New efficient ruthenium metathesis catalyst containing chromenyl ligand

Article abstract of DOI:10.1016/j.jorganchem.2010.02.025

A synthesis of new Hoveyda-Grubbs-type catalyst with chromenyl ligand was described herein. The new catalyst was tested in model RCM and CM reactions. The catalyst proved to be quite efficient. It showed activity comparable or superior to that of commercially available Grubbs second-generation complexes.

Full text of DOI:10.1016/j.jorganchem.2010.02.025

Journal of Organometallic Chemistry 695 (2010) 1265–1270
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
New efficient ruthenium metathesis catalyst containing chromenyl ligand
*
Agnieszka Hryniewicka, Jacek W. Morzycki, Stanisław Witkowski
Institute of Chemistry, University of Białystok, Al. Piłsudskiego 11/4, 15-443 Białystok, Poland
a r t i c l e i n f o
a b s t r a c t
Article history:
A synthesis of new Hoveyda–Grubbs-type catalyst with chromenyl ligand was described herein. The new
catalyst was tested in model RCM and CM reactions. The catalyst proved to be quite efficient. It showed
activity comparable or superior to that of commercially available Grubbs second-generation complexes.
Ó 2010 Elsevier B.V. All rights reserved.
Received 20 November 2009
Received in revised form 11 February 2010
Accepted 22 February 2010
Available online 24 February 2010
Keywords:
Olefin metathesis
Catalyst
Ruthenium
Methylidene complexes
Chroman derivatives
1. Introduction
to design a new Hoveyda–Grubbs-type catalyst, in which the com-
plexing O-isopropoxy fragment is replaced by the etheral oxygen of
The development of well-defined ruthenium alkylidene cata-
lysts (1–3) (Fig. 1) has made olefin metathesis an important and
reliable method for construction of carbon–carbon double bonds
[1,2]. The phosphine-free second-generation Hoveyda–Grubbs-
type catalysts (e.g. 3) have received considerable attention because
of their tolerance to moisture, oxygen, and a large number of or-
ganic functional groups. They show an ease of storage and may
be recovered from the reaction mixture and reused. The structure
of benzylidene moiety exerts a strong influence on reactivity pat-
tern of the ruthenium carbene complexes. It has been found that
these catalysts can be significantly improved by steric or electronic
factors. The experience from vitamin E chemistry prompted us to
introduce a ligand containing 2H-chromenyl fragment. However,
some bicyclic ligands bearing oxygen atom (benzofuran and chro-
man) have been already investigated, e.g. in the catalyst 7 (Fig. 1)
[3,4]. These structures, structurally related to vitamin E, reveal
some specific stereoelectronic effects. The 2p-lone pair electrons
of the oxygen atom in heterocyclic ring adopts an orientation
approximately perpendicular to the plane of the aromatic ring
2H-chromenyl ring. In the catalyst a ruthenium center would coor-
dinate to the heterocyclic oxygen, and the benzylidene fragment
would stiffen this side of complex. The chelating part functions
as a mesomeric donor for a through-bond p-conjugation with the
carbene moiety. The reactivity of the ruthenafuran ring can be af-
fected to some extent by aromatic stabilization. According to the
recently formulated hypothesis [8] the metallacycle in Hoveyda–
Grubbs-type catalysts shows some aromatic character, which
inhibits catalytic activity. For such aromaticity the complexing
oxygen atom should assume the planar hybridization (i.e. sp2)
and be conjugated with the aromatic ring [8]. However, if the oxy-
gen atom is a part of an adjacent non-aromatic ring, it has less free-
dom and may not fulfill this prerequisite. For this reason a
synthesis of catalysts containing chelating ligands with chroman,
benzofuran or benzodioxol moiety was attempted.
2. Results and discussion
and interact with the aromatic
p
-electron system [5,6].
In continuation of our project concerning the synthesis of new
Hoveyda–Grubbs-type catalysts we decided to substitute the
ortho-isopropoxybenzylidene ligand with a chromanyl or benzof-
uranyl moiety. In the previously described catalysts 4–6 the chelat-
ing oxygen atom derived from an isopropoxyl substituent [7],
while in the present approach a new complex was designed with
reversed chromenyl ligand (e.g. 8). In the complex the central
ruthenium atom is chelated by the ring oxygen atom. Due to spe-
cific orientation of 2p-lone pair electrons such complex may reveal
some new attributes (Fig. 2).
