI:10.1002/ejoc.200500779

Three different Palladium-catalyzed reactions (Heck, Suzuki, Sonogashira) were carried out on three different types of linkers on solid supports. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.

Full text of DOI:10.1002/ejoc.200500779

FULL PAPER
DOI: 10.1002/ejoc.200500779
Nitrogen Functionalities in Palladium-Catalyzed Reactions on Solid Supports:
A Case Study
Kerstin Knepper,[a][‡] Sylvia Vanderheiden,[a] and Stefan Bräse*[a]
Keywords: Palladium-catalyzed cross-coupling reactions / Heck reaction / Suzuki reaction / Sonogashira reaction / Solid-
phase chemistry / Triazenes / Amines
Three different Palladium-catalyzed reactions (Heck, Suzuki,
Sonogashira) were carried out on three different types of lin-
kers on solid supports.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2006)
Introduction
Modern metal-catalyzed reactions play a pivotal role in
the synthesis of complex molecular architectures since they
show in general a broad functional group tolerance.[1] In
particular, palladium-mediated processes are valuable tech-
niques in combination with solid phase synthesis for achiev-
ing molecular diversity.[2] However, although both the pal-
ladium-chemistry and solid phase synthesis methodologies
seem to be mature and well established, the combination of
both is met with varied success. In particular, the variation
of reaction types and linkers has to be predictable in order
to execute large library syntheses.
In this article, different palladium-mediated reactions on
different solid-supported substrates are compared to
achieve a better understanding of the influence of reaction
types, linker types, and substrates. The main goal is to inves-
tigate the interaction of nitrogen functionalities with palla-
dium-catalyzed processes. For this purpose, four different
anilines, 2, were immobilized via a diazotization reaction
onto benzylamine resin 1, which was prepared in a one-step
reaction from Merrifield resin (Scheme 1).[3] The triazene
resins were originally designed by the Moore group using a
propylamine resin,[3f] later optimized by us[3a–3d] and also
used by others with success.[3e]
Scheme 1. Synthesis of the triazene resins 3 for comparison of the
palladium-mediated reactions.
ciency of this reaction was determined by cleavage of the
resin 7 with the nucleophilic base sodium methoxide to ob-
tain methyl 3-bromo-4-aminobenzoate (8) in high yields
(Ͼ 90%) and purities (Ͼ 95%). The bromination reaction
of the corresponding carboxyaniline in solution phase was
less selective, and the purification of the product was diffi-
cult due to the formation of the of the amino acid zwitter-
ion.
For purposes of comparison, a 3-bromo-4-aminobenzoic
ester resin, 7 (Scheme 2), was synthesized starting with
Merrifield resin (4). In the first step, p-aminobenzoic acid
(5) was immobilized onto the solid support under basic
conditions. Then the product underwent bromination via
an aromatic substitution with N-bromsuccinimide. The effi-
Efforts to conduct a clean bromination in solution prior
to immobilization were difficult, because by-products such
as the di- and tribrominated aminobenzoic acids were ob-
tained. These products can not be effectively removed by
column chromatography or distillation.
The amine resin 7 was converted into the triazene 11 to
prove that the different reactivities depend on the amino or
triazene moiety and not on the linker system.
The immobilized product was treated with isoamyl nitrite
and borontrifluoride–diethyl ether to yield the diazonium
salt 9. The latter reacted in situ with diethylamine (10) to
yield the triazene resin 11 with a loading of 0.5 mmol/g
(Scheme 3).
[a] Institut für Organische Chemie, Universität Karlsruhe (TH),
Fritz-Haber-Weg 6, 76131 Karlsruhe, Germany
Fax: +49-721-8581
E-Mail: braese@ioc.uka.de
[‡] New address: Institut de Science et d’Ingénierie Supramolecul-
aires (ISIS),
8 allée Gaspard Monge, BP 70028, 67083 Strasbourg Cedex,
France
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Nitrogen Functionalities in Palladium-Catalyzed Reactions on Solid Supports
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ucts were separated by column chromatography and are
listed separately in Table 1.
With all the patterns of substitution, the Heck reaction
generated the products in moderate to good yields. The pu-
rities of all products were higher than 95%. In the case of
the dibrominated resin, the p-monosubstituted product was
always obtained together with the disubstituted product.
This could be confirmed in 2D NMR studies. With these
results in hand, the conclusion was made that the Heck
reaction works for every linker we used therein. However, at
this stage it should be pointed out that although the Heck
reaction on resin 3 yielded the products in good purities,
the yields are still to be improved. An explanation is a
premature cleavage of the N–N bond during the Heck reac-
tion leading to a diminished loading, preserving a high con-
version to the correct product. This effect has been ob-
served in other cases using triazenes as substrates for cross-
coupling reactions, with and without activation,[8] and also
with other linkers.[2] However, because the purity of the
products remains high after cleavage, this method is still
applicable to combinatorial synthesis of compound librar-
ies.
Scheme 2. Synthesis of the 3-bromo-4-aminobenzoic ester resin 7.
Heck Reaction on the 3-Bromo-4-aminobenzoic Ester Resin
The Heck reaction was performed on the aminobenzoic
resin 7 under the same conditions as for the triazene resin
[DMF, Pd(OAc)2, PPh3, Et3N]. In this case, the starting ma-
terial was isolated. Even variations of the reaction tempera-
ture, reaction time, and the use of different alkenes were
not successful. An explanation for these effects could be a
coupling of the palladium atom and the amine. However,
the reports in relevant literature of successful coupling of
o-haloanilines show that this might be applicable in all
cases.[9]
Scheme 3. Synthesis of the ester-bound triazene resin 11.
Heck Reactions of the (Bromophenyl)triazene Resins
For this work, the differently substituted triazene resins
3a–d were treated with four different alkenes, 12–15, under
standard Heck conditions[4] (105 °C, 24 h).[5] During the
reaction, the color of the resins changed from orange–light
brown to dark brown approaching black (Scheme 4).[6]
The resins were cleaved with trifluoroacetic acid and tri-
methylsilyl azide[7] to yield the azides 20a–23d. The results
are listed in Table 1. To cleave the dibrominated resin 3d,
Heck Reaction on the 3-Bromo-4-triazenylbenzoic Ester
Resin
The Heck reaction was then carried out on the ester-
the amounts of all reagents were doubled. In this case, the bound triazene resin using ethyl acrylate (13) under the con-
mono- and disubstituted products were found. The prod- ditions described below. The reaction is shown in
Scheme 4. Heck-reaction on T1 triazene resins 3a–d. For details, see Table 1.
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Table 1. Results of the Heck reaction on the triazene resins.
[a] Isolated yield for purified material over three steps based on the loading of the Merrifield resin.
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Scheme 5. Heck reaction on the ester-bound triazene resin 11.
Scheme 5.[10] The ester 24 was cleaved from the resin under (Scheme 6, Table 2). For the reaction of the dibrominated
basic conditions with sodium methoxide. Product 25 was resin 3d the amount of each reagent was doubled. In this
obtained in an overall yield of 21% and high purity case, the mono- (29d) and disubstituted (29e) products were
(Ͼ95%). The starting material was recovered as the corre- found. These products were separated by column
sponding methyl ester 26 in 34% yield.
chromatography.
With all monosubstitution patterns, the Suzuki reaction
produced very good yields. The purities of the products
were higher than 95%. The disubstituted resin 3d always
yielded the disubstituted product and also the p-monosub-
stituted product. Within the bounds of the experiments, it
could be seen that the Suzuki reaction took place in every
case, with reaction at the p-position preferred over the o-
position.
The Suzuki reactions on the 3-bromo-4-aminobenzoic
ester resin 7 were conducted under the same conditions as
for the triazene resin 3 [boronic acids 27 or 30, DMF/H2O,
(PPh3)2PdCl2, Na2CO3,]. However, only starting material
was isolated. Even variations of the reaction temperature
Suzuki Reaction on (Bromophenyl)triazene Resins
To compare this reaction with the other palladium-medi-
ated reactions, the substituted (bromophenyl)triazene resins
3a–d (Scheme 6) were reacted under standard Suzuki condi-
tions[11] [DMF/H2O, (PPh3)2PdCl2, Na2CO3] with p-me-
thoxybenzeneboronic acid (27). The reaction took place at
85 °C for 12 h in a closed reaction vessel with agitation.
During this time, the color of the resin changed from
orange to light brown to green.
The resins 28a–c were cleaved with trifluoroacetic acid
and trimethylsilyl azide[7] to yield the azides 29a–c
Scheme 6. Suzuki reaction on bromoaryl T1 resins 3a–3d.
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Table 2. Results of the Suzuki reaction on substituted (bro- and the reaction time, as well as the use of different boronic
mophenyl)triazene resins 3a–3d.
acids, were not successful. Similar to the Heck reaction, a
coordination of the palladium fragment to the amine could
be the reason for this failure.
Suzuki Reaction on (3-Bromo-4-triazenyl)benzoic Ester
Resin
The Suzuki reaction on the ester-bound triazene resin 11
(Scheme 7) was conducted under the aforementioned condi-
tions [DMF/H2O, (PPh3)2PdCl2, Na2CO3]. The resulting
resin 33 was cleaved with sodium methoxide to obtain
methyl ester 34 in mediocre yield (31%) and high purity.
Sonogashira Reaction on (Bromophenyl)triazene Resins
For comparison with the other palladium-mediated reac-
tions, the substituted (bromophenyl)triazene resins 3a–d
were reacted under standard Sonogashira reaction condi-
tions[12] [THF, (PPh3)2PdCl2 CuI, Et3N] with ethyl propy-
noate (35). The reaction temperature was varied from room
temperature to 100 °C. In all of these cases, no conversion
was observed. Only the brominated starting material was
found after the reaction. In contrast to the other palladium-
mediated reactions described below, the reason for the fail-
ure of the reaction could be the complexation of the copper
by the triazene. For this reason, in addition to the standard
Sonogashira conditions, the reaction was carried out in a
copper-free variation under Heck conditions with the al-
kyne 35.[13] Two products, which were not separable by col-
umn chromatography, were formed. NMR spectroscopic
studies of the azide products, cleaved by trifluoroacetic acid
and trimethylsilyl azide,[7] showed that the desired products
37a–c were formed, and that the alkenes 17a–c were gener-
ated by a Heck-type reaction (Scheme 8). It is not known
how the alkene, necessary for the Heck-type reaction, was
[a] Isolated yield for purified material over three steps based on the
loading of the Merrifield resin.
Scheme 7. Suzuki reaction on the ester-bound triazene resin.
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Nitrogen Functionalities in Palladium-Catalyzed Reactions on Solid Supports
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Scheme 8. Copper-free Sonogashira reactions on the T1 resin.
formed. It should be noted that the copper-mediated Sono- [THF, (PPh3)2PdCl2 CuI, Et3N]. In this case, no product
gashira reaction failed with ethyl propynoate (35) in some was obtained.
cases on solid supports.[4]
It was shown that the Sonogashira reaction takes place
under copper-free conditions on the solid supported triaz-
enes. An optimization of the reaction conditions should
yield the expected products.
Conclusion
The results of the different palladium-mediated cross-
coupling reactions on different resins (3a–d, 7 and 11) are
listed in Table 3. The Heck reaction took place without any
hindrance in the o-position on the triazene unit, while no
Sonogashira Reaction on 3-Bromo-4-aminobenzoic Ester
Resins
Sonogashira reactions of o-haloanilines were reported to
proceed smoothly on solid supports, for example, in the in-
dole synthesis of Collini and Ellingboe.[14]
The Sonogashira reaction was performed on the amine
resin 7 with ethyl propynoate (35) under the same condi-
tions [THF, (PPh3)2PdCl2 CuI, Et3N] as on the triazene
resin. The cleavage of the resin was completed using sodium
methoxide to obtain the methyl ester 39 (Scheme 9) in good
yield (41% overall yield) and high purity.
conversion took place when there was a free amine in the
o-position. The Suzuki reaction yielded analogous results
to the Heck reaction. The regioselectivity pattern was ex-
plained by combination of the palladium catalyst with the
free amine. The prerequisite for the successful Sonogashira
reaction is the absence of copper. When copper is present,
the free amine in the o-position does not affect the reaction,
as the copper is complexed by the triazene unit. In this case,
no reaction can take place. The Sonogashira reaction con-
ducted under copper-free conditions takes place.
Table 3. Summary of the results of the palladium-mediated reac-
tions on solid supports.
