Reactivity of terminal phenylpentenes in a ruthenium-catalyzed cross-metathesis reaction: Construction of linear bifunctional C-8 alkenes

Article abstract of DOI:10.1007/s00706-012-0905-3

In the present study the behavior of 1-functionalized 2-phenylpent-4-enes in the presence of ruthenium-based metathesis catalysts was investigated. The experimental observations revealed that the outcome of the reaction depends very much on the combination of olefinic partners used in the reaction; only certain combinations delivered satisfactory amounts of unsymmetrical cross-metathesis products, i.e., bifunctional C-8 alkenes.

Full text of DOI:10.1007/s00706-012-0905-3

Monatsh Chem (2013) 144:633–640
DOI 10.1007/s00706-012-0905-3
ORIGINAL PAPER
Reactivity of terminal phenylpentenes in a ruthenium-catalyzed
cross-metathesis reaction: construction of linear bifunctional
C-8 alkenes
ˇ
Bogdan Stefane Franc Pozgan
•
ˇ
Received: 17 October 2012 / Accepted: 14 December 2012 / Published online: 31 January 2013
Ó Springer-Verlag Wien 2013
Abstract In the present study the behavior of 1-function-
alized 2-phenylpent-4-enes in the presence of ruthenium-
based metathesis catalysts was investigated. The experimental
observations revealed that the outcome of the reaction
depends very much on the combination of olefinic partners
used in the reaction; only certain combinations delivered
satisfactory amounts of unsymmetrical cross-metathesis
products, i.e., bifunctional C-8 alkenes.
Furthermore, alkenes are substrates for the catalytic
metathesis reaction, which has become one of the most
powerful tools for the selective formation of new carbon–
carbon bonds [6–9]. Olefin metathesis reactions allow a
facile and straightforward access to more substituted ole-
fins and generally do not produce by-products, except
ethylene, which can be easily removed by evaporation. The
development of well-defined transition-metal alkylidene
metathesis catalysts has advanced organic synthesis (on
both the academic and industrial levels), natural product
synthesis, specialty materials production, and polymer
science [10–18]. Although molybdenum-based catalysts
[19] are generally considered to be more reactive towards
highly substituted and electron-rich olefins, Grubbs’
ruthenium-based complexes [20] have attracted more
attention due to their high functional group tolerance and
remarkable stability towards air and moisture. The incor-
poration of N-heterocyclic carbene (NHC) ligands into
ruthenium alkylidene complexes, for example 2, led to
increased activity relative to 1 [21].
Keywords Metathesis Á Catalysis Á Alkenes Á Ruthenium Á
Isomerization
Introduction
Alkenes represent important intermediates in the prepara-
tion of complex molecular architectures, either naturally or
non-naturally occurring compounds, as well as in the pro-
duction of polymers [1–3], because their p-bond is
sufficiently reactive to be used in a wide range of trans-
formations and the attached functionalities can participate
in functional group interconversion reactions, thus altering
the reactivity and characteristics of the alkenes [4, 5].
Cross-metathesis [22–24] (CM) still remains an under-
represented area when compared to ring-closing metathesis
[25] (RCM) and ring-opening metathesis polymerization
[26]. This has largely resulted from the low catalyst
activity, poor product selectivity, and insufficient stere-
oselectivity in CM reactions. Very recently, Grubbs et al.,
succeeded in the preparation of new ruthenium catalysts
capable of performing the olefin CM with excellent
Z-selectivity [27]. To better understand the olefin cross-
metathesis selectivity and to predict the reaction outcome,
the same research group reported a classification of olefins
according to their ability to dimerize, which is based purely
on an empirical approach [28]. However, the olefin CM
represents a convenient route to higher olefins containing a
wide range of pendant functionalities from simple alkene
This work is dedicated to Professor Slovenko Polanc on the occasion
of his 65th birthday.
ˇ
ˇ
B. Stefane Á F. Pozgan (&)
Faculty of Chemistry and Chemical Technology,
ˇ
University of Ljubljana, Askerceva 5,
SI-1000 Ljubljana, Slovenia
ˇ
e-mail: franc.pozgan@fkkt.uni-lj.si
ˇ
ˇ
B. Stefane Á F. Pozgan
EN-FIST Centre of Excellence, Dunajska 156,
SI-1000 Ljubljana, Slovenia
123

ˇ
B. Stefane, F. Pozgan
ˇ
634
precursors. The CM was successfully applied in the
transformations of unsaturated acid derivatives with func-
tional olefins to bifunctional fatty acids esters and a, x-
nitrile esters [29–31]. Similarly, the CM of fatty acids
esters derived from plant oils with methyl acrylate deliv-
ered a, x-dicarboxylic acid esters [32] while the reaction of
methyl oleate with cis-2-butene-1,4-diyl diacetate resulted
in protected a-hydroxy-x-carboxylic acid derivatives [33].
The CM reaction of a poly(2-oxazoline) featuring terminal
double bonds in the side chains with acrylates allowed the
introduction of functional groups along the polymer
backbone [34]. It was recently reported that the solventless
CM of terminal olefins with ethyl acrylate can be per-
formed by using NHC-ruthenium complexes with loadings
as low as 100 ppm thus demonstrating increased stability
and activity of 2nd generation catalysts [35]. The prepa-
ration of trialkyl-substituted isoprenoid olefins as key
intermediates in tocopherol synthesis was accomplished by
ruthenium-catalyzed CM [36], which was also applied to
access the C-8-alkene containing terminal hydroxy groups
as an early intermediate in the multi-step synthesis of
Annonaceous acetogenins, a diverse class of biologically
active compounds [37]. The use of the catalytic metathesis
reaction has been successfully demonstrated in the syn-
thesis of renin inhibitors [38], such as aliskiren or its
analogues, in which the main C-8 skeleton A can be con-
structed by the CM reaction from appropriate terminal
alkenes [39, 40] (Fig. 1). Moreover, a macrocyle route
toward aliskiren has been reported by Hanessian et al.,
where the selective RCM reaction was crucial for the
production of the nine-membered lactone as a key inter-
mediate in the convergent total synthesis [41]. We have
already reported the formation of macrocycles containing
an unsaturated C1-C8 unit by RCM, which can subse-
quently be opened to give the asymmetric linear alkene
skeleton with a good E/Z ratio [42].
phenyl ketone 5c, alcohol 5d, bromide 5e, dibenzyl amide
5f, Weinreb amide 5 g) due to their easy preparation from
readily available 2-phenylpent-4-enoic acid [43]. At the
outset of our experiments, we examined the activity of four
different ruthenium-based catalysts 1-4 in the CM between
ester 5a and mesylate 5b in the molar ratio 2:1. The
Hoveyda-Grubbs second-generation catalyst (3) turned out
to be the catalyst of choice, since the highest conversion
(72 %) of mesylate into the cross-metathesis product 6ab
was observed when using 2.5 mol % of 3 in refluxing
dichloromethane after 2 h (Scheme 1).
