Convenient and rapid strategies towards 6-(hetero)aryl pyridylmethylamines: First catalytic issues

Article abstract of DOI:10.1016/j.tetlet.2015.01.182

The convenient preparation of new pyridylmethylamines is described using a short two step sequence. The first step involved the straightforward microwave-assisted construction of 6-aryl and 6-heteroaryl pyridine scaffolds bearing carboxaldehyde and nitrile fragments. The pendant arm comprising a second nitrogen atom by mean of amine and oxazoline moieties is installed in the second step. Finally, a first entry towards catalytic activity is given. In this context, modification of the ligand pattern and steric crowding around the central pyridine ring is examined and led to modest to fair ee's in the construction of binaphthyl substrates.

Full text of DOI:10.1016/j.tetlet.2015.01.182

Tetrahedron Letters 56 (2015) 1378–1382
Contents lists available at ScienceDirect
Tetrahedron Letters
journal homepage: www.elsevier.com/locate/tetlet
Convenient and rapid strategies towards 6-(hetero)aryl
pyridylmethylamines: first catalytic issues
⇑
Alexandre Requet, Hasret Yalgin, Damien Prim
Université de Versailles Saint Quentin-en-Yvelines, UMR CNRS 8180, Institut Lavoisier de Versailles, 45, Avenue des Etats-Unis, 78035 Versailles Cedex, France
a r t i c l e i n f o
a b s t r a c t
Article history:
The convenient preparation of new pyridylmethylamines is described using a short two step sequence.
The first step involved the straightforward microwave-assisted construction of 6-aryl and 6-heteroaryl
pyridine scaffolds bearing carboxaldehyde and nitrile fragments. The pendant arm comprising a second
nitrogen atom by mean of amine and oxazoline moieties is installed in the second step. Finally, a first
entry towards catalytic activity is given. In this context, modification of the ligand pattern and steric
crowding around the central pyridine ring is examined and led to modest to fair ee’s in the construction
of binaphthyl substrates.
Received 12 December 2014
Revised 23 January 2015
Accepted 28 January 2015
Available online 4 February 2015
Keywords:
Pyridylmethylamine
Microwave-assisted synthesis
Heterocyclic chemistry
Naphthol oxidative coupling
Binaphthyl platform
Ó 2015 Elsevier Ltd. All rights reserved.
Introduction
and pyridyl remains challenging. There is a strong interest of the
scientific community for this family of compounds and thus a
2-(Aminomethyl) pyridines represent a useful family of ligands
known as ampy, pyme or pma depending on the literature source.
This family of ligands revealed recently efficient in the field of tran-
sition metal complexation and homogeneous catalysis.1–4 Struc-
tural modifications have already been done on the pma scaffold
expanding the scope of the catalytic transformations potentially
promoted by these ligands. Rigid pyridylpiperidines in which the
second nitrogen atom is included within the piperidine ring were
successfully applied to Suzuki coupling.5 Installation of an aryl
group in position 6 of the pma motif resulted in a further generation
of pma-based ligands.6 Such 6-arylpyridylmethyleamine in combi-
nation with group IV metals such as Os, Ru, Pd, Ir or Pt, catalyse
olefin polymerization,7 hydride transfer,8,9 and allylation reactions6
for example. Among these ligands, 6-phenyl or 6-(paratolyl)pyridi-
nemethylamines are of considerable interest since they have been
able to generate stable pincer-type catalyst precursors.6,10 Accesses
to 6-arylpyridylmethylamines have been reported either from aryl
pyridines and further installation of the methylamine fragment
through multistep sequences11 or from arylation of bromopyridin-
ecarboxaldehydes7 followed by reductive amination.8 If phenyl,
tolyl and naphthyl substituted pyridylmethylamine are the most
common members of the 6-arylpyridylmethylamine family, the
installation of heteroaromatics fragments including furyl, thienyl
steady demand for convenient and rapid strategies towards 6-aryl
but also 6-heteroaryl pyridylmethylamines. As part of a research
programme devoted to the synthesis, characterization and reactiv-
ity studies of pyridinemethylamine-based catalytic systems, we
draw particular attention on the installation of various aryl and het-
eroaryl groups in position 6 of the pma system. We reported herein
on a two step preparation procedure of new pma derivatives as
highlighted in Figure 1.
