Metathesis transformations of unsaturated derivatives of β-diketones

Article abstract of DOI:10.2478/s11532-011-0055-1

Selected β-diketones bearing unsaturated derivatives have been demonstrated to undergo homo-metathesis and cross-metathesis with selected olefins in the presence of Grubbs catalysts. The reactions led to respective homo- and cross-metathesis products mainly with good yields and selectivities. Versita Sp. z o.o.

Full text of DOI:10.2478/s11532-011-0055-1

Cent. Eur. J. Chem. • 9(4) • 2011 • 728-736
DOI: 10.2478/s11532-011-0055-1
Central European Journal of Chemistry
Metathesis transformations of unsaturated
derivatives of b-diketones
Research Article
Miłosz Miętkiewski1, Beata Powała1, Bartosz Staniszewski1,
Maciej Kubicki1, Włodzimierz Urbaniak1,2, Cezary Pietraszuk1*
1Faculty of Chemistry, Adam Mickiewicz University, 60-780 Poznan, Poland
2Faculty of Chemical Technology and Engineering,
University of Technology and Life Sciences, 85-326 Bydgoszcz, Poland
Received 3 March 2011; Accepted 11 April 2011
Abstract:
Selected b-diketones bearing unsaturated derivatives have been demonstrated to undergo homo-metathesis and cross-metathesis
with selected olefins in the presence of Grubbs catalysts. The reactions led to respective homo- and cross-metathesis products mainly
with good yields and selectivities.
Keywords: Cross-metathesis • b-diketones • Homogeneous catalysis • Homo-metathesis • Grubbs’ catalysts
© Versita Sp. z o.o.
1. Introduction
and C-C bond formation [3]. The metathesis reactivity
of unsaturated derivatives of β-diketones is nearly
Olefin metathesis has become an important synthetic unexplored. Efficient microwave irradiation assisted
tool in organic and polymer chemistry. The family of cross-metathesis of β-oxoesters with ethyl acrylate was
ruthenium-based catalysts (1-4, Fig. 1) tolerant of reported by Murray [4]. Recently cross-metathesis of
normal organic and polymer processing conditions and unsaturated derivatives of β-oxoamides or β-oxoesters
preserving their catalytic properties in the presence of with selected olefins were tested under thermal and
the majority of functional groups have allowed a great microwaveirradiationconditions[5].Relativelygoodyields
number of new applications [1].
were obtained for cross-metathesis of β-oxoderivatives
A vast number of examples of efficient metathesis with acrylonitrile performed under thermal and microwave
transformations of unsaturated derivatives bearing irradiation conditions in the presence of catalyst 4 [6].
functional groups have been published [1]. A variety of
Herein we report on the efficient homo-metathesis of
available W, Mo, and especially Ru-based alkylidene unsaturated derivatives of selected β-diketones and their
complexes have enabled transformation of unsaturated cross-metathesis with selected olefins in the presence of
derivatives bearing nearly all types of functionalities [1]. Grubbs type ruthenium alkylidene complexes.
Among metathetic methods the cross-metathesis is the
one that offers great opportunities in organic synthesis
2. Experimental Procedure
[1,2]. Pentane-2,4-dione as well as other β-diketones
and their derivatives attract much interest because
of a broad spectrum of applications, especially those
2.1. General
of its metal derivatives, e.g. in analytical chemistry, as
molecular precursors in chemical vapour deposition
techniques, and in medicine [3]. Chelates of β-diketones
with transition metals are often used as catalysts in a
number of catalytic processes such as hydroformylation,
oxidation, hydrogenation, addition to unsaturated bonds
All manipulations were carried out under dry argon using
standard Schlenk techniques. 1H- and 13C-NMR spectra
were recorded on a Varian Gemini 300 at 300 and
75 MHz, respectively. 31P NMR spectra were recorded
on a Mercury 300 operating at 121.5 MHz. The GC/MS
analyses were performed on a Varian Saturn 2100T
* E-mail: pietrasz@amu.edu.pl
728

M. Miętkiewski et al.
PCy3
N
N
N
N
N
N
Cl
Ph
Cl
Cl
N
Cl
Ph
Ru
Ru
Ru
Cl
N
Ru
Cl
Cl
Cl
O
Br
PCy3
PCy3
B r
S econd generation
Hoveyda-G rubbs catalyst
(4)
First generation
G rubbs catalyst
(1)
S econd generation
G rubbs catalyst
(2)
Third generation
G rubbs catalyst
(3)
Figure 1. Well-defined ruthenium-based catalysts of olefin metathesis
equipped with a DB-5 column (30 m I.D. 0.23 mm)
and Ion Trap Detector. GC analyses were carried out
on a Varian CP-3800 equipped with a Rtx-5 column
(30 m, I.D. 0.53 mm) and TCD. Elemental analyses were
performed at the Faculty of Chemistry, Adam Mickiewicz
University, on Elemental Analyser Vario EL III. The
chemicals were obtained from the following sources:
catalysts 1, 2 and 4, allyl diethylmalonate, 2-allyl-2-
methyl-1,3-cyclopentanedione, vinylsilanes, styrene,
dichloromethane, benzene-d6, chloroform-d, decane,
dodecane, calcium hydride and triethylamine were
obtained from Aldrich, toluene, acetone, ethyl acetate,
n-hexane, n-pentane and THF from Chempur. Catalyst
3 [7], diketone derivatives 5a, 9 [8], 6b and 6c [9] were
prepared according to the literature procedures. All
solvents were dried prior to use over CaH2 and stored
under argon. CH2Cl2 was additionally passed through a
column with alumina and after that it was degassed by
repeated freeze-pump-thaw cycles.
