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Regioselective metathesis reactions of various polyunsaturated ketones and alcohols.

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Full Paper
Received: 2 March 2010
Revised: 11 May 2010
Accepted: 29 June 2010
Published online in Wiley Online Library: 2 September 2010
(wileyonlinelibrary.com) DOI 10.1002/aoc.1704
Regioselective metathesis reactions of various
polyunsaturated ketones and alcohols
Chahinez Aoufa , Nicolas Galya , Henri Doucetb and Maurice Santellia∗
The reactivity for metathesis reaction of some polyunsaturated cyclopentanols, and of a polyunsaturated ketone bearing vinyl
groups or vinyl and propenyl groups has been examined. In the presence of two of these reactants, depending on the ruthenium
c 2010 John
catalyst employed, either the ring closing metathesis or the cross-coupling metathesis was observed. Copyright Wiley & Sons, Ltd.
Keywords: metathesis; lactones; indenols; cyclization
Introduction
In recent years, due to discovery of several new generations
of more efficient catalysts, the ring-closing metathesis of 1 − ω
dienes has given a very powerful and simple access to a huge
variety of cyclic and polycyclic derivatives.[1] Therefore, now, from
a synthesis point of view, the major problem remains the access
to such 1 − ω dienes precursors. In previous studies, we described
some allylation reactions allowing the formation in a few steps of
substrates that are interesting for ring-closing metathesis.[2]
The treatment of 1,3-dienes by chlorotrimethylsilane in the
presence of lithium wire led mainly to a reductive dimerization
of this diene, with formation of the bis(allylsilane) derivatives: the
diallylsilane 1 (Bistro)[3] and 2[4] (Scheme 1).
The TiCl4 -mediated reaction of 1 or 2 with acyl chlorides or
anhydrides generally affords the 2,5-divinylcyclopentanols coming
from an intramolecular attack of the second allylsilane moiety on
the electrophilic center.[5] In some cases, in the presence of the
hindered diallylsilane 2, a double acylation takes place to give
polyunsaturated diketones.[6]
First, we studied the synthesis of the bicyclic unsaturated
lactone 7 from 1.[7] Acylation of 1 by acetic anhydride affords the
cyclopentanol 3 in 74% yield.[5] Then, the triene 4 was prepared in
89% yield using allyl bromide as allylation reactant. Next, we examined the reactivity of 4 for the ring-closing metathesis reaction.
Because of the stereochemistry of this reactant, we could expect
to have only two of the three carbon–carbon double bonds react
in the course of this reaction. As expected, we observed that, in the
presence of 5 mol% of the Grubbs–Hoveyda ‘second-generation’
catalyst precursor 5, the oxa-hexahydroindene 6 was formed in
a good yield of 83%,[8] whereas the third carbon–carbon double
bond remained untouched. An allylic oxidation by pyridinium
chlorochromate (PCC) occurs to give the corresponding lactone 7
with an overall yield from Bistro 1 of 31% (22% overall yield from
1,3-butadiene; Scheme 2).[9]
NMR experiments conducted on 6 and 7 allowed us to confirm
the stereochemistry of these two products. The NOESY experiment
revealed the presence of cross peaks between the methyl group
and H6 or H10 (Fig. 1).
The ring-closing metathesis of 4 only led to the cis-ring junction
oxa-indene 6, whereas no formation of the trans-isomer 8 was
detected (Scheme 3). Calculations at the B3LYP/6-31++G(d,p)
level of the theory[10] (without zero-point energy correction)
showed that 6 is the most stable isomer by 7.31 kcal mol−1 (6,
E = −504.017 849 hartrees; 8, E = −504.006 202 hartrees).
