Palladium-catalyzed 1,4-addition of carboxylic acids to butadiene monoxide

Article abstract of DOI:10.1002/adsc.201200059

Palladium complexes catalyze the 1,4-addition of acetic acid to butadiene monoxide to give 4-hydroxybut-2-en-1-yl acetate. The highest 1,4-/1,2-addition selectivity of 18.9 was achieved. The reaction seems to proceed via a Wacker-like mechanism. Copyright

Full text of DOI:10.1002/adsc.201200059

COMMUNICATIONS
DOI: 10.1002/adsc.201200059
Palladium-Catalyzed 1,4-Addition of Carboxylic Acids to
Butadiene Monoxide
Akiyuki Hamasaki,a Shuhei Maruta,a Aki Nakamura,a and Makoto Tokunagaa,b,*
a
Department of Chemistry, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan
Fax : (+81)-92-642-7528; phone: (+81)-92-642-7528; e-mail: mtok@chem.kyushu-univ.jp
International Research Center for Molecular Systems (IRCMS), Kyushu University, Moto-oka 744, Nishi-ku, Fukuoka
b
819-0395, Japan
Received: January 21, 2012; Revised: April 29, 2012; Published online: July 31, 2012
Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/adsc.201200059.
Abstract: Palladium complexes catalyze the 1,4-ad-
dition of acetic acid to butadiene monoxide to give
4-hydroxybut-2-en-1-yl acetate. The highest 1,4-/1,2-
addition selectivity of 18.9 was achieved. The reac-
tion seems to proceed via a Wacker-like mecha-
nism.
Various metal complexes were examined as cata-
lysts in the acetic acid addition to butadiene monox-
ide (Table S-1 in the Supporting Information). Ir, Ru,
Au, Cu and Pt complexes gave undesired 3 as major
products (Table S-1 in the Supporting Information,
entries 2–8). Similar to the results reported in the pat-
ents,[4a,b,c] Pd(0) catalyzed the reaction smoothly but
the selectivity of 2/3 was 0.6 (Table S-1 in the Sup-
porting Information, entry 9). Several Pd(II) com-
Keywords: 1,4-addition; butadiene monoxide; car-
boxylic acids; palladium
plexes were tested and among them, PdCl2ACTHNUTRGNEN(UG MeCN)2
gave 2 as major product although the yield was only
20% (Table S-1 in the Supporting Information,
entry 15). The 2/3 ratio was 4.0. Solvent screening was
Vinyloxiranes are useful substrates for organic synthe- performed at this stage, toluene, THF, 2-propanol,
sis and have high reactivities toward addition reac- pyridine, HMPA, DMSO, and dichloromethane gave
tions with various nucleophiles.[1] Particularly, the almost no conversions or low selectivity of 2. The re-
facile formation of p-allyl Pd-complexes by the cleav- action in acetonitrile and amidic solvents gave gener-
À
age of C-2 O bonds and successive addition to the 4- ally preferable yields and selectivities.
position provides 1,4-addition products.[2] When car-
Then the effect of additive was examined with ace-
boxylic acids were used as nucleophiles, 1,4-bis- tonitrile as solvent. The addition of Ag salts did not
oxygen-functionalized 2-alkenes have been obtained improve the reactivity and selectivity (Table 1, en-
and utilized for natural product syntheses.[3] Although tries 1–3). By the addition of Li, Na, K and Cs salts,
this reaction has a relatively wide scope for internal both the yield and selectivity were improved. The ad-
diene monoxides, few patents are found on unsubsti- dition of basic salts generally increased the yield and
tuted 1,3-butadiene monoxide and the selectivities for bromide salts raised the selectivity. The combination
the 1,4-addition product were low (1,2- vs. 1,4-addi- of basic salts and bromide salts such as K3PO4/LiBr
tion for ~1:1).[4a,b,c] Querci reported an efficient cata- improved both together (Table 1, entry 13). Since the
lytic system using acid anhydrides as nucleophiles and addition of bromide salts gave better results, the reac-
phosphine ligands to give the 1,4-addition product se- tion with [PdBr2ACTHUNRGTNEG(UN MeCN)2] in the presence of K3PO4/
lectively.[4d] However, carboxylic acids are preferable LiBr was examined and resulted in a good selectivity
to acid anhydrides in the point of atom efficiency. The 2/3=10.7 (Table 1, entry 17).