In continuation, the catalyst 3 was used in the CM
reactions between different phenylpentenes 5, but for 24 h
in order to consume at least one metathesis partner. With
regard to the alkenes 5 subjected to the CM reaction, dif-
ferent distributions of the heterodimers 6, homodimers 7,
and isomerized starting compounds 8 were observed under
otherwise identical conditions; full details are summarized
in Table 1.
The CM reaction of methyl ester 5a and mesylate 5b led
to the formation of the unsymmetrically substituted C-8
alkene 6ab, which was isolated by column chromatography
as a mixture of two stereoisomers in a 28 % yield. The
ester 5a showed a significant tendency towards homodi-
merization, as besides the desired product 6ab, the diester
7a was isolated in a 35 % yield. Conducting the same
reaction in refluxing toluene did not improve the yield of
6ab. Interestingly, when almost equimolar quantities of
phenyl ketone 5c and alcohol 5d were reacted in the
presence of the catalyst 3, a higher yield (36 %) of
the isolated heterodimeric product 6cd was obtained. The
substrates 5c and 5d also tend to isomerize [44] under the
applied conditions and, consequently, the internal olefins
8c and 8d were isolated in 12 and 20 % yields, respec-
tively. The ester 5a was the most compatible metathesis
partner in the reaction with bromide 5e, and the heterodi-
meric product 6ae was isolated in a yield of 40 %, which
was the highest yield obtained for an unsymmetrical
alkene. Surprisingly, the combination of alcohol 5d and
mesylate 5b did not lead to the formation of dimer prod-
ucts, neither in dichloromethane nor in refluxing toluene,
and only the isomerized products 8d and 8b together with
the starting compounds were isolated. The reaction of
alcohol 5d with dibenzyl amide 5f gave only 16 % of the
cross-product 6df after column chromatography purifica-
tion. Additionally, a very small amount (3 %) of alcohol
dimer 7d was isolated, while isomeric alcohol 8d
and isomeric amide 8e were isolated in 24 and 41 % yields,
respectively. The latter result shows that alkene isome-
rization predominates over CM in this particular
combination of olefins. Practically the same yield (17 %)
of the cross-product 6af was obtained in the reaction of
ester 5a and dibenzyl amide 5f. Here again, the ester
Herein we report on a detailed study of the cross-
metathesis reaction using different combinations of
1-functionalized 2-phenylpent-4-enes, leading directly to
linear C-8 alkenes with different pendant functionalities.
Results and discussion
As the model substrates we chose differently functional-
ized phenylpentenes 5 (methyl ester 5a, mesylate 5b,
R2
O
R2
O
R3
R3
+
R1
R1
R2
O
R2
O
A
Fig. 1 Retrosynthetic pathway to C-8 skeleton
123

Reactivity of terminal phenylpentenes
635
Scheme 1
Ph CO2Me
5a 6ab
to
Catalyst Conv. /% of
Ph
CO2Me Ph
+
OSO2Me
cat. (2.5 mol%)
1
2
3
4
9
CH2Cl2 , Δ, 2 h
44
72
MeO2SO
5a
5b
Ph
6ab
28
N
N
Mes
Mes
PCy3
N
N
PCy3
Ru
Mes
Mes
Cl
Cl
Cl
Cl
Cl
Cl
Ru
Ru
O
Cl
Cl
Ru
Ph
Ph
PCy3
Ph
Mes
Mes
N
N
PCy3
1
2
3
4
Mes = 2,4,6-trimethylphenyl, Cy = cyclohexyl
5a dimerized to give 7a in a 10 % yield. On the other hand,
the reaction of mesylate 5b and dibenzyl amide 5f gave the
unsymmetrical C-8 alkene 6bf in only a 3 % isolated yield,
but important amounts of starting materials were recov-
ered. Finally, the reaction of mesylate 5b and Weinreb
amide 5g for 40 h in refluxing dichloromethane did not
deliver any metathesis or non-metathesis products and only
the starting materials were recovered using chromatogra-
phy purification of the reaction mixture. The low reactivity
of dibenzyl amide 5f in the CM reactions and the inability
of Weinreb amide 5g to metathesize could be explained by
the coordination of their carbonyl oxygen to the ruthenium
center of the carbene intermediate formed in the metathesis
between the amide and the catalyst 3 [45]. If such a six-
membered chelate becomes too stable, this can inhibit the
catalyst for any further metathesis reaction, which is more
pronounced with the amides 5f and 5g than the ester 5a or
phenyl ketone 5c. In addition, Weinreb amide 5g could
form a stable 5-membered chelate with ruthenium. On the
other hand, the amide 5f is more prone to double-bond
isomerization as significant amounts of isomerized prod-
ucts were isolated in the reactions where 5f was used as a
metathesis partner.
In conclusion, this study revealed that 1-functionalized
2-phenylpent-4-enes can be used as substrates in ruthe-
nium-catalyzed CM reactions and that only certain
combinations successfully led to the formation of syn-
thetically valuable, unsymmetrical C-8 alkenes. It was also
shown that in some combinations of alkene substrates the
double-bond isomerization competed with CM in the
presence of the Hoveyda-Grubbs second-generation cata-
lyst, thus giving significant amounts of isomerized starting
olefins. This was particularly pronounced with dibenzyl
amide and alcohol when used as metathesis partners. The
methyl ester turned out to be a good partner in CM since in
all combinations in which it was used (with mesylate,
bromide, and dibenzyl amide) the desired heterodimeric
products were obtained. On the other hand, dibenzyl amide
and Weinreb amide showed a somewhat lower reactivity in
CM, most probably due to the formation of the more stable
ruthenium chelate intermediates in the catalytic cycle, if
compared to the ester and ketone. Although the isolated
yields of the metathesis products were low, this study
importantly contributes to a better understanding of the
behavior of differently functionalized alkenes in CM
reactions, which need further investigations because of
their great synthetic potential.
