Mechanistic study on rearrangement cascades starting from annulated 2-Aza-hepta-2,4-dienyl-6-ynyl anions: Formation of aniline and azepine derivatives

Article abstract of DOI:10.1002/chem.200601491

Deprotonation of benzothiophene-derived alkynyl imine 11 with lithium diisopropylamide (LDA) and subsequent transmetalation with ZnCl₂ etherate furnished azepine 12 upon aqueous workup. Similarly, alkynyl benzaldimine la gave a mixture of benza

Full text of DOI:10.1002/chem.200601491

FULL PAPER
DOI: 10.1002/chem.200601491
Mechanistic Study on Rearrangement Cascades Starting from Annulated
2-Aza-hepta-2,4-dienyl-6-ynyl Anions: Formation ofAniline and
Azepine Derivatives
Volodymyr Lyaskovskyy, Roland Frçhlich, and Ernst-Ulrich Würthwein*[a]
Dedicated to Professor Dr. Herbert Mayr on the occasion of his 60th birthday
Abstract: Deprotonation of benzothio-
phene-derived alkynyl imine 11 with
lithium diisopropylamide (LDA) and
subsequent transmetalation with ZnCl2
etherate furnished azepine 12 upon
aqueous workup. Similarly, alkynyl
benzaldimine 1a gave a mixture of
benzazepine 13 and naphthylamine 14.
Allylic benzonitriles 15a,b reacted to
produce naphthylamine 16 upon depro-
tonation with LDA at room tempera-
ture. In an analogous manner, imino
benzonitrile 17 may be converted into
4-amino isoquinoline 18 by means of
an intramolecular nucleophilic attack
on the nitrile function upon treatment
with LDA. The allylic benzonitriles
19a,b were prepared by LDA treat-
ment of alkynyl imine 11. They were
further converted to amino dibenzo-
thiophene 20 by LDA deprotonation
and aqueous workup. These various
transformations represent the key steps
of a multistep reaction cascade, which
was previously postulated on the basis
of quantum chemical calculations.
Thus, all features of this complex rear-
rangement mechanism could now be
confirmed experimentally. DFT calcu-
lations support the lower reactivity of
zinc species in the ring-opening step
compared to the lithium intermediates.
All new compounds were completely
characterized by spectroscopic data, in-
cluding X-ray diffraction studies for
the key compounds 12, 19a, and 20.
Keywords: azepines · density func-
tional calculations
·
lithium
·
organic chemistry · ring closure ·
zinc compounds
Introduction
of an intermolecular proton shift combined with a ring-
opening reaction leading to nitrile 5, which is calculated to
be 46.7 kcalmolÀ1 lower in energy than 2. Interestingly, the
more acidic benzylic proton is not involved in the proton
shift, as a transfer of this proton to the vinyl anion would
result in an energetically unfavorable conjugated eight p-
electron seven-membered intermediate 4 with Hückel-anti-
aromatic character. After nucleophilic addition of the allyl
anion moiety to the nitrile function (six p-electrocyclization)
a tautomerism follows, leading to the aromatic 1-amino-
naphthalene anion 7. Trapping of this final intermediate
with various electrophiles yielded the observed N-substitut-
ed products 8. The simple general procedure (deprotonation
of the imine with LDA by À788C and following warming to
room temperature for 16 h), wide applicability (different
carbo- and heterocyclic imines can be used, R=nBu, Ph)
and good yields of the final products (60–90%)[1] render this
reaction synthetically very attractive.[2]
Recently, we have reported a new and unexpected rear-
rangement of annulated 2-aza-hepta-2,4-dien-6-ynyl anions
to give various aniline systems.[1] We proposed a multistep
cascade mechanism to explain the formation of the final
products.[1] This mechanistic proposal was supported by
high-level quantum chemical calculations for a simplified
model system (1, R=Me; Scheme 1). Thus, the deprotona-
tion of imine 1 with lithium diisopropylamide (LDA) leads
to the 2-aza-4,5-benzohepta-2,4-dienyl-6-ynyl anion 2. An
electrocyclic ring-closure reaction of 2, forming a seven-
membered intermediate 3 with a vinyl anion moiety, is
postulated as a second step (calculated activation barrier ap-
proximately 2 kcalmolÀ1). The proposed third step consists
[a]V. Lyaskovskyy, Dr. R. Frçhlich, Prof. Dr. E.-U. Würthwein
Organisch-Chemisches Institut, Westfälische Wilhelms-Universität
Corrensstrasse 40, 48149 Münster (Germany)
Fax : (+49)251-83-39772
Certainly, such a complex multistep mechanistic proposal
requires not only theoretical, but also experimental evi-
dence. In this report, we will present several experimental
observations supporting the proposed mechanism.
E-mail: wurthwe@uni-muenster.de
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3113

tive preference of zinc and lithi-
um species, respectively. As
Table 1 clearly indicates for the
lithium species, the structure
type 5 is significantly preferred
over the type 3 (approximately
33 kcalmolÀ1). For the ZnCl
species, however, the prefer-
ence for type 5 is much smaller
(approximately 12 kcalmolÀ1).
This implies a strong thermody-
namic gradient in favor of the
transformation giving 5 for the
Li compounds, but
a much
Scheme 1. Proposed mechanism of the rearrangement of 1 to give 8 (for 2–8 (R=Me). Relative energies[1] of
the minima are given below the formulas and the relative energies of the transition states are given above the
arrows (G3MP2 theory [kcalmolÀ1]).
smaller one for the correspond-
ing ZnCl derivatives. The sol-
vated species show similar ten-
Results and Discussion
Evidence for the formation of
seven-membered intermediates
oftype 3 : The best indication
for the validity of the proposed
reaction mechanism would be
the isolation or trapping of an
azepine anion intermediate of
type 3 and the subsequent con-
version to an aniline of type 8.