product 1,4-butanediol derivatives are very important
Further optimization of the reaction conditions was
materials in the petroleum and coal chemical indus- carried out with this catalyst system (Table 2). Here,
tries for the production of basic chemicals such as the reactions without solvent gave improved chemical
THF, g-butyrolactone, and synthetic fibres.[5] Since we yields and at lower temperatures also gave high selec-
have been interested in oxygen nucleophile addition tivities. The highest total yield of 2 and 3 was 97% at
to various organic molecules,[6] this time we carried 358C and the selectivity was 6.4 (entry 4) Further low-
out a study to achieve selective the 1,4-addition of erering of the temperature (58C) with LiBr gave
carboxylic acids to butadiene monoxide.
a higher selectivity of 10.7 but the yield was 82%
(entry 7). When LiBr was replaced with KBr, the best
Adv. Synth. Catal. 2012, 354, 2129 – 2134
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
2129

Akiyuki Hamasaki et al.
COMMUNICATIONS
Table 1. Effect of additives.[a]
Entry
Additive
Time [h]
Yield[b] [%]
2a (E/Z)
Ratio of 2a/3a
3a
1
2
3
4
5
6
7
8
AgOAc
AgTFA
AgOTf
LiOAc
Li2CO3
NaOAc
Na2CO3
KOAc
K2CO3
Cs2CO3
K3PO4
LiBr
24
2
2
2
3
2
2
2.5
2
2
2
24
2
2
1
17 (2.0/1)
9 (2.0/1)
0
9
3
2
4
5
6
6
7
9
9
9
6
7
6
0
0
5
1.8/1
3.5/1
0/1
28 (1.3/1)
25 (1.1/1)
37 (1.3/1)
39 (1.4/1)
37 (1.3/1)
43 (1.5/1)
42 (1.4/1)
45 (1.7/1)
30 (1.4/1)
48 (1.4/1)
31 (1.4/1)
0
6.4/1
4.8/1
6.2/1
6.1/1
5.3/1
4.7/1
4.7/1
4.2/1
5.3/1
7.2/1
5.5/1
9
10
11
12
13
14
15
16
17[c]
K3PO4 +LiBr
KF
NaI
LiI
1
2
0
K3PO4 +LiBr
50 (2.1/1)
10.7/1
[a]
The reaction was carried out with butadiene monoxide (1 mmol), AcOH (2.5 equiv.) in 2 mL of acetnitrile under N2.
GC yield.
PdBr2ACHTUNGTRENNUNG(MeCN)2 was used instead of PdCl2ACHUTNGTRENN(UGN MeCN)2.
[b]
[c]
Table 2. Addition of acetic acid to butadiene monoxide catalyzed by palladium complexes under various reaction conditi-
ACHTUNGTRENNUNG
ons.[a]
Entry
Temperature [8C]
Time [h]
Yield[b] [%]
2a (E/Z)
Ratio of 2a/3a
3a
1[c]
2
3
4
5
55
55
45
35
25
15
5
2
2
2
2
2
2
3
3
50 (2.1/1)
70 (1.6/1)
75 (1.6/1)
84 (1.6/1)
72 (1.5/1)
80 (1.4/1)
75 (1.3/1)
68 (1.3/1)
0
5
10.7/1
5.1/1
5.9/1
6.4/1
7.0/1
9.5/1
10.7/1
16.3/1
14
13
13
10
8
7
4
0
6
7
8[d]
9
5
À15
24
[a]
The reaction was carried out with butadiene monoxide (1 mmol) and AcOH (2.5 equiv) without solvent under N2.
