Terpenic compounds as renewable sources of raw materials for cross-metathesis

Article abstract of DOI:10.1055/s-0030-1260605

Dihydromyrcenol is used as a hydrated masked form of citronellene in olefin cross-metathesis reactions in order to solve the selectivity problem that results from the presence of two double bonds in many terpenes. Several ruthenium catalysts are evaluated, with the best, M71-SIPr, utilized in the cross-metathesis of dihydromyrcenol with various olefins affording the expected products in good yields. It is shown that the masked double bond can be regenerated via an acid-catalyzed elimination reaction and the product is then subjected to a further cross-metathesis reaction with a second olefin. Georg Thieme Verlag Stuttgart ? New York.

Full text of DOI:10.1055/s-0030-1260605

PAPER
2125
Terpenic Compounds as Renewable Sources of Raw Materials for
Cross-Metathesis
C
ross-Metathes
t
i
rpenic
e
C
ompound
n
s
ne Borré,a,b Trong Hoa Dinh,a,b Frédéric Caijo,*c Christophe Crévisy,*a,b Marc Mauduit*a,b
a
Ecole Nationale Supérieure de Chimie de Rennes, CNRS, UMR 6226, Avenue du Général Leclerc, CS 50837, 35708 Rennes Cedex 7,
France
Fax +33(2)23238108; E-mail: crevisy@ensc-rennes.fr; E-mail: marc.mauduit@ensc-rennes.fr
Université européenne de Bretagne, 5 Boulevard Laënnec, 35000 Rennes, France
Oméga Cat System, Avenue du Général Leclerc, CS 50837, 35708 Rennes Cedex 7, France
b
c
Received 22 March 2011; revised 21 April 2011
low loadings can be employed. Moreover, owing to both
the presence of more than one double bond in many ter-
penic compounds, and to the strong substrate-dependency
of metathesis reactions, it is necessary to utilize catalysts
Abstract: Dihydromyrcenol is used as a hydrated masked form of
citronellene in olefin cross-metathesis reactions in order to solve the
selectivity problem that results from the presence of two double
bonds in many terpenes. Several ruthenium catalysts are evaluated,
with the best, M71-SIPr, utilized in the cross-metathesis of dihy- that demonstrate high efficiency toward various sub-
dromyrcenol with various olefins affording the expected products in
strates while limiting the formation of by-products. We
good yields. It is shown that the masked double bond can be regen-
have previously developed a library of Hoveyda-type
erated via an acid-catalyzed elimination reaction and the product is
boomerang ruthenium catalysts C1 which contain an ami-
then subjected to a further cross-metathesis reaction with a second
nocarbonyl function linked to a benzylidene ligand
olefin.
(Figure 1).4
Key words: terpenoids, olefin metathesis, chemoselectivity, agro-
resources, dihydromyrcenol
L
Cl
Ru
O
Cl
R
L = SIMes, SIPr
Owing to both the decrease of oil stocks (and consequent-
ly increased prices) and environmental issues such as the
greenhouse effect, the attention of researchers has focused
on the use of renewable feedstocks isolated from agro-re-
sources to produce various types of organic compounds,
for example, raw materials, intermediates, fine chemicals,
organic polymers, solvents, etc.1 Of all the products that
can be isolated from agro-resources (vegetable oils, sug-
ars, etc.), terpenes and terpenoids appear particularly at-
tractive. Some of these, mainly the most expensive, are
used directly, whilst many procedures have been devel-
oped to transform cheaper examples including pinenes, li-
monene and citral into added-value products such as
fragrances.1 To be more eco-compatible, chemical pro-
cesses dedicated to the conversion of raw materials ob-
tained from renewable resources necessitate the use of
environmentally-benign reactions. Catalyzed reactions
are particularly suitable for this purpose, and as most ter-
penic compounds contain one or more carbon–carbon
double bonds, olefin metathesis is potentially a tool of
choice for their conversion into valuable products. Meta-
thesis has long been considered as a versatile tool in oleo-
chemistry,2 however, there are only a few reports
describing the olefin metathesis (notably cross-metathe-
sis) of terpenic compounds.3 To develop fully eco-com-
patible and economically viable processes, sufficiently
stable and active catalysts have to be used such that very
O
NH
R = CF3, CO2Et, Oi-Bu, C6F5, C15H31
C1
i-Pr
i-Pr
N
N
N
N
i-Pr i-Pr
SIPr
SIMes
C1a (M71-SIPr): L = SIPr, R = CF3; C1b (M71-SIMes): L = SIMes, R = CF3;
C1c (M73-SIPr): L = SIPr, R = Oi-Bu; C1d (M73-SIMes): L = SIMes, R = Oi-Bu
Figure 1 Examples of olefin metathesis catalysts
The activity of the pre-catalyst can be controlled efficient-
ly by the nature of the amide group (via the electron-with-
drawing effect). We have at our disposal a large library of
complexes which have varying activities toward a wide
spectrum of metathesis substrates (ring-closing metathe-
sis and cross-metathesis). These complexes remain active
even at very low loading (0.3 mol%) in both ring-closing
metathesis and cross-metathesis and exhibit remarkable
recyclability (ranging between 50–60% at 0.3 mol%) after
silica gel filtration; only a few parts per million of ruthe-
nium waste was detected in the final products (<2 ppm),
attesting to the robustness of these catalysts in the reaction
medium.4a Hence, we can perform efficient screening of
the library and find the best catalyst for a given transfor-
mation whilst reducing the formation of by-products.
