Access to 3-Methyl-4-methylene-N-tosylpyrrolidine and 3,4-Dimethyl-N-tosylpyrroline by Ruthenium-Catalyzed Cascade Cycloisomerization/Isomerization Reactions

Article abstract of DOI:10.1002/ejic.200300224

New RuCl₂(benzimidazole)(arene) complexes have been prepared. Upon reaction with 1,1-diphenylprop-2-ynol they generate catalyst precursors which perform the cycloisomerization of diallyltosylamide into 3-methyl-4-methylene-N-tosylpyrrolidine. T

Full text of DOI:10.1002/ejic.200300224

FULL PAPER
Access to 3-Methyl-4-methylene-N-tosylpyrrolidine and 3,4-Dimethyl-
N-tosylpyrroline by Ruthenium-Catalyzed Cascade Cycloisomerization/
Isomerization Reactions
[a]
[b]
[b]
[a]
[c]
´
Ismail Özdemir, Engin Cetinkaya, Bekir Cetinkaya,* Metin Cicek, David Semeril,
¸
¸
¸ ¸
Christian Bruneau,*[c] and Pierre H. Dixneuf[c]
Keywords: Ruthenium / Benzimidazole / Homogeneous catalysis / Olefination
New RuCl2(benzimidazole)(arene) complexes have been
prepared. Upon reaction with 1,1-diphenylprop-2-ynol they
generate catalyst precursors which perform the cycloiso-
merization of diallyltosylamide into 3-methyl-4-methylene-
N-tosylpyrrolidine. The presence of N-(2,4,6-trimethyl-
benzyl)benzimidazole as ligand leads to a subsequent iso-
merization and gives the 3,4-dimethyl-N-tosylpyrroline.
( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2004)
Introduction
the tetrasubstituted CϭC bond of 3,4-dimethylpyrrolidine
derivatives (Scheme 1).
Transition metal complexes with nitrogen-containing li-
gands have recently shown their potential to perform selec-
tive catalytic transformations of molecules with atom econ-
omy.[1] Especially, a variety of RuX2(arene)(L) complexes
promoting catalytic reactions such as nucleophilic addition
to triple bonds to form furans (L ϭ imidazoline, tetrahydro-
pyrimidine,[2] benzimidazole[3]), hydrogen transfer (L ϭ am-
ino acid,[4] amino alcohol,[5] diamine[6]), cyclopropanation
(L ϭ diamine[7]), or DielsϪAlder cycloaddition and Claisen
rearrangement [L ϭ bis(oxazoline)[8,9]]. It is also well estab-
lished that RuCl2(arene)(L) complexes can easily be trans-
formed by activation of propargylic alcohols into cationic
ruthenium(allenylidene) complexes, which have shown cata-
lytic properties in olefin metathesis.[10]
Scheme 1
Results and Discussion
The reaction of N-alkylbenzimidazoles 2Ϫ4 and the N-
(aralkyl)benzimidazole 5 with the dinuclear [RuCl2(p-cy-
mene)]2 (1a) and [RuCl2(hexamethylbenzene)]2 (1b) com-
We now report (i) the straightforward preparation of new
RuCl2(η6-arene)(L) complexes with an N-coordinated
benzimidazole ligand and (ii) their in situ transformation
into efficient catalyst precursors for cycloisomerization of
diallyltosylamide into 3-methy-4-methylene-N-tosylpyrroli-
dine followed, when a suitable benzimidazole is used (R ϭ
mesityl-CH2), by double bond isomerization to form a
pyrroline derivative. This study reveals a very efficient
ruthenium catalyst for isomerization of the exocyclic Cϭ
CH2 double bond of 3-methyl-4-methylenepyrrolidine into
[a]
Inönü Üniversitesi Fen-Edebiyat Fakültesi,
44069 Malatya, Turkey
[b]
Ege University, Department of Chemistry,
35100 Bornova-Izmir, Turkey
[c]
´
Institut de Chimie, UMR 6509: CNRS Ϫ Universite de Rennes,
´
Organometalliques et Catalyse,
Campus de Beaulieu, 35042 Rennes, France
Scheme 2
418
 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
DOI: 10.1002/ejic.200300224
Eur. J. Inorg. Chem. 2004, 418Ϫ422

3-Methyl-4-methylene-N-tosylpyrrolidine and 3,4-Dimethyl-N-tosylpyrroline
FULL PAPER
Table 1. Selected analytical data for the new (benzimidazole)ruthenium complexes (6)
Complex
Yield of isolated product
[%]
M.p.