2.3. Synthetic procedures
2.3.1. 3,8-diacetyldec-5-ene-2,9-dione (6a)
Round 25 mL flask equipped with reflux condenser was
charged under argon with methylene chloride (5 mL)
and 5a (0.3 mL, 2.04×10-3 mol) and heated to reflux in
an oil bath. Then the second generation Grubbs catalyst
(0.087 g, 1.02×10-4 mol) was added. The reaction was
carried out at 40°C for 24h. After this time solvent was
evaporated and the residue was purified by column
chromatography on silica gel (hexane : THF = 5 : 1
as eluent) to afford 6a as a yellow oil (0.211 g, 83%).
Found C, 66.86; H, 7.86%. C14H20O4 requires C, 66.65;
1
H, 7.99%. H NMR (C6D6; δ (ppm)): 1.73 (s, 12H, CH3)
(enol); 1.76 (s, 12H, CH3) (keto); 2.23-2.31 (m, 4H, CH2)
(keto); 2.40-2.43 (m, 4H, CH2) (enol); 3.08-3.19 (m, 2H,
CHC=O) (keto); 5.03-5.05 (m, 2H, =CH) (enol); 5.08-
5.12 (m, 2H, =CH) (keto); 17.42 (s, 2H, OH) (enol);
13C NMR (C6D6; δ (ppm)) (enol form): 22.58 (CH2); 29.81
(CH3); 107.7 (C=COH); 128.12 (=CH); 191.24 (COH);
MS m/z (rel. int.): 253(M++1, 14), 211(3), 191(20),
153(20), 137(15), 109(100), 101(27), 81(17), 67 (43),
55 (12);
2.2. Catalytic tests (typical procedures)
Homo-metathesis: The oven dried 10 mL glass reactor
equipped with a reflux condenser was charged under
argon with CH2Cl2 2 mL, 3-allyl-pentane-2,4-dione
(10 μL, 6.8×10-5 mol) and decane or dodecane 5 μL
(internal standard). The reaction mixture was stirred and
heated in an oil bath to maintain a gentle reflux. Then a
ruthenium complex (1-5 mol% in relation to diketone)
was added under argon. The reaction progress was
monitored by gas chromatography.
2.3.2. 4,9-dipropionyldodec-6-ene-3,10-dione (6b)
Synthesis of this compound was performed according
to procedure described for 6a: Grubbs catalyst (2)
(0.087 g, 1.02×10-4 mol) was added to the boiling solution
of 5b (0.3 mL, 2.04×10-3 mol) in 5 mL of methylene
chloride. The reaction was carried out at 40°C for 24 h.
After this time solvent was evaporated and the residue
was purified by column chromatography on silica gel
(hexane : THF = 5 : 1 as eluent) to afford 6b as yellow
oil (0.086 g, 71%). Found: C, 70.25; H, 9.09%. C18H28O4
Cross-metathesis: The oven dried 10 mL glass
reactor equipped with a condenser and a magnetic
stirring bar was charged under argon with CH2Cl2
2 mL, 5a (10 μL, 6.8×10-5 mol), decane or dodecane
5 μL (internal standard) and 11a (140 μL, 6.8×10-4 mol).
The reaction mixture was stirred and heated in an oil
bath to maintain a gentle reflux. Then a ruthenium
complex (1-5 mol% in relation to diketone) was added
under argon. The reaction progress was monitored by
gas chromatography.
1
requires C, 70.10; H, 9.15; O, 20.75%. H NMR (C6D6;
δ (ppm)): 0.91 (t, J=7.2 Hz, 12H, CH3,) (keto form); 0.92
(t, J=7.2 Hz, 12H, CH3) (enol form); 2.07 (q, J=7.2 Hz,
8H, CH2) (keto form); 2.08 (q, J=7.2 Hz, 8H, CH2,) (enol
form); 2.32-2.39 (m, 4H, CH2) (keto form); 2.40-2.43 (m,
4H, CH2) (enol form); 3.28 (t, J=7.2 Hz, 2H, CH) (keto
form); 5.15-5.20 (m, 2H, CH=) (enol form); 5.21-5.24 (m,
729

Metathesis transformations of unsaturated
derivatives of b-diketones
2H, CH=) (keto form); 17.59 (s, 2H, OH) (enol form);
13C NMR (C6D6; δ (ppm)): (keto) 7.68 (CH3CH2); 31.25
(CH2); 35.38 (CH3CH2); 66.52 (CH); 129.31 (CH=);
205.18 (C=O); MS m/z (rel. int.): 309 (M++1, 5); 251(1);
223(1); 194(2); 181(5); 167(3); 153(3); 137(3); 129(28);
125(6); 123(44); 99(5); 67(12); 57(100)
2.3.5. (E)-3,3’-(4,4’-(ethene-1,2-diyl)bis(4,1-
phenylene))bis(methylene)dipentane-2,4-dione
(10)
Round 50 mL flask equipped with a reflux condenser
was charged with 20 mL of methylene chloride and
0.6 mL (3.42×10-3 mol) of 9. After 5 min 0.145 g
(1.71×10-4 mol) of the second generation Grubbs
catalyst was added. The reaction was carried out at 40°C
for 24 h. After this time complete conversion of the
substrate was observed by gas chromatography. Then
solvent was evaporated and 10 mL of THF was added to
the solid residue and the content was stirred intensively
for 5 minutes. The solid was filtrated, washed several
times with THF and dried under vacuum to afford 10 as
white microcrystalline solid (0.257 g, 75%). Found: C,
77.41; H, 6.80%. C26H28O4 requires: C, 77.20; H, 6.98;
O, 15.82%; 1H NMR (CDCl3; δ (ppm)): 2.07 (s, 12H, CH3)
(keto); 1.99 (s, 12H, CH3) (enol); 3.06 (d, J=7.5 Hz, 4H,
CH2) (keto); 3.51 (s, 4H, CH2) (enol); 3.92 (t, J=7.5 Hz,
2H, CHC=O) (keto); 6.93 (s, 1H, =CH) (keto); 6.95(s, 1H,
=CH) (enol) 7.05 (d, J=7.8 Hz, 4H, C6H4) (enol and keto
overlapped); 7.32 (d, J=7.8 Hz, 4H, C6H4) (enol and keto
overlapped); 16.75 (s, 1H, OH) (enol); 13C NMR (CDCl3;
δ (ppm)) (keto form): 29.76 (CH3); 33.99 (CH2); 69.92
(CHC=O); 126.81 (Ph); 128.03 (=CH); 128.98 (Ph);
135.86 (C6H4); 137.46 (C6H4); 203.51 (C=O); MS m/z
(rel. int.): 404 (M+, 14), 361(100), 319(8), 305(7), 281(6),
261(48), 243(6), 207(15), 147(4), 113(10), 91(5), 73 (8),
45 (5); M.p. 184-186°C.