Triazene as
Triazene on
Amine on
linker (3a–d)
solid phase (11) solid phase (7)
Heck reaction
Suzuki reaction
Sonogashira reaction not successful
successful, but
successful
successful
successful
successful
not successful
not successful
not successful
successful
Copper-free alkyne
coupling
alkyne and
alkene were
obtained
–
–
However, the Nicolaou–Ullmann reaction[15] of haloaryl-
triazenes with phenolates only takes place when the leaving
group is ortho to the triazene group. The strong complex-
Scheme 9. Sonogashira reaction on the ester-bound amine resin 7.
The Sonogashira reaction was also performed on the es- ation of the copper ion with the triazene moiety[16] facili-
ter-linked triazene resin 11 under the conditions described tates the displacement of the halide. On the other hand, the
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bottom flask. A solution of sodium methoxide in methanol (30%,
1 ml/mmol) was added to the suspension, and the mixture was
shaken for three hours. The resin was filtered, the solution was
hydrolysed with water, and the organic phase was extracted twice
with ethyl acetate. After drying with magnesium sulfate, the solvent
was removed under reduced pressure. The products were purified
by column chromatography (silica, cyclohexane/ethyl acetate, 3:1).
same combination might be responsible for the failure of
the copper-induced Sonogashira reaction. Hence, copper-
free conditions[17] are more suitable in this case.
Experimental Section
General Methods: 1H NMR: Bruker DP 300 (300 MHz), Bruker
DP 400 (400 MHz); δ = 2.50 ppm for [D5]dimethyl sulfoxide,
3.31 ppm for [D3]methanol, and 7.26 ppm for CHCl3. The spectra
were analyzed according to first order. All coupling constants are
absolute values. 13C NMR: Bruker DP 300 (75 MHz), Bruker DP
General Procedure 3. Cleavage Protocol to the Azides: The triazene
resin (500 mg, 0.9 mmol/g) was expanded in dichloromethane
(10 mL) and mixed with azidotrimethylsilane (0.2 mL) and tri-
fluoroacetic acid (0.15 mL).[7] The mixture was shaken for 30 min,
then the residue was filtered off. The solvent was removed under
reduced pressure.
400 (100 MHz);
δ = 39.52 ppm for [D6]dimethyl sulfoxide,
77.16 ppm for CDCl3, and 49.00 for [D4]methanol. The signal
structure was analysed by DEPT and described as follows: + =
primary or tertiary C-atom (positive signal), – = secondary C-atom
(negative signal), q = quaternary C-atom (no signal). IR: Perkin–
Elmer FT-IR 1750. The substances were dissolved in distilled
dichloromethane. The resins were measured as KBr pellets on a
Bruker IFS88 IR; ps = polystyrene. EI-HRMS (electronic ioniza-
tion–high resolution mass spectroscopy): Kratos MS 50 (70 eV)
and Thermo Quest Finnigan MAT 95 XL (70 eV). GC : Hewlett–
Packard HP 5890 Serie II 12 m×0.25 mm capillary column HP I
(carrier gas N2). TLC: Silica gel coated aluminium plates (Merck,
silica gel 60, F254). Detection under UV light at 254 nm, displayed
with molybdato phosphate (5% phosphomolybdic acid in ethanol,
dipping solution) or potassium permanganate (0.45 g potassium
permanganate and 2.35 g of sodium carbonate in 90 mL of water,
dipping solution). Elemental analysis: Elementar vario EL at the
Mikroanalytisches Labor des Kekulé-Instituts für Organische
Chemie und Biochemie der Universität Bonn. Experiments without
nominated temperature were completed at room temperature (r.t.).
Solid materials (except for resins) were powdered. Chemicals, sol-
vents, and reagents were purchased from Aldrich, Fluka, Janssen,
and Merck. Merrifield resin (1–2% cross-linked, 200–400 mesh)
was obtained from CalBioChem-NovaBioChem; loading:
1.06 g·mol–1.
General Procedure 4. Heck Reaction on Solid Supports: Resin
(1 equiv.), triethylamine (1 equiv.), palladium acetate (0.10 equiv.),
triphenylphosphane (0.50 equiv.) and the appropriate alkene
(10 equiv.) in dimethylformamide (10 mL/g resin) were placed in an
argon-flushed vial. The vial was shaken from time to time during
24 h at 105 °C. After cooling to room temperature, the resin was
washed with water, followed by the general washing procedure. The
resin was dried under high vacuum. In the case of the dibrominated
resin, the amounts of all starting materials except for the resin were
doubled.
General Procedure 5. General Procedure for Suzuki Coupling:
Pd(PPh3)4 (0.10 equiv.) was added to a suspension of the polymer-
bound aryl halide (1 equiv.) under argon in DMF. The slurry was
stirred for 5 min, and then benzeneboronic acid (2 equiv.) and a
solution of Na2CO3 (2 , 2.5 equiv.) was added. The mixture was
shaken for 12 h at 85 °C, and then cooled to room temperature,
diluted with NH4OAc solution (25% in water), and shaken for an
additional 5 min before being filtered. The resin was washed follow-
ing the general washing procedure and dried under high vacuum.
[Benzyl(2-bromophenylazo)amino]methylpolystyrene (3a): Following
general procedure 1, Merrifield resin (10.0 g, 1 mmol/g) was reacted
with 8.60 g (50.0 mmol) of 2-bromoaniline. Loading: 0.8 mmol/g.
Elemental analysis (found, %): C 85.06, H 7.299, N 2.752. IR (KBr,
cm–1): ν = 3896 (s), 3811 (s), 3582 (m), 3437 (s), 3082 (m), 3025
Solvents for reactions using organometallic and other sensitive ma-
terials (ether, tetrahydrofuran, dichloromethane) were distilled un-
der argon. All resins were washed sequentially by using a vacuum
reservoir connected to a sintered glass frit. Cleavage was conducted
using Teflon tubes with a frit connected to a vacuum line or with
a glass pipette filled with glass wool or simply paper-filtered. Evap-
oration of the solvent was achieved using a rotary evaporator and/
or high vacuum (ca. 0.1 mbar).
˜
(m, ps), 2926 (s, ps), 2850 (m), 2731(m), 2516 (s), 1943 (m, ps),
1872 (m, ps), 1803 (m, ps), 1678 (m), 1602 (m, ps), 1494 (m, ps),
1452 (m, ps), 1376 (vs), 1154 (s, ps), 983 (s), 907 (m, ps), 762 (m,
ps), 707 (m, ps), 620 (m).
[Benzyl(3-bromophenylazo)amino]methylpolystyrene (3b): Following
general procedure 1, Merrifield resin (10.0 g, 1 mmol/g) was reacted
with 3-bromoaniline (8.60 g, 50.0 mmol). Loading: 0.8 mmol/g. El-
emental analysis (found, %): C 84.28, H 7.265, N 2.723. IR (KBr,
General Washing Procedures: Methanol, THF, pentane, dichloro-
methane − three times. Methanol, DMF, pentane, THF − once.
Pentane, dichloromethane, pentane − two times.
cm–1): ν = 3812 (s), 3579 (m), 3026 (vs, ps), 2914 (vs, ps), 1943 (m,
˜
ps), 1872 (m, ps), 1804 (m, ps), 1673 (m), 1451 (m, ps), 1347 (vs),
1158 (s, ps), 992 (m), 843 (m), 758 (s, ps), 703 (m, ps).
General Procedure 1. Attachment of Amines to Merrifield Resin: The
amine (2.5 mmol) was placed in a round-bottom flask and stirred
in tetrahydrofuran (150 mL) for 15 min at room temperature. Bo-
rontrifluoride–diethyl ether (0.037 mol) was added, the mixture was
stirred for 15 min at room temperature, and then cooled to –15 °C.
Isoamyl nitrite (3.5 mmol) was added, and the mixture was stirred
at –15 °C for two hours.
[Benzyl(4-bromophenylazo)amino]methylpolystyrene (3c): Following
general procedure 1, Merrifield resin (10.0 g, 1 mmol/g) was reacted
with 4-bromoaniline (8.60 g, 50.0 mmol). Loading: 0.8 mmol/g. El-
emental analysis (found, %): C 84.28, H 7.262, N 2.724. IR (KBr,
cm–1): ν = 3895 (s), 3811 (s), 3582 (m), 3437 (s), 3082 (m), 3025
˜
(m, ps), 2926 (s, ps), 2850 (m), 2733(m), 2516 (s), 1943 (m, ps),
1872 (m, ps), 1803 (m, ps), 1678 (m), 1602 (m, ps), 1494 (m, ps),
1452 (m, ps), 1376 (vs), 1154 (s, ps), 983 (s), 907 (m, ps), 762 (m,
ps), 706 (m, ps).
In a round-bottom three-necked flask equipped with an overhead
stirrer, the resin (5 g, 1.0 mmol/g) was expanded in diethyl ether
(100 mL) and pyridine (13.5 mL), and cooled to –25 °C. The diazo-
nium salt dissolved in acetonitrile (100 mL) was added, and the
mixture was slowly warmed to room temperature.
[Benzyl(2,4-dibromophenylazo)amino]methylpolystyrene (3d): Fol-
lowing general procedure 1, Merrifield resin (10.0 g, 1 mmol/g) was
reacted with 2,4-bromoaniline (12.50 g, 50.0 mmol). Loading:
0.9 mmol/g. Elemental analysis (found, %): C 74.33, H 6.396, N
General Procedure 2. Cleavage to Methyl Esters Under Basic Condi-
tions: The resin was expanded in THF (0.1 mmol/ml) in a round-
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2.829. IR (KBr, cm–1): ν = 3896 (s), 3811 (s), 3582 (m), 3437 (s),
3082 (m), 3025 (m, ps), 2926 (s, ps), 2850 (m), 2731(m), 2516 (s),
3813 (vs), 3486 (s), 3384 (m), 3199 (m), 3059 (s), 3026 (m, ps), 2913
(s, ps), 2849 (m), 2632 (s), 2384 (m), 1944 (m, ps), 1872 (m, ps),
˜
1943 (m, ps), 1872 (m, ps), 1803 (m, ps), 1678 (m), 1602 (m, ps), 1803 (m, ps), 1718 (s), 1616 (s, ps), 1494 (m, ps), 1452 (m, ps),1374
1494 (m, ps), 1452 (m, ps), 1376 (vs), 1154 (s, ps), 983 (s), 907 (m,
ps), 762 (m, ps), 707 (m, ps), 620 (m).
(m), 1317 (m), 1248 (m), 1175 (m, ps), 1116 (m), 964 (m), 907 (m,
ps), 825 (m), 765 (m, ps), 706 (m, ps), 622 (m).
1-Azido-2-bromobenzene (2a-N3): Following general procedure 3,
resin 3a (500 mg) was cleaved, yielding a light brown solid (92.1 mg,
0.47 mmol, 93%). 1H NMR (400 MHz, CDCl3, ppm): δ = 7.01 (td,
{(3-Bromo-4-[(diethylamino)diazenyl]phenyl)carbonyloxy}methyl-
polystyrene (11): Resin 7 (4.00 g, 1.00 mmol/g) was reacted with
borontrifluoride–diethyl ether (2.40 mL, 15.0 mmol) and isoamyl
4
3
3J = 7.83 Hz, J = 1.40 Hz, 1 H, 5-H), 7.17 (d, J = 7.83 Hz, 1 H, nitrite (1.50 mL, 15.0 mmol) at –15 °C. To yield the diazonium salt,
3
4
3
6-H), 7.35 (td, J = 7.83 Hz, J = 1.40 Hz, 1 H, 4-H), 7.55 (d, J
diethylamine (0.76 mL, 15.0 mmol) was added, and then the mix-
= 7.83 Hz, 1 H, 3-H). 13C NMR (100 MHz, CDCl3, ppm): δ = ture was warmed to room temperature. The resin was filtered,
114.0 (q, C-2), 119.6 (+, C-6), 126.1 (q, C-4), 128.7 (+, C-5), 134.0
washed following the general washing procedure, and dried under
high vacuum. Loading: 0.5 mmol/g. Elemental analysis (found, %):
C 81.35, H 7.392, N 1.831.
(+, C-3), 138.9 (q, C-1). IR (CH Cl , cm–1): ν = 2132 (N ), 1586
˜
2
2
3
(arene). MS (EI): m/z (%) = 199, 197 [M+, 15], 169, 171 (100), 118
(10), 77 (25), 63 (5), 51 (30). HRMS (C6H4BrN3): calcd. 198.9589;
found 198.9587.