[°C]
ν(CϪN)
13C NMR, C-2 signals
1H NMR, 2-H signals
δ [ppm]
[cmϪ1
]
δ [ppm] (1JC,H [Hz])
6a
6b
6c
6d
6e
6f
85
87
87
90
86
82
86
183.0
206.5
197.0
224.0
307.5
276.0
310.5
1506
1612
1616
1610
1612
1508
1612
142.96 (197.3)
144.52 (198.8)
145.54 (199.5)
144.18 (203.0)
145.08 (201.4)
146.18 (202.6)
144.81 (205.6)
8.44
8.34
8.22
7.92
8.12
7.97
7.70
6g
plexes proceeded smoothly in refluxing toluene to give the straction of chloride with silver triflate followed by addition
RuCl2(benzimidazole)(arene) complexes 6aϪg as crystalline of 1,1-diphenylprop-2-ynol at room temperature in the
solids in 82Ϫ90% yields (Scheme 2, Table 1).
selected solvent (Scheme 3).
Complexes 6aϪg, which are very stable in the solid state
The catalytic performances of these in situ generated pre-
have been characterized by analytical and spectroscopic cursors were evaluated in the transformation of N,N-dial-
techniques (Table 1). The IR data show the presence of a lyltosylamide (8) at 80 °C in various solvents (Scheme 4,
CϭN bond with a ν(CϭN) vibration at 1506Ϫ1616 cmϪ1
and the H NMR spectra clearly exhibit a singlet at δ ϭ
7.70Ϫ8.44 ppm typical of the NϭCHϪN fragment. In the
13C NMR spectrum, the chemical shift of the correspond-
,
Table 2).
1
ing C-2 atom was detected in the region
δ ϭ
142.96Ϫ146.18 ppm with a 1JC,H coupling constant close to
200 Hz. These new complexes show typical spectroscopic
signatures which are in line with those recently reported for
other RuCl2(arene)(benzimidazole) complexes with R ϭ
Me, Et, (CH2)2NEt2, (CH2)2CO2Et.[3]
Scheme 4
Table 2. Catalytic transformation of N,N-diallyltosylamide (8)
Catalyst Solvent Time [h] Conversion [%] 9 [%] 10 [%]
In contrast with the related (arene)RuCl2(phosphane),[11]
(arene)RuCl2(diaminocarbene) complexes,[12,13a]
6
pre-
sented no metathesis catalytic activity for the transform-
ation of N,N-diallyltosylamide (8). The known catalytic ac-
7a
7b
7b
7c
7c
7d
7d
7d
7d
7e
7f
PhCl
PhMe
PhCl
PhMe
PhCl
PhMe
PhMe
PhCl
PhCl
PhCl
PhMe
PhCl
PhCl
18
13
10
12
10
4
10
6
10
18
10
20
20
100
76
100
37
100
76
100
37
82
100
tivities of [RuCl(ϭCϭCϭCPh2)(arene)(L)][X] (L
ϭ
PCy3,[10] diaminocarbene[13]) to perform the ring-closing
metathesis of dienes and ring-opening metathesis polymer-
ization of cyclic olefins, provided impetus to prepare the
corresponding cationic ruthenium(allenylidene)(benzimida-
zole) complexes according to the reaction depicted in
Scheme 3. Indeed, purple complexes were prepared in di-
chloromethane but they were not stable enough to be cle-
anly isolated and characterized. Based on previous results
obtained with more stable ruthenium(allenylidene) com-
plexes from analogous precursors,[10,13] we assumed that the
new organometallic species 7aϪg (Scheme 3) contained the
[RuCl(arene)(benzimidazole)(allenylidene)]ϩ cation. In or-
der to circumvent this instability problem, they were gener-
ated in situ from complexes 6aϪg just before use, by ab-
82
100
100
98
100
65
58
100
79
100
38
100
60
65
58
100
40
7f
7g
39
Thus, the catalyst was first generated by successive ad-
ditions of silver triflate (0.0125 mmol) and HCϵCCPh2OH
(0.0125 mmol) to a solution of 6 (0.0125 mmol, 2.5 mol %)
in 2.5 mL of solvent and stirred at room temperature for
20 min. The diene 8 (0.5 mmol) was then added and the
solution was heated at 80 °C for 4Ϫ20 h. The catalytic pre-
cursors thus prepared in situ showed catalytic activity for
the transformation of the 1,6-diene 8 into the cycloisomeriz-
ation compounds 9 or 10. According to this procedure, the
presence of the diene 8 added just after the preparation of
7 might stabilize organometallic intermediates and generate
catalyst precursors with long-lasting activity.
