Efficient and stereoselective rearrangement of Baylis-Hillman acetates catalyzed by gold(I) chloride/silver(I) trifluoromethanesulfonate

Article abstract of DOI:10.1055/s-0028-1087971

Efficient and stereoselective rearrangement catalyzed by only one mole-percent gold(I) chloride/silver(I) trifluoromethanesulfonate of Baylis-Hillman acetates afforded 2-(acetoxymethyl) alk-2-enoates under mild reaction conditions in good to high yields w

Full text of DOI:10.1055/s-0028-1087971

1170
PAPER
Efficient and Stereoselective Rearrangement of Baylis–Hillman Acetates
Catalyzed by Gold(I) Chloride/Silver(I) Trifluoromethanesulfonate
Rearrangement of
u
B
aylis–Hillm
n
anAcetateskui Liu,a Dajie Mao,a Jianqiang Qian,a Shaojie Lou,a Zhenyuan Xu,*a Yongmin Zhangb
a
State Key Laboratory Breeding Base of Green Chemistry–Synthesis Technology, Zhejiang University of Technology,
310014 Hangzhou, P. R. of China
Fax +86(571)88320609; E-mail: greensyn@zjut.edu.cn
Department of Chemistry, Zhejiang University, Xi-xi Campus, 310028 Hangzhou, P. R. of China
b
Received 24 October 2008; revised 25 November 2008
diates for the synthesis of (E)-cinnamyl alcohols9,10 and
other complicated molecules,11 has been investigated in
the presence of several catalysts, including trimethylsilyl
trifluoromethanesulfonate,12 montmorillonite-K10 clay,13
Abstract: Efficient and stereoselective rearrangement catalyzed by
only one mole-percent gold(I) chloride/silver(I) trifluoromethane-
sulfonate of Baylis–Hillman acetates afforded 2-(acetoxymeth-
yl)alk-2-enoates under mild reaction conditions in good to high
yields with 100% E-selectivity. For cyclohex-2-enone-derived 1,4-diazabicyclo[2.2.2]octane,14 cesium fluoride,15 palla-
dium(II) acetate,16 iron(III) chloride, and ytterbium(III)
Baylis–Hillman acetates, the reaction gave 2-alkylidenecyclohex-3-
trifluoromethanesulfonate.6g However, these procedures
enones in good yields.
Key words: gold/silver catalysis, stereoselectivity, rearrange-
ments, Baylis–Hillman acetate, alk-2-enoates
usually have one or more limitations, such as high catalyst
loading, severe reaction conditions, resulting products
mixed with E- and Z-isomers, and low yields. In view of
gold’s high reactivity and selectivity in reactions1,2 and
Recently, there has been a growing interest in gold-cata- our continued interest in the stereoselective conversion of
lyzed organic transformations, because gold catalysts usu- Baylis–Hillman adducts into trisubstituted alkenes,17 we
ally exhibit extraordinary reactivity and show high have carried out the work reported here, and found an ef-
selectivity in the reactions.1,2 Indeed, gold catalysts have ficient and stereoselective rearrangement of Baylis–Hill-
been able to promote various transformations such as nu- man acetates to 2-(acetoxymethyl)alk-2-enoates in good
cleophilic additions to C–C multiple bonds (alkynes, to high yields with 100% E-selectivity, catalyzed by only
alkenes, allenes), Friedel–Crafts reactions and C–H acti- one mole-percent gold(I) chloride/silver(I) trifluo-
vations, and hydrogenation and oxidation reactions.1 romethanesulfonate under mild reaction conditions
Among these transformations, gold-catalyzed skeletal re- (Scheme 1).
arrangements of propargylic esters have been extensively
studied for their great potential to create diverse product
OAc
patterns.3,4 Allylic esters, the alkene counterparts of prop-
CO2Me
CO2Me
catalyst
argylic esters, have, however, received only little atten-
solvent, r.t.
tion.5,6 To date, only two literature reports have appeared
OAc
1a
2a (E/Z)
on the isomerization of allylic acetates or allenyl esters
catalyzed by gold(I) complexes.5 Therefore, it is still de-
sirable to extend the scope and reaction patterns involving
gold-catalyzed skeletal rearrangements of allylic esters.