The construction of the 6-aryl and 6-heteroaryl pyridine scaf-
fold bearing carboxaldehyde and nitrile fragments is envisioned
through microwave-assisted coupling reactions.
The construction of pendant arms comprising amine or oxazo-
line moieties from precursors such as carboxaldehyde and nitrile
groups is next described. Finally, a first set of catalytic transforma-
tions is given.
We first focused on the synthesis of 6-arylpyridine-2-carboxal-
dehydes and -carbonitriles. In order to obtain aryl or heteroaryl
pyridines in the most practical way, we decided to examine the
Suzuki coupling between commercially available aryl boronic acids
and 6-bromopyridine-2-carboxaldehyde under microwave activa-
tion. Indeed, microwave-assisted organic chemistry has grown in
the last decades as a valuable and versatile tool for organic chem-
ists.12 It was thus of high benefits for us to increase reaction yields
of key materials within this study, reduce reaction times and avoid
undesirable side reactions that may occur in cross-coupling reac-
tions under conventional heating methods (vide infra). After a
⇑
Corresponding author. Tel.: +33 1 39 25 44 54; fax: +33 1 39 25 44 52.
E-mail address: damien.prim@uvsq.fr (D. Prim).
http://dx.doi.org/10.1016/j.tetlet.2015.01.182
0040-4039/Ó 2015 Elsevier Ltd. All rights reserved.

A. Requet et al. / Tetrahedron Letters 56 (2015) 1378–1382
1379
oxazoline
construction
arylation
arylation
reductive amination
O
N
R
N
R
N
HN
R1
N
N
X
Figure 1. General strategy towards 6-(hetero)aryl pyridylmethylamines.
screening of Pd catalyst (Pd2dba3/AsPh3, Na2PdCl4/BINAP,
Pd(PPh3)2Cl2/FeCl3, Pd(PPh3)2Cl2, Pd(PPh3)2Cl2/CuI) base (Na2CO3,
K2CO3) and solvent (THF, DME, dioxane, toluene/EtOH/H2O),
Pd(PPh3)2Cl2, Na2CO3 in toluene/EtOH/H2O represented the best
catalytic compromise. One hour under microwave irradiation at
100 °C revealed optimal conditions to prepare 6-arylpyridine-2-
carboxaldehydes 1 and 2. The latter microwave assisted conditions
(quantitative, 100 °C, 1 h) compares favorably with thermal condi-
tions (74%, 100 °C, 16 h) for the preparation of compound 1 used
the model compound. Interestingly, identical conditions were also
successfully applied to the preparation of the corresponding carbo-
nitriles 3–7 in comfortable yields ranging from 79% to quantitative
(Scheme 1). Our results deserve additional comments: as it can be
effective. Still coupling was also recently applied to the preparation
of symmetrical bipyridines and furyl- or thienyl-pyridine, but
revealed hampered by substantial amounts of homocoupling side
product in the case of unsymmetrical bipyridines.16 In this context
again, microwave-assisted synthesis was expected to reduce the
aforementioned hurdles and drawbacks. We thus began to exam-
ine both Stille- and Suzuki-type couplings as described in Scheme 2
and Table 1. It is worth noting that both reaction conditions, times
and temperatures deeply influenced the reaction issues. Indeed, at
120 °C for 60 min (entry 1) the use of 5% Pd(PPh3)2Cl2 in combina-
tion with 10% CuI did not afford any expected coupling products
albeit the starting material was fully consumed. Noteworthy
debromation and/or homocoupling side reactions take place under
these conditions.