The acylation of 2 by 4-pentenoyl chloride affords the
tetraalkenedione 9 (one isomer) and the meso cyclopentanol
14 (Schemes 4 and 5) in various yields depending on the amount
of 2 employed (1 equiv.: 9, 46%; 14, 31% yield; 2 equiv.: 9, 22%;
14, 58% yield).[6] With the tetraalkenedione 9, in the presence of
metathesis catalysts, we could expect to observe either the ringclosing metathesis reaction to form 12 or the cross-metathesis
reaction to give 10 (Scheme 4). Surprisingly, this reaction was
found to be completely catalyst-dependent. In the presence of
the Grubbs catalyst ‘first-generation’ 11, only the cross-metathesis
reaction occurred to give the polyunsaturated tetraketone 10 in
a good yield of 76% (91% yield from converted 9). Interestingly,
the Grubbs catalyst ‘second-generation’ 13 afforded only the
cyclododecenedione 12 (only one isomer) in the very good yield
of 89% (18% of overall yield from 2,3-dimethylbuta-1,3-diene);
whereas, 10 was not detected (Scheme 4). It should be noted that,
in both cases, only the vinyl group was involved in the metathesis
∗
Correspondence to: Maurice Santelli, Laboratoire Chimie Provence, associé
au CNRS no. 6264, Université d’Aix-Marseille, Avenue Escadrille NormandieNiemen, 13397 Marseille Cedex 20, France. E-mail: m.santelli@univ-cezanne.fr
a Laboratoire Chimie Provence, associé au CNRS no. 6264, Université
d’Aix-Marseille, Avenue Escadrille Normandie-Niemen, 13397 Marseille Cedex
20, France
794
Scheme 1. Reductive dimerization of 1,3-butadiene (1) and 2,3-dimethyl1,3-butadiene (2).
Appl. Organometal. Chem. 2010, 24, 794–797
b Institut Sciences Chimique de Rennes, UMR 6226 ‘Catalyse
et Organométalliques’, Université de Rennes 1, Campus de Beaulieu, 35042
Rennes, France
c 2010 John Wiley & Sons, Ltd.
Copyright Regioselective metathesis reactions of various ketones and alcohols
HO
mole of ethylene) (E = −5.0 kcal mol−1 ) by 4.60 kcal mol−1
(Table 1).
The acylation of 2 with isobutyroyl chloride or 10-undecanoyl
chloride led to the diketone 17 or cyclopentanol 18, respectively
(Scheme 6).[6] However, all attempts to observe a metathesis
reaction in the presence of these two substrates using 13 as
the catalyst precursor failed. Even after 3 days under reflux in
benzene, the starting material was recovered unreacted.
O
NaH / THF
Br
3
4, 89%
N Mes
Mes N
Cl
Ru
Cl
O
Conclusion
O
5 (5 mol %)
PhH,
60 °C, 24 h
PCC (3 eq.)
Our sequence of reactions, reductive dimerization of 1,3-dienes,
acylation reactions followed by metathesis reactions, allows the
access to elaborated molecules from trivial precursors in only
a few steps. Moreover, we observed that, for the metathesis
reaction of some products resulting of the acylation reaction,
two mechanistic pathways occurred depending on the catalyst
precursor employed. These reactions led either to an alkene
cross-coupling metathesis product or to a ring-closing metathesis
product without formation of mixtures. Calculations have shown
that the ring-closing metathesis occurs according to a kinetic
process.
H
6, 83%
O
O
6
pyridine (3 eq.)
CH2Cl2, 45 °C, 3 d.
H
7, 57%
Scheme 2. Synthesis of the lactone 7.
10
H
10
H
O
O
6
H
Experimental
General
O
6
H
6
7
Figure 1. Noesy NMR experiments concerning the ether 6 and the lactone
7.
metathesis
O
H
O
All reactions were run under argon in oven-dried glassware. TLC
was performed on silica gel 60 F254 . 1 H and 13 C NMR spectra were
recorded in CDCl3 solutions at 400 and 300, and 100 and 75 MHz
respectively using a Bruker Advance III nanobay 400 and Bruker
AC300 spectrometers. Chemical shift are reported in ppm relative
to CDCl3 [signals for residual CHCl3 in the CDCl3 : 7.24 for 1 H
NMR and 77.16 (central) for 13 C NMR]. Carbon–proton couplings
were determined by DEPT sequence experiments. ESI-MS analyses
were performed using a Qstar Elite (Applied Biosystems SCIEX)
mass spectrometer. CH2 Cl2 was distilled before use from calcium
hydride.