It is worth noting that the separation of reaction mix-
tures by column chromatography was rather difficult due to
the similar Rf of the products, which consequently resulted
in low isolated yields. Regarding the 1H NMR spectra,
most of the metathesis and isomerized products were iso-
lated as mixtures of two stereoisomers, referred to as major
and minor isomers. The NMR patterns of the olefinic
protons were complex and; hence, it was not possible
to find out whether the predominant isomer was trans
or cis. On the basis of literature data [17, 22, 46] on metal-
catalyzed alkene transformations we assumed that the
major isomers in the isolated products were trans and
the minor cis.
Experimental
NMR spectra were recorded at 29 °C with a Bruker
Avance DPX 300 in DMSO-d6 or CDCl3. 1H NMR spectra
were recorded at 300 MHz using TMS as an internal
standard. 13C NMR spectra were recorded at 75.5 MHz and
are referenced against the central line of the solvent signal
(DMSO-d6 septet at d = 39.5 ppm, CDCl3 triplet at
d = 77.0 ppm). The coupling constants (J) are given in Hz.
For minor isomers of products 6, 7, and 8 only selected 1H
123

ˇ
ˇ
B. Stefane, F. Pozgan
636
Table 1 CM of functionalized phenylpentenes 5
Ph R1
Ph R1
Ph R2
Ph R2
Ph R1
Ph R1
Ph R2
cat. 3 (2.5 mol%)
CH2Cl2 , Δ, 24 h
+
+
+
+
+
Me
Me
R2 Ph
R1 Ph
R2 Ph
5
6
8
7
c
Run
Starting olefins 5
Products; yield/ %b (nminor:nmajor
)
R1:R2 (n1:n2)a
6
7
8
1
2
3
4
5
6
7
8e
a
CO2Me (5a):CH2OMs (5b)
6ab
7a
–
–
–
–
(2:1)
28 (1:4)
6cd
35 (1:4.5)
–
COPh (5c):CH2OH (5d)
8c
8d
(1:1.2)
36 (1:4)
6ae
12 (1:2.2)
–
20 (1:2.5)
–
CO2Me (5a):CH2Br (5e)
–
–
7ed
25
–
(1:2)
40
CH2OMs (5b):CH2OH (5d)
–
8b
8d
(1:2)
30 (1:2)
8d
21 (1:8.2)
CH2OH (5d):CONBn2 (5f)
6df
7d
–
–
–
–
8f
(2:1)
16
3
24 (1:6)
–
41 (1:3.2)
CO2Me (5a):CONBn2 (5f)
6af
7a
8f
(2:1)
17 (1:1.5)
10 (1:2.2)
–
10 (1:2)
–
CH2OMs (5b):CONBn2 (5f)
6bf
3
–
–
(2:1)
CH2OMs (5b):CON(OMe)Me (5g)
–
–
–
(1:2)
Molar ratio between substrates 5
b
c
d
e
Isolated yield by column chromatography
1
Ratio between minor and major isomer determined on the basis of H NMR of olefinic protons for 6 and 7, and methyl protons for 8.
Product not confirmed by MS
Reaction time 40 h
layers were additionally extracted with 15 cm3 CH2Cl2.
NMR resonances are given. IR spectra were obtained with
a Bio-Rad FTS 3000MX spectrometer. The MS spectra
were recorded with a VG-Analytical AutoSpec Q spec-
trometer. Flash chromatography was performed on
230–400 mesh silica gel. Merck silica gel 60 PF254 con-
taining gypsum was used to prepare chromatotron
plates. The 2-Phenylpent-4-enoic acid was prepared
according to a published procedure [43]. Anhydrous tolu-
ene and THF were obtained using standard drying
techniques. All other reagents and solvents were used as
received from commercial suppliers.
The combined organic extracts were dried over anhydrous
Na2SO4, filtered, and concentrated in vacuo to give 456 mg
(83 %) 5a as a yellow oil. The NMR spectroscopic data are
consistent with reported data [47].
2-Phenylpent-4-enyl methanesulfonate (5b, C12H16O3S)
To a cold solution (0 °C) of 790 mg 2-phenylpent-4-en-1-
ol (5d, 4.877 mmol) and 0.5 cm3 methanesulfonyl chloride
(6.472 mmol) in 20 cm3 CH2Cl2, 2 cm3 triethylamine
(14.33 mmol) was added. The reaction mixture was
allowed to warm to room temperature at which it was
stirred for 15 h. Then 20 cm3 H2O was added, layers were
separated, and the aqueous layer was extracted with
2 9 15 cm3 CH2Cl2. The combined organic extracts were
washed with 20 cm3 1 M HCl, dried over anhydrous
Na2SO4, filtered, and concentrated in vacuo to give 1.065 g
Methyl 2-phenylpent-4-enoate (5a)
A
mixture of 0.51 g 2-phenylpent-4-enoic acid
(2.89 mmol), 20 cm3 methanol, and 0.5 cm3 conc. H2SO4
was refluxed for 16 h. After evaporation of methanol under
reduced pressure, 15 cm3 CH2Cl2 was added to a residue
and washed with 3 9 15 cm3 sat. NaHCO3. The aqueous
1
5b (91 %) as an orange oil. H NMR (300 MHz, CDCl3):
123

Reactivity of terminal phenylpentenes
637
d = 2.41–2.60 (m, 2H, CH2CH=), 2.77 (s, 3H, CH3), 3.06–
3.15 (m, 1H, CH), 4.35 (d, J = 6.7 Hz, 2H, CH2O-
SO2CH3), 5.00–5.09 (m, 2H, H2C=CH), 5.61–5.75 (m,
1H, H2C=CH), 7.20–7.28 (m, 3H, Ar), 7.31–7.36 (m, 2H,
Ar) ppm; 13C NMR (75.5 MHz, CDCl3): d = 36.0, 37.0,
44.8, 72.9, 117.3, 127.2, 127.8, 128.6, 134.8, 140.0 ppm;
IR (NaCl): ꢀm = 3,065, 3,028, 2,978, 2,938, 1,642, 1,495,
1,454, 1,354, 1,175, 958, 927, 837, 702 cm-1; HRMS
(ES?, TOF): calcd for C12H16O3SNa ([M ? Na]?)
263.0718, found 263.0716.