In contrast with the catalyst arising from the allenylidene
Scheme 3
complex [RuCl(ϭCϭCϭCPh2)(PCy3)(p-cymene)][OTf],[10]
Eur. J. Inorg. Chem. 2004, 418Ϫ422
www.eurjic.org
 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
419

B. C¸ etinkaya, C. Bruneau et al.
FULL PAPER
no trace of N-tosyl-2,5-dihydropyrrole was detected, which and H migration via an (allyl)(hydrido)ruthenium inter-
indicated that no metathesis reaction took place with pre- mediate A or (ii) if a RuϪH species is formed, by insertion
cursors 7.
of the exocyclic double bond into a RuϪH bond followed
The catalysts resulting from 6aϪc and 6eϪf, which bear by β-elimination (Scheme 5). Both processes should be ster-
an aliphatic R group as substituent of the benzimidazole eoselective as the coordination of the Ru atom should pref-
ligand led to the formation of the 3-methyl-4-methylene het- erentially take place on the less hindered face of 9. Thus, β-
erocycle 9. The reaction was faster in chlorobenzene than elimination from B should be favored with Ha in the syn
in toluene and the total conversion of the starting substrate position, as well as the (allyl)ruthenium formation by coor-
could be achieved in 10 h with the precatalyst 7b and within dination to 9 on the sterically less hindered face.
18Ϫ20 h with 7a and 7f.
Transition-metal-catalyzed cycloisomerization reactions
The catalytic species generated from 7d containing the N- from α,ω-dienes is a topic of current interest.[17] The forma-
(2,4,6-trimethylbenzyl)-substituted benzimidazole ligand 5 tion of 3-methyl-4-methylene cyclic derivatives of type 9 has
was much more efficient and the complete conversion of 8 already been observed with several metal catalysts including
to 9 was carried out in toluene in less than 4 h. Under the palladium,[18,19] nickel,[19] rhodium[20] and titanium.[21]
reaction conditions, a subsequent isomerization took place Other efficient catalytic systems based on ruthenium pre-
which led to 3,4-dimethyl-N-tosylpyrroline (10) bearing a cursors such as [Ru(cod)Cl2]n or Cp*Ru(cod)Cl in protic
tetrasubstituted endocyclic double bond in quantitative solvents,[22] or generated in situ from [RuCl2(p-cymene)]2,
yield at 80 °C after 10 h, whatever the solvent. Apparently, an imidazolinium salt and a base,[15] have been reported.
