Effect of ligand bulk in ruthenium-catalyzed olefin metathesis: IPr* vs IPr

Article abstract of DOI:10.1021/om300719t

Novel ruthenium catalysts, [RuCl₂(IPr*)(PPh ₃)(3-phenylindenylidene)] (1) and [RuCl₂(IPr*)(Py) (3-phenylindenylidene)] (2), bearing the very bulky ligand IPr* are reported. The complexes were tested in ring closing and cross-metathesis, and their activities were compared to that displayed by [RuCl₂(IPr) (PPh₃)(3-phenylindenylidene)] (3) and the new [RuCl ₂(IPr)(Py)(3-phenylindenylidene)] (4), in order to assess how the steric hindrance of the N-heterocyclic carbene influences the catalytic activity of the resulting ruthenium complexes.

Full text of DOI:10.1021/om300719t

IPr* vs IPr in ruthenium olefin metathesis
Simone Manzini, César A. Urbina Blanco and Steven P. Nolan*
Supporting Information
General informations: ..........................................................................................................................2
Synthesis of [RuCl
Synthesis of [RuCl
Synthesis of [RuCl
Synthesis of [RuCl
2
2
2
2
(IPr*)(PPh
(IPr*)(Py)(3-phenylindenylidene)](2):...............................................................23
(IPr)(PPh )(3-phenylindenylidene)](3): ...............................................................3
(IPr)(Py)(3-phenylindenylidene)](4):.................................................................34
3
)(3-phenylindenylidene)](1): .............................................................2
3
General procedure for RCM and Enyne reactions:..............................................................................4
General procedure for CM reactions:.................................................................................................45
NMR data of [RuCl
NMR data of [RuCl
NMR data of [RuCl
NMR data of [RuCl
2
2
2
2
(IPr*)(PPh
(IPr*)(Py)(3-phenylindenylidene)] (2): ..............................................................6
(IPr)(PPh )(3-phenylindenylidene)] (3):.............................................................7
(IPr)(Py)(3-phenylindenylidene)] (4): ................................................................8
3
)(3-phenylindenylidene)] (1):...........................................................5
3
REFERENCES...................................................................................................................................10

General informations:
All reagents were used as received. Dichloromethane and toluene were dispensed from a solvent
purification system from Innovative Technology. Catalyst syntheses were performed in a MBraun
1
31
13
glovebox containing dry Ar and less than 1 ppm oxygen. H, P, and C Nuclear Magnetic
Resonance (NMR) spectra were recorded on Bruker Avance 300 or Bruker Avance II 400
Ultrashield NMR spectrometers. Elemental analyses were performed at the London Metropolitan
University. Substrates 5, 7, 9, 11, 13, 15, 18, 21 and products 6, 8, 10, 12, 14, 16, 19, 20, 22 and 23
1-3
have previously been described in the literature.
2 3
Synthesis of [RuCl (IPr*)(PPh )(3-phenylindenylidene)](1):
In the glovebox, M10 (1.00 g, 1.13 mmol) and IPr* (914 mg, 1.2 mmol)) were charged to a
Schlenk flask and dissolved in toluene (3 mL). The reaction was taken out of the glovebox and
stirred at 40 °C for 10 h under Ar. After this time, the mixture was allowed to cool to RT and the
solvent was removed under vacuum. The remaining solid was recrystallised in a mixture of
dichloromethane / pentane. The mixture was filtered, washed with cold methanol (2 x 5 mL) and
cold hexane (8 x 25 mL), affording [RuCl
2
3
(IPr*)(PPh )(3-phenylindenylidene)] (1) (750 mg, 0.49
1
mmol, 44%) as a microcrystalline solid. H NMR (C
6
D
6
, 400MHz): δ = 8.13 (d, J=7.3 Hz, 1 H),
7
.67 - 8.00 (m, 7 H), 7.57 (t, J=7.8 Hz, 5 H), 6.55 - 7.42 (m, 60 H), 6.24 (s, 1 H), 6.03 (s, 1 H), 5.90
1
3
(
s, 1 H), 4.93 (s, 1 H), 4.51 (s, 1 H), 2.05 (s, 2 H), 1.77 (s, 3 H) ppm, C NMR (CD
δ = 301.02, 185.1, 183.8, 146.9, 146.7, 145.7, 145.2, 144.1, 141.0, 138.2, 135,8, 135.0, 134.8,
32.1, 131.6, 130.0, 129.3, 129.0, 128.6, 128.3, 128.1, 128.1, 126.5, 123.6, 116.7, 50.8, 50.4, 22.5,
2 2
Cl ,75MHz):

