Azetidines as ligands in the Pd(II) complexes series

Article abstract of DOI:10.1016/j.jorganchem.2005.02.041

The preparation of palladium (II) complexes having sterically congested azetidines as ligands is described. Diastereomerically pure α-alkylamino and α-alkylimino azetidines react with Na₂PdCl₄ to afford the corresponding bidendate Pd(II) complexes, whereas 2-cyano azetidines can be used to access bidendate Pd(II) complexes containing an amino-imidate moiety. Preliminary study of the catalytic activity of these new complexes in the Suzuki cross-coupling reaction is presented.

Full text of DOI:10.1016/j.jorganchem.2005.02.041

Journal of Organometallic Chemistry 690 (2005) 2306–2311
www.elsevier.com/locate/jorganchem
Azetidines as ligands in the Pd(II) complexes series
a
a
a,
,a
*
Laurent Keller , Monica Vargas Sanchez , Damien Prim *, Franc¸ois Couty
,
a
Gwilherm Evano , Jerome Marrot
b
´
a
´
Laboratoire SIRCOB, UMR CNRS 8086, Universite de Versailles-Saint-Quentin-en-Yvelines, 78035 Versailles Cedex, France
b
´
Institut Lavoisier, UMR CNRS 8637, Universite de Versailles-Saint-Quentin-en-Yvelines, 78035 Versailles Cedex, France
Received 21 January 2005; accepted 23 February 2005
Available online 14 April 2005
Abstract
The preparation of palladium (II) complexes having sterically congested azetidines as ligands is described. Diastereomerically
pure a-alkylamino and a-alkylimino azetidines react with Na2PdCl4 to afford the corresponding bidendate Pd(II) complexes,
whereas 2-cyano azetidines can be used to access bidendate Pd(II) complexes containing an amino-imidate moiety. Preliminary
study of the catalytic activity of these new complexes in the Suzuki cross-coupling reaction is presented.
ꢀ 2005 Elsevier B.V. All rights reserved.
Keywords: Azetidine; Diamine; Imine; Imidate; Palladium complex
1. Introduction
as substrates for the synthesis of a cyclopalladated di-
meric complex [12].
Saturated 4-membered ring aza-heterocycles, namely
azetidines, represent an understudied class of heterocy-
cles. Recent advances in the synthesis and reactivity of
chiral non racemic azetidines [1–6] are driven by the fact
that such strained heterocycles can be found in several
natural products or synthetic drugs of biological rele-
vance as well as in the field of enantioselective catalysis
[7]. In the latter case, combination of azetidines used as
ligands and transition metals such as Rh [3] or Zn [1–
6,8–10] proved, respectively, efficient for enantioselective
cyclopropanation and addition of diethylzinc to alde-
hydes or ketones. To the best of our knowledge, combi-
nation of azetidines with palladium was reported only
twice. The first example describes the intervention of a
palladium species in a ring opening process involving
four subsequent steps on azetidine substrates [11]. The
second example reports the use of N-benzylazetidines
In this paper, we report the selective preparation of
new palladium (II) complexes having various azetidine li-
gands (Fig. 1). The design of these new bidendate strained
ligands comprises two chelation sites, the first being the
heterocyclic nitrogen atom, the second one being an addi-
tional alkylamine, alkylimine or alkylimidate moiety, lo-
cated in the 2-position of the azetidine. In addition,
preliminary results showing the catalytic activities of
the complexes bearing a diamine, an amine–imine or an
amine–imidate ligand are also reported.
In order to examine the possible use of azetidines as
ligands in palladium-mediated catalysis, we focused on
the synthesis and isolation of chiral, Pd(II)-diamino
complexes.
2. Results and discussion
2.1. Diamine complexes
*
Corresponding author. Tel.: +33 1 39 25 44 54; fax: +33 1 39 25 44
Diamines 1 and 2 were prepared in good yield accord-
ing to our previously described methodology [13], and
52.
E-mail address: prim@chimie.uvsq.fr (D. Prim).