However, all attempts to isolate
such an intermediate by reduc-
ing the reaction time or by low-
Scheme 2.
ering the temperature were un-
successful. Obviously, as sug-
gested by the quantum chemical
Table 1. Relative energies of the lithium and zinc chloride compounds 3
and 5 with and without additional dimethyl ether solvation (quantum-
calculations, the considered lithiated intermediate 3 is too
reactive and additional stabilization is necessary for its char-
acterization. To solve this problem, transmetalation by using
zinc chloride was considered for this purpose with respect to
the well-known reduced reactivity of organozinc compounds
in comparison to organolithium species.[3,4]
chemical DFT calculations B3LYP/6-31+G
U
G
Compound
Erel
Compound
Erel
3-Li
5-Li
3-ZnCl
5-ZnCl
33.23
0.00
11.86
0.00
3-Li·
5-Li·
3-ZnCl·
5-ZnCl·
N
17.48
0.00
4.90
0.00
To estimate the relative stability of the corresponding
cyclic (3) and allylic (5) lithium and zinc intermediates
quantum chemical calculations using the B3LYP/6-31+G-
ACHTREUNG
AHCTREUNG
(d,p) DFT method[5] (including zero-point correction) were
carried out. We performed these calculations both for the Li
dencies, with a preference for the ZnCl compound type 5-
and ZnCl substances 3-Li, 3-ZnCl, 5-Li, and 5-ZnCl, and for
ZnCl·
ZnCl·
ACHTREUNG
+
+
solvated species with Li·
counterions (3-Li·(OMe2)3, 3-ZnCl·
and 5-ZnCl·(OMe2)2; Scheme 2). The relative energies (Erel)
A
N
ACHTREUNG
A
G
A
Lithium–zinc transmetalation was carried out experimen-
tally by using the imine 11, which was synthesized according
to Scheme 3. The literature-known 2,3-dibromobenzo[b]-
thiophene[6] underwent Sonogashira coupling with phenyl
acetylene to give bromide 9, which was transformed into al-
dehyde 10 by base-induced formylation using DMF. The
condensation reaction of compound 10 with benzyl amine
led to the target imine 11.
ACHTREUNG
of the seven-membered intermediates 3-Li and 3-ZnCl with
metalated sp2 carbon atoms (bridging for Li, monohapto
with respect to ZnCl) compared to the metalated allylic ni-
triles 5-Li and 5-ZnCl (with Li in the bridging position and
coordination to the nitrile nitrogen atom and ZnCl with
contact to CN, respectively) were used to estimate the rela-
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Chem. Eur. J. 2007, 13, 3113 – 3119

Aniline and Azepine Derivatives
FULL PAPER
tion times (16 and 32 h). This
might be explained by the
higher reactivity of the respec-
tive seven-membered zinc inter-
mediate in comparison to the
corresponding one attached to
a benzothiophene system. Ap-
Scheme 3. Reagents and conditions: i) PhCCH, [Pd
iii) PhCH2NH2, CH2Cl2, molecular sieves.
A
Compound 11 was deprotonated with LDA at À788C.
The resulting lithium species was then transmetalated by
using zinc chloride etherate at À788C, followed by warming
to 08C with stirring for 1.5 h, and aqueous workup leading
to azepine 12 in 30% yield (Scheme 4). The structure of
azepine 12 was confirmed by X-ray structure analysis
(Figure 1). The formation of 12 may be understood as the
Scheme 5. i) 1. LDA, À788C, 2. ZnCl2·2Et2O, 3. À78–208C, NH4Cl/H2O.
parently, the presence of the
benzazepine 13 in the mixture is
a result of the reaction of the
seven-membered zinc inter-
mediate with some proton sour-
ces (such as diisopropylamine,
before the aqueous workup) in
the reaction mixture. Hence in
this case, the more reactive (in
comparison to the benzothio-
phene compound) seven-mem-
bered zinc intermediate not
only reacts with proton sources
Scheme 4.
(giving benzazepine 13), but
also rearranges to naphthyla-
mine 14 (see Scheme 1) as is known for the lithium com-
pound.[1]
This pathway, used here for the synthesis of azepines 12
and 13, is new and is expected to offer a quick and versatile
method for the preparation other annulated azepine deriva-
tives.[8,9] It adds nicely to our previous electrocyclization
studies on the formation of 2,3- and 4,5-dihydroazepins[10,11]
and 4,5-dihydro-3H-benzo[c]azepines.[12]
Evidence for the formation of nitrile intermediates of type 5
and their electrocyclization: The intramolecular addition of
a carbanion to a nitrile function was observed first by Ko-
bayashi et al.[13–15] DMF was used as solvent (instead of THF
as we used it) and CO2Et and CN groups (instead of Ph)
were present in their work. To investigate the cyclization
under typical conditions for concerted reactions, we synthe-
sized model compound 15. Compound 15 was obtained as a
mixture of (E)-(15a) and (Z)-(15b) isomers (ratio 70:30) by
the Heck reaction of 2-bromobenzonitrile and allylbenzene
in 68% total yield (Scheme 6). Deprotonation under stan-
dard conditions (16 h, À788C to room temperature) gave a
mixture of naphthylamine 16 and the E isomer of the initial
nitrile 15a in a 35:65 ratio. The mixture obtained was again
subjected to deprotonation conditions and stirred at room
temperature for an additional 32 h (not optimized reaction
time) to give the pure amine 16 (50% yield). Apparently,
Figure 1. Molecular structure of 12 as obtained by X-ray diffraction
(SCHAKAL plot).[7]
result of proton addition to an intermediate anion such as 3
during the aqueous workup. There are no indications for an
anion with antiaromatic character such as 4 (Scheme 1). In
contrast, the reaction of the lithiated imine 11 (without
transmetalation) under the same reaction conditions led to a
complex mixture of different compounds (GC analysis), in
which 12 could not be detected by spectroscopic methods
(see below).
The same transmetalation procedure applied for imine 1a
(Scheme 1, R=Ph) gave a (inseparable) mixture of two sub-
stances (ratio 67:33 as determined by GC analysis), which
1
were identified by H and 13C NMR spectra as benzazepine
13 and naphthylamine 14 (Scheme 5). The formation of such
reaction mixtures was also observed in cases of longer reac-
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3115

E.-U. Würthwein et al.
tions (addition of LDA at
À788C, warming to room tem-
perature for 16 h) and aqueous
workup gave a mixture of the
two isomeric nitriles 19a,b. A
X-ray diffraction study of 19a
confirms the postulated struc-
ture (Figure 2). The configura-
tion of the C=C double bond in
nitrile 19b could not be deter-
Scheme 6.
the longer reaction time required in the case of model com-
pound 15 in comparison to the cyclization of imine 1a is de-
pendent on the Z or E configuration of the nitrile 15, as
only the (Z)-(15b)-, but not the (E)-(15a)-derived allyl
anion of type 5 will be involved in the cyclization. As the
formation of the nitrile species from the seven-membered
intermediate 3 leads to the pure (Z)-allyl-anion, the fast cyc-
lization to give the six-membered intermediate 6 is well un-
derstandable. In contrast, the presence of the less reactive E
isomer 15a in the mixture led to an increase of the reaction
time, as in this case obviously the comparably slow rate of
the E–Z isomerization determined the reaction time.