2.3.3.
2,7-dibenzoyl-1,8-diphenyloct-4-ene-1,8-dione
(6c)
Synthesis of this compound was performed according
to procedure described for 6a: Grubbs catalyst (2)
0.054g(6.4×10-5 mol)wasaddedtotheboilingsolutionof
0.34
g
(1.3×10-3 mol) 3-allyl-1,5-diphenyl-2,4-
pentanodione (5c) in 20 mL of methylene chloride. The
reaction was carried out at 40°C. for 24h. After this time
the white solid was precipitated by vigorous mixing of
concentrated (5 mL) reaction mixture with 20 mL of
pentane, filtrated, washed 3×3 mLof methylene chloride/
pentane (1:1) and dried under vacuum to afford 6c as
white microcrystalline powder (0.198 g, 61%). Found: C,
81.80; H, 5.54%. C34H28O4 requires: C, 81.58; H, 5.64;
O, 12.78%; 1H NMR (CDCl3; δ (ppm)) (one stereoisomer
and exclusively keto form observed): 2.72-2.76 (m, 4H,
CH2); 5.16 (t, J=6.6 Hz, 2H, CHC=O); 5.58-5.60 (m, 2H,
=CH); 7.39-7.90 (m, 20H, Ph); 13C NMR (CDCl3; δ (ppm)):
32.30 (CH2); 56.90 (CH); 128.53 (CH aromatic); 128.78
(CH aromatic); 129.71 (=CH); 133.52 (CH aromatic);
135.87 (CH aromatic); 195.50 (C=O); MS m/z (rel. int.):
501 (M++1, 1); 395(4); 290(1); 276(19); 263(1); 237(1);
224(5); 171 (8); 105 (100); 77(25); M.p. 209-210°C.
2.3.6. 3-(3-(triethoxysilyl)allyl)pentane-2,4-dione (12a)
Catalyst 2 (0.1443 g, 1.7×10-4 mol) was added to the
boiling solution of 5a (0.5 mL, 3.4×10-3 mol) and 11a
(7.18 mL, 3.4×10-2 mol) in 20 mL of toluene. The reaction
was carried out under reflux for 24h. After this time
benzene was removed by evaporation and the product
was isolated by column chromatography on silica gel
modified with NEt3 (hexane : ethyl acetate (10:1) as
2.3.4.
2 , 2 ’ - ( b u t - 2 - e n e - 1 , 4 - d i y l ) b i s ( 2 -
methylcyclopentane-1,3-dione) (8)
Synthesis of this compound was performed according
to procedure described for 6a: Grubbs catalyst (2)
0.086g (1.01×10-4 mol) was added to the boiling
solution of 0.30 mL (2.02×10-3 mol) 2-allyl-2-methyl-
1,3-cyclopentanedione (7) in 20 mL of toluene. The
reaction was carried out at 110°C for 24h. Then toluene
was removed by evaporation, the content was washed
3×3 mL of pentane and dried under vacuum to afford
8 as white powder (0.220 g, 79%). The analytically
pure sample of compound 8 was obtained by column
chromatography on silica gel (hexane: ethyl acetate
(2:1) as eluent). Found: C, 69.80; H, 7.20%. C16H20O4
requires C, 69.54; H, 7.30; O, 23.16%; 1H NMR (C6D6); δ
(ppm)): 0.81 (s, 6H, CH3); 1.98-2.08 (m, 8H, CH2); 2.22-
2.29 (m, 4H, CH2CH=CH); 5.11-5.15 (m, 2H, =CH); 13C
NMR (C6D6; δ (ppm)): 19.65 (CH3); 35.27 (CH2); 38.39
(CH2); 56.36 (C); 128.81 (CH=); 215.13 (C=O); MS
m/z (rel. int.): 277(M++1, 1), 249(2), 164(100), 149(84),
137(18), 123(18), 109(50), 99(30), 67(22), 53(13)
1
eluent) to afford 12a as yellow oil (0.52 g, 51%). H
NMR (C6D6; δ (ppm)): 1.18 (t, J=7.0 Hz, 9H, CH3) (enol
form); 1.20 (t, J=7.0 Hz, 9H, CH3) (keto); 1.68 (s, 6H,
CH3) (keto); 1.71 (s, 6H, CH3) (enol); 2.42-2.46 (m, 2H,
CH2) (keto); 2.58-2.63 (m, 2H, CH2) (enol); 3.27 (t, J=7.5
Hz, 1H, CH) (keto); 3.82 (q, J=7.0 Hz, 6H, OCH2) (enol);
3.84 (q, J=7.0 Hz, 6H, OCH2) (keto); 5.52 (dt, J=18.7
Hz; J=2.0 Hz, 1H, =CHSi) (enol); 5.56 (dt, J=18.7 Hz,
J=1.6 Hz, 1H, =CHSi) (keto); 6.40 (dt, J=18.7 Hz, J=6.4
Hz, 1H, =CHCH2) (keto); 6.47 (dt, J=18.7 Hz, J=4.9
Hz, 1H, =CHCH2) (enol); 17.47 (s, 1H, OH) (enol); 13C
NMR (C6D6; δ (ppm)): 18.56 (CH3CH2) (enol and keto);
22.57 (CH3C=OH) (enol); 28.67 (CH3C=O) (keto); 33.78
(CH2C=C) (enol); 34.82 (CH2C=C) (keto); 58.63 (OCH2)
730