in toluene, as the formation of 10 starts only after complete
A few examples of cycloisomerization of 1,6-diene into
conversion of 8, the presence of the starting diene inhibits 1,2-dimethylcyclopentene derivatives involve palladium
the isomerization of 9 to 10. The analogous catalytic system catalysts in the presence of silane[23] or rhodium cata-
7g resulting from the C6Me6-containing precursor was less lysts,[20] and most of the substrates which lead to these
active at 80 °C after 20 h, as the conversion reached only cycloisomerization products are 2,2-diallylmalonate deriva-
79 % and a 1:1 mixture of 9 and 10 was obtained. This tives. In the present ruthenium-catalyzed isomerization of 8
observation is consistent with the hypothesis of the initial to 10, the role of the 2,4,6-trimethylbenzyl ligand in 7d
displacement of the arene ligand to generate the catalytic appears to be crucial. It might result from temporary inter-
species (Scheme 5).[13b,14,15] During the catalytic process, the action of the mesityl group with the metal center as its
formation of indenylidene complexes by rearrangement of coordination operates with closely related diaminocarbene
the allenylidene ligand, cannot be ruled out.[16]
ligands.[13b,14]
Conclusion
New ruthenium species generated in situ from RuCl2(ar-
ene)(benzimidazole) complexes in the presence of 1,1-di-
phenylprop-2-ynol are active catalysts to perform the cyclo-
isomerization of N,N-diallyltosylamide to the N-tosylpyrro-
lidine 9 featuring an exocyclic methylene group under neu-
tral and mild conditions. The catalyst containing the
benzimidazole 5 (R ϭ 2,4,6-Me3C6H2CH2) exhibits specific
catalytic properties. It leads to the fastest cycloisomeriz-
ation reaction and in addition offers the first example of
ruthenium-catalyzed isomerization of 3-methyl-4-methyl-
ene-N-tosylpyrrolidine (9) to 3,4-dimethyl-N-tosylpyrroline
(10).
Experimental Section
Scheme 5
General: Manipulations were carried out with standard Schlenk
techniques under nitrogen with previously dried solvents. The com-
plexes [RuCl2(arene)]2 were prepared according to known meth-
ods.[24] 1-Substituted benzimidazoles 2Ϫ5 were prepared by alky-
lation of the potassium salt of benzimidazole. Infrared spectra were
recorded as KBr pellets in the range 400Ϫ4000 cmϪ1 with an ATI
UNICAM 2000 spectrometer. 1H NMR (300 MHz) and 13C NMR
(75.5 MHz) were recorded with a Bruker AM 300 WB FT spec-
trometer with chemical shifts referenced to residual solvent CDCl3.
From a separate experiment, it was possible to show that
10 resulted from the catalytic isomerization of 9 in the pres-
ence of 7d as catalyst. Thus, by using the catalytic system
prepared in situ from 2.5 mol % of the ruthenium precursor
6d, AgOTf (2.5 mol %) and HCϵCCPh2OH (2.5 mol %) in
2.5 mL of toluene, 9 (0.5 mmol) was completely converted
into 10 at 80 °C after 4 h. Two possible mechanisms could
account for this isomerization: (i) allylic CϪH activation Microanalyses were performed by the TÜBITAK analyses centre.
420  2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim www.eurjic.org
Eur. J. Inorg. Chem. 2004, 418Ϫ422

3-Methyl-4-methylene-N-tosylpyrrolidine and 3,4-Dimethyl-N-tosylpyrroline
FULL PAPER
Preparation of the Ruthenium(benzimidazole) Complexes 6aϪg: A
[(CH3)2CHC6H4CH3], 21.1, 19.8 [(CH3)3C6H2CH2], 18.5
solution of the N-substituted benzimidazole 2Ϫ5 (1.05 mmol) and [(CH3)2CHC6H4CH3] ppm. Yield 0.5 g (90%). C27H32Cl2N2Ru
[RuCl2(p-cymene)]2 or [RuCl2(hexamethylbenzene)]2 (0.5 mmol) in
toluene (15 mL) were heated under reflux for 2 h. Upon cooling
to room temperature, orange crystals of 6aϪg were obtained. The
crystals were filtered, washes with diethyl ether (3 ϫ 10 mL) and
dried under vacuum.
(556.54): calcd. C 58.27, H 5.80, N 5.04; found C 58.32, H 5.86,
N 5.21.