0022-328X/$ - see front matter ꢀ 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2005.02.041

L. Keller et al. / Journal of Organometallic Chemistry 690 (2005) 2306–2311
2307
R3
N
Selected bond lengths and angles are presented in
Table 1. For example, Pd–N(1), Pd–C(2) as well as
N(1)–C(2) bond lengths in complexes 3 and 4 are very
close but not identical. In addition, the asymmetric
structures of both complexes result in significant varia-
R1 = Me, Bn.
R2 = Me, H.
R4
R2
R3 = Ph.
NH
R4 = OMe, Ph, Me
R1
Pd
tions in bond lengths between palladium and nitrogen
˚
Pd–
Cl
Cl
atoms
(Pd–N(1) = 2.075 A
compared
to
˚
˚
N(6) = 2.049 A in complex 3 and Pd–N(1) = 2.074 A
Fig. 1. General structure of the Pd(II) complexes with azetidine
ligands.
˚
compared to Pd–N(6) = 2.042 A in complex 4).
It is worth to note that only bidendate structures were
obtained. No traces of bismonodendate type complexes
were detected, even by using various ratios of substrate/
palladium source.
were reacted with Na2PdCl4 under classical conditions
[14] to give the expected Pd(II) complexes in high yields
(Scheme 1). The reaction proceeds smoothly at room
temperature in freshly distilled methanol. After a few
hours, precipitation of the complexes is observable.
After additional 24 h, the precipitated complexes are
collected by filtration. These palladium complexes are
stable on air and their purification by silica gel chroma-
tography afforded 3 (88%) and 4 (81%) respectively as
yellow and brownish crystalline solids.
2.2. Amino-imine complexes
We next envisioned the rigidification of the carbon-
based link between the two chelating nitrogen atoms
and turned our attention to the amino-imine combi-
nation. The preparation of complex 7 bearing an
amino-imine type ligand is depicted in Scheme 2. 2-Cya-
noazetidine 5 was reacted with PhLi in toluene at 5–
10 ꢁC to give the corresponding imine 6 [16]. Under clas-
sical conditions (Na2PdCl4, MeOH), complex 7 could be
isolated in moderate yield (42%) from crude imine 6,
thus demonstrating that the flexibility of bidendate
strained ligands in the azetidine series is modulable.
Complexes 3 and 4 were fully characterized. Single
crystals suitable for X-ray analysis could be obtained
by slow evaporation of an ethyl acetate solution. Both
ORTEP drawings are depicted in Fig. 2 [15].
Ph
Ph
Ph
Table 1
Ph
Me
˚
Me
Selected list of bond lengths (A) and angles (ꢁ) for 3 and 4
N
NH
Cl
2
N
NH
2
3
4
Me
Pd
3 (88%)
Me
Na PdCl
2
4
Bonds
1
Cl
Pd–Cl(2)
Pd–Cl(1)
Pd–N(1)
Pd–N(6)
N(1)–C(2)
Pd–C(2)
2.284
2.300
2.075
2.049
1.518
2.921
2.307
2.318
2.074
2.042
1.507
2.921
MeOH
Ph
Ph
Me
Me
Me
Me
N
NH Ph
N
N
Ph
H
Me
Me
Pd
4 (81%)
Angles
Cl
Cl
2
N(1)–Pd–N(6)
Pd–N(1)–C(2)
C(5)–N(6)–Pd
N(1)–C(2)–C(5)
N(6)–C(5)–C(2)
N(1)–Pd–Cl(2)
N(6)–Pd–Cl(1)
85.0
84.9
107.8
110.0
113.0
108.5
93.2
109.8
111.2
113.2
111.0
89.9
Scheme 1. Synthesis of diamino complexes 3 and 4.
89.6
93.9
Ph
N
Ph
Ph
N
Ph
NH
Na2PdCl4
Ph
Ph-Li
CN
N
MeOH
Bn
NH
Bn
5
Bn
6
Pd
Cl
Cl
7 42%
Fig. 2. ORTEP drawings of complexes 3 and 4.
Scheme 2. Synthesis of amino-imine complex 7.