Scheme 1
Initially, Baylis–Hillman allylic acetate 1a was chosen as
a model substrate for the optimization of the reaction con-
ditions (Scheme 1, Table 1). The desired product 2a did
not form in the presence of trivalent gold catalysts such as
gold(III) chloride, sodium tetrachloroaurate(III) dihy-
drate, and dichloro(pyridine-2-carboxylato)gold(III)18
(Table 1, entries 1–3). Treatment of 1a with 1 mol% of
gold(I) chloride in dichloromethane gave the isomerized
product 2a in 78% yield (entry 4). The reaction also pro-
ceeded smoothly to give 2a in 75% yield in the presence
of 3 mol% of silver(I) trifluoromethanesulfonate (entry 5).
Although gold(I) chloride or silver(I) trifluoromethane-
sulfonate alone was a suitable catalyst for the reaction, the
best result was obtained when a combination of gold(I)
chloride and silver(I) trifluoromethanesulfonate was used
(90% yield, entry 6). According to previous reports,19,20
the silver salt might play an important role in helping to
remove the chloride anion from gold(I) chloride to gener-
The Baylis–Hillman reaction is well known as a powerful
C–C bond-forming reaction in organic synthesis.7 The
main attraction of this reaction lies in its atom economy,
catalytic process, and the high degree of functionality
present in the products for further transformations. For ex-
ample, Baylis–Hillman acetates, which act as activated
Baylis–Hillman adducts bearing allylic acetate parts and
Michael acceptor units, are valuable synthons and starting
materials for the synthesis of a number of multifunctional
molecules.8
The isomerization of Baylis–Hillman acetates to (E)-2-
(acetoxymethyl)alk-2-enoates, which are useful interme-
SYNTHESIS 2009, No. 7, pp 1170–1174
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Advanced online publication: 24.02.2009
DOI: 10.1055/s-0028-1087971; Art ID: F22008SS
© Georg Thieme Verlag Stuttgart · New York

PAPER
Rearrangement of Baylis–Hillman Acetates
1171
ate a more electrophilic cationic gold(I) species. In the ab-
sence of a transition metal salt, the rearrangement did not
take place, and the starting material was recovered quan-
titatively (entry 10). Solvent screening showed that 1,2-
dichloroethane was also a good solvent for the reaction
(entry 7), while tetrahydrofuran and acetonitrile were less
suitable (entries 8 and 9). It is worth noting that the reac-
tion showed excellent stereoselectivity affording the sin-
gle E-isomer exclusively. The stereoconfiguration of the
product was assigned by comparing the chemical shifts in
1H NMR and 13C NMR spectra with reported relevant val-
ues.12
Table 2 Isomerization of Baylis–Hillman Acetates 1 into 2 Cata-
lyzed by Gold(I) Chloride/Silver(I) Trifluoromethanesulfonatea
Entry
R
1
Time
(h)
Productb Yieldc
(%)
1
2
Ph
1a
1b
1c
1d
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.0
3.5
6.0
2a
2b
2c
2d
2e
2f
90
92
78
82
85
88
87
92
78
76d
Tol
3
4-MeOC6H4
2-MeOC6H4
4
5
1,3-benzodioxol-5-yl 1e
Table 1 Optimization of the Reaction Conditionsa
6
4-ClC6H4
2-ClC6H4
4-BrC6H4
2,4-Cl2C6H3
n-C7H15
1f
1g
1h
1i
Yieldc
(%)
7
2g
2h
2i
Entry Catalyst
(mmol)
Solvent Time E/Z
(h)
CH2Cl2 8.0
CH2Cl2 8.0
CH2Cl2 8.0
ratiob
8
1
2
3
AuCl3 (0.01)
–
–
–
0
0
0
9
NaAuCl4·2H2O (0.01)
10
1j
2j
dichloro(pyridine-2-
a Reagents and conditions: 1 (1 mmol), AuCl (0.01 mmol), AgOTf
(0.01 mmol), CH2Cl2 (3 mL), r.t.
carboxylato)gold(III) (0.01)
b In all cases, 1H and 13C NMR spectroscopy indicate the formation of
only E-isomers.