Figure 2. Molecular structure of 19a as obtained by X-ray diffraction
(SCHAKAL plot).[7]
For comparison, we included the imino nitrile 17
(Scheme 7) into this study. Its cyclization after lithiation
may be considered as further, indirect evidence for the de-
pendence of the reaction rate on the rate of the trans–cis
isomerization of the allyl-anion. In the lithium compound of
imino nitrile 17, the nitrogen atom of the C=N double bond
is expected to reduce the rotational barrier about this bond
and consequently to decrease the reaction time in compari-
son to the one of model compounds 15a,b. Indeed, the cycli-
zation of imine 17 was completed in 16 h (not optimized
period of time), comparably fast as in the case of imine 1a.
Transmetalation by using ZnCl2 after the lithiation also
gives 18, although in a slower reaction. This reaction is also
of interest from the preparative point of view as a new and
mined from the spectra of the mixture. Shorter reaction
times gave a complex mixture of compounds (see above).
Finally, deprotonation of nitriles 19a,b with LDA, stirring
of the resulting lithium species for 36 h at room tempera-
ture, and aqueous workup led to amine 20 in 90% yield (for
X-ray structure see Figure 3). We take this experiment as
additional evidence for the nitrile cyclization upon deproto-
nation.
Scheme 7. i) LDA, À78–208C, 16 h, then NH4Cl/H2O.
simple method for the synthesis of 4-aminoisoquinoline de-
rivatives 18.[16]
Figure 3. Molecular structure of 20 as obtained by X-ray diffraction
(SCHAKAL plot).[7]
Of course, the best evidence
for the occurrence of the nitrile
intermediate during the reac-
tion is its isolation in the case
of slowly reacting substances.
As we found, imine 11 is a pre-
cursor for such a slowly react-
ing intermediate (Scheme 8).
Thus, reaction of imine 11
under standard lithiation condi- Scheme 8. i) LDA, À78–208C, 16 h, then NH4Cl/H2O; ii) LDA, 208C, 32 h, then NH4Cl/H2O.
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Aniline and Azepine Derivatives
FULL PAPER
1-(3-Bromobenzo[b]thiophen-2-yl)-2-phenylacetylene (9): A suspension
of 2,3-dibromobenzo[b]thiophene[6] (2.00 g, 6.84 mmol), triethylamine
Conclusion
(30 mL), phenyl acetylene (0.82 g, 8.04 mmol), [Pd(PPh3)2Cl2](96 mg),
G
The previously discovered novel rearrangement cascade of
lithiated 2-(1-alkynyl)-benzaldimines of type 2 had been elu-
cidated mechanistically on the basis of quantum chemical
calculations, postulating the formation of a seven-membered
heterocyclic intermediate and an open-chain nitrile com-
pound as reaction intermediates. In this report, we present
experimental proof for the postulated mechanism. Thus, we
and CuI (13 mg) was stirred for 19 h at RT. The precipitate was filtered
off. The filtrate was freed from the solvent under reduced pressure. Pu-
rification by flash chromatography (heptane) gave 9 (1.73 g, 5.53 mmol,
81%) as a colorless solid. M.p. 77–798C; IR (KBr): n˜ =3049 (w), 2954
(m), 2923 (s), 2852 (s), 2206 (w), 1593 (m), 1568 (w), 1556 (w), 1521 (w),
1481 (s), 1454 (m), 1438 (m), 1431 (m), 1377 (w), 1319 (m), 1307 (m),
1290 (w), 1276 (w), 1244 (m), 1157 (w), 1097 (w), 1066 (w), 914 (m), 844
(w), 817 (m), 750 (s), 721 (s), 709 (s), 684 cmÀ1 (s); 1H NMR (400 MHz,
CDCl3, 258C): d=7.32–7.53 (m, 5H), 7.59–7.62 (m, 2H), 7.72–7.80 ppm
(m, 2H); 13C NMR (100 MHz, CDCl3, 258C): d=80.85 (C=C), 98.30 (C=
C), 112.86, 119.58, 121.39, 122.80, 124.63, 125.64, 127.60, 128.25, 138.90,
131.64, 136.62, 137.45 ppm; MS (EI): m/z (%): 314 [M]+ (100), 312 [M]+
(100), 232 (42), 202 (71), 189 (52), 163 (9), 127 (39), 98 (6), 57 (22); ele-
mental analysis calcd (%) for C16H9BrS (313.22): C 61.36, H 2.90; found:
C 61.77, H 2.95.
were able to prepare 3,4-diphenyl-3H-benzo
N
N
c]azepine (12) by low-temperature transmetalation of the
highly reactive lithium intermediate to the less reactive
ZnCl compound. Similarly, imine 1a gave a mixture of the
corresponding benzazepine derivate 13 together with the re-
arranged naphthylamine 14 after transmetalation. The ratio
of the two compounds formed was found to depend on the
reaction time applied.
Allyl nitriles 15 were successfully converted to the corre-
sponding aminobenzannulated compound 16. The anion de-
rived from the Z isomer of 15 was found to cyclize much
faster compared to one from the E isomer. The analogous
imino nitrile 17 gave a similar cyclization providing a new
synthetic pathway to amino-isoquinolines, such as 18. The
postulated interconversion of alkynyl imino compounds into
allyl nitriles could be confirmed in the case of 11, which
gives the nitriles 19 under mild conditions. They may be
transformed into the respective dibenzothiophene amine 20
by prolonged treatment with LDA as base.
In summary, we are able to present experimental proof
for the involvement of intermediates of type 3 (azepine
anions) and 5 (allyl anions; Scheme 1) in the cascade reac-
tion mechanism, previously postulated on the basis of quan-
tum chemical calculations. This study also leads to a deeper
understanding of this mechanism and additionally offers the
possibility to enter the reaction cascade from new precursor
compounds, thus widening the scope of the reaction, for ex-
ample, also for the synthesis of new types of compounds in-
cluding new azepines and 4-amino-isoquinolines.
2-(2-Phenyl-1-ethynyl)benzo[b]thiophene-3-carbaldehyde (10): nBuLi
(1.51 mL of 1.6m solution in hexane, 2.42 mmol) was added to a solution
of 9 (0.74 g, 2.37 mmol) in dry THF (50 mL) at À788C under an argon at-
mosphere. The reaction mixture was stirred for 1 h at this temperature.