We have recently synthesized ruthenium complexes with
chromanylmethylidene ligands (4–6) [7] (Fig. 1) which promote
ring-closing metathesis very slowly, and might potentially serve
as a latent olefin metathesis catalyst (e.g. in polymerization). The
above-mentioned feature of the chromanyl moiety prompted us
* Corresponding author. Tel.: +48 85 7457586, fax: +48 85 7457581.
E-mail addresses: wit@uwb.edu.pl, staniwit@wp.pl (S. Witkowski).
0022-328X/$ - see front matter Ó 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2010.02.025

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A. Hryniewicka et al. / Journal of Organometallic Chemistry 695 (2010) 1265–1270
N
N
N
PCy3
Ru
Mes
N
Mes
Mes
Ph
Mes
Cl
Cl
Cl
Cl
Cl
Cl
Ru
O
Ru
Ph
PCy3
PCy3
1
2
3
N
N
Mes
Mes
N
N
Mes
Mes
N
N
Mes
Mes
Cl
Cl
Cl
Cl
Ru
Cl
Cl
4
Ru
O
3
5
Ru
O
6
O
2
R
O
7
O
8
4: R = C16H33
5: R = CH3
6
7
Fig. 1. Selected ruthenium metathesis catalysts. Mes – 2,4,6-trimethylphenyl.
HO
O
O
O
H3COOC
a
O
8
9
10
CHO
Fig. 2. Ligands for new Hoveyda–Grubbs-type catalysts.
O
HO
HO
b
c, d
The synthesis of two other ligands: methyl 5-methyl-7-vinyl-
benzofuran-2-carboxylate (9) and 4-vinyl-1,3-benzodioxol (10)
was also carried out. In these structures the five-membered oxy-
gen-containing heterocyclic ring is less puckered and more rigid,
compared to the chroman system [5].
OHC
8
e, f, g
HO
2.1. Synthesis of ligands and catalysts
O
h
H3COOC
The ligand 8 (6-methyl-8-vinyl-2H-chrom-3-ene) was synthe-
sized in four steps (Scheme 1). p-Cresol (chosen in order to avoid
substitution in p-position) was doubly formylated using Duff
method [9], followed by Wittig methylenation afforded 4-
methyl-2,6-divinylphenol. Etherification with allyl bromide, fol-
lowed by ring-closing metathesis with Grubbs first-generation
complex (1) yielded chromene 8 (overall yield 58%).
The ligand 9 (methyl 5-methyl-7-vinylbenzofuran-2-carboxyl-
ate) was obtained from 2-hydroxy-5-methyl-1,3-benzenedicar-
boxaldehyde in four steps. Monoprotection of the dialdehyde as
dimethylacetal, followed by Wittig methylenation, and finally con-
densation with methyl chloroacetate [10] afforded benzofuran 9
(Scheme 1).
The benzodioxol 10 was synthesized in two steps from com-
mercially available 2,3-dihydroxybenzaldehyde by methylenation
of ortho-dihydroxyl groups, followed by Wittig reaction
(Scheme 2).
The new catalyst 11 was synthesized by an exchange with the
Grubbs second-generation complex (2) [11,12] (Fig. 3). The styrene
8 was heated with the catalyst 2 in dichloromethane in the pres-
ence of CuCl to give the catalyst 11 in 57% yield as a green sub-
OHC
9
Scheme 1. Synthesis of ligands 8 and 9. Reagents and conditions: (a) hexamethy-
lenetetramine, TFA, reflux 24 h, 70%; (b) Ph3CH3P+Brꢀ, BuLi, THF, 90%; (c) allyl
bromide, K2CO3, 18-C-6, acetone, 1 h, 98%; (d) 1 mol% 1, CH2Cl2, reflux, 3 h, 95%;
(e) 2,2-dimethoxypropane, PTSA, MeOH, reflux, 1 h, 52%; (f) Ph3CH3P+Brꢀ, BuLi, THF,
90%; (g) NH4Cl, MeOH, 50 °C, 1 h, 100%; (h) ClCH2COOCH3, K2CO3, TBAB, 36%.