4
5
6
7
8
9
AuCl (0.01)
CH2Cl2 3.0
CH2Cl2 3.0
CH2Cl2 3.0
100:0 78
100:0 75
100:0 90
100:0 88
100:0 65
100:0 68
c Isolated yields.
AgOTf (0.03)
d The reaction was carried out at 45 °C.
AuCl/AgOTf (0.01)
AuCl/AgOTf (0.01)
AuCl/AgOTf (0.01)
AuCl/AgOTf (0.01)
Interestingly, for cyclohex-2-enone-derived Baylis–
Hillman acetates 3, the reaction gave 2-alkylidenecyclo-
hex-3-enones 5 instead of isomerized product 4 by elimi-
nation of one molecule of acetic acid from 3 (Scheme 3).21
DCE
3.0
3.0
3.0
THF
MeCN
10 none
CH2Cl2 8.0
–
0d
O
OAc
O
O
AuCl/AgOTf
(1 mol%)
a Reagents and conditions: 1a (1 mmol), catalyst, solvent (3 mL), r.t.
b The E/Z ratio was determined by 1H NMR analysis.
c Isolated yields.
R
R
R
CH2Cl2, r.t.
OAc
4 (not detected)
d Starting material 1a was recovered quantitatively.
3
5a R = 4-ClC6H4 82%
5b R = 4-BrC6H4 84%
With the optimized conditions in hand, we next turned our
attention to examine the scope of the reaction (Scheme 2,
Table 2). The present method was effective for both aryl-
substituted (Table 2, entries 1–9) and alkyl-substituted
(entry 10) Baylis–Hillman acetates 1, but a slightly elevat-
ed temperature was needed for the latter. The reaction pro-
ceeded smoothly with all the aryl-bearing substrates to
give isomerized products 2 in good to high yields (78–
92%) at room temperature. Various substitution patterns
on the phenyl ring were compatible with the reaction con-
ditions and did not alter the stereochemistry of the isomer-
ized products 2.
Scheme 3
A possible mechanism for the reaction, postulated on the
basis of previous reports,5,12 involving gold(I)-catalyzed
isomerization of Baylis–Hillman acetates 1 is depicted in
Scheme 4. Firstly, the C=C bond in 1 is activated by p-co-
ordination of the alkene moiety to the cationic gold center,
which then induces nucleophilic attack of the carbonyl at
the double bond, resulting in the formation of the six-
membered-ring stabilized cationic species 6. Finally, the
internal olefin is established to form 2 by concerted frag-
mentation of the corresponding C–O and Au–C bond in 6,
leading to 1,3-shift of the acetate group and regeneration
of the gold catalyst.
OAc
CO2Me
AuCl/AgOTf (1 mol%)
R
CO2Me
R
CH2Cl2, r.t.
Regarding stereoselectivity observed in the reaction, it
could be explained by the two possible transition state 6
and 7, which are key precursors to form E- and Z-isomers,
respectively (Scheme 5). The transition state 6 is energet-
ically more favored because both the ester and R group
OAc
2 100% E
1
Scheme 2
Synthesis 2009, No. 7, 1170–1174 © Thieme Stuttgart · New York

1172
Y. Liu et al.
PAPER
rified by chromatography (cyclohexane–EtOAc, 8:1); this gave
CO2Me
pure 2 or 5.
O
Au+
OAc
O
CO2Me
Methyl (2E)-2-(Acetoxymethyl)-3-phenylprop-2-enoate (2a)12
Colorless liquid; Rf = 0.56 (cyclohexane–EtOAc, 8:1).
R
R
IR (neat): 1721 (C=O), 1635 (C=C) cm–1.