Then DMF (0.28 mg, 3.83 mmol) was added and the mixture was stirred
for an additional 3 h while warming to room temperature. After the addi-
tion of diluted ammonium chloride solution (60 mL) and extraction of
the water layer with diethyl ether (3”30 mL), the combined organic ex-
tracts were dried over magnesium sulfate. Purification by flash chroma-
tography (Et2O/pentane 0.3:10) gave 10 (0.50 g, 1.90 mmol, 80%) as a
colorless solid. M.p. 101–101.58C; IR (KBr): n˜ =3057 (w), 2924 (w), 2831
(w), 2202 (m), 1666 (s), 1505 (m), 1481 (m), 1458 (m), 1429 (m), 1394
(w), 1360 (m), 1315 (m), 1291 (w), 1250 (m), 1161 (m), 1140 (m), 1119
(m), 1061 (w), 1041 (w), 1015 (w), 916 (w), 868 (m), 758 (s), 687 (s),
588 cmÀ1 (m); 1H NMR (400 MHz, CDCl3, 258C): d=7.38–7.51 (m, 5H),
7.58–7.60 (m, 2H), 7.76–7.78 (m, 1H), 8.68–8.70 (m, 1H), 10.47 ppm (s,
1H; CHO); 13C NMR (100 MHz, CDCl3): d=79.18 (C=C), 102.03 (C=C),
120.56, 120.81, 124.32, 125.68, 126.00, 127.78, 129.00, 130.99, 134.38,
135.11, 137.76, 138.01, 184.11 ppm (CHO); MS (GCMS): m/z: 262 [M]+,
234, 221, 202, 189, 163, 150, 117, 104, 95, 69, 63, 51; HRMS: m/z: calcd
for C17H10OS: 262.0452; found: 262.0452; elemental analysis calcd (%)
for C17H10OS: 262.33: C 77.84, H 3.84; found: C 77.73, H 3.63.
N-Benzyl-2-(2-phenyl-1-ethynyl)benzo[b]thiophen-3-ylmethanimine (11):
Aldehyde 10 (1.31 g, 5.00 mmol) and benzyl amine (0.53 g, 5.00 mmol)
were mixed together in dry dichloromethane (20 mL) and stirred in the
presence of molecular sieves (4 Š) at RT for 16 h. The molecular sieves
were then removed by filtration and washed with dichloromethane
(20 mL). The solvent was removed in vacuo to afford 11 (1.11 g,
3.15 mmol, 63%) as a brown oil. IR (KBr): n˜ =3084 (w), 3060 (m), 3028
(m), 3003 (w), 2856 (m), 2202 (w), 1631 (s), 1595 (m), 1585 (m), 1571
(w), 1556 (w), 1517 (w), 1494 (m), 1483 (m), 1460 (m), 1452 (m), 1442
(m), 1431 (m), 1382 (w), 1359 (m), 1342 (w), 1315 (m), 1296 (w), 1265
(w), 1249 (w), 1176 (w), 1159 (w), 1143 (m), 1120 (m), 1068 (w), 1026
(m), 999 (w), 947 (w), 914 (w), 858 (w), 756 (s), 732 (s), 690 (s), 669 (w),
642 (w), 592 cmÀ1 (m); 1H NMR (400 MHz, CDCl3, 258C): d=4.86 (s,
Experimental Section
Materials and methods: Solvents were dried by distillation from a drying
agent: THF from K/benzophenone; CH2Cl2 from P2O5. Melting points:
Büchi melting point B-540, uncorrected. IR: Nicolet FTIR 5DXC spec-
trometer. 1H NMR: Bruker WM 300 (300 MHz), Bruker AMX 400
(400 MHz), Varian 500 MHz INOVA (500 MHz), Varian 600 Unity plus
(600 MHz) spectrometers. 13C NMR: Bruker WM 300 (75 MHz), Bruker
AMX 400 (100 MHz), Varian 500 MHz INOVA (125 MHz), Varian 600
Unity plus (150 MHz) spectrometers. TMS as internal standard. GC anal-
ysis: Hewlett Packard 6890 Series, column HP5 (30 m), temperature pro-
gram: 408C, 108CminÀ1, 2808C, 5 min. Electron ionization mass spectra
(EIMS): Finnigan MAT C 312 spectrometer (70 eV). Electrospray mass
spectra (ESIMS): Micromass Quartto LC-Z quadrupole mass spectrome-
ter. GCMS: Varian MAT 8230 spectrometer with GC Varian 3400 plus
datasystem Mass II by using Quartz capillary column HP5. Exact mass
determination (HRMS): Micromass MAT 8200 spectrometer. Elemental
analysis: Elementar Vario EL III analyze automate. Flash chromatogra-
phy: silica gel Merck 60 (0.040–0.063 mm) with excess pressure of about
1.2 bar. TLC: Merck silica gel plates (silica gel 60 F254).
2H; CH2), 7.20–7.36 (m, 10H), 7.78–7.50 (m, 2H), 7.67–7.69 (m, 1H),
13
À
8.88–8.93 ppm (m, 2H); C NMR (75 MHz, CDCl3): d=66.07 (N CH2),
97.82 (C=C), 102.83 (C=C), 121.76, 125.76, 126.25, 126.39, 127.03, 127.17,
127.46, 127.75, 128.04, 128.27, 128.43, 128.65, 128.87, 129.14, 129.34,
131.78, 156.92 ppm; HRMS: m/z: calcd for C24H17NSH: 352.1159; found:
352.1154; elemental analysis calcd (%) for C24H17NS (351.47): C 82.02, H
4.88, N 3.99; found: C 81.93, H 4.75, N 3.88.
3,4-Diphenyl-3H-benzo
N
N
was prepared by adding nBuLi (0.70 mL, 1.12 mmol, 1.6m solution in
hexane) to diisopropylamine (0.12 g, 1.12 mmol) in dry THF (25 mL) at
À788C. Imine 11 (1.00 mmol, 0.35 g) dissolved in THF (10 mL) was then
added dropwise over a period of 30 min. Zinc chloride solution (3 mL,
3 mmol, 1m solution in diethyl ether, ACROS) was added after 1 h of
stirring at À788C. Then, the reaction mixture was stirred for an addition-
al 1 h and was warmed to À208C over 20 min and stirred at À20–08C for
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E.-U. Würthwein et al.
1 h. Diluted ammonium chloride solution (30 mL) was added and the
mixture was extracted with diethyl ether (3”20 mL). The combined or-
ganic layers were washed with brine and dried over magnesium sulfate.