N,N-dibenzyl-2-phenylpent-4-enamide (5f, C25H25NO)
A mixture of 1 g 2-phenylpent-4-enoic acid (5.68 mmol),
1 cm3 oxalyl chloride (11.64 mmol), and 15 cm3 dry
toluene was refluxed for 1 h. The volatiles were evapo-
rated in vacuo and the oily residue was dissolved in
20 cm3 dry CH2Cl2. To the resulting cold (0 °C) solution,
3 cm3 dibenzylamine (15.51 mmol) was added. The
reaction mixture was allowed to warm to room temper-
ature at which it was stirred for 15 h. Then 40 cm3 1 M
HCl was added, the layers were separated, and the
aqueous layer was extracted with 3 9 10 cm3 CH2Cl2.
The combined organic extracts were dried over anhydrous
Na2SO4, filtered, and concentrated in vacuo to give
1,2-Diphenylpent-4-en-1-one (5c)
A
mixture of 356 mg 2-phenylpent-4-enoic acid
(2.02 mmol), 0.35 cm3 oxalyl chloride (4.08 mmol), and
5 cm3 dry toluene was refluxed for 1 h. The volatiles were
evaporated in vacuo and the oily residue was dissolved in
5 cm3 dry THF. To the resulting cold (0 °C) solution
0.8 cm3 phenylmagnesium bromide (2.4 mmol, 3 M in
Et2O) was slowly added under Ar. The reaction mixture
was stirred for 1.5 h at the same temperature and then
allowed to warm to room temperature at which it was
stirred for 15 h. Then 15 cm3 sat. NH4Cl was added and
extracted with 3 9 10 cm3 Et2O. The combined organic
extracts were dried over anhydrous Na2SO4 and concen-
trated in vacuo. Purification of the crude product by radial
chromatography (petroleum ether/EtOAc = 20/1) yielded
300 mg (63 %) 5c as a colorless oil. NMR spectroscopic
data are consistent with reported data [48].
1
1.433 g 5f (71 %) as a colorless oil. H NMR (300 MHz,
DMSO-d6): d = 2.30–2.39 (m, 1H, CHaHbCH=), 2.72–
2.82 (m, 1H, CHaHbCH=), 4.01 (dd, J = 6.3, 8.4 Hz, 1H,
CH), 4.24 (d, J = 15.0 Hz, 1H, NCHa1Hb1Ph), 4.36 (d,
J = 16.9 Hz, 1H, NCHa1Hb1Ph), 4.55 (d, J = 16.9 Hz,
1H, NCHa2Hb2Ph), 4.70 (d, J = 15.0 Hz, 1H, NCHa2
Hb2Ph), 4.92–5.01 (m, 2H, H2C=CH), 5.62–5.75 (m, 1H,
H2C=CH), 7.03–7.08 (m, 4H, Ar), 7.21–7.34 (m, 11H, Ar)
ppm; 13C NMR (75.5 MHz, CDCl3): d = 39.6, 48.3, 49.3,
49.6, 116.7, 126.4, 127.1, 127.2, 127.5, 127.9, 128.0,
128.4, 128.77, 128.80, 136.2, 136.5, 137.4, 139.6,
ꢀ
173.0 ppm; IR (NaCl): m = 3,064, 3,029, 2,921, 1,647,
1,495, 1,452, 1,438, 1,207, 1,178, 699 cm-1; HRMS
(ES?, TOF): calcd for C25H26NO ([M ? H]?) 356.2014,
found 356.2002.
2-Phenylpent-4-en-1-ol (5d)
N-Methoxy-N-methyl-2-phenylpent-4-enamide
(5g, C13H17NO2)
To a cold solution (0 °C) of 356 mg 2-phenylpent-4-enoic
acid (2.02 mmol) in 8 cm3 dry THF, 3 cm3 suspension of
LiAlH4 (6 mmol, 2 M in THF) was slowly added. The
reaction mixture was allowed to warm to room temperature
at which it was stirred for 15 h. The reaction was quenched
by the successive addition of 1 cm3 H2O, 1 cm3 2 M
aqueous NaOH, and 1.5 cm3 H2O. The solid was filtered
and washed with 3 9 10 cm3 CH2Cl2. The organic layer
was washed with 20 cm3 H2O, dried over anhydrous
Na2SO4, filtered, and concentrated in vacuo to give 256 mg
5d (78 %) as an orange oil. The NMR spectroscopic data
are consistent with reported data [49].
A mixture of 1 g 2-phenylpent-4-enoic acid (5.68 mmol),
1 cm3 oxalyl chloride (11.64 mmol), and 15 cm3 dry
toluene was refluxed for 1 h. The volatiles were evaporated
in vacuo and the oily residue was dissolved in 20 cm3 dry
CH2Cl2. To the resulting cold (0 °C) solution, 848 mg
N,O-dimethylhydroxylamine hydrochloride (8.52 mmol)
and 2 cm3 triethylamine (14.33 mmol) were added. The
reaction mixture was allowed to warm to room temperature
at which it was stirred for 15 h. Then 40 cm3 1 M HCl was
added, the layers were separated, and the aqueous layer
was extracted with 3 9 10 cm3 CH2Cl2. The combined
organic extracts were dried over anhydrous Na2SO4,
filtered, and concentrated in vacuo. Purification of the
crude product by radial chromatography (petroleum ether/
EtOAc = 25/1) yielded 772 mg (62 %) 5g as a colorless
5-Bromo-4-phenylpent-1-ene (5e)
A mixture of 563 mg 5b (2.34 mmol), 1.95 g LiBr
(22.4 mmol), and 18 cm3 acetone was refluxed for 5 h.
Then the volatiles were evaporated in vacuo, 50 cm3 H2O
was added to the oily residue and extracted with
3 9 15 cm3 CH2Cl2. The combined organic extracts were
dried over anhydrous Na2SO4, filtered, and concentrated in
vacuo. Purification of the crude product by radial chroma-
tography (petroleum ether/EtOAc = 10/1) yielded 374 mg
(71 %) 5e as a yellow oil. NMR spectroscopic data are
consistent with reported data [50].
1
oil. H NMR (300 MHz, CDCl3): d = 2.41–2.50 (m, 1H,
CHaHbCH=), 2.79–2.89 (m, 1H, CHaHbCH=), 3.15 (s, 3H,
CH3), 3.46 (s, 3H, OCH3), 4.07 (m, 1H, CH), 4.95–5.08 (m,
2H, H2C=CH), 5.67–5.81 (m, 1H, H2C=CH), 7.19–7.34 (m,
5H, Ar) ppm; 13C NMR (75.5 MHz, CDCl3): d = 32.3,
38.2, 47.6, 61.2, 116.5, 126.9, 128.1, 128.5, 136.0, 139.6,
ꢀ
173.9 ppm; IR (NaCl): m = 3,075, 3,030, 2,974, 2,938,
123

ˇ
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B. Stefane, F. Pozgan
638
2,820, 1,730, 1,662, 1,455, 1,440, 1,417, 1,383, 1,175, 992,
700 cm-1; HRMS (ES?, TOF): calcd for C13H18NO2
([M ? H]?) 220.1338, found 220.1335.
