New fluorinated catalysts for olefin metathesis

Article abstract of DOI:10.1016/j.mencom.2016.11.004

New olefin metathesis catalysts, analogues of Grubbs II ones, bearing hexafluoroisopropylmethoxy groups in NHC ligand, provide high conversions in model ring closing metathesis of diallylmalonate and cross metathesis of allylbenzene with 1,3-diacetoxybut-

Full text of DOI:10.1016/j.mencom.2016.11.004

Mendeleev
Communications
Mendeleev Commun., 2016, 26, 474–476
New fluorinated catalysts for olefin metathesis
Salekh M. Masoud,a,b Artur K. Mailyan, Alexander S. Peregudov,
a,c
a
b
a
Christian Bruneau and Sergey N. Osipov*
a
b
c
A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, 119991 Moscow,
Russian Federation. Fax: +7 499 135 5085; e-mail: osipov@ineos.ac.ru
UMR 6226 CNRS-Universite de Rennes 1, Institut des Sciences Chimiques de Rennes, Organometalliques:
Materiaux et Catalyse, Centre for Catalysis and Green Chemistry, Campus de Beaulieu, 35042 Rennes, France
Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA 93106-9510, USA
DOI: 10.1016/j.mencom.2016.11.004
Me
Me
Me
Me
Me
Me
CF3
CF3
CF3
CF3
CF3
CF3
CF3
CF3
New olefin metathesis catalysts, analogues of Grubbs II ones,
bearing hexafluoroisopropylmethoxy groups in NHC ligand,
provide high conversions in model ring closing metathesis
of diallylmalonate and cross metathesis of allylbenzene with
MeO
N
N
OMe
MeO
N
N
OMe
Cl
Cl
Me
Ph
Me
Ru
O
Ru
Cl
Pri
Cl
PCy3
1
,3-diacetoxybut-2-ene.
Grubbs-type catalyst
Hoveyda-type catalyst
Over the past decade, olefin metathesis, with the advent of effi­
cient ruthenium carbene complexes, has experienced dramatic
catalytic properties has been mainly studied by usage of properly
6
7
modified phosphine, styrene ligands, as well as by the replace­
ment of one or two chlorine atoms at ruthenium, for example,
1,2
development. A significant progress in catalyst design was
achieved when N­heterocyclic carbenes (NHCs) were introduced as
ancillary ligands. The formal replacement of phosphine ligand in
first generation of Grubbs catalyst (G-I) for sterically demanding
NHCs, e.g. such as N,N'­dimesitylimidazolin­2­ylidene generally
provides the metal center with considerable steric protection. Due
to typical s­donor properties the non­labile and bulky NHCs can
also stabilize both the catalyst and catalytically relevant intermediates
8
with perfluoroalkoxylates and fluorocatecholates. Therefore,
it is somewhat surprising that the number of publications on
metathesis catalysts decorated with fluorinated NHC ligands is
9–11
extremely limited,
with the first report appearing in early 2000.
CF3 Me
F3C
CF3 Me
F3C
RO
RO
N
N
Cl
Mes
3
formed in metathesis pathways. Therefore, the fine­turning of
N
N
Cl
Mes
these ligands by the introduction of different functionalities into
N­aryl substituents to afford enhanced thermal stability, improved
reactivity and selectivity remains highly desirable.
Me
Ru
O
Cl
Pri
Me
Cl
Ru
Ph
At the same time, the chemistry of fluorinated compounds is
PCy3
4
A
B
an area of tremendous expansion. In particular, CF group is one
3
of the most lipophilic groups in organic chemistry, has one of the
5
highest electronegativity and steric hindrance (Van­der­Waals
Recently we have prepared unsymmetrical 1,3­bis(aryl)­
4,5­dihydroimidazolium salts bearing the hexafluoroisopropyl­
alkoxy group on one of N­aryl moieties and have demonstrated
their potential as precursors for the corresponding NHC ligands of
5
(c)
volume of CF group is close to that of isopropyl group ).