The solvent was evaporated in vacuo. Purification by flash chromatogra-
phy (EtOAc/pentane/Et3N 0.4:10:0.2, 15 cm length column) gave 12
(0.10 g, 0.3 mmol, 30%) as a colorless solid. M.p. 173–1758C; IR (KBr):
n˜ =3060 (m), 3022 (m), 2814 (m), 1643 (m), 1598 (s), 1577 (s), 1571 (m),
1552 (m), 1490 (s), 1444 (s), 1431 (s), 1365 (w), 1342 (m), 1313 (m), 1305
(m), 1259 (m), 1211 (s), 1182 (m), 1157 (w), 1132 (w), 1072 (m), 1031
(w), 1008 (s), 977 (m), 939 (w), 910 (w), 898 (w), 858 (s), 829 (w), 765 (s),
dropwise over a period of 30 min. The reaction mixture was warmed to
RT for 48 h and was then quenched by addition of diluted ammonium
chloride solution (5 mL). Water (20 mL) was added and the mixture was
extracted with diethyl ether (3”20 mL). The combined organic layers
were washed with brine and dried over magnesium sulfate. The solvent
was evaporated. Purification by flash chromatography (EtOAc/pentane
1:10) gave 16 (0.11 g, 0.50 mmol, 50%) as a brown solid. M.p. 98–1008C;
IR (film): n˜ =3363 (s, br), 3224 (s, br), 3055 (s), 3030 (s), 2958 (m), 2925
(m), 2869 (m), 2854 (m), 1955 (m), 1894 (m), 1811 (m), 1643 (s), 1633 (s),
1575 (s), 1548 (s), 1506 (s), 1494 (s), 1463 (s), 1446 (s), 1427 (s), 1394 (s),
1332 (m), 1311 (m), 1280 (m), 1255 (s), 1228 (m), 1180 (m), 1157 (m),
1132 (m), 1099 (m), 1072 (m), 1026 (s), 983 (w), 952 (w), 920 (w), 894
(m), 856 (m), 806 (s), 758 (s), 744 (s), 696 cmÀ1 (s); 1H NMR (100 MHz,
[D6]DMSO, 258C): d=5.39 (brs, 2H; NH2), 7.19–7.27 (m, 2H), 7.36–7.52
(m, 7H), 7.78–7.81 (m, 1H), 8.20–8.24 ppm (m, 1H); 13C NMR (75 MHz,
[D6]DMSO): d=116.56, 119.78, 122.80, 123.07, 124.51, 125.75, 126.79,
127.84, 128.64, 128.97, 129.26, 133.47, 139.84, 140.14 ppm; HRMS: m/z:
calcd for C16H13NH: 220.1126; found: 220.1121; elemental analysis calcd
(%) for C16H13N (219.29): C 87.64, H 5.98, N 6.39; found: C 87.22, H
5.91, N 6.06.
740 (s), 696 (s) cmÀ1 1H NMR (300 MHz, CDCl3, 258C): d=4.94 (brs,
;
À
1H; N CH), 7.12–7.23 (m, 9H), 7.41–7.51 (m, 4H), 7.84–7.88 (m, 1H),
7.95–7.98 (m, 1H), 8.86 ppm (d, 4JH,H =1.7 Hz, 1H; CH=N); 13C NMR
À
(75 MHz, CDCl3, 258C): d=67.53 (N CH), 121.71, 122.53, 122.72,
125.33, 125.96, 126.74, 127.31, 127.80, 127.94, 127.99, 129.13, 132.78,
137.93, 138.35, 139.13, 140.84, 143.19, 145.70, 153.20 ppm; MS (GC-EI):
m/z (%): 350 [MÀH]+, 336, 321, 273, 247, 215, 202, 175, 165, 137, 102, 91,
89, 77; elemental analysis calcd (%) for C24H17NS (351.47): C 82.02, H
4.88, N 3.99; found: C 81.80, H 4.82, N 3.85.
X-ray crystal-structure analysis of 12:[17] Formula: C24H17NS; M=351.45;
colorless crystal; crystal size: 0.30”0.15”0.05 mm; a=17.559(1), b=
2-Benzyliminomethylbenzonitrile (17): Treatment of 2-formylbenzonitrile
(0.65 g, 5.00 mmol) according to the general procedure described for
imine 11 gave 17 (0.63 g, 2.85 mmol, 57%) as a colorless solid. M.p. 63–
658C; IR (film): n˜ =3085 (w), 3062 (w), 3030 (w), 2858 (w), 2844 (w),
2231 (s), 1708 (w), 1647 (s), 1602 (w), 1581 (w), 1496 (m), 1475 (m), 1454
(m), 1434 (m), 1371 (m), 1342 (m), 1315 (w), 1288 (m), 1244 (w), 1168
(w), 1155 (w), 1141 (w), 1095 (w), 1080 (w), 1028 (m), 999 (w), 964 (w),
908 (w), 798 (m), 756 (m), 736 (m), 700 (s), 686 (s), 613 cmÀ1 (m);
6.045(1), c=17.831(1) Š; b=112.14(1)8; V=1753.1(3) Š3; 1calcd
=
1.332 gcmÀ3; m=0.191 mmÀ1; empirical absorption correction (0.945ꢀTꢀ
0.991); Z=4; crystal system: monoclinic; space group: P21/c (no. 14); l=
0.71073 Š; T=198 K; w and f scans; 11311 reflections collected (Æh, Æ
k, Æl), [(sinq)/l]=0.67 ŠÀ1; 4212 independent (Rint =0.058) and 2626 ob-
served reflections [Iꢁ2sI]; 235 refined parameters; R=0.051; wR2=
À3
0.108; max. residual electron density 0.25 eŠ (À0.31); hydrogen atoms
1H NMR (400 MHz, CDCl3, 258C): d=4.90 (d, 4JH,H =1.4 Hz, 2H; N
calculated and refined riding.
À
CH2), 7.25–7.38 (m, 5H), 7.49 (td, 3JH,H =7.6, 4JH,H =1.4 Hz, 1H), 7.61
3,4-Diphenyl-3H-2-benzazepine (13): 3,4-Diphenyl-3H-2-benzazepine
(13) was obtained as a mixture with aminonaphthalene 14[1] from imine
1a[1] in a similar manner as described for the synthesis of 12 from 11
(overall yield 70%). Separation of the mixture (chromatography, silica
gel, Et2O/Et3N/pentane 0.5:0.2:10) was not possible. Spectroscopic data
3
(tm, 3JH,H =7.7 Hz, 1H), 7.67 (dm, 3JH,H =7.7 Hz, 1H), 8.18 (dm, JH,H
=
8.0 Hz, 1H), 8.78 ppm (t, 4JH,H =1.4 Hz, 1H; N=CH); 13C NMR
À
À
(100 MHz, CDCl3, 258C): d=65.35 (N CH2 Ph), 112.93, 117.08, 127.31,
127.70, 128.11, 128.69, 130.78, 132.94, 133.08, 138.39, 138.70, 157.78 ppm.