Formatted: Font: (Default) Symbol, 12 pt,
English (U.S.)
1
2
7
3
1
1.9, ppm, P NMR (162MHz, C
6
D
6
) = δ = 27.54 ppm Anal. Calcd for C103
H
85Cl
2
N
2
PRu C,
Formatted: Font: (Default) Symbol, 12 pt,
English (U.S.)
9.62; H, 5.51; N 1.80; Found: C, 79.77; H, 5.25; N, 1.73.
2
Synthesis of [RuCl (IPr*)(Py)(3-phenylindenylidene)](2):
In the glovebox, M10 (1.00 g, 1.13 mmol) and IPr* (914 mg, 1.2 mmol) were weighed to a
Schlenk flask and dissolved in toluene (3 mL), taken out of the glovebox, connected to a Schlenk

line and stirred at 40 °C for 10 h under Ar. Pyridine (0.45 mL) was then added by syringe, the
resulting solution was left stirring for 0.5 h, after which time pentane was added (35 mL) and the
reaction left stirring for another 0.5 h. The resulting suspension was then cooled to -40°C, filtered
and recrystalsed from dichloromethane/pentane. The mixture was filtered, washed with cold
2
methanol (1 x 10 mL) and cold hexane (3 x 10 mL) affording compound [RuCl (IPr*)(Py)(3-
1
phenylindenylidene)](2) (940 mg, 0.69 mmol, 73% yield). H NMR (CD
2
Cl
2
,400MHz):  δ = 8.12
Formatted: Font: (Default) Symbol, 12 pt,
English (U.S.)
(
d, J=7.2 Hz, 1 H), 7.85 (br. s., 2 H), 7.77 (d, J=5.1 Hz, 2 H), 6.42 - 7.57 (m, 60 H), 6.31 (br. s., 2
H), 6.09 - 6.19 (m, 1 H), 5.95 (s, 1 H), 5.72 - 5.86 (m, 1 H), 5.69 (s, 1 H), 4.97 - 5.01 (m, 1 H), 4.93
(
d, J=1.9 Hz, 1 H), 4.08 (d, J=1.7 Hz, 1 H), 2.24 (s, 3 H), 2.10 - 2.18 (m, 1 H), 1.22 ppm (s, 3 H)
1
3
C NMR (CD
2
Cl
2
,75MHz):  δ = 153.6, 146.3, 143.1, 142.7, 142.0, 140.7, 140.2, 140.0, 139.8,
Formatted: Font: (Default) Symbol, 12 pt,
English (U.S.)
1
1
37.3, 136.5, 135.6, 133.8, 131.7, 130.7, 130.0, 129.3, 128.6, 128.0, 126.8, 126.4, 126.2, 124.6,
24.5, 123.9, 118.1, 22.7, 22.0, 20.8 ppm Anal. Calcd for C89 Ru C, 78.86; H, 5.35; N 3.10;
H
2 3
71Cl N
Found: C, 78.81; H, 5.16; N, 3.05.
2 3
Synthesis of [RuCl (IPr)(PPh )(3-phenylindenylidene)](3):
In the glovebox, M10 (0.500 g, 0.56 mmol) and IPr (240 mg, 0.62 mmol) were charged to a
Schlenk flask and dissolved in toluene (3 mL). The reaction was taken out of the glovebox, stirred
at 40 °C for 4 h under Ar. After this time, the mixture was allowed to cool to RT and the solvent
removed under vacuum. The remaining solid and recrystallised in a mixture of dichloromethane /
pentane. The mixture was filtered, washed with cold methanol (2 x 5 mL) and cold hexane (8 x 25
mL), affording [RuCl
2
3
(IPr)(PPh )(3-phenylindenylidene)] (3) (410 mg, 0.41 mmol, 81%) as a
4
microcrystalline solid. Spectroscopic data for the product were in accordance with the literature.
Anal. Calcd for C61 PRu C, 71.19; H, 6.37; N, 2.72; Found: C, 71.52; H, 6.19; N, 2.62.
2 2
H65Cl N
2
Synthesis of [RuCl (IPr)(Py)(3-phenylindenylidene)](4):
In the glovebox, M10 (1.00 g, 1.13 mmol) and IPr (480 mg, 1.2 mmol) were weighed to a
Schlenk flask and dissolved in toluene (3 mL), taken out of the glovebox, connected to a Schlenk