Methyl 8-bromo-2,7-diphenyloct-4-enoate
(6ae, C21H23BrO2)
Obtained in the reaction of 190 mg 5a (1 mmol) and
450 mg 5e (2 mmol). Column chromatography (petroleum
ether/EtOAc, 20:1) afforded 155 mg (40 %) 6ae. 1H NMR
(300 MHz, CDCl3): d = 2.29–2.52 (m, 3H, CH2CH=
CHCHaHb), 2.67–2.76 (m, 1H, CHaHbCH=CH), 2.94 (m,
1H, CH2CHCH2Br), 3.43–3.49 (m, 2H, CH2Br), 3.53 (m,
1H, CHCO2Me), 3.63 (s, 3H, CO2CH3), 5.23–5.44 (m, 2H,
CH=CH), 7.07–7.15 (m, 2H, Ar), 7.21–7.34 (m, 8H, Ar)
ppm; 13C NMR (75.5 MHz, CDCl3): major d = 36.8, 37.1,
38.3, 47.8, 51.6, 52.5, 126.8, 127.2, 127.8, 128.3, 128.8,
129.2, 129.7, 138.9, 141.6, 173.5 ppm; IR (NaCl):
General procedure for the metathesis reaction
of olefins 5
A mixture of two different olefins 5 in the molar ratio 1 :
1.2–2, 15 cm3 CH2Cl2, and 16 mg Hoveyda-Grubbs cata-
lyst (3) (0.025 mmol, 2.5 mol %) was refluxed for 24 h.
Then the reaction mixture was evaporated under reduced
pressure and the residue was purified by column chroma-
tography on silica gel to give different distributions of
products 6, 7, and 8. For full details see Table 1.
ꢀ
m = 3061, 3,029, 2,951, 2,922, 2,848, 1,736, 1,495,
1,452, 1,435, 1,267, 1,224, 1,197, 1,161, 971, 700 cm-1
;
Methyl 8-(methylsulfonyloxy)-2,7-diphenyloct-4-enoate
(6ab, C22H26O5S)
HRMS (ES?, TOF): calcd for C21H24BrO2 ([M ? H]?)
387.0960, found 387.0960.
Obtained in the reaction of 380 mg 5a (2 mmol) and
240 mg 5b (1 mmol). Column chromatography (petroleum
ether/EtOAc, 25:1, then 5:1) afforded 113 mg (28 %)
N,N-Dibenzyl-8-hydroxy-2,7-diphenyloct-4-enamide
(6df, C34H35NO2)
Obtained in the reaction of 355 mg 5f (1 mmol) and
324 mg 5d (2 mmol). Column chromatography (petroleum
ether/CH2Cl2, 1:5, then CH2Cl2, then CH2Cl2/MeOH, 10:1)
1
6ab. H NMR (300 MHz, CDCl3): minor 5.25–5.31 (m,
0.5H, CH=CH); major d = 2.30–2.47 (m, 3H, CH2CH=
CHCHaHb), 2.67–2.77 (m, 1H, CHaHbCH=CH), 2.74 (s,
3H, OSO2CH3), 2.87–3.03 (m, 1H, CH2CHCH2), 3.53 (dd,
J = 7.3, 7.7 Hz, 1H, CHCO2CH3), 3.63 (s, 3H, CO2CH3),
4.26 (m, 2H, CH2OSO2CH3), 5.31–5.39 (m, 2H, CH=CH),
7.10–7.16 (m, 2H, Ar), 7.22–7.33 (m, 8H, Ar) ppm; 13C
NMR (75.5 MHz, CDCl3): major d = 33.5, 36.5, 38.4,
44.7, 51.8, 52.1, 72.5, 126.4, 127.0, 127.1, 127.5, 128.1,
1
afforded product 6df (78 mg, 16 %). H NMR (300 MHz,
CDCl3): major d = 1.65 (rs, 1H, OH), 2.27–2.60 (m, 3H,
CH2CH=CHCHaHb), 2.68–2.96 (m, 2H, CHaHbCH= and
CHCH2OH), 3.64–3.80 (m, 3H, CH2OH and CHCON),
4.12–4.26 (m, 2H, NCH2Ph), 4.48–4.58 (m, 1H,
NCHaHbPh), 4.97–5.12 (m, 1H, NCHaHbPh), 5.29–5.43
(m, 2H, CH=CH), 7.03–7.34 (m, 20H, Ar) ppm; 13C NMR
(75.5 MHz, CDCl3): major d = 35.6, 48.3, 49.6, 66.7,
126.4, 126.7, 127.0, 127.2, 127.5, 127.9, 128.0, 128.5,
128.7, 128.8, 136.6, 137.4, 139.6, 142.2, 173.1 ppm; IR
ꢀ
129.2, 136.6, 139.8, 173.2 ppm; IR (NaCl): m = 3,029,
2,949, 2,925, 2,853, 1,734, 1,495, 1,455, 1,436, 1,354,
1,173, 956, 838, 701 cm-1; HRMS (ES?, TOF): calcd
for C22H26O5SNa ([M ? Na]?) 425.1399, found 425.1406.
ꢀ
(NaCl): m = 3,448, 3,062, 3,027, 2,925, 1,645, 1,494,
1,453, 1,437, 1,030, 971, 700 cm-1; HRMS (ES?, TOF):
calcd for C34H36NO2 ([M ? H]?) 490.2746, found
490.2737.