CHO
CHO
OH
O
O
O
O
a
b
OH
10
Scheme 2. Synthesis of ligand 10. Reagents and conditions: (a) CH2Cl2, NaH, HMPA,
10 h, 45%; (b) Ph3CH3P+Brꢀ, BuLi, THF, 80%.

A. Hryniewicka et al. / Journal of Organometallic Chemistry 695 (2010) 1265–1270
1267
malonate (14), diethyl 2-allyl-2-methallylmalonate (15), and
diethyl dimethallylmalonate (16) were chosen. The reactions led
to the cyclic products: 17, 18, and 19, bearing di-, tri- and tetrasub-
stituted double bonds, respectively (Table 1).
N
N
Mes
Mes
Cl
Cl
Ru
O
The catalyst 11 was compared with catalyst 2 and Hoveyda–
Grubbs second-generation catalyst (3). The results showed that
11 is the most effective in RCM for diallylmalonate 14 (entry 3;
100% conversion after 45 min), whereas the catalyst 3 yielded com-
plete conversion after 60 min (entry 2) and catalyst 2 after 75 min
(entry 1). It should be mentioned, that our results are similar to
those, obtained for commercially available catalysts: 2 and 3, re-
ported by Ritter et al. [13]. It should be emphasized that the results
collected in Table 1 show that the catalyst 11 reveals activity com-
parable to that of commercial catalysts: 2 and 3. The catalyst 11
proved to be active in RCM reactions leading to tetrasubstituted al-
kenes (entry 9, Table 1), but it is less efficient than catalyst 2 (entry
7).
N
N
H3COOC
Mes
Mes
Cl
Cl
Ru
O
12 (not formed)
N
N
Mes
Mes
11
Cl
Cl
Ru
O
The easily available and not too volatile olefinic substrates for
cross-metathesis reactions were chosen: 20, 21, 22 and 23. Three
CM reactions of allyl-decyl ether (21) were tested: with allyl-cyclo-
hexyl ether (22), but-3-enyl benzoate (23) and ethyl acrylate (20).
The products (24, 25, 26, respectively) were isolated by flash chro-
matography, and analyzed by 1H NMR. The E/Z ratio was deter-
mined by 1H NMR (Table 2). The catalyst 11 appeared to be very
active in these cross-metathesis reactions, in some cases even
superior to the commercially available catalysts. As it could be ex-
pected, the catalyst 11 promotes reaction between deactivated 20
and activated 21 olefins to afford exclusively the product 26 of E
configuration (entry 3, Table 2). In addition to the CM products
24, 25 and 26 the homometathesis product deriving from 21 was
also formed in all reactions in varying amounts. The homometath-
esis products of 22 (entries 1–4, Table 2) and 23 (entries 5–8) were
also obtained in minor amounts.
O
13 (not formed)
Fig. 3. New catalysts.
stance, which proved to be air-stable and could be easily purified
by a standard silica-gel column chromatography. The 1H NMR
spectrum for 11 showed the alkylidene proton signal (H-8b) at
16.44 ppm. This value seems to be characteristic for the active
Hoveyda-type catalysts as reported by Barbasiewicz et al. [8].
Unfortunately, the synthesis of catalysts 12 and 13 proved
unsuccessful. The exchange of ligands 9 and 10 with the catalyst
2 failed. The expected structures were not formed due to weak
coordination to the oxygen ligand. The styrene moiety exchange
in these systems was probably hampered due to the improper dis-
tance between chelating oxygen atom and the ruthenium center.
The similar observation was made by Barbasiewicz et al. for ben-
zofuranyl system [4].
3. Conclusions
In summary, syntheses of ligands: 8, 9 and 10 for construction
of the new Hoveyda–Grubbs-type catalysts have been described.
The oxygen atom coordinating to the metallic center was incorpo-
rated into 5- or 6-membered heterocyclic ring (benzofuran, ben-
zodioxol and 2H-chromene). The corresponding styrenes were
subjected to ligand exchange reaction with catalyst 2. However,
only chromenyl ligand 8 was successfully converted to the new
Hoveyda–Grubbs-type catalyst 11. The new catalyst 11 was tested
in model RCM and CM reactions. The catalyst proved to be quite
efficient. It showed activity comparable or superior to that of com-
mercially available Grubbs second-generation (2) and Hoveyda–
Grubbs second-generation (3) complexes.