M. Miętkiewski et al.
(enol); 58.67 (OCH2) (keto); 67.18 (C=COH) (keto); 363(M++1, 1), 347(1), 333(1), 316(7), 289(14), 271(7),
106.16 (CHC=O) (enol); 120.38 (=CHCH2) (enol); 243(100), 215(15), 199(5), 163(10), 135(6), 107(7),
123.55 (=CHCH2) (keto); 148.46 (=CHSi) (keto); 149.95 45(7).
(=CHSi) (enol); 191.58 (COH) (enol); 202.26 (C=O)
(keto); MS m/z (rel. int.): 303(M++1, 4), 284(8), 269(28), 2.3.9.(E)-3-(4-(2-(triethoxysilyl)vinyl)benzyl)pentane-
256(20), 241(55), 213(85), 177(20), 169(53), 163 (68),
135 (65), 127 (17), 107 (66), 79 (100), 45 (35)
2,4-dione (13)
Catalyst 1 (0.1399 g, 1.7×10-4 mol) was added to the
boiling solution of 9 (0.6 mL, 3.4×10-3 mol) and 11a
(3.6 mL, 1.7×10-2 mol) in 20 mL of CH2Cl2. The reaction
was carried out under reflux for 24h. After this time
2.3.7.
3-(3-(trimethoxysilyl)allyl)pentane-2,4-dione
(12b)
Catalyst 2 (0.1443 g, 1.7×10-4 mol) was added in three methylene chloride was removed by evaporation and
portions within 0.5h to the boiling solution of 5a (0.5 mL, the product was isolated by column chromatography
3.4×10-3 mol) and 11b (5.1 mL, 3.4×10-2 mol) in 20 mL on silica gel modified with NEt3 (hexane:ethyl acetate
of CH2Cl2. The reaction was carried out under reflux for (50:1) as eluent) to afford 13 as brown oil (0.67 g, 52%).
24h.Afterthistimebenzenewasremovedbyevaporation 1H NMR (C6D6; δ (ppm)): 1.24 (t, 9H, CH3) (enol); 1.25
and the product was isolated by vacuum distillation (t, 9H, CH3) (keto); 1.64 (s, 6H, CH3) (keto); 1.68 (s, 6H,
(b.p. 110-112°C / 0.1 mmHg) to afford 12b as yellow oil CH3) (enol); 2.91 (d, J=7.6 Hz, 2H, CH2Ph) (keto); 3.12(s,
(0.60 g, 68%). 1H NMR (C6D6; δ (ppm)): 1.81 (s, 6H, CH3) 2H, CH2Ph) (enol); 3.55 (t, J=7.16, 1H, CHC=O); 3.92
(enol); 1.90 (s, 6H, CH3) (keto); 2.41-2.46 (m, 2H, CH2) (q, 6H, OCH2) (keto); 3.93 (q, 6H, OCH2) (enol), 6.34
(keto), 2.58-2.61 (m, 2H, CH2) (enol); 2.83 (t, J=7.3 Hz, (d, J=19.3 Hz, 1H, =CHSi) (keto); 6.41 (d, J=19.2 Hz,
1H, CH) (keto); 3.44 (s, 9H, OCH3) (enol); 3.45 (s, 9H, 1H, =CHSi) (enol); 7.45 (d, J=19.3 Hz, 1H, =CH-CH2)
CH3) (keto); 5.42(dt, J=1.9 Hz, J=18.8 Hz, 1H, =CHSi) (keto); 7.52 (d, J=19.2 Hz, 1H, =CH-CH2) (enol); 6.82 (d,
(enol); 5.46 (dt, J=1.6 Hz, J=18.8 Hz, 1H, =CHSi) (keto); J=8.4 Hz, 2H, C6H4) (enol); 6.87 (d, J=8.0 Hz, 2H, C6H4)
6.34 (dt, J=6.4 Hz, J=18.6 Hz, 1H, =CH-CH2) (keto); (keto); 7.22 (d, J=8.0 Hz, 2H, C6H4) (keto); 7.28 (d, J=8.0
6.39 (dt, J=4.9 Hz, J=18.8 Hz, 1H, =CH-CH2) (enol); Hz, 2H, C6H4) (enol); 17.52 (s, 1H, OH); 13C NMR (C6D6;
17.42 (s, 1H, -OH); 13C NMR (C6D6; δ (ppm)): 22.57 δ (ppm)): 18.6 (OCH2CH3) (enol and keto overlapped);
(CH2C=C) (keto); 28.70 (CH2C=C) (enol); 33.85 (CH3) 22.90 (CH3) (enol); 29.15 (CH3) (keto); 32.77 (CH2C=C)
(enol); 34.83 (CH3) (keto); 50.34 (OCH3) (keto and enol (enol); 34.02 (CH2C=C) (keto); 58.78 (OCH2) (enol
overlapped); 68.16 (CH2C=O) (keto), 106.46 (C=COH) and keto overlapped); 69.69 (CHC=O) (keto); 108.21
(enol); 118.75 (=CHCH2) (enol); 121.88 (=CHCH2) (C=COH) (enol); 118.58 (=CH) (enol); 118.80 (=CH)
(keto); 145.50 (=CHSi) (keto); 150.80 (=CHSi) (enol); (keto); 127.36 (C6H4) (keto); 127.46 (C6H4) (enol); 127.90
190.64 (COH) (enol); 202.24 (C=O) (keto); MS m/z (rel. (C6H4) (enol); 129.26 (C6H4) (keto); 136.44 (C6H4) (enol);
int.): 261(M++1, 4), 229(10), 217(26), 213(42), 185(99), 136.66 (C6H4) (keto);139.42 (C6H4) (keto); 140.92 (C6H4)
139(12), 121(100), 107(88), 91 (96), 77 (53), 45(19)
(enol); 148.68 (=CHSi) (keto); 148.81 (=CHSi) (enol);
191.82 (COH) (enol); 202.18 (C=O) (keto); MS m/z (rel.