8-Hydroxy-1,2,7-triphenyloct-4-en-1-one
(6cd, C26H26O2)
Obtained in the reaction of 236 mg 5c (1 mmol) and
195 mg 5d (1.2 mmol). Column chromatography (petro-
leum ether/EtOAc, 20:1, then 10:1, then 3:1) afforded
Methyl 8-(dibenzylamino)-8-oxo-2,7-diphenyloct-4-enoate
(6af, C35H35NO3)
1
133 mg (36 %) 6cd. H NMR (300 MHz, CDCl3): minor
Obtained in the reaction of 380 mg 5a (2 mmol) and
355 mg 5f (1 mmol). Column chromatography (petroleum
1
ether/EtOAc, 20:1) afforded 88 mg 6af (17 %). H NMR
d = 4.34 (t, J = 7.3 Hz, 0.25H, CHCOPh), 5.26–5.30 (m,
0.5H, CH=CH); major d = 1.54 (rs, 1H, OH), 2.19–2.48
(m, 3H, CH2CH= and CHCH2OH), 2.65–2.88 (m, 2H,
CH2CH= CH), 3.58–3.70 (m, 2H, H2COH), 4.47 (t,
J = 7.3 Hz, 1H, CHCOPh), 5.34–5.38 (m, 2H, CH=CH),
7.09–7.48 (m, 13H, Ar), 7.88–7.91 (m, 2H, Ar) ppm; 13C
NMR (75.5 MHz, CDCl3): major d = 35.3, 37.0, 48.3,
54.0, 66.6, 126.6, 127.0, 127.9, 128.1, 128.42, 128.44,
128.6, 128.8, 129.4, 130.0, 132.8, 136.7, 139.1, 142.0,
(300 MHz, CDCl3): minor d = 3.42 (t, J = 7.7 Hz, 1H,
CHCO2Me), 3.57 (s, 2H, CO2CH3); major d = 2.30–2.56
(m, 2H, CH2aCH=), 2.67–2.91 (m, 2H, CH2bCH=), 3.52 (t,
J = 7.7 Hz, 1H, CHC2OMe), 3.61 (s, 3H, CO2CH3), 3.65–
3.71 (m, 1H, CHCON), 4.12–4.23 (m, 2H, NCH2Ph), 4.46–
4.54 (m, 1H, NCHaHbPh), 4.94–5.05 (m, 1H, NCHaHbPh),
5.23–5.48 (m, 2H, CH=CH), 7.00–7.02 (m, 2H, Ar), 7.08–
7.10 (m, 2H, Ar), 7.21–7.34 (m, 16H, Ar) ppm; 13C NMR
(75.5 MHz, CDCl3): major d = 36.9, 38.9, 48.8, 49.6,
50.0, 51.9, 52.3, 126.9, 127.7, 128.0, 128.3, 128.4, 128.46,
128.49, 128.9, 129.0, 129.2, 129.3, 137.0, 137.8, 139.1,
ꢀ
199.3 ppm; IR (NaCl): m = 3,425, 3,061, 3,027, 2,920,
1,681, 1,598, 1,494, 1,449, 699 cm-1; HRMS (ES?, TOF):
calcd for C26H27O2 ([M ? H]?) 371.2011, found
371.2014.
123

Reactivity of terminal phenylpentenes
639
140.0, 173.5, 174.4 ppm; IR (NaCl): ꢀm = 3,061, 3,028,
2,950, 2,922, 1,737, 1,646, 1,493, 1,454, 1,436, 1,267,
1,221, 1,156, 970, 698 cm-1; HRMS (ES?, TOF): calcd
for C35H36NO3 ([M ? H]?) 518.2695, found 518.2695.
2,7-Diphenyl-1,8-dibromo-4-octene (7e, C20H22Br2)
Obtained in the reaction of 190 mg 5a (1 mmol) and
450 mg 5e (2 mmol). Column chromatography (petroleum
1
ether/EtOAc, 20:1) afforded 106 mg 7e (25 %). H NMR
(300 MHz, CDCl3): major d = 2.30–2.38 (m, 2H,
2 9 CHaHbCH=), 2.47–2.53 (m, 2H, 2 9 CHaHbCH=),
2.95 (m, 2H, 2 9 CH), 3.44 (m, 4H, 2 9 CH2Br), 5.25–
5.29 (m, 2H, CH=CH), 7.06–7.09 (m, 2H, Ar), 7.24–7.34
(m, 8H, Ar) ppm; 13C NMR (75.5 MHz, CDCl3): major
d = 37.5, 38.1, 47.2, 126.5, 127.0, 127.8, 128.5,
142.6 ppm.
8-(Dibenzylamino)-8-oxo-2,7-diphenyloct-4-enyl methane-
sulfonate (6bf, C35H37NO4S)
Obtained in the reaction of 480 mg 5b (2 mmol) and
355 mg 5f (1 mmol). Column chromatography (petroleum
1
ether/EtOAc, 25:1) afforded 17 mg 6bf (3 %). H NMR
(300 MHz, CDCl3): major d = 2.25–2.41 (m, 3H,
CH2CHCH2CH= and COCHCHaHbCH=), 2.73 (s, 3H,
OSO2CH3), 2.77–2.86 (m, 1H, COCHCHaHbCH=), 2.92–
3.02 (m, 1H, CH2CHCH2CH=), 3.62–3.71 (m, 1H,
CHCON), 4.10–4.27 (m, 4H, CH2O and NCH2Ph), 4.45–
4.54 (m, 1H, NCHaHbPh), 4.93–5.08 (m, 1H, NCHaHbPh),
5.22–5.46 (m, 2H, CH=CH), 6.99–7.01 (m, 2H, Ar), 7.07–
7.13 (m, 4H, Ar), 7.21–7.33 (m, 14H, Ar) ppm; 13C NMR
(75.5 MHz, CDCl3): major d = 37.1, 72.8, 126.5, 127.2,
127.3, 127.86, 127.93, 128.1, 128.5, 128.6, 128.78, 128.83,
136.7, 137.5, 139.5, 140.3, 173.1 ppm; HRMS (ES?,
TOF): calcd for C35H38NO4S ([M ? H]?) 568.2522, found
568.2527.
2-Phenylpent-3-enyl methanesulfonate (8b, C12H16O3S)
Obtained in the reaction of 240 mg 5b (1 mmol) and
324 mg 5d (2 mmol). Column chromatography (petroleum
1
ether/CH2Cl2, 1:1) afforded 72 mg (30 %) 8b. H NMR
(300 MHz, CDCl3): major d = 1.68 (dd, J = 6.7, 1.5 Hz,
3H, CH3CH=), 2.78 (m, 3H, OSO2CH3), 3.67–3.73 (m, 1H,
CH), 4.32–4.39 (m, 2H, CH2), 5.56–5.64 (m, 2H, CH=CH),
7.20–7.36 (m, 5H, Ar) ppm; HRMS (ES?, TOF): calcd for
C12H16O3SNa ([M ? Na]?) 263.0718, found 263.0716.