We have evaluated our catalysts in the cross-metathesis of
terpenic compounds in order to demonstrate that they can
be used efficiently to develop green cross-metathesis-
SYNTHESIS 2011, No. 13, pp 2125–2130
Advanced online publication: 26.05.2011
DOI: 10.1055/s-0030-1260605; Art ID: Z31711SS
© Georg Thieme Verlag Stuttgart · New York
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x.
x
x
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0
1
1

2126
E. Borré et al.
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based routes starting from terpenes or their derivatives, product P2c was observed in the NMR spectra of the
dedicated to the production of valuable intermediates or crude mixture, along with other unidentified products
products. Our results are reported herein.
(Table 1, entry 6). When linalool (S4) was reacted with
two equivalents of crotonaldehyde (O2) in the presence of
C1a (1 mol%), the formation of ring-closing metathesis
product P33a–c,e was observed instead of the expected
cross-metathesis product (Table 1, entry 7). Interestingly,
when the hydroxy group was protected as a pivaloate S5,
no reaction occurred even in the presence of two equiva-
lents of crotonaldehyde at 60 °C (Table 1, entry 8). To
overcome the difficulty arising from the presence of two
double bonds, as in citronellene, two strategies were ex-
plored. The first possibility was to employ terpene deriv-
atives having only one double bond. Thus, when
citronellol acetate (S6) was reacted with n-butyl acrylate
(O1) in ethyl acetate in the presence of pre-catalyst C1a
(1 mol%), the expected product P4 was obtained in 43%
isolated yield (Table 1, entry 9). The alternative solution
consists of masking the second double bond, for instance
as the hydrated form. Indeed, dihydromyrcenol (S7) can
be considered as a derivative of citronellene where one
double bond is masked as a hydroxy group. The double
bond can be regenerated later from the alcohol through a
simple elimination reaction. Thus, the reactivity of dihy-
dromyrcenol (S7) was evaluated. Reaction of S7 with n-
butyl acrylate (two equivalents) in ethyl acetate in the
presence of C1a (1 mol%) over 17 hours at 60 °C gave the
expected cross-metathesis product P5 in a good isolated
yield of 71% (Table 1, entry 10).
The reactivity of terpenoids S1–S7 in cross-metathesis re-
actions with olefins O1–O2 was first investigated in the
presence of pre-catalyst C1a (Scheme 1).
R1
O
R2
O1 R1 = H, R2 = OnBu
O2 R1 = Me, R2 = H
O
catalyst C1a
S1–S7
R2
OH
S1 (+)-limonene
S2 (–)-β-pinene S3 (–)-citronellene
S4 linalool
OPiv
OAc
OH
S7
dihydromyrcenol
S6
S5
citronellol acetate
Scheme 1 Screening of terpenoids S1–S7 in cross-metathesis cata-
lyzed by pre-catalyst C1a
Table 1 Screening of Terpenic Compounds S1–S7 in Cross-Meta-
thesis Reactions
Entry
Substrate Olefin
(equiv)
Conditionsa
Product
(yield)
In most cases, the reactions were run in the absence of sol-
vent (Figure 2, Table 1). When limonene (S1) was treated
with two equivalents of n-butyl acrylate in the presence of
complex C1a (1 mol%) at 60 °C over 24 hours, formation
of the self-metathesis product P1 of n-butyl acrylate was
observed (Table 1, entry 1). A similar result was observed
when b-pinene (S2) was treated for 17 hours with two
equivalents of n-butyl acrylate in the presence of complex
C1a (1 mol%) at 80 °C (Table 1, entry 2). The cross-met-
athesis of citronellene (S3) was not regioselective as reac-
tion with one equivalent of n-butyl acrylate in the
presence of C1a (1 mol%) over 17 hours at room temper-
ature afforded a number of products. Among these, P2a
(15% yield of isolated product), resulting from cross-meta-
thesis reactions on both double bonds, and P2b, arising
formally from successive cross-metathesis between n-bu-
tyl acrylate and the trisubstituted double bond of S3 and
self-metathesis of the product so formed, were identified
(Table 1, entry 3). When an excess (four equivalents) of n-
butyl acrylate was used, diene P2a was isolated in a
slightly higher 22% yield (Table 1, entry 4). Increasing
the temperature to 60 °C resulted in a small improvement