2308
L. Keller et al. / Journal of Organometallic Chemistry 690 (2005) 2306–2311
Although substrate 5 is substituted by a benzyl group, it
is worth noting that no traces of cyclopalladated com-
plex was formed. Thus, complex 7 was selectively pre-
pared through a coordination mode involving both
nitrogen atoms in an 1,2-amino-imine combination.
tra confirmed the formation of the imidate moiety. As
depicted in Fig. 3, amino-imidate complexes 10 and 11
with different substitution pattern have been similarly
prepared from the parent 2-cyanoazetidines, respec-
tively, in 72% and 58% yields.
2.3. Amino-imidate complexes
2.4. Suzuki cross-coupling reactions
We next tried to prepare new Pd(II) complexes by
using 2-cyano azetidines. In this case both the intracyclic
nitrogen atom and the cyano group located in the 2-
position of the azetidine ring may individually serve as
ligand. It was then debatable whether the nitrile group
would participate in the complexation process and act
as a ligand. In fact, 2-cyanoazetidine 8 when treated
with Na2PdCl4 in THF at 60 ꢁC for 24 h, did not afford
bismonodendate complexes even by modifying the sub-
strate–palladium precursor ratio (Scheme 3).
In contrast, we discovered that using methanol as the
solvent lead to the selective formation of amino-imidate
based complex 9 (62%) [17]. Spectroscopic data of com-
plex 9 are in good agreement with its structure. The 13C
NMR spectrum displays a set of six aromatic CH
(d = 128.7, 129.0, 129.1, 131.8, 132.3 and 133.6 ppm)
and two quaternary carbons (d = 128.4 and 129.7 ppm)
which accounts for two residual mono-substituted phe-
nyl groups. Signal indicating the presence of a nitrile
group could not be detected. In contrast, signals at
176.1 ppm in 13C NMR and 3.19 ppm in 1H NMR spec-
At this stage, it was debatable whether these new Pd
(II) complexes bearing azetidinic diamino, amino-imine
or amino-imidate ligands could be involved in a catalytic
process. With this aim, complexes 4, 7 and 11 were tested
in the Suzuki coupling reaction and preliminary results
are shown in Table 2. For example, 4-Nitrobromoben-
zene was reacted with 4-tolylboronic acid under classical
conditions (solvent: DMF–water and base: 2.5 eq.
K2CO3) with low catalyst loadings (1–2%). The expected
biaryl product was obtained in good to high yields irre-
spective of the ligand structure (Table 2, entries 1–3)
leading to the first examples of Suzuki reaction using
azetidine ligands in the palladium catalytic species.
Although reaction conditions were not optimized, it
should be noted that reactions involving aryl bromides
as substrates proceed with high conversion within a few
hours [18]. Combinations of electron rich boronic acids
with either electron poor or electron rich aromatic ha-
lides have been successfully tested leading to variously
substituted biphenyl derivatives. Moreover, catalytic sys-
tems based on palladium and congested azetidine ligands
seem not only efficient in the aromatic bromide series but
also in the more reluctant chloride series. Indeed, under
the above mentioned catalytic conditions, chlorobenzene
and 4-cyanochlorobenzene gave the corresponding bia-
ryl coupling product in 51% yield (entry 4). It is also wor-
thy to note that catalyst loadings could be lowered to
0.1% without decrease of yields and conversions (entry
5). These complexes proved to be particularly stable
and could be stored on air several month without any
appreciable depletion of their catalytic activities.
Ph
Ph
CN
CN PdCl2
N
or
N
Bn
2
2
Bn
PdCl2
Ph
Na2PdCl4
60˚C, 6h
CN
N
Ph
Bn
8
OMe
NH
MeOH
N
Bn
Pd
3. Conclusion
Cl
Cl
9 62%
In summary, a modulable synthesis of new palladium
(II) complexes bearing sterically congested azetidine li-
gands was developed. The use of diamine, amino-imine
and amino-imidate ligands selectively led to bidendate
palladium (II) complexes whose structures were con-
firmed by X-ray analysis. Preliminary results concerning
the use of rigid N,N-bound palladium complexes as cat-
alysts in the Suzuki cross-coupling reaction proved effi-
cient for electron rich and electron poor aromatic
bromides and chlorides. High yields and conversions
were obtained using low (0.1%) catalyst loadings. The
potential of these new complexes in asymmetric catalysis
is under investigation.