[b]
[c]
[d]
GC yield.
MeCN (2 mL) was used as solvent.
KBr was used instead of LiBr.
2130
asc.wiley-vch.de
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2012, 354, 2129 – 2134

Palladium-Catalyzed 1,4-Addition of Carboxylic Acids to Butadiene Monoxide
Table 3. Pd-catalyzed addition of various carboxylic acids to butadiene monoxide.[a]
Entry
RCOOH
MBr
Time [h]
Major product
Yield[b] [%]
2 (E/Z)
Ratio of 2/3
3
1
2
3
4
5
6
LiBr
KBr
LiBr
KBr
LiBr
KBr
3
3
3
3
24
24
2b
2b
2c
2c
2d
2d
58 (1.1/1)
49 (1.1/1)
49 (1.0/1)
44 (1.0/1)
0
5
3
4
3
0
1
11.4/1
17.6/1
13.5/1
16.9/1
15 (1.5/1)
14.3/1
7
8
9
10
11
12
LiBr
KBr
LiBr
KBr
LiBr
KBr
1
1
6
6
10
6
2e
2e
2f
2f
2g
2g
91 (1.8/1)
79 (1.7/1)
52 (1.2/1)
53 (1.1/1)
70 (1.3/1)
60 (1.2/1)
9
6
5
5
5
3
10.4/1
12.4/1
10.9/1
10.3/1
14.2/1
18.9/1
13
14
LiBr
KBr
24
4
2h
2h
0
0
4
32 (1.1/1)
7.1/1
[a]
The reaction was carried out with butadiene monoxide (1 mmol), carboxylic acid (2.5 equiv.) under N2.
GC yield.
[b]
Scheme 1. Possible mechanisms of palladium-catalyzed 1,4-addition of carboxylic acids.
selectivity (16.3) was observed although the yield was thoxyacetic acid was used in the presence of K3PO4/
moderate (72%) (entry 8). Thus we decided upon the LiBr, a 100% yield was achieved with the 2/3 ratio of
two optimized conditions; for the chemical yield: 10 (entry 7). On the other hand, when 4-oxopentanoic
[PdBr
lectivity: [PdBr CHTUNGTRENNUNG
(MeCN)2]+K3PO4/LiBr at 58C, and for the se- acid was used in the presence of K3PO4/KBr, the 2/3
2A(MeCN)2]+K3PO4/KBr at 58C. ratio reached to 19 (entry 12). Since the carboxylic
The reaction was surveyed with several different acids with coordinating functionalities gave a better
carboxylic acids under the optimized conditions yield and selectivity (entries 7 and 12), an interaction
(Table 3). Propanoic and butanoic acids gave slightly of the acids to Pd may play an auxiliary role in this
higher selectivities compared to acetic acid with reaction. Benzoic acid gave lower yields and selectivi-
somewhat lower yields (entries 1–4). When 2-me- ties (entries 13 and 14).
Adv. Synth. Catal. 2012, 354, 2129 – 2134
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
2131

Akiyuki Hamasaki et al.
COMMUNICATIONS
Scheme 2. Addition of acetic acid to cyclopentadiene mon-
oxide with palladium-catalysts.
Scheme 3. Addition of acetic acid to a p-allyl Pd complex 6.
The widely accepted mechanism of this reaction for
internal diene monoxides is depicted as
I in
Scheme 1.[2] The oxidative addition to the Pd(0) spe-
À
cies by the cleavage of C O bonds to form a p-allyl
Pd intermediate followed by nucleophilic attack of
acetic acid. However, since the precursor is a Pd(II)
complex, alternative Wacker-like mechanisms II and
III are also considered for this reaction.[7] The mecha-
nism II includes 1,4-acetoxypalladation, in contrast,
III proceeds via 1,2-acetoxypalladation, successive b-
Scheme 4. Addition of acetic acid to (R)-1 with palladium
H elimination, and hydropalladation of epoxides. catalysts.