2.2. Testing of the new catalyst 11
The catalyst 11 was tested in standard RCM (Table 1) and CM
(Table 2) reactions [10]. For investigation of the relative activity
of different catalysts in RCM, the model reactions of diethyl diallyl-
Table 1
Results of ring-closing metathesis reactions promoted by 2, 3 or 11a.
Entry Substrate
Product
Catalyst Time
Yieldb (%)
75 min >99
60 min >99
1
2
3
EtOOC
EtOOC
COOEt
2
3
COOEt
11
45 min >99
4. Experimental
17
14
15
16
4.1. General remarks
4
5
6
EtOOC
EtOOC
EtOOC
EtOOC
COOEt
COOEt
2
3
11
90 min 63
90 min 80
90 min 68
COOEt
COOEt
All manipulations of organometallic compounds were per-
formed using standard Schlenk techniques under an atmosphere
of dry argon. CH2Cl2 was dried by distillation over CaH2, trifluoro-
acetic acid over P2O5, THF over Na/benzophenone. 1H and 13C NMR
18
19
7
8
9
2
3
11
16 h
16 h
16 h
38
15
18
spectra were recorded on
a Bruker spectrometer (400 and
100 MHz, respectively). Spectra are referenced relative to the
chemical shift (d) of TMS. Mass spectra were obtained at 70 eV
with AMD-604 spectrometer. IR spectra were recorded on a Nicolet
series II Magna-IR 550 FT-IR spectrometer. Flash chromatography
(FC) was performed on Merck silica gel 230–400 mesh.
a
Reaction conditions for substrates 14 and 15: 20 °C, 0.1 M, CH2Cl2, 0.5 mol%
catalyst; for substrate 16: 80 °C, 0.06 M, toluene, 5 mol% catalyst.
Determined by 1H NMR.
b

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A. Hryniewicka et al. / Journal of Organometallic Chemistry 695 (2010) 1265–1270
Table 2
Results of cross-metathesis reactions promoted by 1, 2, 3 or 11a.
Entry
Substrates
Product
Catalyst
E/Zb
(%)c
1
2
3
4
C10H21
O
O
1
2
3
11
3:1
6:1
8:1
8:1
36
21
18
35
C10 H21
O
O
24
21
22
5
6
7
8
C10H21
O
O
C
O
C
1
2
3
11
2:1
6:1
5:1
4:1
19
25
19
23
O
O
C10H21
O
21
23
25
9
C10H21
O
COOEt
C10H21O
1
2
3
11
Only E
Only E
Only E
Only E
5
COOEt
10
11
12
22
67
61
20
21
26
a
b
c
Reaction conditions for entries 1–8: 40 °C, 0.1 M, CH2Cl2, 1 mol% catalyst, 3 h; for entries 9–12: 40 °C, 0.4 M, CH2Cl2, 2.5 mol% catalyst, 3 h.
Determined by 1H NMR.
Isolated by column chromatography.
4.2. Synthesis of ligand 8
1.4 Hz, H-30), 5.25 (dd, 2H, J = 11.0 and 1.0 Hz, @CH2), 5.25 (dd,
1H, J = 10.2 and 1.1 Hz, H-30), 4.27 (d, 2H, J = 5.5 Hz, H-10), 2.32 (s,
3H, H-4a) ppm; 13C NMR (100 MHz, CDCl3) d 151.8, 133.6, 133.3,
131.5, 130.9, 126.2, 117.1, 114.7, 74.8, 20.8 ppm; ESI-MS: 201.1
(M++H, 100%).