CO2Me
O
1H NMR (500 MHz, CDCl3): d = 2.10 (s, 3 H, COCH3), 3.84 (s, 3
H, OCH2), 4.96 (s, 2 H, CH2), 7.37–7.42 (m, 5 H, ArH), 7.99 (s, 1
H, ArCH=).
O
R
1
Au+
MS (EI, 70 eV): m/z = 234 [M+].
CO2Me
O
Methyl (2E)-2-(Acetoxymethyl)-3-(4-tolyl)prop-2-enoate (2b)12
Colorless liquid; Rf = 0.53 (cyclohexane–EtOAc, 8:1).
IR (neat): 1717 (C=O), 1633 (C=C) cm–1.
CO2Me
OAc
Au
O
R
+
R
6
2
1H NMR (500 MHz, CDCl3): d = 2.11 (s, 3 H, COCH3), 2.37 (s, 3
H, ArCH3), 3.84 (s, 3 H, OCH3), 4.96 (s, 2 H, CH2), 7.21 (d, J = 8.0
Hz, 2 H, ArH), 7.28 (d, J = 8.0 Hz, 2 H, ArH), 7.96 (s, 1 H, ArCH=).
Scheme 4 Possible mechanism for the isomerization
MS (EI, 70 eV): m/z = 248 [M+].
CO2Me
CO2Me
OAc
O
R
Au
O
Methyl (2E)-2-(Acetoxymethyl)-3-(4-methoxyphenyl)prop-2-
enoate (2c)
Colorless liquid; Rf = 0.50 (cyclohexane–EtOAc, 8:1).
+
R
6
(E)-2
IR (neat): 1712 (C=O), 1604 (C=C) cm–1.
1H NMR (500 MHz, CDCl3): d = 2.12 (s, 3 H, COCH3), 3.82 (s, 3
H, OCH3), 3.83 (s, 3 H, OCH3), 4.98 (s, 2 H, CH2), 6.93 (d, J = 8.0
Hz, 2 H, ArH), 7.36 (d, J = 8.0 Hz, 2 H, ArH), 7.93 (s, 1 H, ArCH=).
13C NMR (125 MHz, CDCl3): d = 20.89, 52.10, 55.25, 59.51,
114.21, 124.04, 126.61, 131.52, 145.30, 160.88, 167.55, 170.75.
+
OAc
R
O
R
MeO2C
O
CO2Me
Au
7
(Z)-2
Scheme 5 Explanation for the stereoselectivity
MS (EI, 70 eV): m/z = 264 [M+].
Anal. Calcd for C14H16O5: C, 63.63; H, 6.10. Found: C, 63.82; H,
6.06.
adopt axial positions with an opposite orientation, thus
avoiding the steric 1,2-interaction between these two
groups which exists in transition state 7.22
Methyl (2E)-2-(Acetoxymethyl)-3-(2-methoxyphenyl)prop-2-
enoate (2d)13b
In conclusion, we have described an efficient and stereo-
selective isomerization of Baylis–Hillman acetates into 2-
(acetoxymethyl)alk-2-enoates catalyzed by only one
mole-percent gold(I) chloride/silver(I) trifluoromethane-
sulfonate with 100% E-selectivity. The attractiveness of
the present method lies in its low catalyst loading, excel-
lent stereoselectivity, good yields, and mild reaction con-
ditions.
Colorless liquid; Rf = 0.51 (cyclohexane–EtOAc, 8:1).
IR (neat): 1739 (C=O), 1635 (C=C) cm–1.
1H NMR (500 MHz, CDCl3): d = 2.08 (s, 3 H, COCH3), 3.83 (s, 3
H, OCH3), 3.84 (s, 3 H, OCH3), 4.91 (s, 2 H, CH2), 6.90 (d, J = 8.0
Hz, 1 H, ArH), 6.96 (t, J = 8.0 Hz, 1 H, ArH), 7.26 (d, J = 8.0 Hz, 1
H, ArH), 7.36 (t, J = 8.0 Hz, 1 H, ArH), 8.15 (s, 1 H, ArCH=).
MS (EI, 70 eV): m/z = 264 [M+].