in the yield to 32% (Table 1, entry 5). This may be due to
competitive ring-closing metathesis of S3,3g which was
confirmed by reacting citronellene (S3) in the absence of
n-butyl acrylate. In this case, the ring-closing metathesis
1
2
3
S1
S2
S3
O1 (2)
O1 (2)
O1 (1)
60 °C, 24 h
80 °C, 17 h
r.t., 17 h
P1
P1
P2a (15%)
P2b (<25%)b
4
5
6
7
8
9
S3
S3
S3
S4
S5
S6
O1 (4)
O1 (4)
–
r.t., 17 h
P2a (22%)
P2a (32%)
P2cc
60 °C, 17 h
r.t., 17 h
O2 (2)
O2 (2)
O1 (2)
60 °C, 7 h
60 °C, 17 h
P3
_
80 °C, 1 h, EtOAc
(0.25 M)
P4 (43%)
10
S7
O1 (2)
60 °C, 17 h, EtOAc P5 (71%)
(1 mL/1 mmol S7)
a Catalyst C1a (1 mol%) was used in all cases.
b It was not possible to fully purify product P2b which was isolated
along with other unidentified products. Its structure was confirmed by
HRMS (ESI) {m/z [M + Na]+ calcd for C24H40O4Na: 415.2824; found:
415.2820 (1 ppm)}.
c Product P2c was detected in the 1H NMR spectrum of the crude mix-
ture along with other unidentified products.
Synthesis 2011, No. 13, 2125–2130 © Thieme Stuttgart · New York

PAPER
Cross-Metathesis of Terpenic Compounds
2127
CO2n-Bu
Table 2 Evaluation of Catalysts C1a–d, C2 and C3 in the Cross-
Metathesis of S7 and n-Butyl Acrylate
Catalyst
Yield (%)a
n-BuO2C
CO2n-Bu
CO2n-Bu
C1a
71
63
73
67
68
25
CO2n-Bu
P2a
C1b
P1
P2b
CO2n-Bu
C1c
C1d
C2
C3
HO
OAc
CO2n-Bu
a Yield of isolated product P5.
CO2n-Bu
OH
P2c
P3
P4
P5
R1
R2
C1a
R2
Figure 2 Structures of products P1–P5
O1 R1 = H, R2 = CO2n-Bu
O2 R1 = Me, R2 = CHO
Next, four catalysts from our library of Hoveyda-type
boomerang ruthenium catalysts containing an aminocar-
bonyl function (Figure 1) were evaluated in the model re-
action of dihydromyrcenol (S7) and n-butyl acrylate in
order to find the most suitable for the targeted application
(Scheme 2, Table 2). Two additional commercial cata-
lysts, M2 catalyst from Umicore (C2) and Grubbs II cata-
lyst (C3) (Figure 3) were also tested. In each case, 1 mol%
of the catalyst was used and the reagents were heated at 60
°C in ethyl acetate for 17 hours.
O3 R1 = H, R2 = CHO
O4 R1 = H,
OH
OH
P5 R2 = CO2n-Bu
P6 R2 = CHO
S7
R
2 = CH(OH)(CH2)4Me
O6 R1 = H, R2 = NHBoc
P7 R2 = CH(OH)(CH2)4Me
O5 R1 = (CH2)7Me
R1
R2
R
2 = (CH2)7CO2Me
C1a
R2
R1
HO
+
P10
OH
CO2n-Bu
(2 equiv)
OH
OH
CO2n-Bu
P8 R1 = (CH2)7Me
catalyst (1 mol%)
EtOAc (1 mL/1 mmol S7)
60 °C, 17 h
P9 R2 = (CH2)7CO2Me
Scheme 3 Cross-metathesis between dihydromyrcenol (S7) and
olefins O1–O6
OH
OH
P5
S7
Scheme 2 Evaluation of catalysts C1a–d, C2 and C3 in the cross-
metathesis of S7 and n-butyl acrylate
Initially, we reinvestigated the reaction with n-butyl acry-
late; after 18 hours at 60 °C in the presence of 1 mol% of
the catalyst, P5 was isolated in 75% yield (Table 3, entry
1). A decrease in the catalyst loading to 0.5 mol% resulted
in a significant drop in the yield to 47% (Table 3, entry 2),
and further reduction of the catalyst loading (0.2 mol%)
led to a more pronounced drop in the efficiency of the re-
action, affording a 28% yield of product P5 after 17 hours
(Table 3, entry 3). Similar behavior was observed with
crotonaldehyde (O2), which in the presence of 1 mol% of
C1a, afforded aldehyde P6 in 53% yield after 23 hours at
60 °C (Table 3, entry 4). A far better result was observed
with acrolein (O3) and the same product P6 was isolated
in a much higher 80% yield using 0.5 mol% of the catalyst
(Table 3, entry 5). A lower yield of product P7 (43%) was
obtained when 1-octen-3-ol (O4) was used as the olefin
(Table 3, entry 6). The reaction of dihydromyrcenol and
methyl oleate (O5) in the presence of C1a (2 mol%) af-
forded the two expected products in good isolated yields
(61% for P8, and 71% for P9) (Table 3, entry 7). It should
be noted that competitive isomerization of the double
SIMes
SIMes
Cl
Ru
Cl
Ru
Cl
Cl
Cy3P
Cy3P
C2 M2 catalyst
C3 Grubbs II catalyst
Figure 3 Structures of the Umicore M2 and Grubbs II catalysts
While catalysts C1a–d and C2 showed similar behavior
(Table 2), to afford the expected cross-metathesis product
P5 in good yields (63–73%), a poor result was observed
with Grubbs II catalyst C3 which gave P5 in a low 25%
yield.