4.2.1. 2-Hydroxy-5-methyl-1,3-benzenedicarboxaldehyde
To a solution of p-cresol (200 mg, 1.85 mmol) in anhydrous tri-
fluoroacetic acid (10 mL) hexamethylenetetramine (519 mg,
3.7 mmol) was added. The mixture was stirred and refluxed over-
night. The reaction mixture was treated with 1 M HCl for 10 min
and extracted with CH2Cl2. The combined extracts were washed
with brine and water, and dried over MgSO4. After concentration
in vacuo the crude product was purified by FC (hexane–ethyl ace-
tate v/v 20:1) to afford 2-hydroxy-5-methyl-1,3-benzenedicarbox-
aldehyde (212 mg; 70%) as a pale yellow crystalline material. Mp
4.2.4. 6-Methyl-8-vinyl-2H-chrom-3-ene (8)
To
a
solution of 1-allyloxy-4-methyl-2,6-divinylbenzene
(114 mg, 0.57 mmol) in dry CH2Cl2 (2 mL) in a Schlenk flask, a solu-
tion of catalyst 1 (5 mg, 1 mol%) in CH2Cl2 (1 mL) was added. The
reaction mixture was stirred at 40 °C for 5 h and concentrated in
vacuo. The residue was purified by FC (hexane–ethyl acetate v/v
200:1) and product 8 (93 mg; 95%) was obtained as a colorless
124–126 °C, IR (CHCl3)
m ;
1683, 1604, 1217, 962, 749, 626 cm ꢀ1
1H NMR (400 MHz, CDCl3) d 11.44 (s, 1H, –OH), 10.19 (s, 2H, –
CHO), 7.80 (s, 2H, H-3 and 5), 2.37 (s, 3H, H-4a) ppm; 13C NMR
(100 MHz, CDCl3) d 192.1, 161.6, 137.9, 129.5, 122.8, 20.0 ppm.
oil. IR (CHCl3)
m ;
2923, 1628, 1467, 1154, 913 cmꢀ1 1H NMR
(400 MHz, CDCl3) d 7.13 (s, 1H, H-7), 7.01 (m, 1H, @CH), 6.71 (s,
1H, H-5), 6.40 (dt, 1H, J = 9.8 and 1.8 Hz, H-4), 5.80 (dt, 1H, J = 9.8
and 3.6 Hz, H-3), 5.73 (dd, 1H, J = 17.8 and 1.5 Hz, @CH2), 5.25
(dd, 1H, J = 11.2 and 1.5 Hz, @CH2), 4.82 (dd, 2H, J = 3.6 and
1.8 Hz, H-2), 2.26 (s, 3H, H-4a) ppm; 13C NMR (100 MHz, CDCl3)
d 149.1, 131.0, 130.0, 126.7, 126.0, 124.9, 124.8, 122.4, 122.0,
114.2, 65.5, 20.5 ppm; m/z (EI) 172 (84), 171 (100), 157 (57), 129
(27), 128 (43), 127 (13).
4.2.2. 4-Methyl-2,6-divinylphenol
Methyltriphenylphosphonium bromide (928 mg, 2.6 mmol) and
butyllithium (2.5 M solution in hexane; 1.56 ml, 3.9 mmol) were
stirred in dry THF (5 mL) for 3 h under argon atmosphere. A solu-
tion
of
2-hydroxy-5-methyl-1,3-benzenedicarboxyaldehyde
(106 mg, 0.65 mmol) in THF (5 mL) was then added dropwise dur-
ing 1 h and the reaction mixture was refluxed for 5 h. The solvent
was evaporated to dryness, and the residue was dissolved in
CH2Cl2 (10 mL), washed with water, dried over Mg2SO4 and con-
centrated in vacuo. The crude product was purified by FC (hex-
ane–ethyl acetate v/v 50:1) and 4-methyl-2,6-divinylphenol
4.3. Synthesis of ligand 9
4.3.1. 2-Hydroxy-3-dimethoxymethyl-5-methylbenzaldehyde
To a solution 2-hydroxy-5-methyl-1,3-benzenedicarboxalde-
hyde (106 mg, 0.65 mmol) in MeOH (5 mL) 2,2-dimethoxypropane
(93 mg; 90%) was isolated as a yellow oil. IR (CHCl3)
m 3597,
(80 lL, 0.65 mmol) and p-toluenesulphonic acid (5 mg) was added
2925, 1460, 1265, 914 cmꢀ1 1H NMR (400 MHz, CDCl3) d 7.11 (s,
;
and the mixture was refluxed. The reaction progress was moni-
tored by TLC. After 1 h the reaction was quenched with a few drops
of Et3N and the mixture was concentrated in vacuo. The residue
was purified by FC (hexane–ethyl acetate v/v 30:1) and 71 mg of
2-hydroxy-3-dimethoxymethyl-5-methylbenzaldehyde as a pale
2H, H-3 and 5), 6.92 (m, 2H, @CH), 5.77 (dd, 2H, J = 17.7 and
1.3 Hz, @CH2), 5.43 (dd, 2H, J = 11.2 and 1.3 Hz, @CH2), 2.30 (s,
3H, H-4a) ppm; 13C NMR (100 MHz, CDCl3) d 148.0, 131.8, 129.6,
127.3, 125.0, 116.4, 20.5 ppm.