=
metathesis
General Procedure for the Alkene Metathesis Reactions
O
4
6
H
8
Scheme 3. Cyclization modes of allylic ether 4.
Appl. Organometal. Chem. 2010, 24, 794–797
(DL)-1-Allyloxy-1-methyl-2,5-divinylcyclopentane (4)
A 100 ml three-necked flask equipped with a thermometer, septum
cap, magnetic stirring bar and an argon outlet was charged
with NaH (1.30 g, 32.5 mmol) and then anhydrous THF (20 ml).
A solution of 3 (2 g, 9.20 mmol) in anhydrous THF (4 ml) was
added. The solution was refluxed for 1 h, and then cooled to room
temperature and allyl bromide (1.6 ml, 12.4 mmol) was added.
The solution was refluxed for 60 h. The reaction was quenched
c 2010 John Wiley & Sons, Ltd.
Copyright wileyonlinelibrary.com/journal/aoc
795
reaction, and no reaction leading to a tetrasubstituted alkene
occurred.[11]
Next, we studied the metathesis reaction of the cyclopentanol
14, and a similar reactivity was observed.[7] The Grubbs catalyst 11
gave rise to the diol 15 resulting from a cross-metathesis reaction,
while catalyst 13 afforded the hexahydroindenol 16 (only one
isomer) in the excellent yield of 91% (23.2% overall yield from
2,3-dimethylbuta-1,3-diene) (Scheme 5).
Calculations at the B3LYP/6-31++G(d,p) level of the theory (without zero-point energy correction) showed that the
ring-closing metathesis of 1 mol of 14 to give hexahydroindenol 16 (and 1 mol of ethylene) is a more exothermic reaction (E = −9.6 kcal mol−1 ) than the alkene cross-coupling
metathesis of 2 mol of 14 leading to 15 (E-isomer) (and one
A 100 ml three-necked flask equipped with a thermometer,
septum cap, magnetic stirring bar and argon outlet was
charged with anhydrous solvent (40 ml) and Grubbs catalyst
‘first-generation’ 11, Grubbs catalyst ‘second-generation’ 13 or
Grubbs–Hoveyda ‘second-generation’ catalyst 5. To this solution was added the unsaturated alcohol or ketone. Then, the
mixture was stirred for several hours and heated in some
cases. After concentration in vacuo, the residue was flash chromatographed on silica gel with petroleum ether–diethyl ether
(PE–DE).
C. Aouf et al.
O
O
PCy3
Cl
Ru
Cl
PCy3 Ph
11
O
O
O
10, 76%
O
O
N Mes
Mes N
Cl
Ru
Cl
PCy3 Ph 13
9
O
12, 89%
Scheme 4. Synthesis of tetraone 10 or cyclododecenedione 12.
OH
HO
+
4:1
15, 67%
11
HO
HO
13
1-Methyl-2-oxa-9-vinylbicyclo[4.3.0]non-4-ene (6)
14
16, 91%
Scheme 5. Synthesis of diol 15 or hexahydroindenol 16.
Table 1. Calculations of the energies of metathesis reactions from 14
Compound
Energy (hartree)
14
15
16
Ethylene
−739.867 223
−1401.142 749
−661.282 881
−78.599 645
Scheme 6. Attempts of metathesis reaction with 17 or 18.