3
Therefore, fluorinated metal catalysts are attracting interest.
In the field of ruthenium–alkylidene complexes, the steric and
electronic impact of fluorine and fluoroalkyl groups on their
1
2
new family of metathesis catalysts A and B. Herein, we report
F3C
CF3
OH
Me
Me
Me
Me
Me
NH2
Me
H
N
H
N
iii
iv
i, ii
N
H
N
H
Me
HO
Me
Me
Me
1
F3C
CF3
2
F3C
CF3
OH
F3C
CF3
O
CF3 Me
Me
Me Cl– Me
Me
Me
OMe
H
CF3
CF3
CF3
OMe
CF3
N
v, vi
N
vii
N
N
H
MeO
N
N
HO
Me
MeO
F3C
Me
Me F3C
O
Me
Me
Me
F3C
CF3
CF3
3
4
5, 87%
i
Scheme 1 Reagents and conditions: i, glyoxal, H O, Pr OH, 24 h, room temperature, 85%; ii, NaBH , HCl, THF, H O, 2.5 h, 0°C, 70%; iii, HFA·1.5 H O,
2
4
2
2
p­TSA (1 mol%), 100°C, 84%; iv, (CF CO) O/Py, Et O, 1 h, room temperature, 85%; v, MeI, K CO , DMF, 1.5 h, 80°C, 76%; vi, KOH, 18­crown­6,
3
2
2
2
3
DMSO/H O, 1.5 h, 130°C, 80%; vii, HCl/MeOH, then CH(OEt) , 100°C.
2
3
©
2016 Mendeleev Communications. Published by ELSEVIER B.V.
–
474 –
on behalf of the N. D. Zelinsky Institute of Organic Chemistry of the
Russian Academy of Sciences.

Mendeleev Commun., 2016, 26, 474–476
on their symmetrical representatives and their use in ring­closing
metathesis (RCM) of diallylmalonate and in cross­metathesis
Me
Me
CF3
CF3
CF3
OMe
(CM) of allylbenzene with 1,3­diacetoxybut­2­ene.
PCy3
Ru
MeO
N
N
First, we synthesized symmetrical N,N'­bis(aryl)ethylene­
diamine 2 (Scheme 1) with two hexafluoroisopropoxy groups
in the para­position of N­aryl moieties. For this purpose, diamine
Cl
Cl
5
CF3
Cl
toluene,
Ph room tem-
Me
Cl
Me
Ru
PCy3
G-I
perature,
2 h
Ph
1
(
was prepared via slightly modified literature protocol including
i) the condensation of 2,6­dimethylaniline with glyoxal followed
by (ii) the reduction of the resulting diimine with NaBH to afford
PCy3
6a, 30%
4
Me
Me
1
in good yield. Then diamine 1 was (iii) directly alkylated with
CF3
CF3
CF3
1
3
commercially available hexafluoroacetone (HFA) hydrate. The
reaction smoothly proceeded at 100°C in excess of HFA hydrate
under acid catalysis to give the desired dialkylation product 2 in
high yield. Further the synthetic sequence included (iv) protection
of the two secondary amino functions by treatment of 2 with
trifluoroacetic anhydride in pyridine to yield 3, and (v, vi) selective
O­methylation/N­deprotection to afford 4 in 80% yield. The
final heterocyclization of fluorinated diamine 4 to construct the
desired imidazolinium salt 5 was successfully achieved using
conventional treatment of 4 with HCl and triethyl orthoformate.