int.): 378(M+, 1), 335(100), 289(56), 263(5), 245(9),
2.3.8. Diethyl 2-(3-(triethoxysilyl)allyl)malonate (12d)
The second generation Grubbs catalyst (2) (0.107 g, 217(27), 189(14), 163(20), 115 (12), 45 (12).
1.25×10-4 mol) was added to the boiling solution of 5d
(0.5 mL, 2.5×10-3 mol) and 11a (4.3 mL, 2.5×10-2 mol) 2.3.10.
in 20 mL of toluene. The reaction was carried out under
reflux (110°C) for 24h. After this time benzene was
Dichlorobis(tricyclohexylphosphine){4-(2-
acetyl-3-oxobutyl)benzylidene}ruthenium(II)
(14) (Optimised procedure)
removed by evaporation and the product was isolated by Schlenk flask (20 mL) was charged under argon with
column chromatography on silica gel modified with NEt3 [RuCl2(PCy3)2(=CHMe)] (0.114 g, 1.5×10-4 mol), 5 mL of
(hexane : ethyl acetate (10:1) as eluent) to afford 12d CH2Cl2 and 24 μL (1.35×10-4 mol) of 9. The mixture was
1
as yellow oil (0.715 g, 79%). H NMR (C6D6; δ (ppm)): stirred under reflux for 1h. Then, solvent was evaporated
0.92 (t, J=7.1 Hz, 6H, CH3); 1.19 (t, J=7.0 Hz, 9H, CH3); and the solid residue was treated with methanol. The
2.77-2.85 (m, 2H, CH2CH=CH); 3.44 (t, J=7.5 Hz, 1H, precipitate was separated by canula filtration, washed
CH); 3.84 (q, J=7.0 Hz, 6H, CH2); 3.93 (q, J=7.2 Hz, 4H, three times with cold methanol and dried in vacuum to
CH2); 5.65-5.72 (1H, =CH), 6.53-6.60 (1H, =CH); 13C afford 14 as pink microcrystalline solid (0.112 g, yield
NMR (C6D6; δ (ppm)): 14.04 (CH3); 18.55 (CH3); 35.84 80%). Found: C, 63.19; H, 8.43%. C49H80Cl2O2P2Ru
(CH2); 51.45 (CH); 58.62 (OCH2); 61.23 (CH2); 123.75 requires: C, 62.94; H, 8.62; Cl, 7.58; O, 3.42; P, 6.62; Ru,
(=CH); 148.28 (=CH); 168.68 (C=O); MS m/z (rel. int.): 10.81%. 1H NMR (C6D6; δ (ppm)): 1.56-1.58, 1.63-1.68,
731

Metathesis transformations of unsaturated
derivatives of b-diketones
1.97-2.01, (m, 66H, Cy) (keto and enol overlapped); conversion and formation of three isomeric products
1
1.72 (s, 3H, CH3) (enol); 1.68 (s, 3H, CH3) (keto); 2.73 of homo-metathesis (Eq. 1). H NMR analysis of the
(d, J=7.8 Hz, 2H, CH2) (keto); 2.82 (s, 2H, CH2) (enol); reaction mixture indicated the formation of a mixture of
3.64 (t, 1H, J=7.8 Hz, CHC=O) (keto); 8.69-8.72, 6.92- tautomers. In equations 1, 3-5 only one tautomeric form
6.96 (m, 4H, C6H4) (keto and enol overlapped); 17.50 is presented for clarity.