796
wileyonlinelibrary.com/journal/aoc
by the addition of ethyl alcohol (2 ml) and the solution was
concentrated in vacuo. The residue was hydrolysed and extracted
with diethylether. After the usual work-up, the solution was
purified by flash chromatography (PE–DE, 90 : 10) on silica gel
to give 4 (1.58 g, 8.22 mmol) in 89% yield. 1 H NMR (300 MHz,
CDCl3 ) δ 5.96 (ddd, J = 17.2, 10.1, 8.5 Hz, 1H), 5.87 (ddt,
J = 17.1, 10.4, 4.9 Hz, 1H), 5.67 (ddd, J = 17.2, 10.1, 8.5 Hz,
1H), 5.24 (dq, J = 17.2, 1.8 Hz, 1H), 5.06 (dq, J = 10.4, 1.67 Hz,
1H), 5.02–4.95 (m, 4H), 3.88 (m, 2H), 2.71 (td, J = 8.2, 5.6 Hz,
1H), 2.27 (q, J = 8.7 Hz, 1H), 1.98 (m, 1H), 1.82–1.69 (m, 2H),
1.50–1.38 (m, 1H), 1.10 (s, 3H); 13 C NMR (75 MHz, CDCl3 ) δ
140.5 (d), 139.2 (d), 136.4 (d), 115.1 (t), 114.9 (t), 114.6 (t), 86.6
(s), 69.9 (t), 54.4 (d), 50.8 (d), 29.8 (t), 28.5 (t), 19.3 (q). Anal.
calcd for C13 H20 O (192.30): C, 81.20; H, 10.48. Found: C, 81.22; H,
10.58.
The general procedure with benzene as solvent, using Grubbs–
Hoveyda ‘second-generation’ catalyst 5 (125 mg, 0.2 mmol), and
after 24 h of heating at 60 ◦ C, led to 6 as a colourless oil (0.544 g,
3.32 mmol, 83%) after a flash chromatography on silica gel (PE–DE
= 95 : 5). 1 H NMR (300 MHz, CDCl3 ) δ 5.79–5.62 (m, 3H), 5.02 (br d,
J = 15.7 Hz, 1H), 5.01 (br. d, J = 11.0 Hz, 1H), 4.10–4.07 (m, 2H),
2.61 (q, J = 8.0 Hz, 1H), 2.04–1.88 (m, 2H), 1.48–1.35 (m, 2H), 1.07
(s, 3H); 13 C NMR (75 MHz, CDCl3 ) δ 139.0 (d), 128.3 (d), 124.0 (d),
115.3 (t), 81.6 (s), 60.2 (t), 51.1 (d), 43.3 (d), 29.7 (t), 28.7 (t), 20.2 (q).
Anal. calcd for C11 H16 O (164.24): C, 80.44; H, 9.82. Found: C, 80.52;
H, 9.68.
1-Methyl-2-oxa-9-vinylbicyclo[4.3.0]non-4-en-3-one (7)
To a solution of 6 (164 mg, 1 mmol) in CH2 Cl2 (10 ml) under argon
atmosphere was added pyridinium chloro chromate (645 mg,
3 mmol) and, in three steps, pyridine (0.24 ml, 3 mmol). After
3 days of refluxing, the suspension was concentrated in vacuo and
the residue was purified by flash chromatography on silica gel
(PE–DE = 50 : 50) to give 7 (93.5 mg, 0.57 mmol, 57%). 1 H NMR
(300 MHz, CDCl3 δ 6.78 (dd, J = 9.8, 5.2 Hz, 1H), 5.92 (dd, J = 9.8,
1.4 Hz, 1H), 5.70 (ddd, J = 17.7, 9.9, 8.1 Hz, 1H), 5.12–5.05 (m,
2H), 2.82 (q, J = 7.5 Hz, 1H), 2.45 (tdd, J = 8.9, 5.3, 1.4 Hz, 1H),
2.22–2.12 (m, 1H), 2.10–1.98 (m, 1H), 1.65–1.46 (m, 2H), 1.28 (s,
3H); 13 C NMR (75 MHz, CDCl3 ): δ 163.1 (s), 148.2 (d), 136.6 (d), 118.8
(d), 117.0 (t), 91.7 (s), 54.2 (d), 42.8 (d), 30.7 (t), 28.5 (t), 22.7 (q). Anal.