With this new fluorinated NHC salt in hand, we prepared
the ruthenium complexes 6a,b. Following the standard literature
conditions by the reaction of in situ generated carbene with com­
mercially available Grubbs I catalyst RuCl (PCy ) (=CHPh)
PCy3
Ru
MeO
N
N
OMe
CF3
Cl
5
Cl
Cl
Me
Me
toluene,
60 °C,
1 h
O
Ru
Me
Cl
O
Me
H-I
Me
Me
b, 32%
6
Scheme 2
The G-II and H-II catalysts are efficient for the RCM of
diethyl diallylmalonate at 30°C and full conversion obtained
within 30 min. The Grubbs type catalyst 6a behaves similarly
with very close kinetic profiles (Figure 2). On the other hand, the
Hoveyda type catalyst 6b presented a very different reactivity
from the H-II catalyst. Pronounced initiation period (about 30 min)
16
2
3 2
14
i
15
G-I and Hoveyda one RuCl (PCy )(=CH(o­Pr OC H )) H-I,
2
3
6
4
complexes 6a,b were obtained in moderate yields. Purification
by silica gel chromatography and further crystallization from
a DCM/n­pentane mixture afforded dark­brown (6a) and dark­
green (6b) air stable solids (Scheme 2).†
Complexes 6a,b were completely characterized by NMR
spectroscopy and elemental analysis. In addition, single crystal
of 6b was studied by X­ray analysis (Figure 1).
N(2)
N(1)
Cl(2)
‡
C(2)
Ru(1)
Catalytic activities of the prepared catalysts 6a,b were inves­
tigated in RCM reactions with diethyl diallylmalonate and in CM
reaction of allylbenzene with 1,4­diacetoxybut­2­ene following
C(1)
Cl(1)
O(1)
1
6
standard protocols for evaluation of olefin metathesis catalysts.
The commercially available G-II17 and H-II catalysts were
18
used as reference ones.
Figure 1 Molecular structure of complex 6b. Thermal ellipsoids are drawn
at 30% probability. Hydrogen atoms are omitted for clarity.
†
Synthesis of complex 6a. In a flame­dried Schlenk flask compound 5
(
300 mg, 0.44 mmol) was mixed with 20 ml of anhydrous toluene. The
mixture was cooled to 0°C, degassed three times, and then KHMDS
460 ml of 1 m solution in THF, 0.46 mmol) was added to the mixture
under argon. The mixture was stirred for 30 min; then G-I (305 mg,
.37 mmol) was added and the mixture was stirred for 2 h at room tem­
the residue was purified by column chromatography on silica gel using
EtOAc–light petroleum (1:3) as eluent to yield 140 mg (32%) of complex
6b as a green solid. Suitable for X­ray crystals were grown by slow
(
1
diffusion of hexane vapors in CH Cl solution. H NMR (600 MHz, C D )
2
2
6
6
0
d: 16.53 (s, 1H, CHAr), 7.61 (s, 4H, HAr), 7.12 (d, 1H, H , J 7.6 Hz),
Ar H,H
perature. After removal of volatiles, the residue was purified by column
chromatography on silica gel in a gradient manner using EtOAc–light
petroleum (1:8 ® 1:3) as eluent under an argon atmosphere to yield
7.07 (t, 1H, H , J 7.8 Hz), 6.65 (t, 1H, HAr, J 7.5 Hz), 6.29 (d, 1H,
Ar H,H
H,H
3
H , J 8.2 Hz), 4.45 [hept., 1H, OCH(Me) , J 6.1 Hz], 3.26 (s, 6H,
Ar H,H
2
H,H
OMe), 3.22 [s, 4H, (CH ) ], 2.49 (s, 12H, Me), 1.27 [d, 6H, OCH(Me) ,
2
2
2
1
30 mg (30%) of complex 6a as a brown solid. 1H NMR (600 MHz,
3
JH,H 6.2 Hz]. F{ H} NMR (282 MHz, C D ) d: 7.52 (s). C NMR
19
1
13
6 6
C D ) d: 19.55 (s, 1H, CHPh), 8.33 (br.s, 2H, H ), 7.59 (s, 2H, HAr),
(151 MHz, C D ) d: 301.3, 213.2, 152.8, 145.6, 140.9, 129.7, 128.9,
6 6
6
6
Ar
3
2
7
3
2
.15–6.92 (m, 5H, H ), 3.30 (s, 3H, OMe), 3.10 (t, 2H, CH , J 10.2 Hz),
128.8, 128.4, 123.3 (q, J 290 Hz), 122.4, 122.3, 113.3, 83.5 (quint.,
Ar
2
H,H
C,F
3
1
.01 (s, 3H, OMe), 2.93 (t, 2H, CH , J 10.2 Hz), 2.76 (s, 6H, Me),
JC,F 29 Hz), 75.3, 54.3, 51.0, 21.4. Found (%): C, 46.65; H, 4.21; N, 2.94.