RuCl2(hexamethylbenzene)(N-butylbenzimidazole) (6e): 1H NMR
(300 MHz, CDCl3): δ ϭ 8.12 (s, 1 H, NϭCH), 7.80Ϫ7.21 (m, 4 H,
C6H4), 3.99 (t, J ϭ 7.20 Hz, 2 H, CH2CH2CH2CH3), 1.96 [s, 18 H,
C6(CH3)6], 1.67 (m, 2 H, CH2CH2CH2CH3), 1.25 (m, 2 H,
CH2CH2CH2CH3), 0.87 (t, J ϭ 7.38 Hz, 3 H, CH2CH2CH2CH3)
ppm. 13C NMR (75.5 MHz, CDCl3): δ ϭ 145.1 (NϭCH), 133.7,
128.2, 123.8, 121.2, 110.6 (C6H4), 90.9 [C6(CH3)6], 45.5
RuCl2(p-cymene)(N-isopropylbenzimidazole) (6a): 1H NMR
(300 MHz, CDCl3): δ ϭ 8.44 (s, 1 H, NϭCH), 7.33 (m, 4 H, C6H4),
5.42 and 5.32 [2 ϫ d, J ϭ 6.00 Hz, 4 H, (CH3)2CHC6H4CH3], 4.58
[sept, J ϭ 6.70 Hz, 1 H, CH(CH3)2], 2.06 [s, 3 H, (CH3)2-
CHC6H4CH3], 1.83 [sept, J ϭ 7.00 Hz, 1 H, (CH3)2CHC6H4CH3],
1.49 [d, J ϭ 6.70 Hz, 6 H, CH(CH3)2], 1.18 [d, J ϭ 7.00 Hz, 6 H,
(CH3)2CHC6H4CH3] ppm. 13C NMR (75.5 MHz, CDCl3): δ ϭ
142.9 (NϭCH), 142.2, 133.2, 123.8, 123.5, 120.7, 111.5 (m, C6H4),
102.4, 97.9, 82.8, 81.2 [(CH3)2CHC6H4CH3], 49.0 [CH(CH3)2], 30.7
(CH2CH2CH2CH3),
31.7
(CH2CH2CH2CH3),
20.1
(CH2CH2CH2CH3), 15.8 [C6(CH3)6], 13.6 (CH2CH2CH2CH3)
ppm. Yield 0.44 g (86%). C23H32Cl2N2Ru (508.49): calcd. C 54.33,
H 6.34, N 5.51; found C 54.58, H 6.19, N 5.73.
[(CH3)2CHC6H4CH3],
22.5
[CH(CH3)2],
22.3
RuCl2(hexamethylbenzene)[N-(2-methoxyethyl)benzimidazole] (6f):
1H NMR (300 MHz, CDCl3): δ ϭ 7.97 (s, 1 H, NϭCH), 7.20Ϫ7.90
(m, 4 H, C6H4), 3.85 (t, J ϭ 5.00 Hz, 2 H, CH2CH2OCH3), 3.41
[(CH3)2CHC6H4CH3], 18.5 [(CH3)2CHC6H4CH3] ppm. Yield
0.39 g (85%). C20H26Cl2N2Ru (466.42): calcd. C 51.50, H 5.62, N
6.01; found C 51.40, H 5.71, N 6.10.
(t,
J ϭ 5.09 Hz, 2 H, CH2CH2OCH3), 3.12 (s, 3 H,
CH2CH2OCH3), 1.94 [s, 18 H, C6(CH3)6] ppm. 13C NMR
(75.5 MHz, CDCl3): δ ϭ 146.2 (NϭCH), 140.5, 133.2, 123.8, 122.4,
120.7, 111.2 (C6H4), 90.9 [C6(CH3)6], 69.8 (CH2CH2OCH3), 58.6
(CH2CH2OCH3), 45.3 (CH2CH2OCH3), 15.7 [C6(CH3)6] ppm.
Yield 0.42 g (82%). C22H30Cl2N2ORu (510.47): calcd. C 51.76, H
5.92, N 5.49; found C 51.70, H 5.83, N 5.67.