We next evaluated the reactivity of dihydromyrcenol (S7)
toward other olefins using pre-catalyst C1a and ethyl
acetate as the solvent (Scheme 3, Table 3).
Synthesis 2011, No. 13, 2125–2130 © Thieme Stuttgart · New York

2128
E. Borré et al.
PAPER
bond is likely to occur in this case,5 as the presence of a the presence of 5 mol% of sulfuric acid at 120 °C afforded
small amount (<10%) of an impurity having one CH2 a 9:1 mixture of the two expected isomeric elimination
group missing (M – 14) was detected during HRMS anal- products P11 and P11¢ in an acceptable 60% yield. A final
yses of compounds P8 and P9.
cross-metathesis reaction between the regenerated double
bond in P11 and methyl acrylate was undertaken in order
to validate the above-mentioned strategy to overcome the
selectivity problem (Scheme 4). Thus, a mixture of P11/
P11¢ was reacted with methyl acrylate in the presence of
catalyst C1c (1 mol%) for 17 hours at 60 °C to afford the
expected products P12 and P12¢ (ca. 9:1) in a good 72%
yield. This result demonstrates that the difficulty arising
from the presence of two double bonds in many terpenes
such as citronellene can be overcome by protection of one
of the double bonds as an alcohol.
Table 3 Cross-Metathesis Reactions between Dihydromyrcenol
(S7) and Olefins O1–O6
Entry
Olefin
(equiv)
Catalyst
(mol%)
Conditions
Product
(yield)
1
2
3
4
5
6
7
O1 (2)
O1 (2)
O1 (2)
O2 (1.2)
O3 (1)
O4 (1)
O5 (1.5)
1.0
0.5
0.2
1.0
0.5
1.0
2.0
60 °C, 18 h
60 °C, 17 h
60 °C, 17 h
60 °C, 23 h
60 °C, 16 h
50 °C, 24 h
80 °C, 3 h
P5 (75%)
P5 (47%)
P5 (28%)
P6 (53%)a
P6 (80%)b
P7 (43%)
In conclusion, we have shown that the selectivity problem
encountered in the cross-metathesis of terpenic com-
pounds possessing more than one carbon–carbon double
bond can be solved by using masked derivatives such as
dihydromyrcenol in which one of the double bonds is pro-
tected as the hydrated form. The successful cross-meta-
thesis reactions between dihydromyrcenol and various
olefins demonstrate that this procedure has significant po-
tential for the synthesis of valuable synthetic intermedi-
ates from renewable terpenic feedstocks.
P8 (61%)c
P9 (71%)d
8
9
S7
1.0
1.0
80 °C, 3 h
P10 (82%)
O6 (2)
80 °C, 16 h
–
a Isolated as a 95:5 mixture of E/Z isomers.
b Isolated as a 94:6 mixture of E/Z isomers.
c Isolated as an 87:13 mixture of E/Z isomers.
d Isolated as an 86:14 mixture of E/Z isomers.
All non-aqueous reactions were performed under an Ar atm. HPLC
grade EtOAc was used. n-Butyl acrylate, acrolein and crotonalde-
hyde were distilled before use. All other reagents and solvents were
obtained from commercial sources and were used without further
purification. Column chromatography was performed on Merck
When dihydromyrcenol (S7) was reacted at 80 °C in the
presence of pre-catalyst (1 mol%), but in the absence of a
second olefin, self-metathesis occurred to afford P10 as a
mixture of diastereoisomers in a good 82% yield (Table 3,
entry 8). Finally, when protected allylamine O6 was em-
ployed formation of the expected product was not ob-
served.