Calcd for C11 H14 O2 (164.24): C, 74.13; H, 7.92. Found: C, 74.22; H,
7.78.
c 2010 John Wiley & Sons, Ltd.
Copyright Appl. Organometal. Chem. 2010, 24, 794–797
Regioselective metathesis reactions of various ketones and alcohols
6,9,18,21-tetrakis(Propen-2-yl)-6,9,18,21tetramethylhexacosa-1,13,25-trien-5,10,17,22-tetraone
(10)
From 6,9-dimethyl-6,9-bis(propen-2-yl)-tetradeca-1,13-dien-5,10dione 9 (1.32 g, 4 mmol) using the Grubbs catalyst ‘first-generation’
11 (164 mg, 0.2 mmol), a 76% yield was achieved after 4 days at
reflux in CH2 Cl2 (40 ml; 10, 962 mg, 1.52 mmol) [198 mg (0.6 mmol)
of ketone 9 recovered, 91% yield from 9 used up]; PE–DE = 85:15.
1
H NMR (300 MHz, CDCl3 ) δ 5.70 (ddtd, J = 16.8, 10.2, 6.7, 1.4 Hz,
2H), 5.29 (sept. J = 1.7 Hz, 1H), 5.20 (br. t, J = 4.8 Hz, 1H), 4.97 (br.
s, 5H), 4.91 (quint. J = 1.6 Hz, 1H), 4.88 (br. s, 6H), 2.51–2.30 (m,
8H), 2.24–2.08 (m, 8H), 1.53 (m, 12H), 1.41–1.35 (m, 8H), 1.18 (br.
s, 12 H); 13 C NMR (75 MHz, CDCl3 ) δ 212.5–212.4 (s)(2C), 212.34 (s),
212.29 (s), 146.0 (s), 145.9 (s), 145.93 (s), 145.9 (s), 137.57 (d), 137.56
(d), 129.8 (d), 129.3 (d), 115.1 (t)(2C), 113.62 (t), 113.59 (t), 113.54
(t), 113.5 (t), 56.78 (s)(2C), 56.75 (s)(2C), 36.63 (t), 36.6 (t), 36.08 (t),
36.04 (t), 28.6 (t), 28.55 (t), 28.52 (t), 28.5 (t), 28.2 (t)(2C), 27.0 (t), 21.8
(t), 20.3 (q)(4C), 19.9 (q)(4C). ESI-MS calcd for [C42 H64 O4 +NH4 ](+) :
650.5142. Found: 650.5142.
2,5-Dimethyl-2,5-bis(propen-2-yl)cyclododec-9-en-1,6-dione
(12)
From 6,9-dimethyl-6,9-bis(propen-2-yl)-tetradeca-1,13-dien-5,10dione (9) (660 mg, 2 mmol) using with catalyst 13 (170 mg,
0.2 mmol) in CH2 Cl2 (25 ml), an 89% yield was achieved (12,
538 mg, 1.78 mmol) after refluxing for 16 h, PE–DE = 90:10. 1 H
NMR (300 MHz, CDCl3 ) δ 5.28 (br. t, J = 3.2 Hz, 2H), 5.03 (br. s. 2H),
5.02 (br s. 2H), 2.92–2.81 (m, 2H), 2.50–2.39 (m, 3H), 1.90–1.78 (m,
3H), 1.63 (s, 6H), 1.6–1.18 (m, 6H), 1.10 (s, 6H); 13 C NMR (75 MHz,
CDCl3 ) δ 212.1 (s), 147.6 (s), 130.3 (d), 113.1 (t), 56.3 (s), 36.4 (t), 28.0
(t), 25.7 (t), 21.5 (q), 18.2 (q). Anal. calcd for C20 H30 O2 (302.45): C,
79.42; H, 10.00. Found: C, 79.38; H, 9.85.