yellow solid was obtained (52% yield). Mp 60–61 °C; IR (CHCl3)
m
2861, 1683, 1461, 1110, 1047, 747, 685 cmꢀ1 1H NMR (400 MHz,
;
4.2.3. 1-Allyloxy-4-methyl-2,6-divinylbenzene
CDCl3) d 11.10 (s, 1H, –OH), 9.89 (s, 1H, –CHO); 7.62 and 7.35
(2s, 2H, H-3 and 5), 5.69 (s, 1H, H-10), 3.42 (s, 6H, H-2a0, 2b0),
2.36 (s, 3H, H-4a) ppm; 13C NMR (100 MHz, CDCl3) d 196.3,
157.1, 135.7, 133.7, 128.8, 126.1, 120.4, 98.6, 53.9, 20.3 ppm.
The mixture of 4-methyl-2,6-divinylphenol (93 mg, 0.58 mmol)
in dry acetone (3 mL), potassium carbonate (160 mg, 1.16 mmol),
allyl bromide (75 lL, 0.87 mmol) and 18-C-6 (5 mg) was refluxed
for 1 h. The mixture was filtered through a pad of Celite and con-
centrated in vacuo. The residue was purified by FC (hexane–ethyl
acetate v/v 200:1) and 114 mg of 1-allyloxy-4-methyl-2,6-divinyl-
4.3.2. 2-Hydroxy-5-methyl-3-vinylbenzaldehyde
benzene as a colourless oil was obtained (98% yield). IR (CHCl3)
m
The procedure for the synthesis of 4-methyl-2,6-divinylphenol
was followed using methyltriphenylphosphonium bromide
(292 mg, 0.82 mmol), butyllithium (0.49 mL, 1.23 mmol) and
2925, 1288, 1711, 1450, 916 cmꢀ1 1H NMR (400 MHz, CDCl3) d
;
7.25 (s, 2H, H-3 and 5), 6.99 (m, 2H, @CH), 6.05 (m, 1H, H-20);
5.74 (dd, 2H, J = 17.8 and 1.1 Hz, @CH2), 5.42 (dd, 1H, J = 17.1 and
2-hydroxy-3-dimethoxymethyl-5-methylbenzaldehyde
(71 mg,

A. Hryniewicka et al. / Journal of Organometallic Chemistry 695 (2010) 1265–1270
1269
0.34 mmol) in dry THF (5 mL). After extraction, the organic layer
4.5. Synthesis of catalyst 11
was washed 1 M HCl until the protective group was removed
(TLC control, hexane:ethyl acetate 5:1). FC (hexane–ethyl acetate
v/v 40:1) gave 50 mg of 2-hydroxy-5-methyl-3-vinylbenzaldehyde
19a
13a
as a pale yellow oil (90% yield). IR (CHCl3)
m 3027, 2850, 1655,
11 10
19
13
20
22
14
15
1456, 1263, 971 cmꢀ1 1H NMR (400 MHz, CDCl3) d 11.29 (s, 1H,
;
18
23
12
21a
15a
N
N
–OH), 9.85 (s, 1H, –CHO), 7.53 and 7.26 (s, 1H, H-3 and 5), 7.02
(m, 1H, @CH), 5.85 (dd, 1H, J = 17.8 and 0.8 Hz, @CH2), 5.39 (dd,
1H, J = 11.2 and 0.8 Hz, @CH2), 2.35 (s, 3H, H-4a) ppm; 13C NMR
(100 MHz CDCl3) d 196.7, 156.9, 134.7, 133.1, 129.9, 128.8, 126.3,
120.5, 115.8, 20.3 ppm; ESI-MS: 163.1 (M++H, 100%).
21
9
17
Cl
16
8b
Ru
23a
17a
Cl
8
7
1O
8a
6
2
6a
4a
5
3
4
4.3.3. Methyl 5-methyl-7-vinylbenzofuran-2-carboxylate (9)
The mixture of 2-hydroxy-5-methyl-3-vinylbenzaldehyde
(50 mg, 0.31 mmol), methyl chloroacetate (58 lL, 0.64 mmol),
To the mixture of catalyst 2 (39.5 mg, 0.047 mmol) and CuCl (5 mg,
0.05 mmol) in dry CH2Cl2 (2 mL) a solution of 6-methyl-8-vinyl-2H-
chrom-3-ene (8) (8 mg, 0.047 mmol) in CH2Cl2 (1 mL) was added.