Since d+ is locating on the 2 and 4 positions, nucleo-
philic attacks on the 2 and 4 positions are suitable.
Here, in general, hard Lewis acid activation preferred a simple epoxide ring opening mechanism. A plausi-
2-attack, in contrast soft Lewis acid activation acceler- ble pathway to racemic 3 is the p-allyl Pd mechanism
ated 4-attack. Recently, chelating control of the regio- including an equilibrium with the corresponding s-al-
selectivity on Wacker oxidation of allyl-substituted lylpaladium complexes.[11] The other possibility is the
substrates was studied.[8] The oxygen functionality at indirect formation such as isomerization of 2 into 3
the allylic position induces terminal addition of nucle- via p-allyl Pd or 1,3-acetoxy shift. Actually, when 2
ophiles. This chelating effect is also expected for our was exposed to reaction conditions at 558C, gradual
reaction, which supports the mechanism II and might isomerization to 3 was observed. However, the iso-
enhance the 2/3 selectivity.
merization was completely suppressed at 58C. There-
When the cyclic substrate 4 was reacted with nucle- fore, the formation of 3 under the conditions (at 58C)
ophiles, the cis-product was selectively formed with via isomerization is unlikely. Since the unreacted sub-
a Pd(0) catalyst as mentioned in literature reports strate was not racemized, it is also unlikely that the
(Scheme 2).[2] On the other hand, the Pd(II) catalyst reversible formation of a carbocation at the 3-position
optimized for this work afforded complex mixtures or of a p-allyl Pd complex occurs. Although there is
under several different conditions. This result suggests a possibility that halohydrin, which is reversibly
the active species is different from Pd(0) and Wacker- formed by a treatment of butadiene monoxide with
like mechanisms (II or III) seems to be valid.
lithium halide and AcOH,[12] is involved in the reac-
A p-allyl Pd complex (6)[9] derived from 1 was ex- tion path, the unaltered enantiopurity of substrate
amined for the stoichiometric addition of acetic acid 1 negates this assumption.
(Scheme 3). In the presence of PPh3, a similar result
At this moment we think a Wacker-like mechanism
to the Pd(PPh3)4-catalyzed reaction was obtained. In (II or III) is plausible for the major product (2)
ACHTUNGTRENNUNG
contrast, the reaction with K3PO4/LiBr did not give 2a whereas a Pd(0) p-allyl mechanism is likely for the
and 3a. Although a difference of reactivity between minor product (3). The effect of the BrÀ concentra-
neutral and cationic p-allyl complexes should be con- tion to the 2/3 selectivity might be attributable to the
sidered, this result is consistent with the above expect- inhibition of Pd(0) formation and aggregation by
ation.
However, Pd(0)/p-allyl Pd mechanism cannot be
[PdBr4]2À complexation.
In the mechanistic studies of the Wacker oxidation
excluded completely. When optically active (95% ee) of ethylene on the effect of ClÀ concentration, it has
butadiene monoxide [(R)-1][10] was used, the enantio- been proposed that the higher ClÀ concentration
meric excess of obtained 3a was 0% (Scheme 4), brings outer sphere attack of water while a lower con-
while the unreacted substrate kept the initial ee value. centration leads to inner sphere attack.[13a,b] However,
This result suggests that 3 was not formed via recent theoretical studies revealed that outer sphere
2132
asc.wiley-vch.de
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2012, 354, 2129 – 2134

Palladium-Catalyzed 1,4-Addition of Carboxylic Acids to Butadiene Monoxide
attack of water is predominant irrespective of ClÀ
concentration.[13c,d] According to these studies, the BrÀ
concentration presumably does not change inner/
outer attack. On the other hand, a higher BrÀ concen-
[2] B. M. Trost, G. A. Molander, J. Am. Chem. Soc. 1981,
103, 5969–5972; B. M. Trost, S. R. Angle, J. Am. Chem.
Soc. 1985, 107, 6123–6124; T. Tsuda, M. Tokai, T.