seen from yields obtained for
1 and 7, introduction of
paramethoxyphenyl is equally efficient regardless of the carboxal-
dehyde or nitrile groups lying in position 2. The introduction of
heterocycles such as thiophene and furan in compounds 3 and 6,
respectively, was realized with similar efficiency. Installation of
aryl groups that exhibit increased steric crowding is also possible
giving access to compounds 2, 4 and 5. If 4 and 5 could be obtained
in good yields, 2 was isolated in a modest 36% yield mainly due to a
tedious purification step. Noteworthy, yields obtained for isolated
products in our study compare fairly to already reported methods
(see Supplementary material and yields mentioned in brackets).13
We next moved to the construction of the 2,20-bipyridine ana-
logues 8 and 9. 2,20-Bipyridines represent a family of versatile
building blocks in the fields of analytical, photo-, supra-, nano-,
macromolecular chemistry and catalysis.14 Suzuki- and Stille-type
reactions have been developed in order to build up the 2,2-bipyri-
dine scaffold. Although elegant efforts in the Suzuki pathway have
been done to overcome severe drawbacks such as prevalent proto-
deborylation, dimerization and relative low transmetalation steps,
the preparation of unsymmetrical 2,2-bipyridines by coupling
reactions is still considered challenging. To circumvent these draw-
backs, ligands such as phosphite and phosphine oxide as well as
alternate boron-based coupling partners15 were recently shown
In contrast at higher temperatures for shorter reaction times
(entry 2), we were able to isolate bipyridine 8 in 18% yield. Other
solvents were next tested but THF and NMP revealed less effective
than dioxane. Similarly, the use of Pd(PPh3)2Cl2 and CuI was found
superior to other catalyst and mandatory to optimal conversions
respectively. Best results could be obtained at 180 °C for 15 min
(entry 3) whereas prolonged reaction times led to a significant
amount of degradation products and a concomitant decrease of
the isolated yield.
Although yields remained modest, our conditions provide a
good compromise between efficiency and a relative easy purifica-
tion as crude products were only poorly contaminated by side
products. In addition, bipyridine 9 could also be obtained in a high
79% yield under similar conditions. Yields are similar to those
observed recently by Duan7 and Lützen17 but our results compare
favourably in term of reaction times. Attempts to increase yields
were next done under Suzuki-type coupling conditions. The use
of N-phenyldiethanolamino-2-pyridylboronate (see ESI) instead
of a more classical 2-pyridylnucleophile was next examined. Again
high temperature and short reaction times proved efficient provid-
ing an access to bipyridine 8 in a fair 57% yield under microwave
activation (entry 7). K2CO3 as the base, dioxane/water 1:0.1 as
Ar-B(OH)
2,Pd(PPh3)2Cl2, Na2CO3
Br
N
R
Ar
N
R
Toluene/EtOH/H2O, 100 °C, 1 h
microwaves
N
CHO
N
CHO
N
CN
O
MeO
OH
2 36%
1 quant.
3 quant.
(lit. 87%)
(lit. 70%)
N
CN
N
CN
N
CN
N
CN
S
OH
MeO
7 quant.
(lit. 88%)
5 79%
6 94%
(lit. 85%)
4 84%
(lit. 17%)
Scheme 1. 6-(Hetero)aryl-carboxaldehydes and carbonitriles 1–7.

1380
A. Requet et al. / Tetrahedron Letters 56 (2015) 1378–1382
using solvent free microwave activation and 1.2 equiv of (R)-phe-
N-Ph
O
B
nylglycinol. After 2 h at 130 °C, oxazolines 15–19 were isolated in
high yields regardless of the aromatic or heterocycle installed in
position 6 of the central pyridine ring (Scheme 4).
SnBu3
or
O
N
N
B
A
Finally, we describe first entries towards the catalytic activity of
new (hetero)arylpyridylmethylamines. In this context, we focused
our attention to two catalytic transformations, naphthol oxidative
and atroposelective Suzuki–Miyaura couplings, which have
already been described within the pma series. Comparison with
previously reported results obtained using ligands 23 and 24, is
given in Tables 2 and 3 (entries 1). To this end, pyridyloxazolines
21 and 22 were also prepared according to known procedures19
and used in this study. Impacts of (i) the installation of (hetero)aryl
groups at position 6 of the pyridine ring and/or (ii) the modifica-
tion of the pendant arm towards a cyclic oxazoline was examined.