1
Geduran Si60 (40–60 µ) silica gel. H (400 MHz) and 13C (100
MHz) NMR spectra were recorded on a Bruker ARX400 spectrom-
eter with complete proton decoupling for nuclei other than H.
Chemical shifts are reported in ppm with the solvent resonance as
the internal standard (CDCl3, 1H: d = 7.26, 13C: d = 77.0). Data are
reported as follows: chemical shift d in ppm, multiplicity
(s = singlet, d = doublet, t = triplet, q = quartet, sept = septet,
m = multiplet), coupling constant(s) (Hz), integration and assign-
ment. High resolution mass spectroscopy was performed on a
Waters Q-Tof 2 at the Centre Régional de Mesures Physiques de
l’Ouest (CRMPO), Université de Rennes 1.
The possibility of regenerating the double bond via elim-
ination of the alcohol group was next investigated
(Scheme 4). Reaction of compound P5 in acetic acid in
Cross-Metathesis; General Procedure
O
O
O
H2SO4 (5 mol%)
The pre-catalyst was added to a round-bottomed flask under Ar, fol-
lowed by the solvent (when the reaction was carried out in solution)
and then by the two olefin partners. The soln was carefully degassed
(3 vacuum/Ar cycles) and then heated for the required period of
time with continuous stirring. The solvent was removed under vac-
uum and the residue was purified by flash chromatography (cyclo-
hexane–EtOAc).
+
On-Bu
On-Bu
On-Bu
AcOH, 120 °C
2 h, 60%
OH
P5
P11
(9:1)
P11'
Dibutyl (2E,7E)-4-Methylnona-2,7-dienedioate (P2a)
Brown oil (traces of Ru residues); yield: 198 mg (32%).
O
O
2 equiv
CO2Me
+
1H NMR (400 MHz, CDCl3): d = 0.94 (t, J = 7.4 Hz, 3 H, CH2CH3),
0.95 (t, J = 7.4 Hz, 3 H, CH2CH3), 1.07 (d, J = 6.8 Hz, 3 H,
CHCH3), 1.36–1.47 (m, 4 H, CH2), 1.52–1.59 (m, 2 H, CH2), 1.62–
1.70 (m, 4 H, CH2), 2.16–2.24 (m, 2 H, CH2), 2.30–2.38 (m, 1 H,
CHCH3), 4.12 (t, J = 6.8 Hz, 2 H, CH2O), 4.13 (t, J = 6.8 Hz, 2 H,
CH2O), 5.79 (dd, J = 15.6, 1.2 Hz, 1 H, CHCH=CHCO), 5.81 (dt,
J = 15.6, 1.6 Hz, 1 H, CH2CH=CHCO), 6.82 (dd, J = 15.6, 8.0 Hz,
On-Bu
On-Bu
C1c (1 mol%)
CO2Me
P12'
EtOAc, 60 °C, 17 h
72%
CO2Me
P12
Scheme 4 Regeneration of the double bond in P5 via acid-catalyzed
elimination and subsequent cross-metathesis of the isomeric products
with methyl acrylate;the geometry of the newly created double bond
in P12¢ was not determined
1
H, CHCH=CHCO), 6.92 (dt, J = 15.6, 6.8 Hz,
1 H,
CH2CH=CHCO).
Synthesis 2011, No. 13, 2125–2130 © Thieme Stuttgart · New York

PAPER
Cross-Metathesis of Terpenic Compounds
2129
13C NMR (100 MHz, CDCl3): d = 13.7, 19.2, 19.4, 29.7, 30.7, 34.1,
35.9, 64.1, 64.2, 120.4, 121.7, 148.3, 153.3, 166.7, 166.8.
13C NMR (100 MHz, CDCl3): d = 14.1, 21.0, 22.1, 22.7, 29.1, 29.2,
29.3, 29.4, 29.7, 31.9, 32.6, 36.7, 37.6, 44.0, 71.1, 128.7, 136.1.
HRMS (ESI): m/z [M + Na]+ calcd for C18H30O4Na: 333.2042;
HRMS (ESI): m/z [M + Na]+ calcd for C18H36ONa: 291.2664;
found: 333.2043 (0 ppm).
found: 291.2663 (0 ppm).
Butyl (2E)-8-Acetoxy-6-methyloct-2-enoate (P4)
Brown oil (traces of Ru residues); yield: 58 mg (43%).