Ishida, T. Saegusa, J. Org. Chem. 1986, 51, 5216–5221;
M. Gagliardo, N. Selander, N. C. Mehendale, G.
van Koten, R. J. M. K. Gebbink, K. J. Szabꢁ, Chem.
Eur. J. 2008, 14, 4800–4809; P. Zhang, J. P. Morken, J.
Am. Chem. Soc. 2009, 131, 12550–12551.
À
tration increases the amount of [PdBr4]2 and pre-
vents Pd(0) formation. Since Pd(II) metal prefers
softer BrÀ than ClÀ, the former gave the better re-
sults.
[3] D. R. Deardorff, D. C. Myles, K. D. MacFerrin, Tetrahe-
dron Lett. 1985, 26, 5615–5618; Y. Kobayashi, M.
Asano, S. Yoshida, A. Takeuchi, Org. Lett. 2005, 7,
1533–1536; Y. Kobayashi, S. Yoshida, M. Asano, A.
Takeuchi, H. P. Acharya, J. Org. Chem. 2007, 72, 1707–
1716;.
[4] a) S. A. Godleski, PCT Int. Appl. WO 8902883, 1989;
b) R. Pinkos, R. Fischer, German Patent Application
DE 94-4429690, 1995; c) M. Retboll, H. Ono, Japan
Patent Application JP 2000-258360, 2000; d) D. Bianchi,
C. Querci, M. Ricci, R. Santi, Tetrahedron Lett. 1997,
38, 3081–3084.
In conclusion, the highly selective 1,4-addition of
carboxylic acids to butadiene monoxide has been
achieved with Pd(II) catalysts. The highest ever 1,4-/
1,2- selectivity of 18.9 was achieved. In contrast to
Pd(0)-catalyzed 1,4-addition of substituted butadiene
monoxide which proceeds via a p-allyl Pd mechanism,
the present reaction seems to proceed via a Wacker-
like mechanism. The reaction provides useful 1,4-di-
oxygen-functionalized intermediates for basic chemi-
cals production.
[5] K. Weissermel, H.-J. Arpe, Industrial Organic Chemis-
try, 4th edn., Wiley-VCH, Weinheim, 2003; H. A. Witt-
coff. B. G. Reuben, J. S. Plotkin, Industrial Organic
Chemicals, 2nd edn., Wiley-VCH: Hoboken, 2004.
[6] A. Nakamura, M. Tokunaga, Tetrahedron Lett. 2008,
49, 3729–3732; H. Itoh, E. Yamamoto, S. Masaoka, K.
Sakai, M. Tokunaga, Adv. Synth. Catal. 2009, 351,
1796–1800; T. Hirai, A. Hamasaki, A. Nakamura, M.
Tokunaga, Org. Lett. 2009, 11, 5510–5513; A. Hamasa-
ki, A. Yamamoto, H. Ito, M. Tokunaga, J. Organomet.
Chem, 2011, 696, 202–210; A. Nakamura, A. Hamasaki,
S. Goto, M. Utsunomiya, M. Tokunaga, Adv. Synth.
Catal. 2011, 353, 973–984; E. Yamamoto, A. Nagai, A.
Hamasaki, M. Tokunaga, Chem. Eur. J. 2011, 17, 7178–
7182.
Experimental Section
Typical Procedure for Acetic Acid Addition to
1 (Table 2, entry 7)
A mixture of PdBr2ACTHNUTRGNEUNG(MeCN)2 (10.4 mg, 0.03 mmol), K3PO4
(12.7 mg, 0.06 mmol) and LiBr (5.1 mg, 0.06 mmol) was
placed in a screw-cap tube. To this screw-cap tube, acetic
acid (150 mg, 2.5 mmol), triglyme[14] (45 mL, 0.25 mmol) as
an internal standard, and butadiene monoxide (70 mg,
1 mmol) were added. The mixture was stirred at 58C for 3 h.
Yields of the products were determined by GC analysis rela-
tive to an internal standard.