2
H,H
.43 (s, 6H, Me), 2.04 (q, 3H, PCy , JH,P 11.7 Hz), 1.68–1.50 (m, 16H,
Calc. for C H Cl F N O Ru (%): C, 46.36; H, 4.00; N, 2.92.
3
37 38
2
12
2
3
19
1
‡
PCy ), 1.37–1.26 (m, 6H, PCy ), 1.11–1.00 (m, 8H, PCy ). F{ H} NMR
Crystal data for 6b: C H Cl F N O Ru, M = 958.67. APEXII,
37 38 2 12 2 3
3
3
3
31
(
376 MHz, C D ) d: 7.49 (s). P NMR (162 MHz, C D ) d: 20.93 (s).
Bruker­AXS diffractometer, MoKa radiation (l = 0.71073 Å), T = 150(2) K,
6
6
6
6
2
1
3
C NMR (151 MHz, C D ) d: 299.7 (br.s), 220.2 (d, J 79.3 Hz),
orthorhombic, space group Pc2 b (#29), a = 11.7016(12), b = 13.0525(14)
6
6
C,P
1
1
3
–3
1
52.8, 152.7, 142.2, 141.0, 139.9, 138.8, 123.3 (d, J 290 Hz), 123.1
and c = 26.190(3) Å, V = 4000.1(7) Å , Z = 4, d = 1.588 g cm , m =
= 0.620 mm . The structure was solved by direct methods using the SIR97
C,F
1
1
–1
(d, J 289 Hz), 83.4 (m), 54.5, 54.3, 51.3, 35.9, 35.5, 33.0 (d, J 16 Hz),
C,F
C,P
3
2
2
9.1, 27.9 (d, J 10 Hz), 27.2 (d, J 12 Hz), 20.8, 19.4. Found (%):
program, and then refined with full­matrix least­square methods based on
C,P
C,P
2
C, 53.04; H, 5.56; N, 2.44. Calc. for C H Cl F N O PRu (%): C, 52.88;
F (SHELXL­97) with the aid of the WINGX program. All non­hydrogen
52
65
2
12
2
2
H, 5.55; N, 2.37.
atoms were refined with anisotropic atomic displacement parameters.
H atoms were finally included in their calculated positions. A final refine­
Synthesis of complex 6b. In a flame­dried Schlenk flask compound 5
2
(360 mg, 0.54 mmol) was mixed with 20 ml of anhydrous toluene. The
ment on F with 7338 unique intensities and 516 parameters converged
2
mixture was cooled to 0°C and degassed three times; then KHMDS
560 ml of 1 m solution in THF, 0.56 mmol) was added to the mixture
at wR(F ) = 0.1105 [R(F) = 0.0516] for 5541 observed reflections with
(
I > 2s(I).
under an argon atmosphere. The reaction mixture was stirred for 30 min at
room temperature; then Hoveyda catalyst H-I (270 g, 0.45 mmol) was added
and the mixture was stirred for 1 h at 60°C. After removal of volatiles,
CCDC 1030290 contains the supplementary crystallographic data for
this paper. These data can be obtained free of charge from The Cambridge
Crystallographic Data Centre via http://www.ccdc.cam.ac.uk.
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475 –

Mendeleev Commun., 2016, 26, 474–476
EtO2C
CO2Et
EtO C CO Et
Online Supplementary Materials
Supplementary data associated with this article can be found
in the online version at doi:10.1016/j.mencom.2016.11.004.