Methyl 4-Amino-3-bromobenzoate (8): Following general procedure
2, resin 7 (500 mg) were cleaved yielding a light brown solid
1
1-Azido-3-bromobenzene (2b-N3): Following general procedure 3,
resin 3b (500 mg) was cleaved, yielding a light brown solid (87.0 mg,
(86.1 mg, 0.38 mmol, 84%). H NMR (400 MHz, CDCl3, ppm): δ
3
= 3.09 (s, 1 H, CH3), 4.50 (br. s, 2 H, NH2), 6.72 (d, J = 8.46 Hz,
1
0.44 mmol, 97%). H NMR (300 MHz, CDCl3, ppm): δ = 6.54 (t,
1 H, 5-H), 7.78 (dd, 3J = 8.46 Hz, 4J = 2.02 Hz, 1 H, 6-H), 8.11
4J = 1.66 Hz, 1 H, 2-H), 7.83 (t, 3J = 7.94 Hz, 1 H, 5-H), 6.99– (d, J = 2.02 Hz, 1 H, 2-H). 13C NMR (100 MHz, CDCl3, ppm): δ
4
7.06 (m, ca. 2 H, 4-H, 6-H). 13C NMR (75 MHz, CDCl3, ppm): δ
= 117.8 (+, C-2), 122.2 (+, C-6), 123.3 (q, C-3), 128.0 (+, C-4), 130.3 (+, C-6), 134.6 (+, C-2), 148.2 (q, C-4), 166.0 (q, CO2). IR
= 51.9 (+, OCH3), 107.9 (q, C-3), 114.3 (+, C-5), 121.0 (q, C-1),
130.9 (+, C-5), 141.6 (q, C-1). IR (CH Cl , cm–1): ν = 2101 (N ),
(CH Cl , cm–1): ν = 3604, 1574, 906. MS (EI): m/z (%) = 228, 226
˜
2 2
˜
2
2
3
1588 (Ar), 855. MS (EI), m/z (%) = 199, 197 [M+, 15], 169, 171
(35), 90 (100), 63 (30). HRMS (C6H4BrN3): calcd. 198.9589; found
198.9585.
[M+, 60], 197, 195 (100), 169, 167 (10), 142 (5), 98 (5), 89 (35), 62
(10), 51 (5). HRMS (C8H8BrNO2): calcd. 228.9738; found
228.9745.
1-Azido-4-bromobenzene (2c-N3): Following general procedure 3,
resin 3c (500 mg) was cleaved, yielding a light brown solid (92.1 mg,
{Benzyl[2-(tert-butoxycarbonylethenyl)phenylazo]amino}methyl-
polystyrene (16a): Following general procedure 4, resin 3a (1.00 g,
0.47 mmol, 95%). 1H NMR (300 MHz, CDCl3, ppm): δ = 6.81 (d, 0.9 mmol/g) was treated with tert-butyl acrylate (1.00 mL,
3J = 7.83 Hz, 2 H, 5-H), 7.45 (d, 3J = 7.83 Hz, 2 H, 6-H). 13C 10 mmol). Loading: 0.6 mmol/g. Elemental analysis (found, %): C
NMR (75 MHz, CDCl3, ppm): δ = 117.8 (q, C-4), 120.7 (+, C-2,6),
84.14, H 7.91, N 2.252. IR (KBr, cm–1): ν = 3646 (s), 3026 (s, ps),
˜
132.8 (+, C-3,5), 139.7 (q, C-1). IR (CH Cl , cm–1): ν = 2132 (N ), 2921 (vs, ps), 2602 (m), 1944 (m, ps), 1875 (m, ps), 1804 (m, ps),
˜
2
2
3
1586 (Ar). MS (EI), m/z (%) = 199, 197 [M+, 10], 169, 171 (100),
1677 (s), 1604 (m, ps), 1494 (m, ps), 1452 (m, ps), 1346 (s), 1249
(m), 1175 (m, ps), 1108 (s), 1030 (m), 906 (m, ps), 831 (m), 756 (m,
ps), 702 (m, ps).
118 (5), 105 (5), 89 (20), 63 (10).
1-Azido-2,4-dibromobenzene (2d-N3): Following general procedure
3, resin 3d (500 mg) was cleaved, yielding a lightly brown solid
{Benzyl[2-(ethoxycarbonylethenyl)phenylazo]amino}methyl-
polystyrene (17a): Following general procedure 4, resin 3a (1.00 g,
1
(128 mg, 0.47 mmol, 93%). H NMR (300 MHz, CDCl3, ppm): δ
= 7.02 (d, 3J = 8.66 Hz, 1 H, 6-H), 7.44 (dd, 3J = 8.66 Hz, 4J = 0.9 mmol/g) was treated with ethyl acrylate (1.43 mL, 10 mmol).
2.07 Hz,1 H, 5-H), 7.69 (d, 4J = 2.07 Hz, 1 H, 3-H). 13C NMR Loading: 0.7 mmol/g. Elemental analysis (found, %): C 85.57, H
(75 MHz, CDCl3, ppm): δ = 114.8 (q, C-2), 117.9 (q, C-4), 120.6
7.361, N 2.541. IR (KBr, cm–1): ν = 3547 (m), 3343 (vs), 3027 (s,
˜
(+, C-6), 131.7 (+, C-5), 136.3 (+, C-3), 138.2 (q, C-1). IR (CH2Cl2,
ps), 2847 (s), 2602 (s), 2311 (s), 1943 (m, ps), 1873 (m, ps), 1804
(m, ps), 1741 (s), 1601 (m, ps), 1452 (m, ps), 1324 (s), 1180 (s, ps),
1105 (m), 1029 (m), 906 (m, ps), 842 (m), 756 (m, ps), 703 (m, ps).
cm–1): ν = 2099 (N ), 1574 (arene).
˜
3
[(4-Aminophenyl)carbonyloxy]methylpolystyrene (6): Merrifield
resin (3.00 g, 1.00 mmol/g) was treated with p-aminobenzoic acid
(0.82 g, 6.00 mmol) and cesium carbonate (1.95 g, 6.00 mmol) at
50 °C for 24 h while stirring. The resin was washed following the
general washing procedure and dried under high vacuum. Loading:
1.1 mmol/g. Elemental analysis (found, %): C 87.03, H 7.234, N
{Benzyl[2-(p-methoxystyryl)phenylazo]amino}methylpolystyrene
(18a): Following general procedure 4, resin 3a (1.00 g, 0.9 mmol/g)
was treated with p-methoxystyrene (0.40 mL, 10 mmol). Loading:
0.7 mmol/g. Elemental analysis (found, %): C 86.84, H 7.403, N
2.538. IR (KBr, cm–1): ν = 3645 (m), 3026 (s, ps), 2921 (vs, ps),
˜
1.543. IR (KBr, cm–1): ν = 3646 (vs), 3484 (s), 3383 (s), 3222 (m),
2602 (m), 2057 (m), 1944 (m, ps), 1875 (m, ps), 1804 (m, ps), 1677
(m), 1604 (m, ps), 1452 (m, ps), 1346 (s), 1249 (m), 1175 (s, ps),
˜
3059 (s), 3025 (m, ps), 2936 (s, ps), 2849 (m), 2667 (s), 2527 (s),
2382 (m), 2255 (m), 2114 (m), 1945 (m, ps), 1873 (m, ps), 1804 (m, 1108 (s), 1030 (m), 964 (m), 906 (m, ps), 832 (m), 756 (m, ps), 702
ps), 1713 (s), 1606 (s, ps), 1452 (m, ps), 1374 (m), 1311 (s), 1174 (m, ps).
(m, ps), 1112 (s), 1028 (m), 965 (m), 907 (m, ps), 773 (s, ps), 709
{Benzyl[2-(p-methoxystyryl)phenylazo]amino}methylpolystyrene
(m, ps).
(19a): Following general procedure 4, resin 3a (1.00 g, 0.9 mmol/
[(4-Amino-3-bromophenyl)carbonyloxy]methylpolystyrene (7): In a g) was treated with p-chlorostyrene (1.25 mL, 10 mmol). Loading:
round-bottom flask, resin 6 (1.00 g, 1.10 mmol/g) was expanded
in DMF (100 mL) and reacted with N-bromosuccinimide (0.89 g,
5.00 mmol) for 24 h at room temperature while shaking. The resin
was washed with water, followed by the general washing procedure,
and dried under high vacuum. Loading: 1.0 mmol/g. Elemental
0.7 mmol/g. Elemental analysis (found, %): C 86.84, H 7.403, N
2.538. IR (KBr, cm–1): ν = 3896 (s), 3811 (s), 3582 (m), 3437 (s),
˜
3082 (m), 3025 (m, ps), 2926 (s, ps), 2850 (m), 2731(m), 2516 (s),
1943 (m, ps), 1872 (m, ps), 1803 (m, ps), 1678 (m), 1602 (m, ps),
1494 (m, ps), 1452 (m, ps), 1376 (vs), 1154 (s, ps), 983 (s), 907 (m,
ps), 762 (m, ps), 707 (m, ps), 620 (m).
analysis (found, %): C 84.27, H 7.82 N 2.154. IR (KBr, cm–1): ν =
˜
Eur. J. Org. Chem. 2006, 1886–1898
© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
1893

K. Knepper, S. Vanderheiden, S. Bräse
FULL PAPER
{Benzyl[3-(tert-butoxycarbonylethenyl)phenylazo]amino}methyl-
polystyrene (16b): Following general procedure 4, resin 3b (1.00 g,
0.9 mmol/g) was treated with tert-butyl acrylate (1.00 mL,
10 mmol). Loading: 0.7 mmol/g. Elemental analysis (found, %): C
{Benzyl[4-(p-chlorostyryl)phenylazo]amino}methylpolystyrene (19c):
Following general procedure 4, resin 3c (1.00 g, 0.9 mmol/g) was
treated with p-chlorostyrene (1.25 mL, 10 mmol). Loading:
0.7 mmol/g. Elemental analysis (found, %): C 85.27, H 7.185, N
85.81, H 7.657, N 2.466. IR (KBr, cm–1): ν = 3646 (s), 3026 (s, ps), 2.504. IR (KBr, cm–1): ν = 3896 (s), 3811 (s), 3582 (m), 3437 (s),
˜
˜
2921 (vs, ps), 2602 (m), 1944 (m, ps), 1875 (m, ps), 1804 (m, ps), 3082 (m), 3025 (m, ps), 2926 (s, ps), 2850 (m), 2731(m), 2516 (s),
1677 (s), 1604 (m, ps), 1494 (m, ps), 1452 (m, ps), 1346 (s), 1249
(m), 1175 (m, ps), 1108 (s), 1030 (m), 906 (m, ps), 831 (m), 756 (m,
ps), 702 (m, ps).
1943 (m, ps), 1872 (m, ps), 1803 (m, ps), 1678 (m), 1602 (m, ps),
1494 (m, ps), 1452 (m, ps), 1376 (vs), 1154 (s, ps), 983 (s), 907 (m,
ps), 762 (m, ps), 707 (m, ps), 620 (m).
{Benzyl[3-(ethoxycarbonylethenyl)phenylazo]amino}methyl-
polystyrene (17b): Following general procedure 4, resin 3b (1.00 g,
0.9 mmol/g) was treated with ethyl acrylate (1.43 mL, 10 mmol).
Loading: 0.7 mmol/g. Elemental analysis (found, %): C 85.14, H
{Benzyl[2,5-bis(tert-butoxycarbonylethenyl)phenylazo]amino}-
methylpolystyrene (16d): Following general procedure 4, resin 3d
(1.00 g, 0.9 mmol/g) was treated with tert-butyl acrylate (2.00 mL,
10 mmol). Loading: 0.6 mmol/g. Elemental analysis (found %): N
7.36, N 2.523. IR (KBr, cm–1): ν = 3811 (s), 3433 (vs), 2924 (s, ps),
2.319, C: 84.09, H 7.109. IR (KBr, cm–1): ν = 3398 (s), 3060 (m),
˜
˜
2849 (m), 2336 (m), 1944 (m, ps), 1873 (m, ps), 1804 (m, ps), 1739
(s), 1602 (m, ps), 1494 (m, ps), 1452 (m, ps), 1347 (s), 1179 (s, ps),
1108 (m), 991 (m),845 (m), 758 (m, ps), 699 (m, ps).
2923 (vs, ps), 2604 (m), 1943 (m, ps), 1871 (m, ps), 1803 (m, ps),
1706 (s), 1632 (m), 1601 (m, ps), 1452 (m, ps), 1150 (s, ps), 982
(m), 907 (m, ps), 847 (m), 760 (m, ps), 703 (m, ps).