Methyl (2E)-2-(Acetoxymethyl)-3-(1,3-benzodioxol-5-yl)prop-
2-enoate (2e)
Colorless liquid; Rf = 0.48 (cyclohexane–EtOAc, 8:1).
IR (KBr): 1719 (C=O), 1618 (C=C) cm–1.
1H NMR (500 MHz, CDCl3): d = 2.12 (s, 3 H, COCH3), 3.83 (s, 3
H, OCH3), 4.96 (s, 2 H, CH2), 6.0 (s, 2 H, OCH2O), 6.84 (d, J = 7.5
Hz, 1 H, ArH), 6.90–6.93 (m, 2 H, ArH), 7.87 (s, 1 H, ArCH=).
13C NMR (125 MHz, CDCl3): d = 20.91, 52.19, 59.35, 101.55,
108.57, 109.28, 124.71, 125.0, 128.11, 145.33, 148.07, 149.01,
167.43, 170.70.
IR spectra were recorded on a Bruker EQUINOX 55 spectrometer.
1H and 13C NMR spectra of samples in CDCl3 were obtained on a
Bruker AVANCE III 500 (500 MHz) instrument; TMS was used as
internal standard. Mass spectra were obtained on an HP 5989B mass
spectrometer. Elemental analyses were performed on an EA-1110
instrument. GC-MS experiments were performed with an Agilent
6890N GC system equipped with a 5973N mass-selective detector.
The Baylis–Hillman acetate starting materials 1 and 3 were pre-
pared according to literature procedures.23
MS (EI, 70 eV): m/z = 278 [M+].
Isomerization of Baylis–Hillman Acetates 1 into 2, and Conver-
sion of 3 into 5; General Procedure
Anal. Calcd for C14H14O6: C, 60.43; H, 5.07. Found: C, 60.71; H,
5.10.
AuCl (2.3 mg, 0.01 mmol), AgOTf (2.6 mg, 0.01 mmol), and
CH2Cl2 (2 mL) were added to a 10-mL flask. The mixture was
stirred at r.t. for 5 min before a CH2Cl2 soln (1 mL) of Baylis–
Hillman acetate 1 or 3 (1 mmol) was added. The mixture was stirred
at r.t. for the time given in Table 1 or 2. Upon completion of the re-
action, the resulting mixture was dissolved in pentane and filtered
through Celite. After evaporation of the solvent, the residue was pu-
Methyl (2E)-2-(Acetoxymethyl)-3-(4-chlorophenyl)prop-2-
enoate (2f)12
Colorless liquid; Rf = 0.55 (cyclohexane–EtOAc, 8:1).
IR (neat): 1744 (C=O), 1636 (C=C) cm–1.
Synthesis 2009, No. 7, 1170–1174 © Thieme Stuttgart · New York

PAPER
Rearrangement of Baylis–Hillman Acetates
1173
1H NMR (500 MHz, CDCl3): d = 2.10 (s, 3 H, COCH3), 3.85 (s, 3
H, OCH3), 4.93 (s, 2 H, CH2), 7.32 (d, J = 8.5 Hz, 2 H, ArH), 7.38
(d, J = 8.5 Hz, 2 H, ArH), 7.91 (s, 1 H, ArCH=).
13C NMR (125 MHz, CDCl3): d = 24.59, 38.19, 124.82, 128.75,
130.53, 131.22, 131.51, 131.73, 133.89, 134.49, 199.95.
MS (EI, 70 eV): m/z = 218 [M+], 220 [M+ + 2].
MS (EI, 70 eV): m/z = 268 [M+], 270 [M+ + 2].
Anal. Calcd for C13H11ClO: C, 71.40; H, 5.07. Found: C, 71.21; H,
5.02.
Methyl (2E)-2-(Acetoxymethyl)-3-(2-chlorophenyl)prop-2-
enoate (2g)13b
Colorless liquid; Rf = 0.54 (cyclohexane–EtOAc, 8:1).
IR (neat): 1735 (C=O), 1638 (C=C) cm–1.