R
(s, 1H, OH) (enol); 20.55 (s, 1H, Ru=CH) (keto and enol
R
O
O
overlapped); 31P NMR (C6D6; δ (ppm)): 36.15; (keto);
36.05 (enol); 13C NMR C6D6; δ (ppm)): 26.9 (CH3) (keto);
30.2 (CH3) (enol); 27.8-32.7 (Cy) (keto and enol); 33.8
(CH2) (enol); 34.6 (CH2) (keto); 68.7 (CHC=O) (keto);
107.6 (C=COH) (enol); 129.7 (C6H4) (enol); 130.1 (C6H4)
(keto); 131.9 (C6H4) (keto); 132.1 (C6H4) (enol); 140.1
O
R
R
[Ru]=CHR
(1)
2
O
O
-
O
R
R
5
6
R = Me(a), Et (b), Ph(c), OEt (d)
(C6H4) (keto); 141.6 (C6H4) (enol); 152.1 (C6H4) (enol); Compound 5b in the presence of 2 exhibits similar
152.2 (C6H4) (keto); 191.7 (COH) (enol); 201.8 (C=O) reactivity and forms four isomeric products (as indicated
(keto); 293.4 (Ru=C) (keto and enol overlapped); M.p. by GC-MS). In contrast, homo-metathesis of 5c led
141-142°C (air)
to formation of a single product (as observed by GC).
Reactivity of diketones was compared with that of
allyl diethylmalonate (5d), known to readily undergo
2.4. X-Ray structure determination
Diffraction data were collected at room temperature homo-metathesis [13]. In this case, nearly quantitative
by the ω-scan technique on an Oxford Diffraction and selective transformation was observed (Table 1).
Xcalibur four-circle diffractometer with Eos CCD- Efficiency of the reactions was found to depend on
detector with graphite-monochromatized MoKα radiation the catalyst used. Low conversion of the substrates
(λ=0.71073 Å). The data were corrected for Lorentz- was observed in the presence of 1 irrespective of
polarization as well as for absorption effects [10]. the reaction duration. In contrast, nearly complete
Accurate unit-cell parameters were determined by a conversions and high yields were observed when
least-squares fit of 9398 reflections of highest intensity, catalyst 2, 3 or 4 was applied. Effective conversion in
chosen from the whole experiment. The structures the presence of catalyst 4 required a higher reaction
were solved with SIR92 [11] and refined with the full- temperature (80°C). For all reagents tested, the reaction
matrix least-squares procedure on F2 by SHELXL97 proceeded highly stereoselectively. When compound
[12]. Scattering factors incorporated in SHELXL97 were 5a, 5b or 5d was used as reagent, analysis of the
used. The function Σw(Fo2-Fc2)2 was minimized, reaction mixtures by GC/MS and 1H NMR spectroscopy
with w-1=[σ2(Fo)2+(0.0562P)2+0.2776P] (P
=
[Max indicated a high predominance of one stereoisomer.
(Fo2, 0) + 2Fc2]/3). All non-hydrogen atoms were refined The homo-metathesis of allyl derivative of cyclic
anisotropically. The hydrogen atoms were found in diketone 7 proceeded efficiently with the formation
the difference Fourier maps and isotropically refined. of two stereoisomers in a E/Z ratio exceeding 20/1
Relevant crystal data are listed in Table 1, together with (Eq. 2) (Table 1).
refinement details.
O
O
Crystallographic data (excluding structure factors)
for the structures in this paper has been deposited
with the Cambridge Crystallographic Data Centre
as supplementary publication No. CCDC-799216.
Copies of the data can be obtained free of charge, on
O
2 (5mol%)
(2)
O
toluene
110oC, 24h
O
7
8
O
application to CCDC, 12 Union Road, Cambridge, CB2 Treatment of 3-[4-(ethenyl)benzyl]pentane-2,4-dione (9)
1EZ, UK. Fax: +44-(0)1223-336033 or e-mail: deposit@ with 5 mol% of 1 or 2 in boiling CH2Cl2 results in formation
ccdc.cam.ac.uk.
of homo-metathesis product (Eq. 3) (Table 1). While the
first generation Grubbs catalyst (1) exhibited relatively
low activity in the reaction, quantitative conversion
was observed in the presence of 2. Monitoring of the
reaction by GC/MS showed formation of a single broad
3. Results and Discussion
1
peak of the product. H NMR analysis of the reaction
Treatment of 3-allyl-pentane-2,4-dione in refluxing
methylene chloride with 5 mol% of the ruthenium
complex 1 results in evolution of a gas. Analysis of the
reaction mixture by GC and GC-MS proved substrate
mixture indicated the formation of single stereoisomer
of stilbene derivative 10 being a mixture of tautomers
(Eq. 3, Table 1).
732

M. Miętkiewski et al.
This symmetry enforces the trans disposition of the
double bond and ideal coplanarity of the planar – within
0.016(1) Å - phenyl rings of the molecule.
O
O
O
Unsaturated derivatives of pentane-2,4-dione and
(3) diethylmalonate were tested in cross-metathesis with
triethoxyvinylsilane and styrene in the presence of
ruthenium benzylidene complexes. Trialkoxyvinylsilanes
were selected as reaction partners because they are
highly active in CM and do not undergo homo-metathesis
[Ru]=CHR
CH2Cl2, 24h
O
O
O
9
10
mixture of tautomers
Products of all reactions were isolated and [16]. Moreover they easily react with silica so that
characterised spectroscopically. To the best of the trialkoxysilyl derivatives can be readily immobilised on
authors’ knowledge products 6b, 6c, 8 and 10 have siliceous surfaces. On the other hand styrene is known
not been reported in the literature. Compound 6a was to undergo homo-metathesis slowly in the presence
reported to be formed as a minor by-product during of 1 and readily in the presence of second and further
allylation of pentane-2,4-dione with Z-2-butene-1,4-diol generations of Grubbs catalysts [17].