The solution was stirred at 40 °C for 1 h. The reaction mixture
was concentrated in vacuo, and the residue was dissolved in a small
volume of ethyl acetate. The insoluble material was filtered off, and
the filtrate was evaporated to dryness. The crude product was puri-
fied by FC (hexane–ethyl acetate v/v 5:1) to give 17 mg (57% yield)
K2CO3 (88 mg, 0.64 mmol), TBAB (10 mol%, 10 mg) was stirred
mechanically and heated at 110 °C. After 10 min the temperature
of the oil bath was increased to 150 °C and heating was continued
for next 30 min. After cooling, water was added, and the reaction
mixture was extracted with CH2Cl2. The combined extracts were
washed successively with brine and water, and dried over MgSO4.
After concentration in vacuo the crude product was purified by FC
(hexane–ethyl acetate v/v 20:1) and compound 9 was obtained
of the green catalyst 11. IR (CHCl3)
m 2993, 2921, 1606, 1480,
(24 mg; 36%) as a colorless oil. IR (CHCl3)
m 2955, 1727, 1578,
1268 cmꢀ1 1H NMR (400 MHz, CDCl3) d 16.44 (s, 1H, H-8b), 7.09
;
1438, 1300 cmꢀ1 1H NMR (400 MHz, CDCl3) d 7.49 (s, 1H, H-3),
;
(s, 4H, H-14, 16, 20 and 22), 6.94, 6.49 (2d, 2H, J = 1.6 Hz; 1.2 Hz,
H-5 and 7), 6.3 (dt, 1H, J = 10.1 and 2.0 Hz, H-4), 5.59 (dt, 1H,
J = 10.0 and 3.4 Hz, H-3), 4.88 (dd, 2H, J = 3.3 and 2.1 Hz, H-2),
4.14 (s, 4H, H-10 and 11), 2.47 (s, 12H, H-13a, 17a, 19a and 23a),
2.42 (s, 6H, H-15a and 21a), 2.31 (s, 3H, H-6a) ppm; 13C NMR
(100 MHz, CDCl3) d 291.8, 210.2, 146.3, 142.8, 138.8, 138.6, 136.2,
132.9, 129.5, 126.8, 122.7, 122.5, 121.2, 67.5, 51.7, 21.1, 20.2,
19.2 ppm; TOF MS FD+ (4,34 eV; m/z): 636,13; calculated for
C32H36Cl2N2O102Ru: 636.1248, found: 636.1285.
7.36 and 7.29 (2s, 2H, H-4 and 6), 7.0 (m, 1H, @CH), 6.28 (dd, 1H,
J = 17.8 and 0.9 Hz, @CH2), 5.53 (dd, 1H, J = 11.3 and 0.9 Hz,
@CH2), 3.98 (s, 3H, ꢀOCH3), 2.46 (s, 3H, H-5a) ppm; 13C NMR
(100 MHz, CDCl3) d 160.0, 154.2, 151.9, 145.6, 145.4, 133.4,
130.9, 127.3, 121.5, 118.1, 113.7, 52.2, 21.5 ppm; ESI-MS: 239.1
(M++Na, 55%), 455.1 (2M++Na, 100%).
4.4. Synthesis of ligand 10
4.6. General RCM procedure for 14 and 15
4.4.1. 4-Formyl-1,3-benzodioxol
To a suspension of sodium hydride (139 mg 50% suspension in
oil, 2.9 mmol) in HMPA (10 mL) a solution of 2,3-dihydroxybenzal-
dehyde (200 mg, 1.45 mmol) in HMPA (2 mL) was added with stir-
ring within 10 min. After evolution of gas stopped,
dibromomethane (0.15 mL, 2.2 mmol) was added and the solution
was stirred for additional 20 min. Then cold water was added and
the mixture was extracted with CH2Cl2. The combined extracts
were washed successively with brine and water, dried over MgSO4
and evaporated in vacuo. The oily residue was purified by FC (hex-
ane–ethyl acetate v/v 20:1) affording 98 mg (45%) of 4-formyl-1,3-
To a solution of diene 14 or 15 (1 mmol) in CH2Cl2 (8 mL, c
0.1 M) a solution of catalyst 2, 3 or 11 (0.5 mol%) in CH2Cl2
(2 mL) was added. The resulting mixture was stirred at room temp.
for 90 min and controlled by TLC. The crude product was analyzed
by 1H NMR.