1
RuCl2(p-cymene)(N-butylbenzimidazole) (6b): H NMR (300 MHz,
CDCl3): δ ϭ 8.34 (s, 1 H, NϭCH), 7.95Ϫ7.27 (m, 4 H, C6H4), 5.47
and 5.32 [2 ϫ d, J ϭ 5.96 Hz, 4 H, (CH3)2CHC6H4CH3], 3.98 (t,
J ϭ 7.21 Hz, 2 H, CH2CH2CH2CH3), 2.77 [sept, J ϭ 6.89 Hz, 1
H, (CH3)2CHC6H4CH3], 2.05 [s, 3 H, (CH3)2CHC6H4CH3], 1.72
(m, 2 H, CH2CH2CH2CH3), 1.26 (m, 2 H, CH2CH2CH2CH3), 1.21
[d, J ϭ 4.82 Hz, 6 H, (CH3)2CHC6H4CH3], 0.86 (t, J ϭ 7.38 Hz, 3
H, CH2CH2CH2CH3) ppm. 13C NMR (75.5 MHz, CDCl3): δ ϭ
144.5 (NϭCH), 142.5, 133.7, 124.0, 123.4, 120.5, 110.9, (C6H4),
102.4, 97.8, 82.9, 81.1[(CH3)2CHC6H4CH3], 45.7 (CH2CH2-
CH2CH3), 31.6 (CH2CH2CH2CH3), 30.7 [(CH3)2CHC6H4CH3],
22.3 [(CH3)2CHC6H4CH3], 19.9 (CH2CH2CH2CH3), 20.0
[(CH3)2CHC6H4CH3], 13.6 (CH2CH2CH2CH3) ppm. Yield 0.42 g
(87%). C21H28Cl2N2Ru (480.45): calcd. C 52.50, H 5.87, N 5.83;
found C 52.43, H 6.01, N 5.96.
RuCl2(hexamethylbenzene)[N-(2,4,6-trimethylbenzyl)benzimidazole]
(6g): 1H NMR (300 MHz, CDCl3): δ ϭ 7.70 (s, 1 H, NϭCH),
8.05Ϫ7.26 (m, 4 H, C6H4), 6.95 [s, 2 H, (CH3)3C6H2CH2], 5.21 [s,
2 H, (CH3)3C6H2CH2], 2.31, 2.23 [s, 9 H, (CH3)3C6H2CH2], 1.87
[s, 18 H, C6(CH3)6] ppm. 13C NMR (75.5 MHz, CDCl3): δ ϭ 141.8
(NϭCH), 141.2, 134.1, 123.9, 123.0, 121.0, 110.3 (C6H4), 139.1,
137.3, 129.7, 126.9 [(CH3)3C6H2CH2], 90.7 [C6(CH3)6], 43.7
[(CH3)3C6H2CH2], 21.1, 19.8 [(CH3)3C6H2CH2], 15.6 [C6(CH3)6]
ppm. Yield 0.50 g (86%). C29H36Cl2N2Ru (584.60): calcd. C 59.58,
H 6.21, N 4.79; found C 59.37, H 6.26, N 4.93.
RuCl2(p-cymene)[N-(2-methoxyethyl)benzimidazole] (6c): 1H NMR
(300 MHz, CDCl3): δ ϭ 8.22 (s, 1 H, NϭCH), 7.94Ϫ7.26 (m, 4 H,
C6H4), 5.47 and 5.31 [2 ϫ d, J ϭ 6.00 Hz, 4 H, (CH3)2-
CHC6H4CH3)], 3.92 (t, J ϭ 5.00 Hz, 2 H, CH2CH2OCH3), 3.47 (t,
J ϭ 5.10 Hz, 2 H, CH2CH2OCH3), 3.16 (s, 3 H, CH2CH2OCH3),
2.78 [sept, J ϭ 6.90 Hz, 1 H, (CH3)2CHC6H4CH3], 2.38 [d, J ϭ
Compounds 9[15a] and 10[25] were separated by GCMS chromatog-
raphy and identified by 1H NMR and compared with data from
the literature.