Scheme 3. Synthesis of amino-imidate complex 9.
Ph
N
Ph
N
OMe
NH
OMe
NH
Me
Bn
Me
Pd
Pd
Cl
Cl
Cl
Cl
10 72%
11 58%
Fig. 3. Structure of complexes 10 and 11 with bidentate amino-imidate
ligands.

L. Keller et al. / Journal of Organometallic Chemistry 690 (2005) 2306–2311
2309
Table 2
Suzuki coupling: aromatic substrates, Pd(II) catalysts and yields
Entry
1
Arylhalide
Boronic acid
Ligand type
Conditions
Biaryl
Yield (%)
77
Diamino 4
Cat(1%), 100 ꢁC, 6 h
B(OH)2
Me
Br
Me
NO2
O2N
2
3
4
Amino-imine 7
Amino-imidate 11
Amino-imine 7
Cat(1%), 100 ꢁC, 5 h
Cat(1%), rt, 18 h
85
61
51
Cat(2%), 100 ꢁC, 6 h
B(OH)2
OMe
OMe
Cl
OMe
OMe
CN
Br
NC
5
Amino-imidate 11
Cat(0.1%), 100 ꢁC, 6 h
87
OMe
OMe
B(OH)2
l
OMe
NO2
OMe
O2N
4. Experimental
20 min, MeOH (10 mL) was added. After 1 h, the
reaction was quenched with a saturated aqueous NH4Cl
solution (5 mL) and extracted with AcOEt (3 · 10 mL).
The combined organic extracts were washed with brine,
dried over magnesium sulfate, filtered and evaporated
under reduced pressure. The resulting solid residue was
triturated with petroleum ether, filtered and washed with
small amounts of cold ether to obtain the crude imine
4.1. General methods
NMR spectra were recorded on a Bruker AC spec-
trometer at 200 or 300 (1H) and 75 (13C) MHz. Low res-
olution mass spectra were recorded on a HP MS Eingin
5989B, in positive electrospray mode using a Branford
Analytica source. Ranges of mass peaks reported here
are characteristic of the isotopic dispersion in molecules
containing Pd and Cl atoms. Solvents were freshly dis-
tilled prior to use. THF was distilled from sodium/ben-
zophenone ketyl and MeOH was distilled from MgI2.
All other reagents were commercially available and were
used as received. All reactions were carried under an in-
ert atmosphere of argon unless otherwise stated. Biphe-
nyl products listed in this paper are known in the
chemical literature [19–21], except for 4-cyano-30,40-
dimethoxy-2,20-biphenyl (vide infra).
1
which was used without further purification. H NMR
(200 MHz) d: 7.6 (d, J = 7.5 Hz, 2H), 7.30 (m, 10H),
7.10 (m, 3H), 4.73 (d, J = 8.8 Hz, 1H), 3.90 (m, 2H),
3.55 (m, 3H).
4.3. General procedure for preparation of Pd(II)
complexes
To a mixture of sodium tetrachloropalladate (II)
(0.45 mmol, 145 mg) in freshly distilled and thoroughly
degassed appropriate solvent (5 mL) was added the
ligand (0.46 mmol). The red solution was allowed to
stand for 4 h at room temperature. After removal of
the solvent under reduced pressure or filtration of the
precipitate, the solid was purified by flash chromatogra-
phy on silica gel (AcOEt) to afford the expected palla-
dium (II) complexes.
4.2. Synthesis of imine (6)
To a solution of 2-cyano azetidine 5 (1 mmol,
250 mg) in dry THF (10 mL) at 0 ꢁC was added
Phenyllithium (2 mmol) under argon. After stirring for

2310
L. Keller et al. / Journal of Organometallic Chemistry 690 (2005) 2306–2311
4.3.1. Complex 3 (88%)
IR (KBr): 3310, 3253, 3055, 3030 cmꢀ1
4.3.6. Complex 11 (58%)
IR (KBr): 3492, 3169, 3058, 1639 cmꢀ1 1H NMR
.