Methyl (9E)-15-Hydroxy-11,15-dimethylhexadec-9-enoate (P9)
Colorless oil; yield: 111 mg (71%).
1H NMR (400 MHz, CDCl3): d = 0.92 (d, J = 6.6 Hz, 3 H, CHCH3),
0.93 (t, J = 7.4 Hz, 3 H, CH2CH3), 1.23–1.73 (m, 9 H, 4 × CH2, CH),
2.03 (s, 3 H, CH3CO), 2.13–2.28 (m, 2 H, CH2CH=), 4.03–4.16 (m,
4 H, 2 × CH2O), 5.81 (dt, J = 15.6, 1.5 Hz, 1 H, CH=CHCO), 6.94
(dt, J = 15.6, 6.8 Hz, 1 H, CH=CHCO).
13C NMR (100 MHz, CDCl3): d = 13.7, 19.1 (2 × C), 21.0, 29.3,
29.5, 30.7, 35.0, 35.2, 62.6, 64.1, 121.4, 148.9, 166.7, 171.1.
1H NMR (400 MHz, CDCl3): d (E-isomer) = 0.95 (d, J = 6.8 Hz, 3
H, CHCH3), 1.19 [s, 6 H, C(OH)(CH3)2], 1.23–1.65 (m, 16 H, 8 ×
CH2), 1.96 (q, J = 6.8 Hz, 2 H, =CHCH2), 2.06 (sept, J = 7.0 Hz, 1
H, CHCH3), 2.29 (t, J = 7.2 Hz, 2 H, CH2COOMe), 3.66 (s, 3 H,
OCH3), 5.23 (ddt, J = 15.2, 7.6, 1.2 Hz, 2 H, CHCH=CH), 5.33 (dtd,
J = 15.6, 6.4, 0.5 Hz, 1 H, CH=CHCH2).
13C NMR (100 MHz, CDCl3): d = 21.0, 22.0, 24.9, 28.9, 29.1, 29.2,
29.6, 32.5, 34.1, 36.7, 37.6, 44.0, 51.4, 71.0, 128.6, 136.2, 174.3.
Butyl (2E)-8-Hydroxy-4,8-dimethylnon-2-enoate (P5)
Colorless oil; yield: 1.1 g (72%).
HRMS (ESI): m/z [M + Na]+ calcd for C19H36O3Na: 335.2562;
found: 335.2566 (1 ppm).
1H NMR (400 MHz, CDCl3): d = 0.93 (t, J = 7.2 Hz, 3 H, CH2CH3),
1.05 (d, J = 6.4 Hz, 3 H, CHCH3), 1.19 [s, 6 H, C(OH)(CH3)2],
1.31–1.67 (m, 10 H, 5 × CH2), 2.27–2.37 (m, 1 H, CH), 4.13 (t,
J = 6.8 Hz, 2 H, CH2O), 5.77 (dd, J = 15.6, 1.0 Hz, 1 H,
CH=CHCO), 6.85 (dd, J = 15.6, 8.0 Hz, 1 H, CH=CHCO).
13C NMR (100 MHz, CDCl3): d = 13.7, 19.2, 19.4, 21.9, 29.3, 30.7,
36.4, 36.5, 43.8, 64.1, 70.9, 119.7, 154.4, 167.0.
(7E)-2,6,9,13-Tetramethyltetradec-7-ene-2,13-diol (P10)
Colorless oil; yield: 117 mg (82%).
1H NMR (400 MHz, CDCl3): d = 0.95 and 0.96 (2 × d, J = 6.4 Hz,
6 H, CHCH3), 1.19 and 1.20 [2 × s, 12 H, C(OH)(CH3)2], 1.20–1.48
(m, 12 H, 6 × CH2), 2.00–2.12 (m, 2 H, CHCH3), 5.13–5.24 (m, 2
H, CH=CH).
HRMS (ESI): m/z [M + Na]+ calcd for C15H28O3Na: 279.1936;
found: 279.1928 (3 ppm).
13C NMR (100 MHz, CDCl3): d = 21.1, 21.4, 21.9, 22.0, 29.1, 29.2,
29.5, 36.6, 37.0, 37.6, 37.7, 43.9, 71.0, 71.1, 134.5, 134.7.
HRMS (ESI): m/z [M + Na]+ calcd for C18H36O2Na: 307.2608;
found: 307.2613 (2 ppm).
(2E)-8-Hydroxy-4,8-dimethylnon-2-enal (P6)
Colorless oil; yield: 147 mg (80%).