{Benzyl[3-(p-methoxystyryl)phenylazo]amino}methylpolystyrene
(18b): Following general procedure 4, resin 3b (1.00 g, 0.9 mmol/g)
was treated with p-methoxystyrene (0.40 mL, 10 mmol). Loading:
0.7 mmol/g. Elemental analysis (found, %): C 86.87, H 7.40, N
{Benzyl[2,4-bis(ethoxycarbonylethenyl)phenylazo]amino}methyl-
polystyrene (17d): Following general procedure 4, resin 3d (1.00 g,
0.9 mmol/g) was treated with ethyl acrylate (2.86 mL, 20 mmol).
Loading: 0.6 mmol/g. Elemental analysis (found, %): C 84.14,
2.535. IR (KBr, cm–1): ν = 3645 (m), 3026 (s, ps), 2921 (vs, ps), H 7.113, N 2.252. IR (KBr, cm–1): ν = 3436 (vs), 2923 (s, ps), 2336
˜
˜
2602 (m), 2057 (m), 1944 (m, ps), 1875 (m, ps), 1804 (m, ps), 1677
(m), 1604 (m, ps), 1452 (m, ps), 1346 (s), 1249 (m), 1175 (s, ps),
1108 (s), 1030 (m), 964 (m), 906 (m, ps), 832 (m), 756 (m, ps), 702
(m, ps).
(m), 1944 (m, ps), 1872 (m, ps), 1803 (m, ps), 1733 (s), 1602 (m,
ps), 1452 (m, ps), 1248 (vs), 1179 (s, ps), 1029 (m), 907 (m, ps), 757
(m, ps), 700 (m, ps).
{Benzyl[2,4-bis(p-methoxystyryl)phenylazo]amino}methyl-
polystyrene (18d): Following general procedure 4, resin 3d (1.00 g,
0.9 mmol/g) was treated with p-methoxystyrene (0.80 mL,
20 mmol). Loading: 0.8 mmol/g. Elemental analysis (found, %): C
{Benzyl[3-(p-chlorostyryl)phenylazo]amino}methylpolystyrene (19b):
Following general procedure 4, resin 3b (1.00 g, 0.9 mmol/g) was
treated with p-chlorostyrene (1.25 mL, 10 mmol). Loading:
0.7 mmol/g. Elemental analysis (found, %): C 85.62, H 7.216, N
83.47, H 7.256 N 2.579. IR (KBr, cm–1): ν = 3645 (m), 3026 (s, ps),
˜
2.452. IR (KBr, cm–1): ν = 3896 (s), 3811 (s), 3582 (m), 3437 (s),
2921 (vs, ps), 2602 (m), 2057 (m), 1944 (m, ps), 1875 (m, ps), 1804
(m, ps), 1677 (m), 1604 (m, ps), 1452 (m, ps), 1346 (s), 1249 (m),
˜
3082 (m), 3025 (m, ps), 2926 (s, ps), 2850 (m), 2731(m), 2516 (s),
1943 (m, ps), 1872 (m, ps), 1803 (m, ps), 1678 (m), 1602 (m, ps), 1175 (s, ps), 1108 (s), 1030 (m), 964 (m), 906 (m, ps), 832 (m), 756
1494 (m, ps), 1452 (m, ps), 1376 (vs), 1154 (s, ps), 983 (s), 907 (m,
ps), 762 (m, ps), 707 (m, ps), 620 (m).
(m, ps), 702 (m, ps).
{Benzyl[2,3-bis(p-chlorostyryl)phenylazo]amino}methylpolystyrene
(19d): Following general procedure 4, resin 3d (1.00 g, 0.9 mmol/
g) was treated with p-chlorostyrene (2.50 mL, 20 mmol). Loading:
0.8 mmol/g. Elemental analysis (found, %): C 85.90, H 7.251, N
{Benzyl[4-(tert-butoxycarbonylethenyl)phenylazo]amino}methyl-
polystyrene (16c): Following general procedure 4, resin 3c (1.00 g,
0.9 mmol/g) was treated with tert-butyl acrylate (1.00 mL,
10 mmol). Loading: 0.7 mmol/g. Elemental analysis (found, %): C 2.574. IR (KBr, cm–1): ν = 3647 (m), 3026 (vs, ps), 2911 (vs, ps),
˜
85.47, H 7.563, N 2.495. IR (KBr, cm–1): ν = 3646 (s), 3026 (s, ps), 2603 (m), 1944 (m, ps), 1873 (m, ps), 1804 (m, ps), 1602 (m, ps),
˜
2921 (vs, ps), 2602 (m), 1944 (m, ps), 1875 (m, ps), 1804 (m, ps), 1547 (m), 1493 (m), 1452 (m, ps), 1347 (vs), 1162 (s, ps), 1093 (s),
1677 (s), 1604 (m, ps), 1494 (m, ps), 1452 (m, ps), 1346 (s), 1249
(m), 1175 (m, ps), 1108 (s), 1030 (m), 906 (m, ps), 831 (m), 756 (m,
ps), 702 (m, ps).
1029 (m), 907 (m, ps), 825 (m), 762 (m, ps), 707 (m, ps), 620 (m).
[3-(Ethoxycarbonylethenyl)-4-(N,N-diethyltriazenyl)phenyl]carbon-
yloxymethylpolystyrene (24): Following general procedure 4, resin
11 (1.00 g, 0.9 mmol/g) was treated with ethyl acrylate (1.43 mL,
10 mmol). Loading: 0.4 mmol/g. Elemental analysis (found, %): C
83.16, H 7.286, N 1.388.
{Benzyl[4-(ethoxycarbonylethenyl)phenylazo]amino}methyl-
polystyrene (17c): Following general procedure 4, resin 3c (1.00 g,
0.9 mmol/g) was treated with ethyl acrylate (1.43 mL, 10 mmol).
Loading: 0.7 mmol/g. Elemental analysis (found, %): C 85.57, H
tert-Butyl 2-Azidocinnamate (20a): Following general procedure 2,
resin 15a (500 mg) was cleaved, yielding a slightly brown liquid
7.361, N 2.541. IR (KBr, cm–1): ν = 3547 (m), 3343 (vs), 3027 (s,
˜
ps), 2847 (s), 2602 (s), 2311 (s), 1943 (m, ps), 1873 (m, ps), 1804
(m, ps), 1741 (s), 1601 (m, ps), 1452 (m, ps), 1324 (s), 1180 (s, ps),
1105 (m), 1029 (m), 906 (m, ps), 842 (m), 756 (m, ps), 703 (m, ps).
1
(134 mg, 0.55 mmol, 61%). H NMR (400 MHz, CDCl3, ppm): δ
3
= 1.54 (s, 9 H, CH3), 6.39 (d, J = 16.16 Hz, 1 H, CHCO2), 7.10–
3
3
4
7.19 (m, ca. 2 H, 5,6-H), 7.36 (ddd, J = 7.57 Hz, J = 7.57 Hz, J
3
4
{Benzyl[4-(p-methoxystyryl)phenylazo]amino}methylpolystyrene
(18c): Following general procedure 4, resin 3c (1.00 g, 0.9 mmol/g)
was treated with p-methoxystyrene (0.40 mL, 10 mmol). Loading:
0.8 mmol/g. Elemental analysis (found, %): C 85.90, H 7.251, N
= 1.51 Hz, 1 H, 4-H), 7.55 (dd, J = 7.83 Hz, J = 1.38 Hz, 1 H,
3-H), 7.80 (d, J = 16.16 Hz, 1 H, CArCH). 13C NMR (100 MHz,
3
CDCl3, ppm): δ = 28.3 (+, CH3), 80.7 (q, CCH3), 118.9 (+,
CHCO2), 122.1 (+, C-4), 125.0 (+, C-6), 126.5 (q, C-2), 128.3 (+,
C-3), 131.0 (+, C-5), 137.9 (+, CArCH), 139.1 (q, C-1), 166.2 (q,
2.574. IR (KBr, cm–1): ν = 3803 (m), 3649 (m), 3025 (m, ps), 2925
˜
(s, ps), 2848 (m), 2602 (m), 2336 (m), 1943 (m, ps), 1872 (m, ps),
1803 (m, ps), 1677 (m), 1602 (m, ps), 1452 (m, ps), 1348 (s), 1174
(s, ps), 1104 (m), 985 (m), 906 (m, ps), 836 (m), 758 (m, ps), 703
(m, ps).
CO ). IR (CH Cl , cm–1): ν = 2140 (N ), 1694 (ester), 1635 (al-
˜
2
2
2
3
kene), 1596 (Ar). MS (EI): m/z (%) = 245 [M+, 15], 172 (25), 147
(5), 143 (15), 133 (5), 115 (30), 104 (5), 89 (30), 63 (10), 57 (100).
HRMS (C13H15N3O2): calcd 245.1164; found 245.1173.
1894
www.eurjoc.org
© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2006, 1886–1898

Nitrogen Functionalities in Palladium-Catalyzed Reactions on Solid Supports
FULL PAPER
3
3
Ethyl 2-Azidocinnamate (21a): Following general procedure 3, resin
17a (500 mg) was cleaved yielding a slightly brown liquid (51.8 mg,
6.31 Hz, 1 H, 5-H), 7.28 (d, J = 7.84 Hz, 1 H, 6-H), 7.54 (d, J =
16.04 Hz, 1 H, CH). 13C NMR (100 MHz, CDCl3, ppm): δ = 14.7
(+, CH3), 61.0 (–, CH2), 118.5 (+, C-2), 120.1 (+, CHCO2), 121.0
1
0.23 mmol, 53%). H NMR (300 MHz, CDCl3, ppm): δ = 1.34 (t,
3J = 7.06 Hz, 3 H, CH3), 4.26 (q, 3J = 7.06 Hz, 1 H, CH2), 6.47 (+, C-6), 125.0 (+, C-4), 130.6 (+, C-5), 136.7 (q, C-3), 141.2 (q,
(d, 3J = 16.10 Hz, 1 H, CHCO2), 7.11–7.19 (m, ca. 2 H, 5,6-H),
7.42 (ddd, 3J = 8.48 Hz, 3J = 8.48 Hz, 4J = 1.32 Hz, 1 H, 4-H),
7.55 (dd, 3J = 6.78 Hz, 4J = 0.94 Hz, 1 H, 3-H), 7.90 (d, 3J =
C-1), 143.3 (q, CH), 167.0 (q, CO ). IR (CH Cl , cm–1): ν = 2096
˜
2 2 2
(N3), 1702 (ester), 1580 (Ar). MS (EI): m/z (%) = 217 [M+, 40], 189
(100), 172 (35), 160 (5), 143 (45), 132 (10), 116 (50), 104 (10), 89
16.10 Hz, 1 H, CArCH). 13C NMR (75 MHz, CDCl3, ppm): δ = (40), 78 (5), 72 (5), 63 (15), 51 (5). HRMS (C11H11N3O2): calcd.
14.4 (+, CH3), 60.7 (–, CH2), 118.9 (+, CHCO2), 120.2 (+, C-4), 217.0851; found 217.0846.
125.0 (+, C-6), 126.3 (q, C-2), 128.3 (+, C-3), 131.3 (+, C-5), 138.9
3-Azido-4Ј-methoxystilbene (22b): Following general procedure 3,
resin 18b (500 mg) was cleaved, yielding a slightly brown liquid
(23.7 mg, 0.09 mmol, 21%). H NMR (400 MHz, CDCl3, ppm): δ
(+, CArCH), 139.3 (q, C-1), 166.9 (q, CO ). IR (CH Cl , cm–1): ν
˜
2
2
2
= 2095 (N3), 1702 (ester), 1638 (Ar). MS (EI): m/z (%) = 217 [M+,
40], 189 (5), 172 (30), 161 (5), 143 (25), 130 (90), 117 (100), 105 (5),
89 (60), 77 (5), 63 (25), 58 (5). HRMS (C11H11N3O2): calcd.
217.0851; found 217.0843.
1
= 3.75 (s, 3 H, CH3), 6.80–7.40 (m, ca. 10 H, 8×HAr, 2×CH). 13C
NMR (100 MHz, CDCl3, ppm): δ = 55.36 (+, OCH3), 114.3 (+, C-
3Ј,5Ј), 116.5 (+, C-2), 117.7 (+, C-6), 123.0 (+, C-4), 125.5 (+, C-
5), 127.9 (+, C-3Ј,5Ј), 129.5, 129.7 (+, CH=CH), 130.0 (q, C-1Ј),
139.6 (q, C-3), 140.4 (q, C-1), 160.0 (q, C-4Ј). IR (CH2Cl2, cm–1):
2-Azido-4Ј-methoxystilbene (22a): Following general procedure 3,
resin 18a (500 mg) was cleaved, yielding a slightly brown liquid
1
(22.1 mg, 0.09 mmol, 20%). H NMR (400 MHz, CDCl3, ppm): δ
ν = 2108 (N ), 1596 (Ar), 1512 (OMe). MS (EI): m/z (%) = 251
˜
3
3
(100) [M+], 222 (15), 192 (10), 180 (35), 165 (10), 152 (15), 127 (5),
105 (5), 89 (5), 77 (5). HRMS (C15H13N3O): calcd. 251.1059; found
251.1060.