[14]. Crystal structure of product 10 confirmed expected
Treatment of a mixture of 5 and vinylsilane 11 in
formationofE-stereoisomer.Fig.2showstheperspective the presence of 5 mol% of Grubbs catalyst gives rise
view of the molecule (see supplementary data for the list to conversion of reacting olefins and the evolution of
of some relevant geometrical parameters). The molecule ethene. To avoid homo-metathesis of 5, vinylsilane
is symmetrical (Ci), the middlepoint of the central double was used in five- or tenfold excess. Examination of the
bond lies in special position, at the center of symmetry. reaction mixtures by 1H NMR and GC-MS confirmed the
Table 1. Homo-metathesis of unsaturated derivatives of β-diketones and allyl diethylmalonate
Product(s)
Cat.
Solvent
Temp.
[°C]
Yield [%]
(isolated)
Stereoselectivity
[%]
Tautomer
ratio
1
2
3
4
CH2Cl2
CH2Cl2
CH2Cl2
40
40
40
80
37
99 (83)
99
90
90
1 / 4a
1 / 4a
1 / 4a
1 / 4a
O
O
O
O
O
benzene
85
6a
2
CH2Cl2
CH2Cl2
40
99 (71)
74 (61)
5 / 1b
Et
Et
O
O
O
Et
Et
6b
Ph
2
40
100
100
ketob
Ph
O
O
O
O
Ph
Ph
6c
1
2
3
4
CH2Cl2
CH2Cl2
CH2Cl2
toluene
40
40
40
69
95
99
99
ketob
ketob
ketob
ketob
EtO
OEt
O
O
O
O
110
EtO
OEt
6d
2
toluene
110
40
90 (79)
95
-
O
O
O
O
8
2
CH2Cl2
98 (75)
100
10 / 1b
O
O
O
O
10
Reaction conditions: 24 h, [diketone]:[Ru] = 1 : 5×10-2; a[total ketone form] / [total enol form] ratio determined by 1H NMR in C6D6; b[total ketone form] /
[total enol form] ratio determined by 1H NMR in CDCl3;
733

Metathesis transformations of unsaturated
derivatives of b-diketones
Figure 2.
Perspective view of the molecule 10 with labeling scheme. The ellipsoids are drawn at the 50% probability level, hydrogen atoms are
depicted as spheres of arbitrary radii [15]. The unlabelled part of the molecule is related with the labeled one by the symmetry operation
-x,-y,-z. Some geometrical data: C1-C1(-x,-y,-z) 1.324(3) Å; C10-O11 1.1967(17) Å, C14-O15 1.2026(17) Å;
formation of CM products (Eq. 4). When compound 5a are presented in Table 2. To our knowledge, cross-
was used as a reacting partner, the reaction results in metathesis products summarised in Table 2 except for
formation of a mixture of tautomers.
12c and 12e were not described in the literature.
To learn more on the reaction mechanism
the interaction of benzylidene complex 1 with equimolar
R1
R1
O
O
O
[Ru]=CHR
-
+
R2
1
amount of 9 was monitored by H NMR spectroscopy.
O
(4) Effective formation of styrene and new alkylidene
complex (14) was observed, which indicates the
stoichiometric metathesis according to Eq. 6.
R1
R1
R2
12 (see Table 2)
5
11
R1 = Me (a), OEt (d);
R
2 = Si(OEt)3 (a), Si(OMe)3 (b), Ph (c)
O
O
O
CM requires more drastic reaction conditions
O
PCy3
Ru
Cl
than those of homo-metathesis. Relatively high yields
were obtained for the reactions run in the presence
of catalysts 2, 3 or 4 in boiling benzene or toluene.
Each time stereoselective formation of E isomer was
observed and confirmed on the basis of 1H NMR spectra.
Selective synthesis of 12c and 12e by CM (Table 2)
failed due to preference of 5a, 5d and styrene to form
Ph
PCy3
Ru
+
(6)
H2C=CHPh
C6D6, r.t., 1h
Cl
Cl
PCy3
Cl
PCy3
1
9
14
yield = 95%
[ketone] / [ enol] = 1 / 1.6
In C6D6 solution complex 14 is a mixture of tautomers.
homo-metathesis products under conditions used. Keto to enol form ratio was calculated on the basis of
Products 12c [18] and 12e [19] can be more effectively 1H NMR spectrum. Compound 14 was synthesised
synthesised by catalysed coupling of pentane-2,4-dione and characterised spectroscopically. Stoichiometric
with an appropriate organic derivative. 3-[4-(ethenyl) metathesis of second generation Grubbs catalyst (2)
benzyl]pentane-2,4-dione (9) was successfully tested in with 9 showed formation of minor amounts of a second
cross-metathesis with triethoxyvinylsilane (11a) (Eq. 5). generation analogue of 14. However, in the presence of
2 homo-metathesis proceeds too fast for the propagative
O
O
carbene to accumulate in the reaction mixture. Reaction
O
1 (5mol%)
-
CH2Cl2
40°C, 24h
+
O
Si(OEt)3
(5) of complex 14 with fivefold excess of compound 9
proceeds slowly and leads to formation of methylene
complex and stilbene derivative 10. After 6h of reaction
9
11a
13
Si(OEt)3
To avoid competitive homo-metathesis of 9, in C6D6 at 40°C formation of 15% of methylene complex
triethoxyvinylsilane (11a) was used in tenfold excess. [RuCl2(PCy3)2(=CH2)] and corresponding amount of
1
The reaction proceeded highly stereoselectively and led 10 were observed by the H NMR spectroscopy. The
to exclusive formation of E-isomer of cross-metathesis results of the equimolar reactions support metathesis
product 13, being a mixture of two tautomers. The results mechanism of the reaction.
734

M. Miętkiewski et al.
Table 2. Cross metathesis of unsaturated derivatives of β-diketones and allyl diethylmalonate
Product
Cat.