HRMS: m/z: calcd for C15H12N2Na: 243.0898; found: 243.0893; elemental
analysis calcd (%) for C15H12N2 (220.28): C 81.79, H 5.49, N 12.72; found:
C 81.52, H 5.35, N 12.62.
for 13 and 14 were taken from the spectra of the reaction mixture.
1
À
À
H NMR (500 MHz, CDCl3): d=4.21 (brs; NH2, 14), 5.14 (s; Ph CH N,
13), 6.97 (s; =CH, 13), 7.07–7.10 (m), 7.14–7.24 (m), 7.28–7.31 (m), 7.33–
7.39 (m), 7.45–7.51 (m), 7.56 (d, 3J=7–9 Hz), 7.83–7.87 (m), 8.62 ppm (d,
3-Phenyl-4-isoquinolinamine (18): Isoquinoline 18 was synthesized from
imine 17 (0.22 g, 1 mmol) by following the method described for the syn-
thesis of 16 (16 h of stirring before workup). Purification by flash chro-
matography (tert-butyl methyl ether) gave 18 (0.11 g, 0.50 mmol, 50%) as
a colorless solid. M.p. 89–928C; IR (KBr): n˜ =3321 (s, br), 3222 (s, br),
3047 (m), 2962 (m), 2925 (m), 2856 (m), 1629 (s), 1571 (s), 1560 (s), 1543
(s), 1490 (s), 1448 (m), 1425 (m), 1396 (s), 1340 (m), 1311 (m), 1261 (s),
1164 (m), 1105 (m), 1072 (s), 1018 (m), 956 (w), 906 (m), 896 (m), 856
(m), 804 (m), 763 (s), 723 (m), 709 (s), 594 (m), 576 (m), 545 (m), 484
4J=1.7 Hz, CH=N, 13); C NMR (125 MHz, CDCl3): d=65.26 (Ph CH
N, 13), 119.55 (14), 121.11 (14), 121.68 (14), 125.21 (14), 126.12 (14),
126.22 (14), 126.46 (14), 126.53 (13), 126.89 (13), 127.06 (13), 127.42 (14),
122.77 (14), 127.79 (14), 127.82 (13), 127.85 (13), 128.42 (13), 128.55 (13),
128.55 (14), 128.59 (14), 128.64 (13), 129.61 (13), 129.84 (14), 129.96 (13),
131.27 (13), 133.34 (14), 134.60 (13), 137.24 (13), 138.21 (14), 139.31 (14),
140.36 (14), 140.40 (13), 140.68 (13), 142.07 (14), 145.76 (13), 160.98 ppm
(CH=N, 13).
13
À
À
(m), 470 (w), 447 (w), 432 (w) cmÀ1 1H NMR (400 MHz, CDCl3, 258C):
;
2-[(E)-3-Phenyl-1-propenyl]benzonitrile (15a) and 2-[(Z)-3-phenyl-1-
propenyl]benzonitrile (15b): Compounds 15a and 15b were prepared in
d=4.33 (brs, 2H; NH2), 7.34–7.38 (tt, 3JH,H =7.4, 4JH,H =1.3 Hz, 1H),
7.45–7.55 (m, 3H), 7.59–7.63 (m, 1H), 7.70–7.73 (m, 2H), 7.80 (dd,
3JH,H =8.5, 4JH,H =0.9 Hz, 1H), 7.88 (d, 3JH,H =7.9 Hz, 1H), 8.80 ppm (d,
4JH,H =0.8 Hz, 1H); 13C NMR (100 MHz, CDCl3, 258C): d=120.42,
126.58, 126.85, 127.79, 127.90, 128.20, 128.89, 129.18, 129.26, 133.68,
136.25, 139.37, 142.52 ppm; HRMS: m/z: calcd for C15H12N2H: 221.1079;
found: 221.1073; elemental analysis calcd (%) for C15H12N2 (220.28): C
81.79, H 5.49, N 12.72; found: C 81.53, H 5.28, N 12.66.
analogy to
a
published procedure.[18] 2-Bromobenzonitrile (0.18 g,
1.00 mmol), 1-allylbenzene (0.12 g, 1 mmol, 0.13 mL), triethylamine
(0.20 g, 2.00 mmol, 0.28 mL), palladium acetate (5 mg), tri-o-tolylphos-
phine (12 mg), and acetonitrile (8 mL) were combined in a dried Schlenk
flask under an argon atmosphere and warmed to 80–858C. Water
(20 mL) was added after disappearance of the initial compounds
(checked by TLC, approximately 40 h) and the mixture was extracted
with diethyl ether (3”20 mL). The combined organic extracts were dried
over magnesium sulfate and the solvent was removed in vacuo. Purifica-
tion of the residue by flash chromatography (EtOAc/pentane 1:10) gave
a mixture of 15a and 15b (0.15 g, 0.68 mmol, 68%, 15a/15b 68:32 (as de-
2-[(E)-2,3-Diphenyl-2-propenyl]benzo[b]thiophen-3-yl cyanide (19a) and
2-[(E,Z)-2,3-diphenyl-1-propenyl]benzo[b]thiophen-3-yl cyanide (19b):
Compounds 19a,b were synthesized from imine 11 (0.35 g, 1 mmol) by
following the method described for the synthesis of amine 16 (16 h of stir-
ring before workup). Purification by flash chromatography (EtOAc/pen-
tane 1:10) gave 19a and 19b (70 mg, 0.20 mmol, 20%) as colorless solids.
IR (KBr): n˜ =3051 (w), 3024 (w), 2947 (w), 2912 (w), 2218 (m), 1597 (w),
1519 (w), 1492 (w), 1460 (w), 1434 (m), 1359 (w), 1315 (w), 1296 (w),
1263 (w), 1245 (w), 1199 (w), 1176 (w), 1155 (w), 1128 (w), 1078 (w),
1068 (w), 1022 (w), 999 (w), 987 (w), 950 (w), 923 (m), 877 (m), 850 (w),
813 (w), 802 (w), 758 (s), 748 (m), 729 (m), 700 (s), 646 (m), 617 (w), 547
termined by 1H NMR spectroscopy) as
a
colorless oil. 1H NMR
3
(300 MHz, CDCl3, 258C): d=3.56 (d, 3JH,H =7.1 Hz), 3.70 (d, JH,H
=
6.80 Hz), 6.19–6.20 (m), 6.43–6.53 (m), 6.76–6.81 (m), 7.12–7.34 (m),
7.40–7.59 ppm (m); MS (ESI): m/z: 242 [M+Na]+, 237, 217, 191, 157,
115, 113, 83, 55, 41, 23.