= 3.83 (s, 3 H, OCH3), 6.90 (d, J = 6.82 Hz, 1 H, 3Ј,5Ј-H), 7.05
3
(d, J = 16.42 Hz, 1 H, CH), 7.11–7.30 (m, ca. 4 H, HAr), 7.45 (d,
3
3J = 6.82 Hz, 2 H, 2Ј,6Ј-H), 7.63 (d, J = 16.42 Hz, 1 H, CH). 13C
NMR (100 MHz, CDCl3, ppm): δ = 55.5 (+, OCH3), 114.3 (+, C-
3Ј, C-5Ј), 118.7 (+, C-4), 121.0 (+, C-6), 125.0 (+, C-3), 126.3 (+,
CH), 128.1 (+, C-2Ј, C-6Ј), 128.4 (+, CH), 129.7 (q, C-2), 130.0 (+,
C-5), 130.3 (q, C-1Ј), 137.4 (q, C-1), 159.7 (q, C-4Ј). IR (CH2Cl2,
3-Azido-4Ј-chlorostilbene (23b): Following general procedure 3,
resin 19b (500 mg) was cleaved, yielding a slightly brown liquid
1
(25.2 mg, 0.10 mmol, 22%). H NMR (400 MHz, CDCl3, ppm): δ
3
4
4
cm–1): ν = 2122 (N ), 1606 (Ar), 1512 (OMe). MS (EI): m/z (%) =
= 6.85 (ddd, J = 7.83 Hz, J = 1.26 Hz, J = 1.01 Hz, 1 H, 4-H),
˜
3
3
251 [M+, 55], 223 (70), 208 (100), 190 (10), 180 (35), 165 (15), 152
(20), 149 (10), 127 (5), 111 (5), 89 (5), 77 (5), 57 (5). HRMS
(C15H13N3O): calcd. 251.1059; found 251.1058.
6.87–7.20 (m, ca. 5 H, 3×HAr, 2×CH), 7.23 (d, J = 8.59 Hz, 2 H,
3Ј,5Ј-H), 7.33 (d, 3J = 8.59 Hz, 2 H, 2Ј,6Ј-H). 13C NMR (100 MHz,
CDCl3, ppm): δ = 116.9 (+, C-2), 118.4 (+, C-6), 123.4 (+, C-4),
127.9 (+, C-2Ј,6Ј), 128.3 (+, C-5), 128.8 (+, CH=CH), 129.1 (+, C-
3Ј,5Ј), 130.2 (+, CH=CH), 133.8 (q, C-3), 135.54 (q, C-1Ј), 139.0
2-Azido-4Ј-chlorostilbene (23a): Following general procedure 3,
resin 19a (500 mg) was cleaved, yielding a slightly brown liquid
(q, C-4Ј), 140.7 (q, C-1). IR (CH Cl , cm–1): ν = 2103 (N ), 1581
˜
2
2
3
1
(103 mg, 0.41 mmol, 92%). H NMR (300 MHz, CDCl3, ppm): δ
(Ar). MS (EI): m/z (%) = 257, 255 (M+, 35, 100), 229, 227 (20, 70),
199 (10), 192 (80), 190 (40), 177 (10), 165 (90), 152 (10), 139 (5),
115 (5), 95 (10), 82 (10), 63 (5). HRMS (C14H10ClN3): calcd.
255.0563; found 255.0564.
= 6.91–7.54 (m, ca. 10 H, CH). 13C NMR (75 MHz, CDCl3, ppm):
δ = 118.8 (+, C-4), 123.8 (+, C-6), 125.1 (+, C-3), 126.6 (+,
CH=CH), 128.0 (+, C-2Ј, C-6Ј), 126.3 (+, CH), 128.9 (q, C-2),
129.0 (+, C-3Ј, C-5Ј), 129.0 (+, CH=CH), 129.1 (+, C-5), 133.6 (q,
C-4Ј), 136.0 (q, C-1), 137.6 (q, C-1Ј). IR (CH Cl , cm–1): ν = 2122
˜
2
2
tert-Butyl 4-Azidocinnamate (20c): Following general procedure 3,
resin 16c (500 mg) was cleaved, yielding a slightly brown liquid
(N3), 1606 (arene). MS (EI): m/z (%) = 257, 255 (M+, 5, 15), 229,
227 (35, 100), 216, 214 (15, 5), 199 (5), 192 (30), 177 (5), 165 (40),
139 (5), 113 (5), 90 (10), 82 (5), 63 (5). HRMS (C14H10ClN3): calcd.
255.0563; found 255.0568.
1
(23.1 mg, 0.09 mmol, 21%). H NMR (400 MHz, CDCl3, ppm): δ
3
= 1.52 (s, 9 H, CH3), 6.29 (d, J = 15.98 Hz, 1 H, CHCO2), 7.00
3
3
(d, J = 6.82 Hz, 2 H, 2,6-H), 7.47 (d, J = 6.82 Hz, 2 H, 3,5-H),
7.52 (d, 3J = 15.98 Hz, 1 H, CArCH). 13C NMR (100 MHz, CDCl3,
ppm): δ = 28.3 (+, CH3), 80.6 (q, CCH3), 119.5 (+, C-2,6), 120.0
(+, CHCO2), 129.5 (+, C-3,5), 131.7 (q, C-4), 141.7 (q, C-1), 142.4
tert-Butyl 3-Azidocinnamate (20b): Following general procedure 3,
resin 16b (500 mg) was cleaved, yielding a slightly brown liquid
1
(35.3 mg, 0.14 mmol, 32%). H NMR (300 MHz, CDCl3, ppm): δ
(q, CArCH), 166.3 (q, CO ). IR (CH Cl , cm–1): ν = 2086 (N ),
3
˜
2
2
2
3
= 1.47 (s, 9 H, CH3), 6.30 (d, J = 15.92 Hz, 1 H, CHCO2), 6.79
1695 (ester), 1636 (Ar). MS (EI): m/z (%) = 245 [M+, 30], 217 (30),
202 (5), 189 (5), 172 (30), 161 (100), 143 (90), 134 (10), 116 (20),
104 (5), 89 (20), 78 (5), 63 (10), 57 (30). HRMS (C13H15N3O2):
calcd. 245.1164; found 245.1162.
(m, 1 H, 2-H), 6.95 (ddd, 3J = 7.91 Hz, 4J = 2.26 Hz, 4J = 1.13 Hz,
1 H, 6-H), 7.07 (t, 4J = 2.07 Hz, 1 H, 5-H), 7.20 (m, 1 H, 4-H),
3
7.46 (d, J = 15.92 Hz, 1 H, CArCH). 13C NMR (75 MHz, CDCl3,
ppm): δ = 28.3 (+, CH3), 80.9 (q, CCH3), 118.1 (+, C-1), 120.5 (+,
CHCO2), 121.7 (+, C-6), 124.7 (+, C-4), 130.3 (+, C-5), 136.6 (q,
C-3), 140.9 (q, C-1), 142.4 (+, CArCH), 166.0 (q, CO2). IR
Ethyl 4-Azidocinnamate (21c): Following general procedure 3, resin
17c (500 mg) was cleaved, yielding a slightly brown liquid (32.2 mg,
(CH Cl , cm–1): ν = 2095 (N ), 1695 (ester), 1581 (Ar) (cm–1). MS
˜
2
2
3
1
0.15 mmol, 33%). H NMR (400 MHz, CDCl3, ppm): δ = 1.33 (t,
(EI): m/z (%) = 245 [M+, 25], 217 (100), 172 (60), 161 (50), 143
(45), 132 (5), 116 (45), 105 (10), 89 (30), 78 (5), 63 (10), 57 (50).
HRMS (C13H15N3O2): calcd. 245.1164; found 245.1166.
3J = 7.14 Hz, 3 H, CH3), 4.25 (q, 3J = 7.14 Hz, 2 H, CH2), 6.36
3
3
(d, J = 16.04 Hz, 1 H, CHCO2), 7.01 (d, J = 6.69 Hz, 2 H, 2,6-
H), 7.49 (d, 3J = 6.69 Hz, 2 H, 3,5-H), 7.62 (d, 3J = 16.04 Hz, 1
H, CArCH). 13C NMR (100 MHz, CDCl3, ppm): δ = 14.4 (+, CH3),
60.6 (–, CH2), 118.0 (+, CHCO2), 119.6 (+, C-2,6), 129.7 (+, C-
3,5), 131.4 (q, C-4), 142.0 (q, C-1), 143.4 (q, CArCH), 167.0 (q,
Ethyl 3-Azidocinnamate (21b): Following general procedure 3, resin
17b (500 mg) was cleaved, yielding a slightly brown liquid (48.8 mg,
1
0.23 mmol, 50%). H NMR (400 MHz, CDCl3, ppm): δ = 1.26 (t,
3J = 7.07 Hz, 3 H, CH3), 4.19 (q, 3J = 7.07 Hz, 2 H, CH2), 6.35 CO ). IR (CH Cl , cm–1): ν = 2087 (N ), 1695 (ester), 1641 (Ar).
˜
2
2
2
3
(d, 3J = 16.04 Hz, 1 H, CHCO2), 6.96 (ddd, 3J = 8.96 Hz, 4J =
1.26 Hz, 4J = 0.99 Hz, 1 H, 4-H), 7.18 (ddd, 4J = 2.15 Hz, 4J =
1.77 Hz, 4J = 0.38 Hz, 1 H, 2-H), 7.20 (dd, 3J = 6.31 Hz, 3J =
MS (EI): m/z (%) = 217 [M+, 45], 189 (65), 176 (5), 172 (15), 161
(15), 143 (100), 134 (10), 115 (20), 104 (5), 89 (25), 78 (5), 63 (10).
HRMS (C11H11N3O): calcd. 217.0851; found 217.0844.
Eur. J. Org. Chem. 2006, 1886–1898
© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
1895

K. Knepper, S. Vanderheiden, S. Bräse
FULL PAPER
4-Azido-4Ј-methoxystilbene (22c): Following general procedure 3,
C-6Ј), 129.8 (q, C-4), 131.5 (q, C-1), 133.1 (+, CH=CH), 133.9 (q,
resin 18c (500 mg) was cleaved, yielding a slightly brown liquid
C-4Ј), 135.3 (q, C-1Ј). IR (CH Cl , cm–1): ν = 2089, 1596. MS (EI):
˜
2
2
1
(67.8 mg, 0.27 mmol, 60%). H NMR (400 MHz, CDCl3, ppm): δ m/z (%) = 332 [M+, 5], 306 (40), 293 (100), 269 (10), 225 (10), 211
3
= 3.83 (s, 3 H, OCH3), 6.93 (d, J = 8.50 Hz, 2 H, 3Ј,5Ј-H), 6.98
(10), 191 (30), 178 (90), 151 (5), 95 (5), 87 (15), 74 (10), 62 (5).
3
3
1
(d, J = 16.38 Hz, 1 H, CH=CH), 7.07 (d, J = 7.85 Hz, 2 H, 2,6-
HRMS (C14H9BrClN3): calcd. 332.9668; found 332.9667. 23e: H
H), 7.22 (d, 3J = 16.38 Hz, 1 H, CH=CH), 7.46 (m, ca. 4 H, NMR (300 MHz, CDCl3, ppm): δ = 6.79–7.61 (m, ca. 15 H). 13C
3,5,2Ј,6Ј-H). 13C NMR (100 MHz, CDCl3, ppm): δ = 55.4 (+,
OCH3), 114.3 (+, C-3Ј,5Ј), 119.3 (+, C-2,6), 125.5 (+, C-3, C-5),
127.6 (+, CH=CH), 127.7 (+, C-2Ј,6Ј), 128.1 (+, CH=CH), 130.0
(q, C-4), 134.7 (q, C-1Ј), 138.6 (q, C-1), 159.4 (q, C-4Ј). IR
NMR (75 MHz, CDCl3, ppm): δ = 114.3 (+, C-3), 2×127.0 (+,
2 ×CH), 127.1 (+, C-2Ј,6Ј), 127.6 (+, CH), 128.7 (+, C-2ЈЈ,6ЈЈ),
129.2 (+, C-3Ј,3ЈЈ,5Ј,5ЈЈ), 129.8 (q, C-4), 130.9 (+, CH), 133.9 (q,
C-4Ј,4ЈЈ), 134.7 (+, CH), 135.7 (q, C-2), 137.9 (q, C-1Ј), 139.5 (q,
(CH Cl , cm–1): ν = 2113 (N ), 1608 (Ar), 1513 (C=C). MS (EI):
C-1ЈЈ). IR (CH Cl , cm–1): ν = 2089 (N ), 1596 (Ar). MS (EI):
˜
˜
2
2
3
2
2
3
m/z (%) = 251 [M+, 45], 223 (100), 208 (20), 190 (10), 180 (15), 165
(10), 152 (15), 127 (5), 111 (5). HRMS (C15H13N3O): calcd.