Solvent
Temp.
[°C]
Time
[h]
Yield (isolated) Tautomer
E / Z
ratioa
[%]
2
2
4
CH2Cl2
toluene
toluene
40
24
24
24
80
90 (71)
90
1/ 2
1/ 2
1/ 2
>10 / 1
O
110
110
Si(OEt)3
O
12a
2
1
2
CH2Cl2
CH2Cl2
toluene
40
24
24
24
85 (67)b
1/ 1.3
1/ 1.3
-
>10 / 1
>10 / 1
>10 / 1
O
O
Si(OMe)3
12b
40
15
O
O
12c
110
90 (79)
OEt
O
Si(OEt)3
O
OEt
12d
1
1
CH2Cl2
40
40
24
24
20
-
>10 / 1
OEt
O
OEt
O
12e
CH2Cl2
73 (52)c
1 / 1.8
E
Si(OEt)3
O
O
13
a)
Reaction conditions: 24h, [diketone]:[olefin]:[Ru]=1:10:5×10-2; [ketone form] / [enol form] ratio determined by 1H NMR in C6D6; b) [5a]:[11b] = 1:5;
c) [9]:[11a] = 1:5;
4. Conclusion
Acknowledgement
We have demonstrated that olefin metathesis catalysed Financial support from the Ministry of Science and
by Grubbs type ruthenium alkylidene complexes can be Higher Education (Poland), (project No. N 204 1935 33)
conveniently used for synthesis and functionalisation is gratefully acknowledged.
of unsaturated derivatives of β-diketones. Conditions
of efficient homo-metathesis of selected diketone
derivatives
and
their
cross-metathesis
with
Supplementary data
vinyltrialkoxysilanes were demonstrated. Results of
equimolar reactions support the expected carbene
mechanism of the reaction.
Supplementary data associated with this article can be
found separately.
References
[1]
[2]
R.H. Grubbs (Ed.), Handbook of Metathesis
(Wiley-VCH, Weinheim, 2003)
R.H. Grubbs, A.G. Wenzel, A.K. Chatterjee, In:
T. Hiyama (Ed.), Comprehensive Organometallic
Comprehensive
Coordination
Chemistry
II
(Elsevier, Amsterdam, 2004) Vol. 1, Chapter 1.6; c)
J. Zabicky (Ed.), The chemistry of metal enolates
(Wiley, Chichester, 2009) Part 1
Chemistry III (Elsevier, Amsterdam, 2006) Vol. 11, [4] F. Bargiggia, W.V. Murray, J. Org. Chem. 70, 9636
Chapter 11.06
(2005)
R.C. Mehrotra, C. Bohra, D.P. Guar, Metal [5] A. Michaut, T. Boddaert, Y. Coquerel, J. Rodriguez,
β-Diketonates and Allied Derivatives (Acad.Press,
Synthesis 18, 2867 (2007)
New York, 1978); b) C. Pettinari, F. Marchetti, [6] T. Boddaert, Y. Coquerel, J. Rodriguez, C.R. Chim.
A. Drozdov, In: J.A. McCleverty, T.J. Meyer (Eds.),
12, 872 (2009)
[3]
735
735

Metathesis transformations of unsaturated
derivatives of b-diketones
[7] J.A. Love, J.P. Morgan, T.M. Trnka, R.H. Grubbs, [15] Stereochemical Workstation Operation Manual,
Angew. Chem. Int. Ed. 41, 4035
(2002)
Release 3.4. (SiemensAnalytical X-ray Instruments
Inc., Madison, Wisconsin, USA, 1989)
[8] B. Staniszewski, W. Urbaniak, Chem. Pap. 63, 212 [16] C. Pietraszuk, B. Marciniec, H. Fischer,
(2009)
Organometallics 29, 913 (2000); b) C. Pietraszuk,
H. Fischer, S. Rogalski, B. Marciniec, J. Organomet.
Chem. 690, 5912 (2005)
[9] X. Han, R.A. Widenhoefer, J. Org. Chem. 69, 1738
(2004)
[10] CrysAlis PRO (Version 1.171.33.36d) (Oxford [17] A.K. Chatterjee, T.L. Choi, D.P. Sanders,
Diffraction Ltd., Oxford, 2009)
[11] A. Altomare, G. Cascarano, C. Giacovazzo
A. Gualardi, J. Appl. Cryst. 26, 343 (1993)
[12] G.M. Sheldrick, Acta Cryst. A64, 112 (2008)
[13] a) M.B. Runge, M.T. Mwangi, N.B. Bowden,
J. Organomet. Chem. 691, 5278 (2006);
R.H. Grubbs, J. Am. Chem. Soc. 125, 11360
(2003)
[18] (a) Z.S. Qureshi, K.M. Deshmukh, P.J. Tambade,
B.M. Bhanage, Tetrahedron Lett. 51, 724 (2010);
(b) M. Rueping, B.J. Nachtsheim, A. Kuenkel, Org.
Lett. 9, 825 (2007)
b) M.T. Mwangi, M.B. Runge, N.B. Bowden, J. Am. [19] (a) S.K. Moiseev, R.V. Lebedev, A.I. Polosukhin,
Chem. Soc. 128, 14434 (2006)
[14] M. Sakamoto, I. Shimizu,A. Yamamoto, Bull. Chem.
Soc. Japan 69, 1065 (1996)
V.N. Kalinin, Russ. Chem. Bull., 50, 554 (2001);
(b) N.T. Patil, Y. Yamamoto, Tetrahedron Lett. 45,
3101(2004)
736
736