.
1H NMR
(DMSO-d6) d: 8.49 (d, J = 6.5 Hz, 2H), 7.40 (m, 3H),
7.15 (m, 3H), 6.69 (d, J = 7 Hz, 2H), 5.21 (br s, 2H),
4.10 (d, J = 6.5 Hz, 1H), 3.84 (m, 1H), 3.48 (m, 2H),
2.05 (d, J = 6.2 Hz, 3H), 1.42 (s, 3H). 13C NMR d:
133.9, 133.3, 132.1, 128.9, 128.4, 128.2, 128.0, 126.3,
79.9, 71.9, 62.4, 52.0, 44.8, 17.6. Anal. Calc. for
C18H22Cl2N2Pd: C, 48.72; H, 5.00; N, 6.31. Found: C,
48.59; H, 4.92; N, 6.21%. MS (m/z): 446–454
[LPdClMeCN]+.
(CDCl3) d: 7.95 (m, 2H), 7.50 (m, 3H), 7.35 (m, 3H),
7.10 (d, J = 7.7 Hz, 2H), 4.82 (m, 3H), 4.45 (d,
J = 7.7 Hz, 1H), 3.72 (s, 3H), 3.55 (m 2H), 1.90 (brs,
1H). 13C NMR d: 176.4, 136.6, 131.8, 131.4, 129.8,
129.2, 129.1, 128.2, 126.7, 77.5, 65.8, 64.2, 56.8, 41.2.
Anal. Calc. for C18H20Cl2N2Pd: C, 47.24; H, 4.40; N,
6.12. Found: C, 47.35; H, 4.62; N, 5.89%. MS (m/z):
460–468 [LPdClMeCN]+.
4.4. Typical procedure for Suzuki reaction
4.3.2. Complex 4 (81%)
1
IR (KBr): 3204, 3029 cmꢀ1: H NMR (DMSO-d6) d:
Boronic acid (1.1 mmol), aryl halide (1 mmol) and
K2CO3 (2.5 mmol) were successively added to the appro-
priate palladium (II) complex (0.01 mmol, Table 2) and
the mixture was dried under vacuum for 1 h. Freshly dis-
tilled and degassed DMF (2 mL) followed by degassed
water (0.2 mL) were next added. The reaction mixture
was then allowed to stir at room temperature for 1 h
and was heated at reflux. After completion of the reac-
tion, water (10 mL) followed by AcOEt (5 mL) were
added. The aqueous layer was separated and extracted
with AcOEt (3 · 5 mL). The combined organic extracts
were dried over magnesium sulfate, filtered and the sol-
vent was removed under reduced pressure. The residue
was purified by flash chromatography on silica gel to
afford the expected biaryl compounds.
8.73 (d, J = 7.2 Hz, 2H), 8.01 (dd, J = 2 and 6.6 Hz, 2H),
7.61 (m, 2H), 7.40 (m, 4H), 5.20 (brs, 1H), 4.55 (d,
J = 13 Hz, 1H), 3.70 (m, 12H), 3.25 (d, J = 13 Hz,
1H), 3.05 (m, 2H), 2.52 (s, 3H), 1.47 (d, J = 6.8 Hz,
3H). 13C NMR d: 135.4, 133.5, 130.5(2CH), 129.5,
129.0, 128.9, 128.8, 77.5, 68.2, 59.1, 51.2, 47.0, 41.8,
16.2, 11.5. Anal. Calc. for C20H26Cl2N2Pd: C, 50.92;
H, 5.56; N, 5.94. Found: C, 51.03; H, 5.35; N, 5.95%.
MS (m/z): 472–482 [LPdClMeCN]+.
4.3.3. Complex 7 (42%)
IR (KBr): 3416, 3030, 1637 cmꢀ1. H NMR (CDCl3)
1
d: 7.30 (m, 15H), 4.40 (d, J = 8.3 Hz, 1H), 3.89 (d,
J = 12.9 Hz, 2H), 3.78 (m, 1H), 3.70 (d, J = 12.7 Hz,
1H), 3.33 (m, 2H). 13C NMR d: 185.0, 135.6, 134.1,
131.8, 131.7, 129.8(2CH), 129.5, 129.3, 129.0, 128.4,
127.5, 126.5, 83.6, 66.6, 64.6, 44.1. Anal. Calc. for
C23H22Cl2N2Pd: C, 54.84; H, 4.40; N, 5.56. Found: C,
54.61; H, 4.30; N, 5.29%. MS (m/z): 446–454
[LPdClMeCN]+.