2-Phenyl-1-naphthalenamine (16): A solution of LDA was prepared by
adding nBuLi (0.70 mL, 1.12 mmol, 1.6m in hexane) to diisopropylamine
(0.12 g, 1.12 mmol) in dry THF (25 mL) at À788C. Then, the mixture of
15a and 15b (1.00 mmol, 0.22 g) dissolved in THF (10 mL) was added
1
(w), 511 (w), 503 (w), 480 (w), 443 cmÀ1 (w); H NMR (600 MHz, CDCl3,
258C): d=4.26 (s), 4.54 (s), 6.70 (s), 6.98–7.00 (m), 7.08–7.10 (m), 7.6–
3118
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Chem. Eur. J. 2007, 13, 3113 – 3119

Aniline and Azepine Derivatives
FULL PAPER
7.17 (m), 7.19–7.41 (m), 7.52–7.53 (m), 7.62 (dd, 3JH,H =8.0, 4J=0.5 Hz),
[2]V. Lyaskovskyy, R. Frçhlich, E.-U. Würthwein, unpublished results.
[3]E. Nakamura, in: Organometallics in Synthesis. A Manual (Ed.: M.
Schlosser), 2nd ed., Wiley, Chichester, 2002, pp. 581–585.
[4]P. Knochel, N. Millot, A. L. Rodriguez, Org. React. 2001, 58, 440–
441.
4
7.67 (dd, 3JH,H =8.2, 4JH,H =0.6 Hz), 7.78 ppm (td, 3JH,H =7.3, JH,H
=
0.7 Hz); 13C NMR (150 MHz, CDCl3, 258C): d=31.47, 41.06, 114.23,
121.95, 122.13, 122.45, 122.49, 125.55, 125.68, 125.78, 126.65, 127.13,
127.69, 127.81, 128.07, 128.10, 128.67, 128.78, 128.79, 128.87, 129.29,
130.17, 132.09, 136.35, 137.00, 137.29, 137.54, 137.75, 138.44, 138.95,
140.62, 158.07 ppm; MS (GCMS): two GC peaks were observed (25.20
and 25.68 min, relative intensity: 39 and 61%, correspondingly); peak
25.20 min: m/z: 351 [M]+, 332, 324, 274, 259, 240, 227, 214, 202, 191, 178,
172, 165, 152, 128, 115, 102, 89, 77, 63, 51; peak 25.68 min: m/z: 351 [M]+
, 351, 334, 324, 274, 259, 240, 227, 178, 172, 165, 152, 145, 128, 115, 102,
91, 77, 63, 51.
[5]Gaussian 03, Revision C.01, M. J. Frisch, G. W. Trucks, H. B. Schle-
gel, G. E. Scuseria, M. A. Robb, J. R. Cheeseman, J. A. Montgomer-
y, Jr., T. Vreven, K. N. Kudin, J. C. Burant, J. M. Millam, S. S. Iyen-
gar, J. Tomasi, V. Barone, B. Mennucci, M. Cossi, G. Scalmani, N.
Rega, G. A. Petersson, H. Nakatsuji, M. Hada, M. Ehara, K.
Toyota, R. Fukuda, J. Hasegawa, M. Ishida, T. Nakajima, Y. Honda,
O. Kitao, H. Nakai, M. Klene, X. Li, J. E. Knox, H. P. Hratchian,
J. B. Cross, C. Adamo, J. Jaramillo, R. Gomperts, R. E. Stratmann,
O. Yazyev, A. J. Austin, R. Cammi, C. Pomelli, J. W. Ochterski, P. Y.
Ayala, K. Morokuma, G. A. Voth, P. Salvador, J. J. Dannenberg,
V. G. Zakrzewski, S. Dapprich, A. D. Daniels, M. C. Strain, O.
Farkas, D. K. Malick, A. D. Rabuck, K. Raghavachari, J. B. Fores-
man, J. V. Ortiz, Q. Cui, A. G. Baboul, S. Clifford, J. Cioslowski,
B. B. Stefanov, G. Liu, A. Liashenko, P. Piskorz, I. Komaromi, R. L.
Martin, D. J. Fox, T. Keith, M. A. Al-Laham, C. Y. Peng, A. Na-
nayakkara, M. Challacombe, P. M. W. Gill, B. Johnson, W. Chen,
M. W. Wong, C. Gonzalez, J. A. Pople, Gaussian, Inc., Wallingford
CT, 2004. Details of the quantum chemical calculations may be ob-
tained from E.-U. Würthwein upon request.
X-ray crystal-structure analysis of 19a: Crystals obtained by crystalliza-
tion from CHCl3/pentane of the mixture of compounds.[17] Formula
C23H17NS; M=353.45; colorless crystal; crystal size: 0.40”0.30”
0.20 mm; a=9.619(1), b=11.441(1), c=18.196(1) Š; a=77.11(1), b=
81.52(1), g=72.93(1)8; V=1858.8(3) Š3; 1calcd =1.263 gcmÀ3
;
m=
1.591 mmÀ1; empirical absorption correction (0.569ꢀTꢀ0.741); Z=4;
¯
crystal system: triclinic; space group P1 (no. 2); l=1.54178 Š; T=223 K;
w and f scans; 21392 reflections collected (Æh, Æk, Æl), [(sinq)/l]=
0.60 ŠÀ1; 6430 independent (Rint =0.034) and 6166 observed reflections
[Iꢁ2sI]; 469 refined parameters; R=0.045; wR2=0.128; max. residual
À3
electron density 0.32 eŠ (À0.52); two almost identical molecules in the
asymmetric unit; hydrogen atoms calculated and refined riding.
[6]W. Ried, H. Bender, Chem. Ber. 1955, 88, 34–38.
[7]Schakal, E. K. Keller, Freiburg, 2005.