1H NMR (400 MHz, CDCl3): d (E-isomer) = 1.10 (d, J = 6.8 Hz, 3
H, CHCH3), 1.20 [s, 6 H, C(OH)(CH3)2], 1.32–1.48 (m, 6 H, 3 ×
CH2), 2.40–2.51 (m, 1 H, CH), 6.08 (ddd, J = 15.6, 7.6, 1.2 Hz, 1 H,
CHCHO), 6.74 (dd, J = 15.6, 7.6 Hz, 1 H, CH=CHCHO), 9.50 (d,
J = 7.6 Hz, 1 H, CHO).
13C NMR (100 MHz, CDCl3): d = 19.1, 21.9, 29.2, 29.3, 36.3, 37.0,
43.7, 70.8, 131.3, 163.9, 194.3.
Butyl (2E)-4,8-Dimethylnona-2,7-dienoate (P11) and
Butyl (2E)-4,8-Dimethylnona-2,8-dienoate (P11¢)
Compound P5 (600 mg, 2.34 mmol) was treated with a soln of
H2SO4 (6 mL) in AcOH (600mL). The mixture was heated for 2 h at
120 °C and then diluted with EtOAc (25 mL). The organic phase
was washed with a sat. aq NaHCO3 soln (3 × 10 mL) and dried over
MgSO4. The solvent was removed under vacuum and the residue
was purified by flash chromatography (eluent: cyclohexane–
EtOAc, 90:10) to give a 9:1 mixture of P11 and P11¢.
HRMS (ESI): m/z [M + Na]+ calcd for C11H20O2Na: 207.1361;
found: 207.1358 (1 ppm).
Colorless oil; yield: 334 mg (60%).
(7E)-2,6-Dimethyltetradec-7-ene-2,9-diol (P7)
Colorless oil; yield: 110 mg (43%).
1H NMR (400 MHz, CDCl3): d (data for P11) = 0.94 (t, J = 7.6 Hz,
3 H, CH2CH3), 1.04 (d, J = 6.8 Hz, 3 H, CHCH3), 1.32–1.46 and
1.56–1.70 (m, 6 H, 3 × CH2), 1.58 and 1.68 [br s, 6 H, C(CH3)2],
1.98 (q, 2 H, J = 7.2 Hz, CH2CH=), 2.31 (sept, J ~ 7.0 Hz, 1 H,
CHCH=), 4.12 (t, J = 6.8 Hz, 2 H, CH2O), 5.04–5.09 (m, 1 H,
CH=CMe2), 5.77 (dd, J = 15.6, 1.2 Hz, 1 H, CH=CHCO), 6.86 (dd,
J = 15.6, 8.0 Hz, 1 H, CHCH=CH).
1H NMR (400 MHz, CDCl3): d (selected data for P11¢) = 4.65 and
4.69 (2 × br s, 2 H, C=CH2).
13C NMR (100 MHz, CDCl3): d (data for P11) = 13.7, 17.7, 19.2,
19.3, 25.6, 25.7, 30.7, 36.0, 36.1, 64.1, 119.7, 124.0, 131.9, 154.4,
167.0.
1H NMR (400 MHz, CDCl3): d = 0.86 (t, J = 6.8 Hz, 3 H, CH2CH3),
0.96 and 0.97 (2 × d, J = 6.8 Hz, 3 H, CHCH3), 1.18 [s, 6 H,
C(OH)(CH3)2], 1.24–1.57 (m, 14 H, 7 × CH2), 2.05–2.18 (m, 1 H,
CHCH3), 4.01 (q, J = 6.4 Hz, 1 H, CHOH), 5.38 and 5.39 (2 × dd,
J = 15.6, 6.4 Hz, 1 H, =CHCHOH), 5.46 and 5.47 (2 × dd, J = 15.6,
7.6 Hz, 1 H, CH=CHCHOH).
13C NMR (100 MHz, CDCl3): d = 14.0, 20.6 (2 × C), 21.9, 22.0,
22.6, 25.1, 25.2, 29.1, 29.2, 29.3, 31.7, 36.3, 36.4, 37.1, 37.3, 37.4,
43.8, 43.9, 71.0, 73.1, 73.2, 131.6, 137.5, 137.7.
HRMS (ESI): m/z [M + Na]+ calcd for C16H32O2Na: 279.2300;
found: 279.2300 (0 ppm).
HRMS (ESI): m/z (mixture of P11 and P11¢) [M + Na]+ calcd for
C15H26O2Na: 261.1831; found 261.1830 (0 ppm).
(7E)-2,6-Dimethylhexadec-7-en-2-ol (P8)
Colorless oil; yield: 82 mg (61%).
1-Butyl 9-Methyl (2E,7E)-4-Methylnona-2,7-dienedioate (P12)
and 10-Butyl 1-Methyl (2E/Z,8E)-3,7-Dimethyldeca-2,8-diene-
dioate (P12¢)
Brown oil (traces of Ru residues); yield: 194 mg (72%); ratio (P12/
P12¢) = ca. 9:1.