Oxidative naphthol coupling has been recently reported by us
and others using iron or copper–amine complexes20 including
sparteine, proline-derived diamines, 1,5-diaza-cis-decalin, BINAM
or even pma.1 The catalytic systems were prepared in situ from
CuI (5%) and pyridylmethylamines (5%) in dichloroethane (DCE).
The experiments were performed under an oxygen atmosphere
at temperatures and time indicated in Table 2 in agreement with
a previous study.1 As shown in Scheme 5 and Table 2 (entry 1),
within the pma series, the use of ligand 24 gave 50% yield and
61% ee which represented the best results obtained.
Br
N
R
N
R
conditions
N
8
R = CHO
9 R = CN
Scheme 2. Synthesis of bipyridine-carboxaldehyde 8 and carbonitrile 9.
the solvent and a temperature of 150 °C for 15 min represented the
best compromise obtained that has to be compared with higher
reaction temperatures (entry 6) or other catalytic system such as
PddppfCl2. Experiments were run at a 90 mg scale of the starting
bromopyridine derivative. Attempts to scale up were however
hampered by the presence of larger amounts of side products
and thus more tedious purification steps affording lower yields of
expected targets.
We next focused on the preparation of new 6-arylpyridylmeth-
ylamines. Carboxaldehydes 1, 2 and 8 reacted smoothly with
methylbenzylamine or -(R)-methylnaphthylamine to afford the
intermediate imines which were in situ reduced using NaBH4 in
methanol to afford the corresponding pma 10–14 in high yields
(Scheme 3).18
a-(R)-
a
An increase of steric crowding around the complexation site
after installation of 4-MeOPh group in 10 and 11 as well as of
p-
deficient pyridyl substituent in 13 appears detrimental to the con-
struction of the binaphthyl platform. At best, a poor 10% isolated
yield of 20 could be reached (entry 4). Interestingly, moving from
We further examined the preparation of oxazolines starting
from nitriles 3–7 and 9. Based on a previous study,19 we were able
to efficiently transform nitriles into the corresponding oxazolines
Table 1
Preparation of bipyridines 8 and 9: comparison of Suzuki and Stille coupling reactions
Entry
Conditions
Temp (°C)/time (min)
Compound (yield %)
1
2
3
4
6
7
A, Pd(PPh3)2Cl2 5%, CuI 10%, dioxane
A, Pd(PPh3)2Cl2 5%, CuI 10%, dioxane
A, Pd(PPh3)2Cl2 5%, CuI 10%, dioxane
A, Pd(PPh3)2Cl2 5%, CuI 10%, dioxane
B, Pd(PPh3)2Cl2 10%, K2CO3 3 equiv, dioxane/H2O
B, Pd(PPh3)2Cl2 10%, K2CO3 3 equiv, dioxane/H2O
120/60 min
180/10 min
180/15 min
180/15 min
180/15 min
150/15 min
8(ꢀ)
8(18)
8(72)a
9(79)b
8(48)
8(57)
a
Obtained in 70% yield by Lützen.17
Obtained in 81% yield by Duan.7
b
RNH2, MgSO4,
DCM, rt, 2h
N
(hetero)aryl
N
CHO
(hetero)aryl
NHR
then
MeOH, NaBH4, rt 1h
N
N
N
HN
HN
HN
MeO
MeO
OH
10
1
11
1
88% from
quant. from
12
2
60% from
N
N
N
HN
N
HN
13
8
95% from
14
8
67% from
Scheme 3. Synthesis of new pma derivatives.

A. Requet et al. / Tetrahedron Letters 56 (2015) 1378–1382
1381
(R)-phenylglycinol 1.2eq.
O
N
(hetero)aryl
N
CN
(hetero)aryl
N
N
MW 130°C, 2h
O
O
O
N
N
O
N
N
N
OH
17 53% from 3
15 50% from 5
16 42% from 4
O
N
O
N
N
N
N
S
19 64% from 9
18 76% from 6
Scheme 4. Synthesis of pyridyl-oxazolines.
Table 2
CO2Me
Copper catalysed oxidative coupling
L 10%
CO2Me
OH
CuI 10%
OH
OH
Entry
Ligand
Yield (%)
Ee (%)
Conf.