line and stirred at 40 °C for 4 h under Ar. Pyridine (0.45 mL) was then added by syringe, the
resulting solution was left stirring for 0.5 h, after which time pentane was added (35 mL) and the
reaction left stirring for another 0.5 h. The resulting suspension was then cooled to -40°C. Filtration
and recrystalysation in dichloromethane/pentane. The mixture was filtered, washed with cold
methanol (1 x 10 mL) and cold hexane (3 x 10 mL) affording compound [RuCl
2
(IPr*)(Py)(3-
1
phenylindenylidene)](2) (630 mg, 0.76 mmol, 66% yield). H NMR (400 MHz, C
6
D
6
) δ ppm = 0.66
-
0.94 (m, 4 H) 1.00 - 1.39 (m, 6 H) 1.52 - 1.91 (m, 5 H) 2.80 - 2.97 (m, 1 H) 3.12 - 3.23 (m, 1 H)
3
6
.23 - 3.38 (m, 1 H) 4.63 - 4.81 (m, 1 H) 6.06 (t, J=6.92 Hz, 1 H) 6.31 - 6.42 (m, 2 H) 6.60 (s, 1 H)
.64 - 6.75 (m, 1 H) 6.87 - 6.95 (m, 2 H) 7.02 - 7.13 (m, 1 H) 7.32 - 7.45 (m, 2 H) 7.74 (d, J=7.52
1
3
Hz, 1 H) 8.19 (d, J=5.12 Hz, 1 H) 8.67 (d, J=7.217 Hz, 1 H) ppm C NMR (75 MHz, CD
2 2
Cl ) δ
ppm = 243.095, 25.202, 25.54-26.10, 26.545-26.91, 27.62, 28.94, 29.878, 30.106-30.72, 124.14,
1
1
276.096, 127.767, 128.44, 129.19, 129.52, 130.81-131.56, 132.42, 132.54, 132.60-132.73, 137.24,
37.40, 140.04, 141.20, 141.878, 142.21, 145.71, 153.325, 181.656, 300.765 ppm Anal. Calcd for
48 2 3
C H55Cl N Ru C, 68.15; H, 6.55; N, 4.97; Found: C, 67.68; H, 6.72; N, 5.04.
General procedure for RCM and Enyne reactions:
In a Radley carousel under argon or nitrogen, a reaction tube was charged with the substrate (0.25
mmol) and the solvent (2.5 mL) (CH
2
Cl
2
for reaction at RT and 40 °C, toluene for reactions at 80
1
°
C), then precatalyst (0.0025 mmol). The progress of the reaction was monitored by H NMR.
1
Conversion determined by H NMR spectroscopy by integrating the characteristic signals for allylic
proton resonances.
General procedure for CM reactions:
In a Radley carousel under argon or nitrogen, a reaction tube was charged with one equivalent of
the electron rich substrates (0.25 mmol) and two equivalents of the electron poor olefin (0.5 mmol)
solvent (2.5 mL), then precatalyst (0.0025 mmol). The progress of the reaction was monitored by
1
H NMR. At reaction completion solvent was removed under vacuum and the crude residue was