251.0159; found 251.1057.
m/z (%) = 391 [M+, 10], 363 (100), 255 (40), 227 (10), 201 (5), 192
(45), 165 (60), 152 (10), 139 (10), 105 (5), 82 (5), 75 (5). HRMS
(C22H15Cl2N3): calcd. 391.0643; found 391.0641.
Ethyl 4-Azido-3-bromocinnamate (21d) and Ethyl 2-Azido-4-ethoxy-
carbonyl(vinyl)cinnamate (21e): Following general procedure 3,
500 mg of resin 17d were cleaved yielding 35.8 mg (0.12 mmol,
27%) of 21d as a slightly brown liquid and 52.4 mg (0.16 mmol,
4-Azido-4Ј-chlorostilbene (23c): Following general procedure 3,
resin 19c (500 mg) was cleaved, yielding a slightly brown liquid
1
(16.1 mg, 0.06 mmol, 14%). H NMR (300 MHz, CDCl3, ppm): δ
3
4
= 7.00–7.03 (m, ca. 4 H, 2×CH, 2,6-H), 7.32 (dt, J = 6.78 Hz, J
= 2.08 Hz, 2 H, 3Ј,5Ј-H), 7.41 (dt, 3J = 8.48 Hz, 4J = 2.26 Hz, 2
H, 3,5-H), 7.49 (dt, 3J = 6.78 Hz, 4J = 2.08 Hz, 2 H, 2Ј,6Ј-H).
13C NMR (75 MHz, CDCl3, ppm): δ = 119.5 (+, C-2,6), 127.3 (+,
CH=CH), 127.7 (+, C-3,5), 128.0 (+, C-2Ј,6Ј), 128.3 (+, CH=CH),
129.0 (+, C-3Ј,5Ј), 133.4 (q, C-4), 134.1 (q, C-4Ј), 135.8 (q, C-1Ј),
1
37%) of 21e as a slightly brown liquid. 21d: H NMR (400 MHz,
CDCl3, ppm): δ = 1.23 (s, 3 H, CH3), 4.06 (m, 2 H, CH2), 6.23 (d,
3J = 15.87 Hz, 1 H, CH=CH), 7.21 (d, 3J = 7.82 Hz, 1 H, 6-H),
3
4
7.39 (dd, J = 7.82 Hz, J = 1.66 Hz, 1 H, 5-H), 7.45 (m, 1 H, 3-
H), 7.82 (d, J = 15.87 Hz, 1 H, CH=CH). 13C NMR (100 MHz,
3
139.5 (q, C-1). IR (CH Cl , cm–1): ν = 2105 (N ), 1603 (Ar), 1507
CDCl3, ppm): δ = 14.4 (+, CH3), 60.1 (+, CH2), 114.1 (q, C-2),
118.6 (+, C-6), 122.0 (+, CH=CH), 128.2 (+, C-5), 139.2 (q, C-4),
133.3 (+, C-3), 139.7 (q, C-1), 140.5 (+, CH=CH), 166.2 (q, CO2).
˜
2
2
3
(C=C). MS (EI): m/z (%) = 257, 255 [M+, 10, 40], 229, 227 (30,
100), 201 (5), 192 (45), 165 (60), 152 (10), 139 (10), 105 (5), 82 (5),
75 (5). HRMS (C14H10ClN3): calcd. 255.0563; found 255.0571.
IR (CH Cl , cm–1): ν = 2127, 1709, 1637. 21e: 1H NMR (300 MHz,
˜
2
2
CDCl3, ppm): δ = 1.31 (td 3J = 7.16 Hz, 4J = 1.50 Hz, 6 H,, CH3),
4.25 (qd 3J = 7.16 Hz, 4J = 1.88 Hz, 4 H,, CH2), 6.37 (d, 3J =
tert-Butyl 4-Azido-3-bromocinnamate (20d) and tert-Butyl 2-Azido-
4-tert-butoxycarbonyl(vinyl)cinnamate (20e): Following general pro-
cedure 3, resin 16d (500 mg) was cleaved, yielding 20d (53.4 mg,
0.14 mmol, 32 %) as a light brown solid and 20e (18.9 mg,
0.06 mmol, 13 %) as a slightly brown liquid. 20e: 1H NMR
(400 MHz, CDCl3, ppm): δ = 1.48 (s, 18 H, CH3), 6.06 (d, 3J =
3
16.01 Hz, 1 H, CO2CH), 6.48 (d, J = 16.20 Hz, CO2CH), 7.16 (d,
3J = 8.29 Hz, 1 H, 6-H), 7.49–7.64 (ca. 3 H, 3-H, 2×CH), 7.81 (d,
3J = 16.01 Hz, 1 H, 5-H). 13C NMR (75 MHz, CDCl3, ppm): δ =
14.3 (+, 2×CH3), 60.6 (+, 2×CH2), 118.8 (+, C-3), 119.3 (+, CH),
120.9 (+, CH), 126.5 (q, C-4), 127.9 (+, C-6), 130.2 (+, C-5), 131.4
(q, C-2), 138.0 (+, CH), 140.5 (q, C-1), 142.6 (+, CH), 166.5 (+,
3
13.90 Hz, 1 H, CH=CH), 6.30 (d, J = 15.81 Hz, 1 H, CH=CH),
6.91 (d, 3J = 7.85 Hz, 1 H, 6-H), 7.53 (d, 3J = 15.81 Hz, 1 H,
CH=CH), 7.56 (d, 3J = 13.90 Hz, 1 H, CH=CH), 6.85 (d, 3J =
7.85 Hz, 1 H, 5-H), 7.72 (m, 1 H, 3-H). 13C NMR (100 MHz,
CDCl3, ppm): δ = 28.2 (+, CH3), 77.8 [q, C(CH3)3], 113.6 (+, C-
3), 116.9 (+, CH=CH), 118.3 (+, CH=CH), 124.3 (+, C-6), 126.7
(+, C-5), 128.6 (q, C-4), 134.9 (q, C-2), 139.1 (q, C-1), 144.6 (+,
CH=CH), 146.6 (+, CH=CH), 164.9 (q, CO2). IR (CH2Cl2, cm–1):
2×CO ). IR (CH Cl , cm–1): ν = 2087 (N ), 1695 (ester), 1643 (al-
˜
2
2
2
3
kene), 1599 (Ar). MS (EI), m/z (%) = 317, 315 (M+, 35, 35), 287,
285 (100, 100), 270, 268 (45, 45), 259 (10), 241 (65), 228 (15), 215
(25), 196 (35), 186 (25), 170 (90), 156 (15), 140 (45), 130 (25), 115
(30), 97 (5), 83 (5), 57 (10). HRMS (C16H17N3O4): calcd. 315.1219;
found 315.1219.
4-Azido-3-bromo-4Ј-methoxystilbene (22d) and 2-Azido-4-(4ЈЈ-meth-
oxystyryl)-4Ј-methoxystilbene (22e): Following general procedure 3,
500 mg of resin 18d were cleaved yielding 66.6 mg (0.20 mmol,
45%) of 22d as a slightly brown liquid and 70.7 mg (0.18 mmol,
ν = 2100 (N ), 1695 (ester), 1641 (alkene), 1600 (Ar). MS (EI):
˜
3
m/z (%) = 373, 371, 369 (M+, 10, 30, 20), 345, 343, 341 (3, 5, 1),
300, 298, 296 (10, 45, 30), 270 (5), 231 (50), 213 (45), 187 (70),
170 (15), 159 (5), 140 (15), 115 (10). HRMS (C20H25N3O4): calcd.
371.1845; found 371.1849. 20d: 1H NMR (400 MHz, CDCl3, ppm):
δ = 1.55 (s, 9 H, CH3), 6.25 (d, 3J = 15.81 Hz, 1 H, CH=CH), 7.16
1
41%) of 22e as a slightly brown liquid. 22d: H NMR (400 MHz,
3
CDCl3, ppm): δ = 3.91 (s, 3 H, CH3), 6.74 (d, J = 7.85 Hz, 1 H,
6-H), 6.82–7.55 (ca. 8 H, CH). 13C NMR (100 MHz, CDCl3, ppm):
δ = 55.4 (+, OCH3), 111.0 (q, C-2), 114.3 (+, C-3Ј,5Ј), 119.5 (+, C-
6), 124.1 (+, C-5), 126.4 (CH=CH), 127.9 (+, C-3), 129.5 (+, C-
2Ј,6Ј), 131.2 (+, CH=CH), 136.2 (q, C-4), 136.9 (q, C-1), 159.7 (q,
3
3
4
(d, J = 7.85 Hz, 1 H, 6-H), 7.39 (dd, J = 7.85 Hz, J = 1.66 Hz,
1 H, 5-H), 7.41 (m, 1 H, 3-H), 7.82 (d, 3J = 15.81 Hz, 1 H,
CH=CH). 13C NMR (100 MHz, CDCl3, ppm): δ = 28.2 (+, CH3),
80.9 [q, C(CH3)3], 114.3 (q, C-2), 119.6 (+, C-6), 121.2 (+,
CH=CH), 128.1 (+, C-5), 139.2 (q, C-4), 133.0 (+, C-3), 139.9 (q,
C-4Ј). IR (CH Cl , cm–1): ν = 2126 (N ), 1606 (Ar), 1511 (C=C).
˜
2
2
3
MS (EI), m/z (%) = 329, 327 [M+, 15], 302, 300 (40), 287, 285 (10),
222 (100), 207 (15), 190 (20), 165 (10), 152 (15), 126 (5), 97 (5), 71
(5), 57 (10). HRMS (C15H12BrN3O): calcd. 329.0164; found
329.0160. 22e: 1H NMR (400 MHz, CDCl3, ppm): δ = 3.76 (s, 6
H, CH3), 6.82–7.63 (ca. 15 H). 13C NMR (100 MHz, CDCl3, ppm):
δ = 55.4 (+, 2×OCH3), 114.3 (+, C-3), 114.7 (+, C-3Ј,3ЈЈ,5Ј,5ЈЈ),
124.1 (+, C-6), 126.6 (+, C-2Ј,6Ј), 127.0 (+, CH), 127.1 (+, C-5),
128.3 (+, C-2ЈЈ,6ЈЈ), 128.7 (q, C-1ЈЈ), 129.8 (q, C-4), 130.9 (+, CH),
C-1), 140.8 (+, CH=CH), 165.7 (q, CO ). IR (CH Cl , cm–1): ν =
˜
2
2
2
2100, 1695, 1641, 1600.
4-Azido-3-bromo-4Ј-chlorostilbene (23d) and 2-Azido-4-(4ЈЈ-chlo-
rostyryl)-4Ј-chlorostilbene (23e): Following general procedure 3,
resin 19d (500 mg) was cleaved, yielding 23d (46.3 mg, 0.14 mmol,
31%) as a slightly brown liquid and 23e (51.0 mg, 0.13 mmol, 29%)
as a slightly brown liquid. 23d: 1H NMR (300 MHz, CDCl3, ppm):
3
δ = 6.62 (d, J = 7.87 Hz, 1 H, 6-H), 6.82–7.55 (m, ca. 8 H, CH). 132.8 (q, C1Ј), 134.7 (+, CH), 135.7 (q, C-2), 139.7 (q, C-1), 160.1
13C NMR (75 MHz, CDCl3, ppm): δ = 111.0 (q, C-2), 116.4 (+, C- (q, C-4Ј, C-4ЈЈ). IR (CH Cl , cm–1): ν = 2126 (N ), 1606 (Ar), 1512
˜
2
2
3
6), 122.8 (+, C-5), 127.1 (CH=CH), 127.6 (+, C-3), 128.7 (+, C-2Ј,
(C=C). MS (EI), m/z (%) = 385, 383 (M+, 5, 5), 344, 342 (100, 100),
1896
www.eurjoc.org
© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2006, 1886–1898

Nitrogen Functionalities in Palladium-Catalyzed Reactions on Solid Supports
FULL PAPER
322 (5), 302 (25), 279 (5), 251 (40), 238 (5), 222 (20), 208 (5), 181
2-Azido-4Ј-methoxybiphenyl (29a): Following general procedure 3,
(20), 165 (20), 137 (10), 125 (15), 11 (25), 97 (30), 57 (25). HRMS resin 28a (500 mg) was cleaved, yielding a slightly brown liquid
1
(C24H21N3O2): calcd. 383.1634; found 383.1636.