1
2
3
4
5
6
7
8
9
24
10
11
13
21
22
15
17
18
50
—
61a
—
—
nd
75
43
-
rac.
nd
(S)
—
—
—
(R)
(S)
—
—
—
DCE, O2, 40°C, 6d
CO2Me
—
10b
35
L : 11, 13, 15, 17, 18, 21-24
20
25
—
42
Traces
R
O
O
N
N
N
N
HN
N
21
22
a
See Ref. 1.
Experiment run in four days.
b
23 R : Ph ref. 1
24
this work
R : ferrocenyl ref.1
Scheme 5. b-Naphthol oxidative coupling.
Table 3
Suzuki coupling
Entry
Ligand
Conv. (%)
Yield (%)
Ee (%)
Conf.
to the more coordinating thiophene 18 led only to traces of the tar-
get (entry 9). This first set of experiments seems to indicate that a
further rigidification of the ligand platform induces an increase of
steric crowding around the metal centre which becomes detrimen-
tal to the targeted transformation. A similar trend is observed
whether the pendant arm nitrogen atom is embedded into a rigid
oxazoline heterocycle or not.
1
2
3
4
5
6
7
23
10
11
13
21
17
19
Quant.
60
40
34
84
70
19
30
21
34
14
—
40a
10
8
(S)
b
b
7
21
10
—
(R)
(S)
—
62
15
a
Atroposelective Suzuki–Miyaura coupling was next examined.
If Cammidge and Buchwald21 paved the way to such catalytic
transformation some years ago, this research area remains chal-
lenging. Indeed, 2-MeObinaphthyl 25 is commonly used as the
benchmark target to the evaluation of catalytic systems. Several
groups reached appealing compromise between high ee and com-
fortable yields.22 Based on a similar strategy, ligands 10, 11, 13
were compared to previously results obtained within the pma ser-
ies. As shown in Scheme 6 and Table 3 (entry 1) reference ligand
23, which displays an acyclic pendant arm, afforded 70% yield
and 40% ee. Neither bidentate 10 and 11 nor tridentate 13 ligands
allowed an increase of both yields and ee’s (entries 2–4). Modest
conversions and isolated yields were obtained together with ee’s
ranging from 7 to 10%. An increase of conversion, yield and ee to
84%, 34% and 21%, respectively was observed when oxazoline 21
was used. Further substitution of ligand 21 by a furan or a pyridine
See Ref. 1.
Not determined.
b
acyclic pendant arm to cyclic oxazoline as in 21 and 22 revealed
beneficial in this transformation (entries 5, 6). Albeit in modest
yields, binaphthol 20 could be obtained in 75 and 43% ee, respec-
tively. Unfortunately, installation of aromatic groups at position 6
of the pyridine-oxazoline 21 led to a severe decrease of conversion
and selectivity. Indeed, installation of the 2,6-diMePh group at the
central pyridine led to any conversion (entry 7). The presence of
heterocycles instead of phenyl rings was next examined. In this
context
p-excessive furan 17 and thiophene 18 were further
tested. Interestingly, best isolated yield (42%) was obtained with
the less coordinating heterocycle furan (entry 8). In the latter case
binol 20 was obtained in a racemic form. Disappointingly, moving

1382
A. Requet et al. / Tetrahedron Letters 56 (2015) 1378–1382
2. Grach, G.; Dinut, A.; Marque, S.; Marrot, J.; Gil, R.; Prim, D. Org. Biomol. Chem.
2011, 9, 497–503.
3. (a) Suzuki, K.; Oldenburg, P. D.; Que, L., Jr. Angew. Chem., Int. Ed. 2008, 47, 1887–
1889; (b) Wu, M.; Wang, B.; Wang, S.; Xia, C.; Sun, W. Org. Lett. 2009, 11, 3622–
3625; (c) Griffiths, D. V.; Al-Jeboori, M. J.; Arnold, P. J.; Cheong, Y.-K.;
Duncanson, P.; Motevalli, M. Inorg. Chim. Acta 2010, 363, 1186–1194.