2,3-Diphenyldibenzo[b,d]thiophen-1-amine (20): Compound 20 was syn-
G
thesized from the mixture of nitriles 19a,b (0.35 g, 1 mmol) by following
the method described for the synthesis of amine 16. Purification by flash
chromatography (EtOAc/pentane 1:10) gave 20 (0.32 g, 0.91 mmol, 91%)
as a colorless solid. M.p. 172–173.58C; IR (KBr): n˜ =3479 (w), 3429 (w),
3350 (m), 3047 (w), 3030 (w), 3018 (w), 2995 (w), 2922 (w), 2852 (w),
1606 (m), 1598 (m), 1583 (m), 1556 (w), 1537 (m), 1504 (m), 1492 (m),
1471 (w), 1454 (m), 1438 (m), 1425 (m), 1402 (s), 1313 (m), 1299 (m),
1288 (m), 1228 (m), 1190 (w), 1174 (m), 1157 (w), 1143 (w), 1072 (m),
1051 (w), 1026 (m), 1006 (w), 989 (w), 968 (w), 954 (w), 914 (w), 848 (w),
837 (w), 788 (w), 767 (m), 738 (m), 727 (m), 702 (s), 667 (w), 636 (m),
626 (w), 609 (w), 574 (m), 536 (m), 511 (w), 480 (w), 457 (w), 430 cmÀ1
(w); 1H NMR (300 MHz, CDCl3, 258C): d=4.35 (brs, 2H; NH2), 7.14–
7.50 (m, 12H), 7.87–7.90 (m, 1H), 8.23–8.26 ppm (m, 1H); 13C NMR
(75 MHz, CDCl3, 258C): d=114.71, 121.34, 123.01, 123.36, 124.11, 124.60,
125.42, 126.46, 127.29, 127.66, 128.81, 129.89, 131.75, 135.81, 137.38,
139.56, 139.97, 141.12, 141.76, 141.80 ppm; MS (GCMS): m/z: 351 [M]+,
334, 273, 245, 213, 175, 167, 159, 89, 69, 63; HRMS: m/z: calcd for
C24H17NS: 351.1082; found: 351.1082; elemental analysis calcd (%) for
C24H17NS (351.47): C 82.02, H 4.88, N 3.99; found: C 81.85, H 4.75, N
3.88.
[8]V. Lyaskovskyy, K. Bergander, R. Frçhlich, E.-U. Würthwein, un-
published results.
[9]R. K. Smalley in Methods of Organic Synthesis (Houben–Weyl),
Vol. 9d, 4th ed. (Ed.: E. Schaumann), Thieme, Stuttgart, 1998, pp.
108–298.
[10]S. Klçtgen, E.-U. Würthwein, Tetrahedron Lett. 1995, 36, 7065–7068.
[11]S. Klçtgen, R. Frçhlich, E.-U. Würthwein, Tetrahedron 1996, 52,
14801–14812.
[12]K. Gerdes, P. Sagar, R. Frçhlich, B. Wibbeling, E.-U. Würthwein,
Eur. J. Org. Chem. 2004, 3465–3476.
[13]K. Kobayashi, H. Tanaka, H. Takabatake, T. Kitamura, R. Nakaha-
shi, O. Morikawa, H. Konishi, Bull. Chem. Soc. Jpn. 1999, 72, 1071–
1074.
[14]K. Kobayashi, K. Takada, H. Tanaka, T. Uneda, T. Kitamura, O.
Morikawa, H. Konishi, Chem. Lett. 1996, 25–26.
[15]K. Kobayashi, T. Uneda, K. Takada, H. Tanaka, T. Kitamura, O.
Morikawa, H. Konishi, J. Org. Chem. 1997, 62, 664–668.
[16]S. Andreae in Methoden der Organischen Chemie (Houben–Weyl),
Vol. E7a, 4th ed. (Ed.: R. Kreher), Thieme, Stuttgart, 1991, pp. 571–
740.
[17]Data sets were collected with Nonius KappaCCD diffractometers, in
case of Mo-radiation equipped with rotating anode generator. Pro-
grams used: data collection COLLECT (Nonius B. V., 1998), data
reduction Denzo-SMN (Z. Otwinowski, W. Minor, Methods Enzy-
mol. 1997, 276, 307–326), absorption correction SORTAV (R. H.
Blessing, Acta Crystallogr. Sect. A 1995, 51, 33–37; R. H. Blessing, J.
Appl. Crystallogr. 1997, 30, 421–426) and Denzo (Z. Otwinowski, D.
Borek, W. Majewski, W. Minor, Acta Crystallogr. Sect. A 2003, 59,
228–234), structure solution SHELXS-97 (G. M. Sheldrick, Acta
X-ray crystal-structure analysis of 20:[17] Formula: C24H17NS; M=351.45;
colorless crystal; crystal size: 0.50”0.30”0.15 mm; a=24.915(1), b=
8.374(1), c=20.748(1) Š; b=125.39(1)8; V=3529.0(5) Š3; 1calcd
=
1.323 gcmÀ3; m=1.658 mmÀ1; empirical absorption correction (0.491ꢀTꢀ
0.789); Z=8; crystal system: monoclinic; space group: C2/c (no. 15); l=
1.54178 Š; T=223 K; w and f scans; 14069 reflections collected (Æh, Æ
k, Æl), [(sinq)/l]=0.60 ŠÀ1, 3110 independent (Rint =0.037) and 2996 ob-
served reflections [Iꢁ2sI], 243 refined parameters; R=0.035; wR2=
À3
0.093; max. residual electron density 0.21 eŠ (À0.25); hydrogen atoms
at N1 from Fourier map; other calculated and refined riding.
Crystallogr. Sect.
A 1990, 46, 467–473), structure refinement
SHELXL-97 (G. M. Sheldrick, Universität Gçttingen, 1997).
CCDC-620928 (12), -620929 (19a), and 620930 (20) contain the
supplementary crystallographic data for this paper. These data can
be obtained free of charge from the Cambridge Crystallographic
Data Centre via www.ccdc.cam.ac.uk/data_request/cif/
Acknowledgement
The authors thank the NRW Graduate School of Chemistry (Münster)
and the Sonderforschungsbereich 424 (Deutsche Forschungsgemein-
schaft) for financial support of this work.
[18]R. F. Heck, Org. React. 1982, 27, 360–361.
[1]P. Sagar, R. Frçhlich, E.-U. Würthwein, Angew. Chem. 2004, 116,
5812–5815; Angew. Chem. Int. Ed. 2004, 43, 5694–5697.
Received: October 19, 2006
Published online: January 5, 2007
Chem. Eur. J. 2007, 13, 3113 – 3119
ꢀ 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
3119