[7] P. M. Henry, J. Am. Chem. Soc. 1972, 94, 7305–7310;
O. S. Andell, J.-E. Bꢂckvall, J. Organomet. Chem. 1983,
244, 401–407.
Supporting Information
Additional experimental procedures and spectral data are
available as Supporting Information.
[8] S.-K. Kang, K.-Y. Jung, J.-U. Chung, E.-Y. Namkoong,
T.-H. Kim, J. Org. Chem. 1995, 60, 4678–4679; J.
Muzart, Tetrahedron 2007, 63, 7505–7521; B. W. Michel,
A. M. Camelio, C. N. Cornell, M. S. Sigman, J. Am.
Chem. Soc. 2009, 131, 6076–6077; B. W. Michel, J. R.
McCombs, A. Winkler, M. S. Sigman, Angew. Chem.
2010, 122, 7470–7473; Angew. Chem. Int. Ed. 2010, 49,
7312–7315.
[9] J. Kjellgren, J. Aydin, O. A. Wallner, I. V. Saltanova,
K. J. Szabꢁ, Chem. Eur. J. 2005, 11, 5260–5268.
[10] M. Tokunaga, J. F. Larrow, F. Kakiuchi, E. N. Jacobsen,
Science 1997, 277, 936–938.
Acknowledgements
The present work is supported by a Grant-in-Aid for Global-
COE program, “Science for Future Molecular Systems”, Sci-
entific Research (A) (No. 20245014) from the Ministry of
Education, Culture, Science, Sports and Technology of Japan.
We appreciate a financial support from Mitsubishi Chemical
Corporation.
[11] a) B. M. Trost, R. C. Lemoine, Tetrahedron Lett. 1996,
37, 9161–9164; b) R. Prꢃtꢄt, A. Pfaltz, Angew. Chem.
1998, 110, 337–339; Angew. Chem. Int. Ed. 1998, 37,
323–325; c) B. M. Trost, R. C. Bunt, R. C. Lemoine,
T. L. Calkins, J. Am. Chem. Soc. 2000, 122, 5968–5976;
d) B. M. Trost, W. Tang, Org. Lett. 2001, 3, 3409–3411;
e) similar p-allyl Pd intermediates are also considered
for allylic acetoxylation: H. Grennberg, J. E. Bꢂckvall,
Chem. Eur. J. 1998, 4, 1083–1089.
References
[1] C. Jaime, R. M. OrtuÇo, J. Font, J. Org. Chem. 1988, 53,
139–141; B. Olofsson, U. Khamrai, P. Somfai, Org. Lett.
2000, 2, 4087–4089; J. Muzart, Tetrahedron 2005, 61,
5955–6008; M. Kimura, R. Mukai, T. Tamaki, Y.
Horino, Y. Tamaru, J. Am. Chem. Soc. 2007, 129, 4122–
4123; J. Muzart, Eur. J. Org. Chem. 2011, 4717–4741.
[12] J. S. Bajwa, R. C. Anderson, Tetrahedron Lett. 1991, 32,
3021–3024.
Adv. Synth. Catal. 2012, 354, 2129 – 2134
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
2133

Akiyuki Hamasaki et al.
COMMUNICATIONS
[13] a) O. Hamed, P. M. Henry, Organometallics 1997, 16,
4903–4909; b) O. Hamed, P. M. Henry, C. Thompson, J.
Org. Chem. 1999, 64, 7745–7750; c) A. Comas-Vives, A.
Stirling, A, Lledꢁs, G, Ujaque, Chem. Eur. J. 2010,
16, 8738–8747; d) N. N. Nair, J. Phys. Chem. B 2011,
115, 2312–2321.
[14] There is a possibility that triglyme have some influence
on the product selectivity by acting as a ligand. Howev-
er, similar yields of entries 3 and 7 in Table 2 were ob-
tained when o-xylene (20 mL) was used as an internal
standard instead of triglyme.
2134
asc.wiley-vch.de
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2012, 354, 2129 – 2134