2
2
[
Ru] cat. (1 mol%)
CH2Cl2, 0.1 M, 30 °C
References
H-II
1
00
G-II
1 (a) R. R. Schrock, Angew. Chem. Int. Ed., 2006, 45, 3748; (b) R. H.
Grubbs, Angew. Chem. Int. Ed., 2006, 45, 3760; (c) S. J. Connon and
S. Blechert, in Ruthenium Catalysts and Fine Chemistry, eds. C. Bruneau
and P. H. Dixneuf, Springer, Berlin, 2004, vol.11, pp. 93–124; (d) Olefin
Metathesis Theory and Practice, ed. K. Grela, Wiley, Hoboken, 2014.
8
6
4
2
0
0
0
0
0
6
a
6
b
2
(a) G. C. Vougioukalakis and R. H. Grubbs, Chem. Rev., 2010, 110,
746; (b) C. Fischmeister and P. H. Dixneuf, in Metathesis Chemistry:
1
From Nanostructure Design to Synthesis of Advanced Materials, eds.
Y. Imamoglu and V. Dragutan, Springer, Dordrecht, 2007, pp. 3–27;
0
30
60
90
t/min
120
150
180
(c) M. R. Buchmeiser, Chem. Rev., 2000, 100, 1565; (d) A. Leitgeb,
J. Wappel and C. Slugovc, Polymer, 2010, 51, 2927.
(a) C. Samojłowicz, M. Bieniek and K. Grela, Chem. Rev., 2009, 109,
Figure 2 RCM of diethyl diallylmalonate with catalysts 6a and 6b as
compared to G-II and H-II.
3
4
3
2
708; (b) C. Deraedt, M. d’Halluin and D. Astruc, Eur. J. Inorg. Chem.,
013, 4881.
was necessary before it could achieve full conversion with lower
reaction rates and thus in longer reaction times (4 h).
(a) P. Kirsch, Modern Fluoroorganic Chemistry, Wiley­VCH, Weinheim,
2004; (b) K. L. Kirk, J. Fluorine Chem., 2006, 127, 1013; (c) D. O’Hagan,
Chem. Soc. Rev., 2008, 37, 308; (d) J. Nie, H.­C. Guo, D. Cahard and
J.­A. Ma, Chem. Rev., 2011, 111, 455.
In CM of allylbenzene with an excess of 1,3­diacetoxybut­
2
­ene, these differences in reactivity did not exist and all com­
5
6
(a) K. Uneyama, Organofluorine Chemistry, Blackwell, Oxford, UK,
plexes allowed an equilibrium to be reached at 70–80% conver­
sion within 30 min with closely related kinetic profiles (Figure 3).
2
006; (b) M. Jagodzinska, F. Huguenot, G. Candiani and M. Zanda,
ChemMedChem, 2009, 4, 49.
(a) R. Tuba, R. C. da Costa, H. S. Bazzi and J. A. Gladysz, ACS Catal.,
2
012, 2, 155; (b) R. Tuba, E. N. Brothers, J. H. Reibenspies, H. S. Bazzi
Ph
[
Ru] cat. (2.5 mol%)
OAc
and J. A. Gladysz, Inorg. Chem., 2012, 51, 9943.
+
Ph
CH2Cl2, 0.2 M, 25 °C
AcO
OAc
7 (a) M. Matsugi, Y. Kobayashi, N. Suzumura, Y. Tsuchiya and T. Shioiri,
J. Org. Chem., 2010, 75, 7905; (b) J. Kví cˇ ala, M. Schindler, V. Kelbichová,
M. Babun eˇ k, M. Rybá cˇ ková, M. Kví cˇ alová, J. Cva cˇ ka andA. B rˇ ezinová,
J. Fluorine Chem., 2013, 153, 12; (c) J. Lim, S. S. Lee and J. Y. Ying,
Chem. Commun., 2008, 4312; (d) Q. Yao and Y. Zhang, J. Am. Chem.
Soc., 2004, 126, 74.