4-cyano-30,40-dimethoxy-2,20-biphenyl (51%). IR
1
(KBr): 3075, 2222, 1247, 1220 cmꢀ1. H NMR (CDCl3)
d: 7.63 (d, J = 8.1 Hz, 2H), 7.57 (d, J = 8.1 Hz, 2H), 7.09
(dd, J = 9.3 and 2.1 Hz, 1H), 7.01 (d, J = 2.1 Hz, 1H),
6.90 (d, J = 9.3 Hz, 1H), 3.89 (s, 3H), 3.87 (s, 3H). 13C
NMR d: 149.5, 145.5, 134.2, 132.6, 131.9, 127.3, 119.8,
119.0, 111.6, 110.3, 56.0, 55.9.
4.3.4. Complex 9 (62%)
IR (KBr): 3482, 3168, 3057, 1639 cmꢀ1 1H NMR
.
Acknowledgements
(CDCl3) d: 8.15 (m, 4H), 7.42 (m, 6H), 5.12 (d,
J = 10 Hz, 1H), 5.03 (dd, J = 4 and 12 Hz, 1H), 4.83
(d, J = 11 Hz, 1H), 4.40 (m, 1H), 4.16 (m, 1H), 3.75 (d,
J = 11 Hz, 1H), 3.20 (s, 3H). 13C NMR d: 176.1, 133.6,
132.3, 131.8, 129.6, 129.1, 129.0, 128.9, 128.7, 75.2,
65.8, 62.3, 55.1, 37.6. Anal. Calc. for C18H20Cl2N2Pd:
C, 47.24; H, 4.40; N, 6.12. Found: C, 47.12; H, 4.46;
N, 6.06%. MS (m/z): 460–468 [LPdClMeCN]+.
´
We thank the CNRS and the Universite de Versailles
Saint-Quentin-en-Yvelines for financial support. The
authors are gratefull to V. Steinmetz for helpful discus-
sion about mass analyses.
Appendix A. Supplementary data
4.3.5. Complex 10 (72%)
IR (KBr): 3483, 3199, 3029, 1636 cmꢀ1 1H NMR
.
Supplementary data associated with this article can
be found, in the online version at doi:10.1016/
j.jorganchem.2005.02.041.
(CDCl3) d: 7.90 (d, J = 10 Hz, 2H), 7.42 (m, 3H), 5.44
(m 1H), 4.85 (brs, 1H), 4.03 (brs, 1H), 3.48 (s, 3H),
3.12 (s, 3H), 1.57 (d, J = 6.8 Hz, 3H). 13C NMR d:
178.3, 133.6, 129.0, 128.7, 128.5, 76.1, 71.0, 56.1, 46.9,
40.6, 16.5. Anal. Calc. for C13H18Cl2N2Pd: C, 39.47;
H, 4.59; N, 7.08. Found: C, 39.11; H, 4.46; N, 6.92%.
MS (m/z): 398–405 [LPdClMeCN]+.
References
[1] C. Agami, F. Couty, G. Evano, Tetrahedron: Asymmetry 13
(2002) 297.

L. Keller et al. / Journal of Organometallic Chemistry 690 (2005) 2306–2311
2311
[2] F. Couty, D. Prim, Tetrahedron: Asymmetry 13 (2002) 2619.
[3] C. Agami, F. Couty, N. Rabasso, Tetrahedron Lett. 43 (2002)
4633.
6437 reflections measured of which 3894 were independent,
211 refined parameters, R1 = 0.0345, wR2 = 0.0870.