1
1
checked by H NMR. Conversion determined by H NMR spectroscopy by integrating the
characteristic signals for allylic proton resonances.
NMR data of [RuCl
2
(IPr*)(PPh
3
)(3-phenylindenylidene)] (1):
1
H NMR of complex 1 in C
6
6
D :
Ph
Ph
Ph
Ph
N
Ph
Cl
N
Ph
Ph
Ph
Cl
Ph
Ru
PPh
3
9.5
9.0
8.5
8.0
7.5
7.0
6.5
6.0
5.5
5.0
4.5
4.0
3.5
3.0
2.5
2.0 ppm
3
1
6 6
P NMR of complex 1 in C D :

Ph
Ph
Ph
Ph
N
Ph
Cl
N
Ph
Ph
Ph
Cl
Ph
Ru
PPh
3
120 110 100
90
80
70
60
50
40
30
20
10
0
-10 -20 -30 -40 -50 -60 ppm
1
3
1
C{ H}zz NMR of complex 1 in CD
2
Cl
2
Ph
Ph
Ph
Ph
N
Ph
Cl
N
Ph
Ph
Ph
Cl
Ph
Ru
PPh
3
320
300
280
260
240
220
200
180
160
140
120
100
ppm
NMR data of [RuCl
2
(IPr*)(Py)(3-phenylindenylidene)] (2):
1
H NMR of complex 1 2 in CD
2
Cl
2
:

Ph
Ph
Ph
Ph
N
Ph
Cl
N
Ph
Ph
Ph
Cl
Ph
Ru
N
8.5
8.0
7.5
7.0
6.5
6.0
5.5
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5 ppm
1
3
1
2 2
C{ H} NMR of complex 21 in CD Cl :
Ph
Ph
Ph
Ph
N
Ph
Cl
N
Ph
Ph
Ph
Cl
Ph
Ru
N
300
250
200
150
100
50
ppm
NMR data of [RuCl
2
(IPr)(PPh
3
)(3-phenylindenylidene)] (3):
1
H NMR of complex 1 3 in C D :
6
6

N
N
Cl
Ph
Ru
Cl
PPh
3
9
8
7
6
5
4
3
2
ppm
3
1
6 6
P NMR of complex 1 3 in C D :
N
N
Cl
Ph
Ru
Cl
PPh
3
120 110 100
90
80
70
60
50
40
30
20
10
0
-10 -20 -30 -40 -50
ppm
NMR data of [RuCl
H NMR of complex 1 4 in C
2
(IPr)(Py)(3-phenylindenylidene)] (4):
1
6
6
D :

N
N
Cl
Ph
Ru
N
Cl
9
8
7
6
5
4
3
2
1
ppm
1
3
1
6 6
C{ H} NMR of complex 1 4 in C D :
N
N
Cl
Ph
Ru
N
Cl
300
250
200
150
100
50
ppm

Formatted: Font: (Default) Times, 12 pt, Bold,
Spanish (Venezuela)
REFERENCES
Formatted: Spanish (Venezuela)
(
(
1)
2)
Clavier, H.; Nolan, S. P. Chem.—Eur. J. 2007, 13, 8029.
Rix, D.; Caijo, F.; Laurent, I.; Boeda, F.; Clavier, H.; Nolan, S. P.; Mauduit, M. J. Org. Chem. 2008,
Formatted: Spanish (Venezuela)
Field Code Changed
7
3, 4225.
(
(
3)
4)
Boeda, F.; Bantreil, X.; Clavier, H.; Nolan, S. P. Adv. Synth. Catal. 2008, 350, 2959.
Jafarpour, L.; Schanz, H.-J.; Stevens, E. D.; Nolan, S. P. Organometallics 1999, 18, 5416.