3-Methyl-4-methylene-N-tosylpyrrolidine (9): 1H NMR (200 MHz,
CDCl3): δ ϭ 7.68 (d, J ϭ 8.1 Hz, 2 H, arom. CH), 7.30 (d, J ϭ
8.1 Hz, 2 H, arom. CH), 4.93 (dm, J ϭ 1.6 Hz, 1 H, CϭCHH),
4.88 (dm, J ϭ 1.6 Hz, 1 H, CϭCHH), 3.93 (dm, J ϭ 14.1 Hz, 1 H,
CH2Cϭ), 3.71 (dm, J ϭ 14.1 Hz, 1 H, CH2Cϭ), 3.35Ϫ3.65 (m, 1
H, CHMe), 2.66 (m, 2 H, NCH2CH), 2.41 (s, 3 H, CH3Ar), 1.01
(d, J ϭ 6.3 Hz, 3 H, CHMe) ppm. 13C NMR (75.5 MHz, CDCl3):
δ ϭ 149.3, 143.7, 137.1, 129.7, 127.8, 106.1, 55.1, 52.2, 37.5, 21.6,
16.1 ppm.
6.90 Hz,
6
H, (CH3)2CHC6H4CH3)], 2.03 [s,
3
H,
(CH3)2CHC6H4CH3)] ppm. 13C NMR (75.5 MHz, CDCl3): δ ϭ
145.5 (NϭCH), 142.2, 133.4, 124.1, 123.2, 120.2, 111.3 (C6H4),
102.5,
97.8,
82.9,
81.2
[(CH3)2CHC6H4CH3)],
69.9
(CH2CH2OCH3), 58.7 (CH2CH2OCH3), 45.6 (CH2CH2OCH3),
30.6 [(CH3)2CHC6H4CH3], 21.9 [(CH3)2CHC6H4CH3)], 18.4
[(CH3)2CHC6H4CH3)] ppm. Yield 0.42 (87%). C20H26Cl2N2ORu
(482.42): calcd. C 49.80, H 5.43, N 5.81; found C 49.97, H 5.55,
N 6.03.
3,4-Dimethyl-N-tosylpyrroline (10): 1H NMR (200 MHz, CDCl3):
δ ϭ 7.36 (m, 4 H, arom. CH), 4.04 (s, 4 H, 2 ϫ CH2), 2.48 (s, 3
H, CH3Ar),1.60 (s, 6 H, 2 ϫ CH3Cϭ) ppm. 13C NMR (75.5 MHz,
CDCl3): δ ϭ 143.7, 134.6, 130.2, 128.2, 127.3, 126.6, 66.3, 21.9,
11.6 ppm.
RuCl2(p-cymene)[N-(2,4,6-trimethylbenzyl)benzimidazole] (6d): 1H
NMR (300 MHz, CDCl3): δ ϭ 7.92 (s, 1 H, NϭCH), 7.99Ϫ7.20
(m, 4 H, C6H4), 6.85 [s, 2 H, (CH3)3C6H2CH2], 5.29 and 5.20 [2 ϫ
d, J ϭ 5.75 Hz, 4 H, (CH3)2CHC6H4CH3], 5.14 [s, 2 H, (CH3)3-
C6H2CH2], 2.54 [sept, J ϭ 6.90 Hz, 1 H, (CH3)2CHC6H4CH3], 2.26
[s,
3 H, (CH3)2CHC6H4CH3), 2.13, 2.23 [s, 9 H, 2,4,6-
(CH3)3C6H2CH2], 1.01 [d, J ϭ 6.90 Hz, 6 H, (CH3)2CHC6H4CH3]
ppm. 13C NMR (75.5 MHz, CDCl3): δ ϭ 144.2 (NϭCH), 142.5,
133.7, 124.0, 123.4, 120.5, 110.9 (C6H4), 139.1, 137.8, 129.9, 126.7
[(CH3)3C6H2CH2], 101.9, 98.1, 83.0, 80.9 [(CH3)2CHC6H4CH3],
Acknowledgments
The authors are grateful to the EU COST Chemistry programme
43.9 [(CH3)3C6H2CH2], 30.6 [(CH3)2CHC6H4CH3], 24.1 (D17/0003/00) and TUBITAK (MISAG-COST-D17) for support.
Eur. J. Inorg. Chem. 2004, 418Ϫ422
www.eurjic.org  2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim 421

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Published Online October 30, 2003
422
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