4. (a) Zhang, L.; Zuo, Z.; Wan, X.; Huang, Z. J. Am. Chem. Soc. 2014, 136, 15501–
15504; (b) Chen, J.; Xi, T.; Lu, Z. Org. Lett. 2014. http://dx.doi.org/10.1021/
ol503282r.
5. (a) Puget, B.; Roblin, J.-P.; Prim, D.; Troin, Y. Tetrahedron Lett. 2008, 49, 1706–
1709; (b) Gunawan, M.-A.; Qiao, C.; Abrunhosa-Thomas, I.; Puget, B.; Roblin, J.-
P.; Prim, D.; Troin, Y. Tetrahedron Lett. 2010, 51, 5392–5394.
6. (a) Wang, T.; Hao, X.-Q.; Zhang, X.-X.; Gong, J.-F.; Song, M.-P. Dalton Trans.
2011, 40, 8964–8976; (b) Nareddy, P.; Mantilli, L.; Guénée, L.; Mazet, C. Angew.
Chem., Int. Ed. 2012, 51, 3826–3831.
OCH3
5 mol% L,
Br
5 mol% Pd(PhCN)2Cl2
OCH3
Cs2CO3, Tol/EtOH/H2O
25
Scheme 6. Atroposelective palladium catalysed coupling.
B(OH)2
ring was finally examined. The use of ligand 17 led to a clear
decrease of both yield and ee to 14% and 10%, respectively.
Catalytic combination using bipyridine 19 afforded poor conver-
sion. Results obtained in the Suzuki–Miyaura coupling are deeply
impacted by an increase of steric crowding and of rigidification
of the ligand.
In summary, we succeeded in the convenient microwave-
assisted synthesis of a series of arylpyridines bearing valuable
carboxaldehyde and carbonitrile fragments. Both functionalized
groups have been efficiently transformed into amines and oxazo-
lines affording a broad panel of (hetero)arylpyridylmethylamines.
First lines of catalytic activity of these new ligands have been
described in the atroposelective Suzuki–Miyaura and naphthol
oxidative couplings. The influence of additional substituents
installed at position 6 of the central pyridine and of the nature,
cyclic or acyclic, of the ligand pendant arm considerably impact
conversion. Modification of the ligand pattern led to modest to fair
ee’s in the construction of binaphthyl substrates.
7. (a) Liao, L.-Y.; Kong, X.-R.; Duan, X.-F. J. Org. Chem. 2014, 79, 777–782; (b)
Wang, C.-Y.; Liu, Y.-H.; Peng, S.-M.; Liu, S.-T. J. Organomet. Chem. 2006, 691,
4012–4020.
8. Faler, C. A. Tetrahedron Lett. 2010, 51, 5621–5623.
9. (a) Baratta, W.; Siega, K.; Rigo, P. Adv. Synth. Catal. 2007, 349, 1633–1636; (b)
Baratta, W.; Rigo, P. Eur. J. Inorg. Chem. 2008, 4041–4053; (c) Baratta, W.;
Chelucci, G.; Gladiali, S.; Siega, K.; Toniutti, M.; Zanette, M.; Zangrando, E.; Rigo,
P. Angew. Chem., Int. Ed. 2005, 44, 6214–6219; (d) Baratta, W.; Ballico, M.; Del
Zotto, A.; Herdtweck, E.; Magnolia, S.; Peloso, R.; Siega, K.; Toniutti, M.;
Zangrando, E.; Rigo, P. Organometallics 2009, 28, 4421–4430.
10. Baratta, W.; Ballico, M.; Chelucci, G.; Siega, K.; Rigo, P. Angew. Chem., Int. Ed.
2008, 47, 436–4365.
11. Baratta, W.; Benedetti, F.; Del Zotto, A.; Fanfoni, L.; Felluga, F.; Magnolia, S.;
Putignano, E.; Rigo, P. Organometallics 2010, 29, 3563–3570.
12. See for recent review: Kappe, C. O.; Stadler, A.; Dalinger, D. Microwaves in
Organic and Medicinal Chemistry, 2nd ed.; Wiley-VCH: Weinheim, Germany,
2012.