(E)-1,6-[2,5-Dimethyl-1-hydroxy-2,5-bis(propen-2yl)cyclopentyl]hex-3-ene (15)
From (2S∗ ,5R∗ )-1-(but-3-enyl)-2,5-dimethyl-2,5-bis(propen-2-yl)
cyclopentanol (14) (1 g, 4 mmol), using catalyst 11 (164 mg,
0.2 mmol) in CH2 Cl2 , a 67% yield was achieved (625 mg, 1.33 mmol;
315 mg, 1.27 mmol of alcohol 14 recovered, 98% yield from 14
used up) after 8 days at room temperature (PE–DE = 90 : 10). 1 H
NMR (300 MHz, CDCl3 ) (E)-isomer (80%). 1 H NMR (300 MHz, CDCl3 )
δ 5.19 (tt, J = 3.7, 1.5 Hz, 2H), 4.76 (m, 4H), 4.75 (s, 4H), 2.03 (q,
J = 6.7 Hz, 4H), 1.97 (m, 3H), 1.80 (s, 12H), 1.67–1.46 (m, 10H), 1.22
(s, 12H); (Z)-isomer (20%), δ 5.12 (tt, J = 4.5, 1.15 Hz, 2H), 1.23 (s,
12H); 13 C NMR (75 MHz, CDCl3 ) δ 151.7 (s), 131.1 (d), 110.5 (t), 85.3
(s), 54.4 (s), 36.8 (t), 34.0 (t), 27.9 (t), 25.0 (q), 22.1 (q); (Z)-isomer
(20%), δ 130.5 (d), 85.2 (s), 36.9 (t), 34.0 (t), 24.9 (q), 22.7 (q). ESI-MS
calcd for [C32 H52 O2 + NH4 ](+) : 486.4305. Found: 486.4307.
7-(Propen-2-yl)-1,2,7-trimethylbicyclo[4.3.0]nonan-6-ol (16)
From
(2S∗ ,5R∗ )-1-(but-3-enyl)-2,5-dimethyl-2,5-bis(propen-2yl)cyclopentanol (14) (1 g, 4 mmol), using catalyst 13 (170 mg,
0.2 mmol) in CH2 Cl2 , a 91% yield was achieved (800 mg,
3.64 mmol) after 3.5 h of refluxing, PE–DE = 90:10. 1 H NMR
(300 MHz, CDCl3 ) δ 5.41 (br d, J = 6.5 Hz, 1H), 4.69 (quint.,
J = 1.4 Hz, 1H), 4.64 (br. d, J = 1.2 Hz, 1H), 2.04–1.84 (m, 3H), 1.82
(br. s, 3H), 1.64 (quint., J = 1.2 Hz, 3H), 1.54–1.26 (m, 5H), 1.22 (s,
3H), 1.17 (s, 3H); 13 C NMR (75 MHz, CDCl3 ) δ 151.4 (s), 140.8 (s),
121.4 (d), 109.3 (t), 81.4 (s), 53.6 (s), 48.1 (s), 33.6 (t), 32.6 (t), 32.2 (t),
25.5 (q), 21.9 (q), 20.9 (t), 20.7 (q), 20.0 (q). Anal. calcd for C15 H24 O
(220.35): C, 81.76; H, 10.98. Found: C, 81.64; H, 10.82.
Acknowledgments
N.G. is grateful to the CNRS and the Région Provence-Alpes-Côte
d’Azur for a grant. We thank Mrs R. Rosas for the preparation of
2D NMR spectra. This work was financially supported by the CNRS
and the Ministère de l’Education Nationale.
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797
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c 2010 John Wiley & Sons, Ltd.
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