(64.8 mg, 0.29 mmol, 64%). H NMR (300 MHz, CDCl3, ppm): δ
3
= 3.76 (s, 3 H, OCH3), 6.28 (d, J = 7.78 Hz, 1 H, 6-H), 6.65–7.10
Methyl 3-Bromo-4-[(diethylamino)diazenyl]benzoate (26): Following
general procedure 2, resin 11 (500 mg) was cleaved, yielding a light
brown solid (52.1 mg, 0.15 mmol, 34 %). 1H NMR (300 MHz,
CDCl3, ppm): δ = 1.09 (t, 3J = 7.00 Hz, 6 H, CH2CH3), 3.29 (q,
3J = 7.00 Hz, 2 H, CH2), 3.92 (s, 3 H, OCH3), 7.72 (d, 3J = 7.21 Hz,
1 H, 5-H), 8.08 (dd, 3J = 7.21 Hz, 4J = 1.67 Hz, 1 H, 6-H), 8.23
(m, ca. 7 H, CH). 13C NMR (75 MHz, CDCl3, ppm): δ = 55.4 (+,
OCH3), 107.9 (+, C-6), 119.3 (+, C-3Ј, C-5Ј), 120.4 (+, C-4), 121.7
(+, C-2Ј,6Ј), 125.3 (q, C-2), 126.8 (+, C-3), 131.2 (+, C-5), 139.6
(q, C-1), 143.2 (q, C-1Ј), 157.6 (q, C-4Ј). IR (CH Cl , cm–1): ν =
˜
2
2
2127, 1612. MS (EI): m/z (%) = 225 [M+, 30], 197 (55), 182 (65),
167 (10), 154 (100), 139 (10), 127 (35), 98 (10), 76 (10), 62 (10), 50
(5). HRMS (C13H11N3O4): calcd. 225.0902; found 225.0904.
4
(d, J = 1.67 Hz, 1 H, 2-H). 13C NMR (75 MHz, CDCl3, ppm): δ
= 11.8 (+, CH2CH3), 46.4 (–, CH2), 52.1 (+, OCH3), 110.4 (q, C-
3), 113.7 (+, C-5), 125.1 (q, C-1), 132.3 (+, C-6), 134.9 (+, C-2),
147.1 (q, C-4), 165.7 (q, CO2).
3-Azido-4Ј-methoxybiphenyl (29b): Following general procedure 3,
resin 28b (500 mg) was cleaved, yielding a slightly brown liquid
1
(51.0 mg, 0.13 mmol, 51%). H NMR (300 MHz, CDCl3, ppm): δ
Methyl 3-(Ethoxycarbonylethenyl)-4-[(diethylamino)diazenyl]benzo-
ate (25): Following general procedure 2, resin 24 (500 mg) was
cleaved, yielding a light brown solid (31.5 mg, 0.09 mmol, 21%).
3
= 3.86 (s, 3 H, OCH3), 6.82 (d, J = 8.46 Hz, 2 H, 5Ј,6Ј-H), 7.02
3
3
(dd, J = 7.83 Hz, J = 7.70 Hz, 1 H, 5-H), 7.08–7.14 (m, ca. 4 H,
2,6,2Ј,6Ј-H), 7.34 (m, 1 H, 4-H). 13C NMR (75 MHz, CDCl3,
ppm): δ = 55.4 (+, OCH3), 113.3 (+, C-3Ј, C-5Ј), 115,1 (+, C-4),
115.7 (+, C-2), 121.7 (+, C-6), 127.3 (+, C-5), 131.8 (+, C-2Ј, C-
6Ј), 133.4 (q, C-1Ј), 139.6 (q, C-1), 145.0 (q, C-3), 159.6 (q, C-4Ј).
IR (CH Cl , cm–1): ν = 2127, 1612.
3
1H NMR (300 MHz, CDCl3, ppm): δ = 1.11 (t, J = 7.00 Hz, 6 H,
CH2CH3), 1.24 (t, 3J = 7.18 Hz, 3 H, CH2CH3), 3.19 (q, 3J =
3
7.00 Hz, 2 H, CH2), 3.87 (s, 3 H, OCH3), 4.14 (q, J = 7.18 Hz, 2
H, CH2), 6.07 (d, 3J = 13.96 Hz, 1 H, CH=CH), 7.58 (d, 3J =
13.96 Hz, 1 H, CH=CH), 7.92 (d, 3J = 7.21 Hz, 1 H, 5-H), 8.06
2
2
˜
3
4
4
(dd, J = 7.21 Hz, J = 1.67 Hz, 1 H, 6-H), 8.13 (d, J = 1.67 Hz,
1 H, 2-H). 13C NMR (75 MHz, CDCl3, ppm): δ = 11.8 (+, CH3),
14.4 (+, CH3), 46.3 (–, CH2), 51.3 (+, OCH3), 60.0 (–, OCH2),
115.7 (+, CH=CH), 120.3 (q, C-1), 123.6 (+, C-5), 128.8 (q, C-3),
129.5 (+, C-2), 132.0 (+, C-6), 141.9 (+, CH=CH), 152.2 (q, C-4),
161.6 (q, CO2), 167.3 (q, CO2).
4-Azido-4Ј-methoxybiphenyl (29c): Following general procedure 3,
500 mg of resin 28c were cleaved yielding 73.9 mg (0.33 mmol) of
a slightly brown liquid. 73%. H NMR (300 MHz, CDCl3, ppm):
1
3
δ = 3.85 (s, 3 H, OCH3), 6.98 (d, J = 8.86 Hz, 2 H, 2,6-H), 7.07
3
3
(d, J = 8.85 Hz, 2 H, 3Ј,5Ј-H), 7.49 (d, J = 8.86 Hz, 2 H, 3,5-H),
7.53 (d, J = 8.85 Hz, 2 H, 2Ј,6Ј-H). 13C NMR (75 MHz, CDCl3,
3
{Benzyl[2-(p-methoxyphenyl)phenylazo]amino}methylpolystyrene
(28a): Following general procedure 5, resin 3a (1.00 g, 0.9 mmol/g)
ppm): δ = 55.5 (+, OCH3), 114.5 (+, C-2,6), 119.5 (+, C-3Ј,5Ј),
128.0 (+, C-3,5), 128.1 (+, C-2Ј,6Ј), 132.9 (q, C-1Ј), 137.9 (q, C-4),
was treated with 4-methoxybenzeneboronic acid (304 mg, 138.7 (q, C-1), 159.4 (q, C-4Ј). IR (CH Cl , cm–1): ν = 2106, 1696,
˜
2
2
5.00 mmol). Loading: 0.8 mmol/g. Elemental analysis (found, %):
1606, 1597. MS (EI), m/z (%) = 225 [M+, 35], 197 (100), 182 (45),
C 85.90, H 7.251, N 2.574. IR (KBr, cm–1): ν = 3618 (s), 3027 (vs, 167 (5), 154 (30), 139 (10), 127 (25), 98 (10), 76 (5), 62 (5). HRMS
˜
ps), 2913 (vs, ps), 1943 (m, ps), 1873 (m, ps), 1804 (m, ps), 1672
(m), 1602 (m, ps), 1493 (m, ps), 1452 (m, ps), 1349 (vs), 1178 (s,
ps), 1109 (m), 1004 (m), 907 (m, ps), 830 (m), 757 (m, ps), 704 (m,
ps).
(C13H11N3O4): calcd. 225.0902; found 225.0903.
1-Azido-2,4-bis(4Ј-methoxyphenyl)benzene (29e) and 2-Azido-3-
bromo-1-(4Ј-methoxy)biphenyl (29d): Following general procedure
3, resin 28d (500 mg) was cleaved, and the mixture separated by
column chromatography, yielding 29d (53.2 mg, 0.18 mmol, 39%)
and 31e (76.0 mg, 0.23 mmol, 51%)as slightly brown liquids. 29d:
1H NMR (400 MHz, CDCl3, ppm): δ = 3.91 (s, 3 H, OCH3), 6.84
{Benzyl[3-(p-methoxyphenyl)phenylazo]amino}methylpolystyrene
(28b): Following general procedure 5, resin 3b (1.00 g, 0.9 mmol/g)
was treated with 304 mg (5.00 mmol) of 4-methoxybenzeneboronic
acid. Loading: 0.8 mmol/g. Elemental analysis (found) (%): N
3
3
(d, J = 7.23 Hz, 1 H, 6-H), 6.95 (d, J = 7.23 Hz, 1 H, 5-H), 7.35
(m, ca. 5 H, CH). 13C NMR (100 MHz, CDCl3, ppm): δ = 55.6 (+,
OCH3), 102.1 (q, C-2), 108.3 (+, C-6), 114.7 (+, C-3Ј, C-5Ј), 123.9
(+, C-5), 128.7 (+, C-2Ј, C-6Ј), 130.2 (+, C-3), 133.1 (q, C-1), 134.7
2.574, C: 85.90, H 7.251. IR (KBr, cm–1): ν = 3809 (m), 3589 (m),
˜
3447 (m), 3027 (m, ps), 2914 (s, ps), 2850 (m), 1943 (m, ps), 1871
(m, ps), 1804 (m, ps), 1673 (m), 1451 (m, ps), 1348 (vs), 1148 (s,
ps), 1075 (m), 993 (m), 843 (m), 762 (s, ps), 704 (m, ps).
(q, C-1Ј), 139.7 (q, C-4), 159.2 (q, C-4Ј). IR (CH Cl , cm–1): ν =
˜
2
2
2108, 1704, 1603, 904. MS (EI): m/z (%) = 305/303 [M+, 15], 276/
274 (20), 263/261 (40), 246 (10), 225 (50), 199/197 (100), 182 (40),
167 (5), 156/154 (20), 138 (5), 126 (20), 98 (5), 76 (5), 63 (5). 29e:
1H NMR (400 MHz, CDCl3, ppm): δ = 3.85 [s, 3 H, (OCH3)Ј],
3.91 [s, 3 H, (OCH3)ЈЈ], 6.85 (m, ca. 11 H, CH). 13C NMR
(100 MHz, CDCl3, ppm): δ = 55.3 [+, (OCH3)Ј], 55.4 [+, (OCH3)
ЈЈ], 109.6 (+, C-6), 114.3 (+, C-3ЈЈ, C-5ЈЈ), 118.3 (+, C-3Ј, C-5Ј),
121.9 (+, C-2Ј, C-6Ј), 124. 2 (+, C-3), 126.8 (+, C-2ЈЈ, C-6ЈЈ), 128.8
(+, C-5), 136.4 (q, C-4), 140.2 (q, C-1ЈЈ), 142.6 (q, C-1Ј), 146.1 (q,
{Benzyl[4-(p-methoxyphenyl)phenylazo]amino}methylpolystyrene
(28c): Following general procedure 5, resin 3c (1.00 g, 0.9 mmol/g)
was treated with 4-methoxybenzeneboronic acid (304 mg,
5.00 mmol). Loading: 0.8 mmol/g. Elemental analysis (found, %):
C 85.90, H 7.251, N 2.574. IR (KBr, cm–1): ν = 3618 (s), 3027 (vs,
˜
ps), 2913 (vs, ps), 1943 (m, ps), 1873 (m, ps), 1804 (m, ps), 1672
(m), 1602 (m, ps), 1493 (m, ps), 1452 (m, ps), 1349 (vs), 1178 (s,
ps), 1109 (m), 1004 (m), 907 (m, ps), 830 (m), 757 (m, ps), 704 (m,
ps).
C-1), 157.8 (q, C-4Ј), 158.1 (q, C-4ЈЈ). IR (CH Cl , cm–1): ν = 2107,
˜
2
2
{Benzyl[2,4-bis(p-methoxyphenyl)phenylazo]amino}methyl-
polystyrene (28d): Following general procedure 5, resin 3d (1.00 g,
0.9 mmol/g) was treated with 4-methoxybenzeneboronic acid
(608 mg, 10.00 mmol). Loading: 0.8 mmol/g. Elemental analysis
1701, 1603. MS (EI): m/z (%) = 331 [M+, 5], 286 (10), 246 (5), 225
(50), 197 (100), 182 (40), 167 (5), 154 (20), 138 (5), 126 (20), 98 (5),
76 (5), 63 (5).