1,2-Diphenylpent-3-en-1-one (8c, C17H16O)
Obtained in the reaction of 236 mg 5c (1 mmol) and
195 mg 5d (1.2 mmol). Column chromatography (petro-
leum ether/EtOAc, 20:1, then 10:1, then 3:1) afforded
28 mg 8c (12 %). 1H NMR (300 MHz, CDCl3): minor
d = 1.75 (dd, J = 1.7, 6.9 Hz, 1.36H, CH3CH=), 5.52 (d,
J = 6.6 Hz, 0.45H, CHCH=); major d = 1.71 (dd,
J = 1.2, 6.5 Hz, 3H, CH3CH=), 5.24 (d, J = 8.1 Hz, 1H,
CHCH=), 5.49–5.61 (m, 1H, CHa=CHb), 5.95–6.06 (m, 1H,
CHa=CHb), 7.19–7.51 (m, 8H, Ar), 7.94–7.99 (m, 2H, Ar)
ppm; HRMS (ES?, TOF): calcd for C17H16ONa
([M ? Na]?) 259.1099, found 259.1096.
Dimethyl 2,7-diphenyloct-4-enedioate (7a, C22H24O4)
Obtained in the reaction of 380 mg 5a (2 mmol) and
240 mg 5b (1 mmol). Column chromatography (petroleum
ether/EtOAc, 25:1, then 5:1) afforded 123 mg (35 %) 7a.
1H NMR (300 MHz, CDCl3): minor d = 2.47–2.56 (m,
0.5H, 2 9 CHaHb), 2.78–2.86 (m, 0.5H, 2 9 CHaHb), 3.45
(t, J = 7.8 Hz, 0.5H, 2 9 CH), 3.62 (s, 1.5H, 2 9 OCH3),
5.28–5.31 (m, 0.5H, CH=CH); major d = 2.35–2.43 (m,
2H, 2 9 CHaHb), 2.67–2.76 (m, 2H, 2 9 CHaHb), 3.52
(dd, J = 6.9, 7.7 Hz, 2H, 2 9 CH), 3.63 (s, 6H,
2 9 OCH3), 5.37–5.41 (m, 2H, CH=CH), 7.20–7.32 (m,
10H, Ar) ppm; 13C NMR (75.5 MHz, CDCl3): major
d = 36.9, 51.5, 52.0, 127.9, 128.3, 128.6, 129.4, 139.1,
2-Phenylpent-3-en-1-ol (8d, C11H14O)
Obtained in the reaction of 236 mg 5c (1 mmol) and
195 mg 5d (1.2 mmol). Column chromatography (petro-
leum ether/EtOAc, 20:1, then 10:1, then 3:1) afforded
39 mg 8d (20 %). 1H NMR (300 MHz, CDCl3): minor
d = 1.70 (dd, J = 1.5, 6.7 Hz, 1.2H, H3CCH=); major
d = 1.50 (rs, 1H, OH), 1.72 (d, J = 4.5 Hz, 3H,
H3CCH=), 3.43–3.50 (m, 1H, CH), 3.71–3.77 (m, 2H,
CH2OH), 5.55–5.64 (m, 2H, CH=CH), 7.21–7.26 (m, 3H,
Ar), 7.30–7.35 (m, 2H, Ar) ppm; 13C NMR (75.5 MHz,
CDCl3): major d = 18.1, 51.7, 66.4, 126.7, 127.8, 128.1,
128.7, 130.9, 141.4 ppm; HRMS (ES?, TOF): calcd for
C11H15O ([M ? H]?) 163.1123, found 163.1131.
ꢀ
173.1 ppm; IR (NaCl): m = 2,956, 2,925, 2,854, 1,742,
1,457, 1,378, 1,159 cm-1; HRMS (ES?, TOF): calcd for
C22H25O4 ([M ? H]?) 353.1753, found 353.1757.
2,7-Diphenyloct-4-ene-1,8-diol (7d, C20H24O2)
Obtained in the reaction of 355 mg 5f (1 mmol) and
324 mg 5d (2 mmol). Column chromatography (petroleum
ether/CH2Cl2, 1:5, then CH2Cl2, then CH2Cl2/MeOH, 10:1)
afforded product 7d (9 mg, 3 %). 1H NMR (300 MHz,
CDCl3): major d = 1.26 (rs, 2H, 2 9 OH), 2.22–2.41 (m,
4H, 2 9 CH2CH=), 2.69–2.82 (m, 2H, 2 9 CH), 3.62–3.77
(m, 4H, 2 9 CH2OH), 5.29–5.35 (m, 2H, CH=CH), 7.13–
N,N-dibenzyl-2-phenylpent-3-enamide (8f, C25H25NO)
Obtained in the reaction of 355 mg 5f (1 mmol) and
324 mg 5d (2 mmol). Column chromatography (petroleum
ether/CH2Cl2, 1:5, then CH2Cl2, then CH2Cl2/MeOH, 10:1)
ꢀ
7.35 (m, 10H, Ar) ppm; IR (NaCl): m = 3,361, 3,026,
2,923, 2,888, 1,631, 1,494, 1,452, 1,054, 973, 701 cm-1
;
HRMS (ES?, TOF): calcd for C20H25O2 ([M ? H]?)
297.1855, found 297.1852.
123

ˇ
B. Stefane, F. Pozgan
ˇ
640
1
20. Fu GC, Nguyen ST, Grubbs RH (1993) J Am Chem Soc 115:9856
21. Scholl M, Ding S, Lee CW, Grubbs RH (1999) Org Lett 1:953
22. Connon SJ, Blechert S (2003) Angew Chem Int Ed 42:1900
23. Netscher T (2006) J Organomet Chem 691:5155
24. Prunet J (2005) Curr Top Med Chem 5:1559
25. Chattopadhyay SK, Karmakar S, Biswas T, Majumdar KC,
Rahaman H, Roy B (2007) Tetrahedron 63:3919
26. Bielawski CW, Grubbs RH (2007) Prog Polym Sci 32:1
27. Keitz BK, Endo K, Patel PR, Herbert MB, Grubbs RH (2012) J
Am Chem Soc 134:693
afforded product 8f (146 mg, 41 %). H NMR (300 MHz,
CDCl3): minor d = 1.44 (dd, J = 1.8, 6.9 Hz, 0.94H,
CH3CH=); major d = 1.67 (dd, J = 1.3, 6.4 Hz, 3H,
CH3CH=), 4.12–4.56 (m, 4H, NCH2Ph, NCHaHbPh and
CHCH=), 4.94–4.99 (m, 1H, NCHaHbPh), 5.31–5.43 (m,
1H CHa=CHb), 5.91–6.00 (m, 1H, CHa=CHb), 7.01–7.38
(m, 15H, Ar) ppm; IR (NaCl): ꢀm = 3,030, 2,926, 1,630,
1,443, 1,214, 976, 699 cm-1; HRMS (ES?, TOF): calcd
for C25H26NO ([M ? H]?) 356.2014, found 356.2021.