1H NMR (400 MHz, CDCl3): d (data for P12) = 0.94 (t, J = 7.4 Hz,
3 H, CH2CH3), 1.06 (d, J = 6.8 Hz, 3 H, CHCH3), 1.35–1.68 (m, 6
H, 3 × CH2), 2.12–2.24 (m, 2 H, CH2), 2.28–2.39 (m, 1 H, CHCH=),
1H NMR (400 MHz, CDCl3): d (E-isomer) = 0.87 (t, J = 6.8 Hz, 3
H, CH2CH3), 0.95 (d, J = 6.8 Hz, 3 H, CHCH3), 1.20 [s, 6 H,
C(OH)(CH3)2], 1.23–1.46 (m, 18 H, 9 × CH2), 1.96 (q, J = 6.6 Hz,
2 H, =CHCH2), 2.05 (sept, J = 6.8 Hz, 1 H, CHCH3), 5.23 (ddt,
J = 15.2, 7.6, 1.2 Hz, 1 H, CHCH=CH), 5.35 (dt, J = 15.2, 6.8 Hz,
1 H, CH=CHCH2).
Synthesis 2011, No. 13, 2125–2130 © Thieme Stuttgart · New York

2130
E. Borré et al.
PAPER
3.72 (s, 3 H, CO2CH3), 4.13 (t, 2 H, J = 6.6 Hz, CH2O), 5.79 (dd,
J = 15.6, 1.2 Hz, 1 H, CH=CHCO2Bu), 5.81 (dt, J = 15.6, ~1.5 Hz,
1 H, CH=CHCO2Me), 6.81 (dd, J = 15.6, 8.2 Hz, 1 H, CHCH=CH),
6.92 (dt, J = 15.6, 7.0 Hz, 1 H, CH2CH=CH).
1H NMR (400 MHz, CDCl3): d (selected data for P12¢) = 3.81 (s, 3
H, CO2CH3), 6.86 (s, 1 H, =CHCO2CH3).
13C NMR (100 MHz, CDCl3): d (data for P12) = 13.7, 19.2, 19.4,
29.8, 30.7, 34.1, 35.9, 51.4, 64.2, 120.4, 121.3, 148.6, 153.2, 166.8,
167.0.
Caijo, F.; Crévisy, C.; Mauduit, M. Chem. Today 2009, 27,
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Technol. 2008, 31, 700. (e) Rybak, A.; Meier, M. A. R.
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D.; Margl, P.; Maughon, B. R.; Mokhtar-Zadeh, T.; Saucier,
P. C.; Wasserman, E. P. Organometallics 2004, 23, 2027.
(g) Dinger, M. B.; Mol, J. C. Adv. Synth. Catal. 2002, 344,
671; and references cited therein.
(3) (a) Meylemans, H. A.; Quintana, R. L.; Goldsmith, B. R.;
Harvey, B. G. ChemSusChem 2011, 4, 465. (b) Vieille-
Petit, L.; Clavier, H.; Linden, A.; Blumentritt, S.; Nolan, S.
P.; Dorta, R. Organometallics 2010, 29, 775. (c) Monfette,
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HRMS (ESI): m/z [M + Na]+ calcd for C15H24O4Na: 291.1572;
found: 291.1575 (1 ppm).
Organometallics 2009, 28, 944. (d) Mathers, R. T.;
McMahon, K. C.; Damodaran, K.; Retarides, C. J.; Kelley,
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Acknowledgment
The authors thank the European Union and Région Bretagne (FMR-
FEDER no. 32981) and OSEO (contract no. A0904006 E) for finan-
cial support. We are grateful to the European Union for financial
support through the seventh framework program (CP-FP 211468-2-
EUMET), and Région Bretagne and CBB Développement (project
BioOM).
(4) (a) Clavier, H.; Caijo, F.; Borre, E.; Rix, D.; Boeda, F.;
Nolan, S. P.; Mauduit, M. Eur. J. Org. Chem. 2009, 25,
4254. (b) Rix, D.; Caijo, F.; Laurent, I.; Boeda, F.; Clavier,
H.; Nolan, S. P.; Mauduit, M. J. Org. Chem. 2008, 73, 4225.
(c) Mauduit M., Laurent I., Clavier H. WO 2008065187,
2008, Chem. Abstr. 2008, 149, 32434. (d) Borre, E.; Caijo,
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(5) (a) Hong, S. H.; Sanders, D. P.; Lee, C. W.; Grubbs, R. H.
J. Am. Chem. Soc. 2005, 127, 17160. (b) Bourgeois, D.;
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Synthesis 2011, No. 13, 2125–2130 © Thieme Stuttgart · New York