13. Comparison with yields reported in associated literature is given in ESI.
14. For reviews, see: (a) Kaes, C.; Katz, A.; Hosseini, M. W. Chem. Rev. 2000, 100,
3553–3590; (b) Chelucci, G.; Thummel, R. P. Chem. Rev. 2002, 102, 3129–3170;
(c) Newkome, G. R.; Patri, A. K.; Holder, E.; Schubert, U. S. Eur. J. Org. Chem.
2004, 235–254; (d) Hapke, M.; Brandt, L.; Lützen, A. Chem. Soc. Rev. 2008, 37,
2782–2797.
15. (a) Yang, D. X.; Colletti, S. L.; Wu, K.; Song, M.; Li, G. Y.; Shen, H. C. Org. Lett.
2009, 11, 381–384; (b) Billingsley, K. L.; Buchwald, S. L. Angew. Chem., Int. Ed.
2008, 120, 4773–4776; (c) Dick, G. R.; Woerly, E. M.; Burke, M. D. Angew. Chem.,
Int. Ed. 2012, 51, 2667–2672.
16. (a) Yabe, Y.; Maegawa, T.; Monguchi, Y.; Sajiki, H. Tetrahedron 2010, 66, 8654–
8660; (b) Verniest, G.; Wang, X.; De Kimpe, N.; Padwa, A. J. Org. Chem. 2010, 75,
424–433.
Acknowledgments
The authors are grateful to the French Research Ministry, CNRS
– France, the University of Versailles Saint Quentin-en-Yvelines
and ANR – France (ANR-11-BS07-030-01) for the financial support
and grant (AR).
17. Gütz, C.; Lützen, A. Synthesis 2010, 1, 85–90.
18. (a) Eidamshaus, C.; Reissig, H.-U. Tetrahedron: Asymmetry 2011, 22, 1644–
1652; (b) Terrasson, V.; Prim, D.; Marrot, J. Eur. J. Inorg. Chem. 2008, 2739–
2745.
Supplementary data
19. Hassani, R.; Requet, A.; Marque, S.; Gaucher, A.; Prim, D.; Kacem, Y.; Ben
Hassine, B. Tetrahedron: Asymmetry 2014, 25, 1275–1279.
Supplementary data (experimental details as well as character-
ization data and copies of NMR spectra, HPLC and MW profiles)
associated with this article can be found, in the online version, at
http://dx.doi.org/10.1016/j.tetlet.2015.01.182.
20. See for example: (a) Egami, H.; Katsuki, T. J. Am. Chem. Soc. 2009, 131, 6082–
6083; and references cited therein (b) Kozlowski, M. C.; Morgan, B. J.; Linton, E.
C. Chem. Soc. Rev. 2009, 38, 3193–3207. and references cited therein.
21. Cammidge, A. N.; Crépy, K. V. L. Chem. Commun. 2000, 1723–1724; (b) Yin, J.;
Buchwald, S. L. J. Am. Chem. Soc. 2000, 122, 12051–12052.
22. For recent selected examples: (a) Bermejo, A.; Ros, A.; Fernandez, R.; Lassaletta,
J. M. J. Am. Chem. Soc. 2008, 130, 15798–15799; (b) Ros, A.; Estepa, B.; Bermejo,
A.; Álvarez, E.; Fernandez, R.; Lassaletta, J. M. J. Org. Chem. 2012, 77, 4740–
4750; (c) Benhamou, L.; Besnard, C.; Kündig, E. P. Organometallics 2014, 33,
260–266; (d) Wang, T.; Hao, X.-Q.; Huang, J.-J.; Wang, K.; Gong, J.-F.; Song, M.-
P. Organometallics 2014, 33, 194–205.
References and notes
1. Grach, G.; Pieters, G.; Dinut, A.; Terrasson, V.; Medimagh, R.; Bridoux, A.;
Razafimahaleo, V.; Gaucher, A.; Marque, S.; Marrot, J.; Prim, D.; Gil, R.; Planas, J.
G.; Vinas, C.; Thomas, I.; Roblin, J.-P.; Troin, Y. Organometallics 2011, 30, 4074–
4086. and references cited therein.