28. Chatterjee AK, Choi T-L, Sanders DP, Grubbs RH (2003) J Am
Chem Soc 125:11360
29. Malacea R, Fischmeister C, Bruneau C, Dubois J-L, Couturier
J-L, Dixneuf PH (2009) Green Chem 11:152
30. Miao X, Blokhin A, Pasynskii A, Nefedov S, Osipov SN, Roisnel
T, Bruneau C, Dixneuf PH (2010) Organometallics 29:5257
31. Miao X, Fischmeister C, Malacea R, Bruneau C, Dixneuf PH
(2011) Green Chem 13:2911
Acknowledgments The Ministry of Higher Education, Science and
Technology of the Republic of Slovenia and the Slovenian Research
Agency (P1-0230-0103) are gratefully acknowledged for their finan-
cial support. This work was performed and financed as a part of the
ˇ
EN ? FIST Centre of Excellence. Dr. B. Kralj and Dr. D. Zigon
ˇ
(Center for Mass Spectroscopy, Jozef Stefan Institute, Ljubljana,
Slovenia) are gratefully acknowledged for the mass measurements.
32. Rybak A, Meier MAR (2007) Green Chem 9:1356
´
33. Behr A, Perez Gomes J (2011) Beilstein J Org Chem 7:1
34. Montero de Espinosa L, Kempe K, Schubert US, Hoogenboom R,
Meier MAR (2012), Macromol Rapid Commun. doi:10.1002/
marc.201200487
References
35. Abbas M, Slugovc C (2011) Tetrahedron Lett 52:2560
36. Netscher T (2005) Curr Top Med Chem 5:1579
37. Marshall JA, Sabatini JJ (2006) Org Lett 8:3557
1. Kricheldorf HR, Nuyken O, Swift G (2005) Handbook of poly-
mer synthesis, 2nd edn. Marcel Dekker, New York
2. Nicolaou KC, Bulger PG, Sarlah D (2005) Angew Chem Int Ed
44:4442
3. Zhao P, Shpasser D, Eisen MS (2012) J Polym Sci Part A Polym
Chem 50:523
4. Mackenzie K (1964) In: Patai S (ed) The chemistry of alkenes.
Wiley, New York
5. Semmelhack MF (ed) (1991) Comprehensive organic synthesis:
additions to and substitutions at C-C p-bonds, vol 4. Pergamon
Press, Oxford
¨
38. Rahuel J, Rasetti V, Maibaum J, Ru¨eger H, Goschke R, Cohen
N-C, Stutz S, Cumin F, Fuhrer W, Wood JM, Gru¨tter MG (2000)
Chem Biol 7:493
39. Dominguez B, Dyke A, Hems W, Mathes C, O’Sullivan AC,
Sedelmeier G (2008) Process for the synthesis of intermediates of
renin inhibitors such as aliskiren. WO 2008/155338 A2, Dec 24,
2008
´
40. Hanessian S, Chenard E (2012) Org Lett 14:3222
41. Hanessian S, Guesne S, Chenard E (2010) Org Lett 12:1816
´
´
ˇ
ˇ
ˇ
42. Pozgan F, Stefane B, Kidemet D, Smodis J, Zupet R (2012)
¯
6. Grubbs RH (ed) (2003) Handbook of metathesis, vol 3. Wiley,
Weinheim
7. Hoveyda AH, Zhugralin AR (2007) Nature 450:243
8. Astruc D (2005) New J Chem 29:42
Tetrahedron 68:5081
43. Duguet N, Slawin AMZ, Smith AD (2009) Org Lett 11:3858
44. Schmidt B (2004) Eur J Org Chem 1865
45. Fu¨rstner A, Langemann K (1997) J Am Chem Soc 119:9130
46. Arisawa M, Terada Y, Nakagawa M, Nishida A (2002) Angew
Chem Int Ed 41:4732
47. Tsuji J, Shimizu I, Minami I, Ohashi Y, Sugiura T, Takahashi K
(1985) J Org Chem 50:1523
9. Trnka TM, Grubbs RH (2001) Acc Chem Res 34:18
10. Fu¨rstner A (2000) Angew Chem Int Ed 39:3012
11. Deiters A, Martin SF (2004) Chem Rev 104:2199
12. McReynolds MD, Dougherty JM, Hanson PR (2004) Chem Rev
104:2239
48. Yan X–X, Liang C-G, Zhang Y, Hong W, Cao B-X, Dai L-X,
Hou X-L (2005) Angew Chem Int Ed 44:6544
13. Nicolaou KC, Bulger PG, Sarlah D (2005) Angew Chem Int Ed
44:4490
49. Kim D, Wang L, Caldwell CG, Chen P, Finke PE, Oates B,
MacCoss M, Mills SG, Malkowitz L, Gould SL, DeMartino JA,
Springer MS, Hazuda D, Miller M, Kessler J, Danzeisen R,
Carver G, Carella A, Holmes K, Lineberger J, Schleif WA, Emini
EA (2001) Bioorg Med Chem Lett 11:3103
50. Baker RK, Kayser F, Bao J, Kotliar A, Parsons WH, Rupprecht
KM, Claiborne CF, Liverton N, Claremon DA, Thompson WJ
(2007) Benzamide potassium channel inhibitors. EP 1 126 836
B1, February 14, 2007
´
14. Gradillas A, Perez-Castells J (2006) Angew Chem Int Ed 45:6086
15. van Otterlo WAL, De Koning CB (2009) Chem Rev 109:3743
16. Nolan SP, Clavier H (2010) Chem Soc Rev 39:3305
17. Prunet J (2011) Eur J Org Chem 3634
˙
ˇ
˘
18. Pozgan F, Dixneuf PH (2007) In: Imamoglu Y, Dragutan V,
Karabulut S (eds) Metathesis chemistry: from nanostructure
design to synthesis of advanced materials, vol 243. Springer,
Dordrecht London, p 195
19. Schrock RR, Murdzek JS, Bazan GC, Robbins J, DiMare M,
O’Regan M (1990) J Am Chem Soc 112:3875
123