(found, %): C 86.11, H 7.352 N 2.321. IR (KBr, cm–1): ν = 3811
{4-[(Diethylamino)azo]-3-(4-tert-butylphenyl)phenyl}carbonyloxy-
methylpolystyrene (33): Following general procedure 5, resin 11
˜
(s), 3582 (m), 3441 (vs), 3060 (m), 3026 (m, ps), 2920 (s, ps), 2849
(m), 1943 (m, ps), 1873 (m, ps), 1804 (m, ps), 1602 (m, ps), 1452 (1.00 g, 0.9 mmol/g) was reacted with 4-methoxybenzeneboronic
(s, ps), 1348 (s), 1175 (s, ps), 1026 (m), 983 (m), 906 (m, ps), 759
(m, ps), 702 (m, ps), 622.
acid (608 mg, 10.00 mmol). Loading: 0.7 mmol/g. Elemental analy-
sis (found, %): C 85.62, H 7.216, N 2.452. IR (KBr, cm–1): ν =
˜
Eur. J. Org. Chem. 2006, 1886–1898
© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
1897

K. Knepper, S. Vanderheiden, S. Bräse
3896 (s), 3811 (s), 3582 (vs), 3437 (s), 3082 (m), 3025 (m, ps), 2926 (q, C-5), 125.2 (q, C-1), 131.2 (+, C-6), 134.5 (+, C-2), 153.6 (q,
FULL PAPER
(s, ps), 2850 (m), 2731(m), 2516 (s), 1943 (m, ps), 1872 (m, ps),
1803 (m, ps), 1678 (m), 1602 (m, ps), 1494 (m, ps), 1452 (m, ps),
1376 (vs), 1154 (s, ps), 983 (s), 907 (m, ps), 762 (m, ps), 707 (m,
ps), 620 (m).
CO2Et), 158.7 (q, C-4), 166.4 (q, CO2Me).
Acknowledgments
Our work was supported by the Deutsche Forschungsgemeinschaft
(BR1750/2, Graduiertenkolleg 804 and CFN) and Fonds der
Chemischen Industrie. We also thank the BASF AG, Bayer AG
and Calbiochem-Novabiochem AG for the donation of chemicals.
We gratefully acknowledge Robert E. Ziegert for his help during
the preparation of this manuscript.
Methyl 4-[(Diethylamino)azo]-3-(4-tert-butylphenyl)benzoate (34):
Following general procedure 2, resin 33 (500 mg) was cleaved,
1
yielding a light yellow solid (51.2 mg, 0.14 mmol, 31%). H NMR
(300 MHz, CDCl3, ppm): δ = 1.12 (t, 3J = 7.00 Hz, 6 H, CH2CH3),
3
1.22 [s, 9 H, CH(CH3)3], 3.19 (q, J = 7.00 Hz, 4 H, CH2), 3.88 (s,
3 H, OCH3), 7.46 (d, 3J = 8.05 Hz, 2 H, 2Ј,6Ј-H), 7.55 (d, 3J =
8.05 Hz, 2 H, 3Ј,5Ј-H), 8.06–8.23 (m, ca. 3 H, CH). 13C NMR
(75 MHz, CDCl3, ppm): δ = 11.8 (+, CH2CH3), 30.18 [+, C(CH3)
3], 33.7 [q, C(CH3)3], 46.4 (–, CH2), 54.2 (+, OCH3), 108.4 (+, C-
5), 122.1 (q, C-1), 124.1 (q, C-3), 124.7 (+, C-2Ј, C-6Ј), 125.2 (q,
C-3Ј, C-5Ј), 130.4 (+, C-2), 132.5 (+, C-6), 146.1 (q, C-1Ј), 150.2
(q, C-4), 151.2 (q, C-4Ј), 166.3 (q, CO2).
[1] For a discussion, see: D. J. Cárdenas, Angew. Chem. Int. Ed.
2003, 42, 384–387; Angew. Chem. 2003, 115, 398–401.
[2] S. Bräse, J. Köbberling, J. Kirchhoff, Tetrahedron 2003, 59, 885–
939.
[3] a) S. Bräse, Acc. Chem. Res. 2004, 37, 805–816; b) N. Vignola,
S. Dahmen, D. Enders, S. Bräse, J. Comb. Chem. 2003, 5, 138–
144; c) C. Gil, A. Schwögler, S. Bräse, J. Comb. Chem. 2004, 6,
38–42; d) K. Knepper, M. E. Lormann, S. Bräse, J. Comb.
Chem. 2004, 6, 460–463; e) S. Schunk, D. Enders, J. Org. Chem.
2002, 67, 8034–8042; f) J. K. Young, J. C. Nelson, J. S. Moore,
J. Am. Chem. Soc. 1994, 116, 10841–10842.
[4] For early examples: a) K.-L. Yu, M. S. Deshpande, D. M. Vyas,
Tetrahedron Lett. 1994, 35, 8919–8922; b) M. Hiroshige, J. R.
Hauske, P. Zhou, Tetrahedron Lett. 1995, 36, 4567–4570.
[5] The reactions were executed in closed vials while being heated,
and with occasional shaking.
[6] In all cases, the reaction mixture was hydrolysed with water
and the resins obtained were washed with different polar and
apolar solvents.
[7] a) F. Avemaria, V. Zimmerman, S. Bräse, Synlett 2004, 1163–
1166; b) Caution: This mixture might produce potentially ex-
plosive HN3, however the authors never observed any incident.
See also: S. Bräse, C. Gil, K. Knepper, V. Zimmermann, Angew.
Chem. Int. Ed. 2005, 44, 5188–5240; Angew. Chem. 2005, 117,
5320–5374 (review article).
[8] a) T. Saeki, T. Matsunaga, E.-C. Eun-Cheol, K. Tamao, Adv.
Synth. Catal. 2004, 346, 1689–1692; b) T. Saeki, E.-C. Son, K.
Tamao, Org. Lett. 2004, 6, 617–619.
[9] Y. Dong, C. A. Busacca, J. Org. Chem. 1997, 62, 6464–6465.
[10] All resins were characterized by IR spectroscopy and elemental
analysis to calculate the loading based on nitrogen content.
[11] For early examples: B. J. Backes, J. A. Ellman, J. Am. Chem.
Soc. 1994, 116, 11171–11172.
[12] For early examples: J. K. Young, J. C. Nelson, J. S. Moore, J.
Am. Chem. Soc. 1994, 116, 10841–10842.
Ethyl (2-Azidophenyl)propynoate (37a) and Ethyl 2-Azidocinnamate
(21a): Following general procedure 3, resin 36a/17a (500 mg) was
cleaved. 1H NMR (300 MHz, CDCl3, ppm): δ = 1.34 (t, 3J =
3
3
7.06 Hz, 3 H, CH3), 1.35 (t, J = 7.10 Hz, 3 H, CH3), 4.19 (q, J
3
= 7.10 Hz, 1 H, CH2), 4.26 (q, J = 7.06 Hz, 1 H, CH2), 6.47 (d,
3J = 16.10 Hz, 1 H, CHCO2), 7.11–7.55 (m, ca. 8 H, HAr), 7.90 (d,
3J = 16.10 Hz, 1 H, CArCH).
Ethyl (3-Azidophenyl)propynoate (37b) and Ethyl 3-Azidocinnamate
(21b): Following general procedure 3, resin 37b/17b (500 mg) was
cleaved. 1H NMR (400 MHz, CDCl3, ppm): δ = 1.26 (t, 3J =
3
7.07 Hz, 3 H, CH3), 1.36 (t, J = 7.09 Hz, 3 H, CH3), 4.19 (m, ca.
4 H, CH2), 6.35 (d, 3J = 16.04 Hz, 1 H, CHCO2), 6.85–7.28 (m,
3
ca. 8 H, HAr), 7.54 (d, J = 16.04 Hz, 1 H, CH).
Ethyl (4-Azidophenyl)propynoate (37c) and Ethyl 4-Azidocinnamate
(21c): Following general procedure 3, resin 37c/17c (500 mg) was
1
cleaved. H NMR (400 MHz, CDCl3, ppm): δ = 1.33 (m, ca. 6 H,
3
CH3), 4.18 (q, 3J = 7.10 Hz, 2 H, CH2), 4.25 (q, J = 7.14 Hz, 2
3
H, CH2), 6.36 (d, J = 16.04 Hz, 1 H, CHCO2), 7.01–7.15 (m, ca.
6 H, HAr), 7.49 (d, 3J = 6.69 Hz, 2 H, HAr), 7.62 (d, 3J = 16.04 Hz,
1 H, CArCH).
4-Amino-3-(ethoxycarbonylethynyl)phenylcarbonyloxymethylpoly-
styrene (38): Resin 7 (1.00 g, 0.9 mmol/g) was treated with tetrakis-
(triphenylphosphane)palladium(0) (83.2 g, 0.01 mmol), triethyl-
amine (0.2 mL, 1.00 mmol), copper iodide (95 mg, 0.50 mmol) and
ethyl propynoate (1.00 mL, 5.00 mmol) in DMF (10 mL) under ar-
gon at 80 °C for two days while shaking. The resin was hydrolysed
with saturated ammonium chloride solution, washed following the
general washing procedure, and then dried under high vacuum.
Loading: 0.6 mmol/g. Elemental analysis (found, %): C 83.12, H
[13] a) K. Heuzé, D. Méry, D. Gauss, J.-C. Blais, D. Astruc, Chem.
Eur. J. 2004, 10, 3936–3944; b) S. Urgaonkar, J. G. Verkade, J.
Org. Chem. 2004, 69, 5752–5755.
[14] M. D. Collini, J. W. Ellingboe, Tetrahedron Lett. 1997, 38,
7963–7966.
[15] K. C. Nicolaou, C. N. C. Boddy, S. Natarajan, T.-Y. Yue, H.
Li, S. Bräse, J. M. Ramanjulu, J. Am. Chem. Soc. 1997, 119,
3421–3422.
[16] S. Bräse, S. Dahmen, F. Lauterwasser, N. E. Leadbeater, E. L.
Sharp, Bioorg. Med. Chem. Lett. 2002, 12, 1845–1848, and ref-
erences cited therein.
7.123 N 1.615. IR (KBr, cm–1): ν = 3484 (m), 3382 (s), 3059 (m),
˜
3026 (m, ps), 2925 (vs, ps), 2632 (s), 2337 (m), 1943 (m, ps), 1873
(m, ps), 1803 (m, ps), 1738 (s), 1613 (s, ps), 1452 (m, ps), 1246 (s),
1029 (m, ps), 964 (m), 824 (m), 762 (m, ps).
[17] For other references in this field: a) H. A. Dieck, R. F. Heck,
J. Organomet. Chem. 1975, 93, 259–263; b) V. P. Bohm, W. A.
Herrmann, Eur. J. Org. Chem. 2000, 3679–3681; c) N. E. Lead-
beater, B. J. Tominack, Tetrahedron Lett. 2003, 44, 8653–8656;
d) D. A. Alonso, C. Najera, M. C. Pacheco, Adv. Synth. Catal.
2003, 345, 1146–1158; e) A. Soheili, J. Albaneze-Walker, J. A.
Murry, P. G. Dormer, D. L. Hughes, Org. Lett. 2003, 5, 4191–
4194, and references cited therein.
Methyl 4-Amino-3-(ethoxycarbonylethynyl)benzoate (39): Following
general procedure 2, resin 38 (500 mg) was cleaved, yielding a light
brown solid (40.0 mg, 0.18 mmol, 41 %). 1H NMR (300 MHz,
3
CDCl3, ppm): δ = 1.35 (t, J = 7.11 Hz, 3 H, CH2CH3), 3.34 (br.
s, 2 H, NH2), 3.83 (s, 3 H, OCH3), 4.25 (q, 3J = 7.11 Hz, 2 H,
3
3
4
CH2), 6.52 (d, J = 8.72 Hz, 1 H, 5-H), 7.65 (dd, J = 8.72 Hz, J
= 1.82 Hz, 1 H, 6-H), 7.94 (d, J = 1.82 Hz, 1 H, 2-H). 13C NMR
4
(75 MHz, CDCl3, ppm): δ = 14.2 (+, CH2CH3), 54.2 (+, OCH3),
62.7 (–, CH2), 79.3 (q, CϵC), 83.0 (q, CϵC), 109.2 (q, C-3), 115.8
Received: October 7, 2005
Published Online: February 9, 2006
1898
www.eurjoc.org
© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2006, 1886–1898