1
00
H-II
G-II
6a
8
6
4
2
0
8
(a) L. Yang, M. Mayr, K. Wurst and M. R. Buchmeiser, Chem. Eur. J.,
004, 10, 5761; (b) T. S. Halbach, S. Mix, D. Fischer, S. Maechling,
0
0
0
0
6
b
2
J. O. Krause, C. Sievers, S. Blechert, O. Nuyken and M. R. Buchmeiser,
J. Org. Chem., 2005, 70, 4687; (c) S. Monfette, K. D. Camm, S. I. Gorelsky
and D. E. Fogg, Organometallics, 2009, 28, 944.
(a) S. Fustero, A. Simón­Fuentes, P. Barrio and G. Haufe, Chem. Rev.,
2
9
015, 115, 871; (b) V. Siano, I. d’Auria, F. Grisi, C. Costabile and
0
10
20
30
40
50
60
P. Longo, Cent. Eur. J. Chem., 2011, 9, 605.
t/min
10 A. Fürstner, L. Ackermann, B. Gabor, R. Goddard, C. W. Lehmann,
R. Mynott, F. Stelzer and O. R. Thiel, Chem. Eur. J., 2001, 7, 3236.
Figure 3 CM of allylbenzene with 1,3­diacetoxybut­2­ene with catalysts
1
1 (a) T. Ritter, M. W. Day and R. H. Grubbs, J. Am. Chem. Soc., 2006,
28, 11768; (b) D. R. Anderson, D. J. O’Leary and R. H. Grubbs, Chem.
Eur. J., 2008, 14, 7536.
6
a and 6b as compared to G-II and H-II.
1
In conclusion, we prepared new symmetrical fluorinated
12 S. M. Masoud, A. K. Mailyan, V. Dorcet, T. Roisnel, P. H. Dixneuf,
N,N'­diarylimidazolidinium salt containing two hexafluoroiso­
propylmethoxy groups in para­positions of N­aryl substituents
serving as precursors for the corresponding N­heterocyclic carbene
ligands. Two ruthenium carbene complexes with these ligands
belonging to the families of second generation Grubbs and
Hoveyda olefin metathesis catalysts were obtained. The per­
formance of the new Grubbs type catalyst in olefin metathesis
has proved to be similar to that of the classical Grubbs second
generation catalyst. Meantime, the new Hoveyda type catalyst
behaves differently from the symmetrical Hoveyda­II catalyst
C. Bruneau and S. N. Osipov, Organometallics, 2015, 34, 2305.
1
3 (a) E. E. Gilbert, E. S. Jones and J. P. Sibilia, J. Org. Chem., 1965, 1001;
b) N. D. Chkanikov, V. D. Sviridov, A. E. Zelenin, M. V. Galakhov,
A. F. Kolomiets and A. V. Fokin, Bull. Acad. Sci. USSR, Div. Chem. Sci.,
990, 39, 323 (Izv. Akad. Nauk SSSR, Otdel. Khim. Nauk, 1990, 383).
(
1
1
4 P. Schwab, M. B. France, J. W. Ziller and R. H. Grubbs, Angew. Chem.,
Int. Ed. Engl., 1995, 34, 2039.
15 J. S. Kingsbury, J. P. A. Harrity, P. J. Bonitatebus, Jr. and A. H. Hoveyda,
J. Am. Chem. Soc., 1999, 121, 791.
6 T. Ritter, A. Hejl, A. G. Wenzel, T. W. Funk and R. H. Grubbs, Organo-
metallics, 2006, 25, 5740.
7 M. Scholl, S. Ding, C. W. Lee and R. H. Grubbs, Org. Lett., 1999, 1, 953.
18 S. B. Garber, J. S. Kingsbury, B. L. Gray and A. H. Hoveyda, J. Am.
Chem. Soc., 2000, 122, 8168.
1
1
equipped with the H IMes carbene ligand in ring closing meta­
2
thesis of malonate derivatives and shows a latent character testified
by an induction period followed by a lower reaction rate.
This work was supported by the Russian Science Foundation
(grant no. 16­13­10364).
Received: 10th August 2016; Com. 16/5026
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