– C20H26Cl2N2Pd, Orthorhombic, space group P2(1)2(1)2(1),
4
˚
a = 10.1524(1) A, b = 14.0255(1) A, c = 14.6409(2) A, V =
˚
˚
[4] F. Couty, F. Durrat, D. Prim, Tetrahedron Lett. 44 (2003) 5209.
[5] F. Couty, G. Evano, N. Rabasso, Tetrahedron: Asymmetry 14
(2003) 2407.
2084.75(4) A , Z = 4,
q
calc = 1.503 g cmꢀ3
,
l(Mo Ka) =
3
˚
1.151 mmꢀ1, F(0 0 0) = 960, 14,653 reflections measured of which
5452 were independent, 230 refined parameters, R1 = 0.0325,
wR2 = 0.0674. Data reduction were performed with the SAINT
software. The absorption correction was based on multiple and
symmetry-equivalent reflections in the data set using the SADABS
program based on the method of Blessing. The structures were
solved by direct methods and refined by full-matrix least-squares
using the SHELX-TL package. Crystallographic data for the
structures reported in this paper have been deposited with the
Cambridge Crystallographic Data Center as supplementary pub-
lication no. CCDC 253195 & 253196. Copies of the data can be
obtained free of charge on application to CCDC, 12 Union Road,
Cambridge CB2 1EZ, UK [fax: +44 1223 336 033; e-mail:
deposit@ccdc.cam.ac.uk].
[6] A. Carlin-Sinclair, F. Couty, N. Rabasso, Synlett (2003) 726.
[7] F. Couty, G. Evano, D. Prim, Mini-Rev. Org. Chem. 1 (2004)
133.
[8] P.J. Hermsen, J.G.O Cremers, L. Thijs, B. Zwanenburg, Tetra-
hedron Lett. 42 (2001) 4243.
[9] M. Shi, J.K. Jiang, Tetrahedron: Asymmetry 10 (1999) 1673.
[10] J. Wilken, S. Erny, S. Wassmann, J. Martens, Tetrahedron:
Asymmetry 11 (2000) 2143.
[11] S.-I. Murahashi, N. Yoshimura, T. Tsumiyama, T. Kojima, J.
Am. Chem. Soc. 105 (1983) 5002.
ˆ
[12] A. Marinetti, P. Hubert, J.-P. Genet, Eur. J. Org. Chem. (2000)
1815.
[13] F. Couty, G. Evano, D. Prim, J. Marrot, Eur. J. Org. Chem.
(2004) 3893.
[16] Imines derived from nucleophilic addition on 2-cyanoazetidines
cannot be purified since they are hydrolyzed to 2-acylazetidines on
silica gel. See Ref. [2].
[14] V.V. Dunina, L.G. KuzÕmina, M.Y. Kazakova, O.N. Gorunova,
Y.K. Grishin, E.I. Kazakova, Eur. J. Inorg. Chem. (1999) 1029.
[15] Crystal data and structure refinements for 3 and 4: A colorless
crystal (0.70 · 0.45 · 0.06 mm for 3 and 0.46 · 0.14 · 0.10 mm for
4) was analyzed with a Siemens SMART three-circle diffractom-
eter equipped with a CCD bidimensional detector using Mo Ka
[17] R.A. Michelin, M. Mozzon, R. Bertani, Coord. Chem. Rev. 147
(1996) 299.
[18] Various amounts of homocoupling products were obtained in
addition to the expected biaryl product.
˚
monochromatized radiation (k = 0.71073 A). 3 – C18H22Cl2N2Pd,
[19] H. Musso, H. Pietsch, Chem. Ber. 100 (1967) 2854.
[20] C.-H. Cho, H.-S. Yun, K. Park, J. Org. Chem. 68 (2003) 3017.
[21] K. Shudo, T. Ohta, T. Okamoto, J. Am. Chem. Soc. 103 (1981)
645.
˚
Monoclinic, space group P2(1), a = 6.8611(1) A, b = 13.3799(3) A,
˚
3
˚
˚
c = 10.4445(2) A, b = 106.871(1)ꢁ. V = 917.55(3) A , Z = 2,
calc = 1.606 g cmꢀ3 l(Mo ka) = 1.303 mmꢀ1
F(0 0 0) = 448,
q
,
,