4.7. General RCM procedure for 16
To a solution of diene 16 (0.5 mmol) in toluene (6 mL, c 0.06 M)
a solution of catalyst 2, 3 or 11 (5 mol%) in toluene (2 mL) was
added. The resulting mixture was stirred at 80 °C for 16 h and con-
trolled by TLC. The crude product was analyzed by 1H NMR.
benzodioxol as a colorless oil. IR (CHCl3)
m 1690, 1464, 1235,
1059 cmꢀ1 1H NMR (400 MHz, CDCl3) d 10.1 (s, 1H, –CHO), 7.27–
;
6.88 (m, 3H, H-5, 6 and 7), 6.11 (s, 2H, H-2) ppm; 13C NMR
(100 MHz, CDCl3) d 187.9, 149.2, 148.8, 121.7, 121.0, 119.3,
113.3, 102.4 ppm.
4.8. General CM procedure for 24 and 25
To a mixture of alkenes 21 and 22 or 21 and 23 (1 mmol both) in
CH2Cl2 (8 mL, c 0.1 M) a solution of catalyst 1, 2, 3 or 11 (1 mol%) in
CH2Cl2 (2 mL) was added. The resulting mixture was stirred at
40 °C for 3 h and controlled by TLC. The crude product was purified
by FC and analyzed by 1H NMR.
4.4.2. 4-Vinyl-1,3-benzodioxol (10)
The procedure for the synthesis of 4-methyl-2,6-divinylphenol
was followed using methyltriphenylphosphonium bromide
(278 mg, 0.78 mmol), butyllithium (0.47 mL, 1.17 mmol) and 4-
formyl-1,3-benzodioxol (98 mg, 0.65 mmol) in dry THF (5 mL). FC
(hexane–ethyl acetate v/v 80:1) gave pure product 10 (77 mg;
4.9. General CM procedure for 26
80%) as a colorless oil. IR (CHCl3)
m ;
1731, 1454, 1247, 1051 cmꢀ1
1H NMR (400 MHz, CDCl3) d 6.89–6.65 (m, 4H, H-5, 6 and 7;
@CH), 6.01 (s, 2H, H-2), 5.92 (d, 1H, J = 17.7 and 1.3 Hz, @CH2),
5.4 (dd, 1H, J = 11.2 and 1.3 Hz, @CH2) ppm; 13C NMR (100 MHz,
CDCl3) d 147.6, 144.9, 131.1, 121.4, 120.4, 120.3, 116.8, 107.6,
100.9 ppm.
To a mixture of alkenes 20 and 21 (1 mmol both) in CH2Cl2
(2 mL, c 0.4 M) a solution of catalyst 1, 2, 3 or 11 (2.5 mol%) in
CH2Cl2 (0.5 mL) was added. The resulting mixture was stirred at
40 °C for 3 h and controlled by TLC. The crude product was purified
by FC and analyzed by 1H NMR.

1270
A. Hryniewicka et al. / Journal of Organometallic Chemistry 695 (2010) 1265–1270
[5] G.W. Burton, T. Doba, E.J. Gabe, L. Hughes, F.L. Lee, L. Prasad, K.U. Ingold, J. Am.
Acknowledgement
Chem. Soc. 107 (1985) 7053–7065.
[6] G.W. Burton, K.U. Ingold, Acc. Chem. Res. 19 (1986) 194–201.
[7] A. Hryniewicka, J.W. Morzycki, L. Siergiejczyk, S. Witkowski, J. Wójcik, A. Gryff-
Keller, Austr. J. Chem. 62 (2009) 1363–1370.
This work was supported by the Polish State Committee for Sci-
entific Research (Grant Number: PBZ-KBN-126/T09/2004).
[8] M. Barbasiewicz, A. Szadkowska, A. Makal, K. Jarzembska, K. Woz´niak, K. Grela,
Chem. Eur. J. 14 (2008) 9330–9337.
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