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Y. Miyaki et al. / Journal of Organometallic Chemistry 616 (2000) 135–139
4). It is suggested again that the existence of the hemi-
labile side-arm alcohol appears to play a key role.
When 9 was treated with ethylene (1 atm) in CD2Cl2 at
room temperature for 3 min, a new 31P peak (l 65.6)
completely replaced that of 9 (l 61.8) and a new
hydridic peak (l −9.56, JPH=32.4 Hz) and two new
broad peaks for ethylene (l 2.2–2.4) were detected in
1H-NMR spectra. This new species seems to be a
hydride ethylene complex with the side-arm alcohol set
free; cf. l(CH2O) 3.60 for the new complex with
l(CH2O) 3.05 and 3.52 for 9. Further transformations
(e.g. insertion of ethylene) of this complex did not take
place when the CD2Cl2 solution was heated for 17 h.
In conclusion, cycloisomerization and RCM of a,v-
dienes proceeded with the same catalyst precursor 1a by
choosing the appropriate co-catalyst. The amine co-cat-
alyst may assist generation of a hydride species, while
phenylacetylene would react with 1a to give a vinyli-
dene ruthenium species, which is responsible for the
RCM reactions. It is well known that the reaction of
coordinately unsaturated ruthenium complexes with
terminal alkynes afforded vinylidene complexes [10],
though not detected in the present system, and that
some vinylidene or allenylidene ruthenium complexes
act as catalysts for RCM [11]. The exact functions of
the side arm alcohol during the present catalyses cannot
be specified at this moment, except for a possible role
as a source of the hydride ligand in the cycloisomeriza-
tion. It is also speculated that the hemilabile nature of
the side arm alcohol ligand or an aldehyde one, if
formed by b-hydrogen transfer from alkoxy group to
ruthenium, could help to prevent, via weak coordina-
tion, decomposition of an otherwise unstable, coordi-
nately unsaturated active intermediate.
o-allylphenol and allyl bromide in DMSO containing
KOH. The complexes [Ru(h6-C6H6)(PCy3)Cl2] and
[Ru(h6-C6H6)(PCy3)Cl2](BF4)2 were synthesized in man-
ners similar to those [12,13] for analogous complexes.
3.3. Typical procedure for cycloisomerization of
h,ꢀ-dienes
To a solution of 4a (251 mg, 1.0 mmol) and triethyl-
amine (7.0 ml, 0.05 mmol) in CH2C12 (10 ml) was added
1a (32 mg, 0.05 mmol). The reaction mixture was
refluxed at 50°C for 64 h. The yield of the products was
calculated by GC using n-pentadecane as an internal
standard. Cycloisomerization products 5a [4] and 5b
[14] were known compounds.
3.4. Typical procedure for RCM of h,ꢀ-dienes
To a solution of 4a (251 mg, 1.0 mmol) containing
phenylacetylene (5.5 ml, 0.05 mmol) in CH2Cl2 (10 ml)
was added 1a (32 mg, 0.05 mmol). The reaction mixture
was refluxed at 50°C for 24 h. The yield of products
was calculated by NMR using nitromethane as an
internal standard. RCM products 6a [15], 6b [16], 6c
[17], and 6d [18] were known compounds.
3.5. Synthesis of alcohol chelate ruthenium complex
[Ru{p6:p1-Ph(CH2)3OH}(PCy3)Cl]BF4 (1a)
This was prepared similarly to the literature method
[1b]. 1H-NMR (CDCl3): l 1.18–2.21 (m, 35H), 2.82
(brs, 2H), 3.80 (brs, 2H), 4.69 (brs, 1H), 5.38 (brt, 1H),
5.98 (brs, 3H). 31P-NMR (CDCl3): l 36.95 (s). Anal.
Calc. for C27H4BClF4OPRu: C, 50.68; H, 7.09. Found:
C, 50.31; H, 6.99%.
3. Experimental
3.6. Synthesis of ruthenium hydride complex
[Ru(p6-C6H6)(PCy3)HCl] (8)
3.1. General remarks
The treatment of [Ru(h6-C6H6)(PCy3)Cl2] (93 mg,
0.175 mmol) with one equivalent of sodium formate in
MeOH (10 ml) for 1 h gave a black–yellow suspension.
This was filtered off with celite and the filtrate was
evaporated under N2. Recrystallization from benzene–
hexane gave fine yellow powders (58%). 1H-NMR
Most of the commercially available reagents were
used without further purification. Solvents were dried
1
by standard methods and distilled prior to use. H- and
31P-NMR spectra were recorded with a JEOL GSX-270
spectrometer. Gas chromatographic analyses were per-
formed on a HITACHI G-3000 equipped with a SHI-
MAZU CBP-10 capillary column (25 m×0.25 mm)
with helium as carrier gas.
2
(C6D6): l −7.04 (d, JPH=51.0 Hz, 1H), 1.11–2.12
(m, 33H), 4.99 (s, 6H). 31P-NMR (C6D6): l 62.94 (s).
Anal. Calc. for C28H48ClPRu: C, 58.11; H, 8.13.
Found: C, 57.88; H, 8.17%.
3.2. Starting materials
3.7. Synthesis of cationic ruthenium hydride complex
[Ru{p6:p1-Ph(CH2)3OH}(PCy3)H]BF4 (9)
Compound 4a was prepared from diallylamine and
tosyl chloride in CH2Cl2. Compounds 4b and 4c were
prepared from diethylallyl malonate and allyl bromide
(4b) or homoallyl bromide (4c) in THF containing
sodium hydride. Compound 4d was prepared from
The treatment of 1a (337 mg, 0.527 mmol) with one
equivalent of AgBF4 and sodium formate in MeOH (10
ml) for 1 h gave a yellow suspension. This was filtered