1H NMR (500 MHz, CDCl3): d = 2.07 (s, 3 H, COCH3), 3.87 (s, 3
H, OCH3), 4.85 (s, 2 H, CH2), 7.29–7.35 (m, 3 H, ArH), 7.44 (d, J =
8.5 Hz, 1 H, ArH), 8.05 (s, 1 H, ArCH=).
(E)-2-(4-Bromobenzylidene)cyclohex-3-enone (5b)
Colorless liquid; Rf = 0.61 (cyclohexane–EtOAc, 8:1).
IR (neat): 1692 (C=O), 1614 (C=C) cm–1.
1H NMR (500 MHz, CDCl3): d = 2.57–2.69 (m, 4 H), 6.16–6.21 (m,
1 H), 6.84–6.86 (m, 1 H), 7.27–7.52 (m, 5 H).
13C NMR (125 MHz, CDCl3): d = 24.61, 38.19, 122.77, 124.81,
130.57, 131.46, 131.56, 131.71, 131.81, 134.33, 199.97.
MS (EI, 70 eV): m/z = 268 [M+], 270 [M+ + 2].
MS (EI, 70 eV): m/z = 262 [M+], 264 [M+ + 2].
Methyl (2E)-2-(Acetoxymethyl)-3-(4-bromophenyl)prop-2-
enoate (2h)
Colorless liquid; Rf = 0.54 (cyclohexane–EtOAc, 8:1).
IR (neat): 1742 (C=O), 1637 (C=C) cm–1.
Anal. Calcd for C13H11BrO: C, 59.34; H, 4.21. Found: C, 59.02; H,
4.26.
1H NMR (500 MHz, CDCl3): d = 2.10 (s, 3 H, COCH3), 3.84 (s, 3
H, OCH3), 4.92 (s, 2 H, CH2), 7.25 (d, J = 8.5 Hz, 2 H, ArH), 7.54
(d, J = 8.5 Hz, 2 H, ArH), 7.88 (s, 1 H, ArCH=).
13C NMR (125 MHz, CDCl3): d = 20.83, 52.33, 59.01, 124.0,
127.30, 130.93, 131.93, 133.0, 143.95, 166.93, 170.46.
Acknowledgment
Financial support was provided by the Natural Science Foundation
of Zhejiang Province (No. Y407168) and the Opening Foundation
of Zhejiang Provincial Top Key Discipline.
MS (EI, 70 eV): m/z = 312 [M+], 314 [M+ + 2].
References
Anal. Calcd for C13H13BrO4: C, 49.86; H, 4.18. Found: C, 49.61; H,
4.21.
(1) For representative reviews, see: (a) Hashmi, A. S. K. Gold
Bull. 2003, 36, 3. (b) Hashmi, A. S. K. Gold Bull. 2004, 37,
51. (c) Hashmi, A. S. K.; Hutchings, G. J. Angew. Chem. Int.
Ed. 2006, 45, 7896. (d) Hashmi, A. S. K. Chem. Rev. 2007,
107, 3180. (e) Jiménez-Núñez, E.; Echavarren, A. M. Chem.
Commun. 2007, 333. (f) Li, Z.; Brouwer, C.; He, C. Chem.
Rev. 2008, 108, 3239. (g) Arcadi, A. Chem. Rev. 2008, 108,
3266. (h) Skouta, R.; Li, C.-J. Tetrahedron 2008, 64, 4917.
(i) Muzart, J. Tetrahedron 2008, 64, 5815.
(2) For recent examples, see: (a) Lalonde, R. L.; Sherry, B. D.;
Kang, E. J.; Toste, F. D. J. Am. Chem. Soc. 2007, 129, 2452.
(b) Huang, X.; Zhang, L. J. Am. Chem. Soc. 2007, 129,
6398. (c) Lavallo, V.; Frey, G. D.; Donnadieu, B.;
Methyl (2E)-2-(Acetoxymethyl)-3-(2,4-dichlorophenyl)prop-2-
enoate (2i)
Colorless liquid; Rf = 0.55 (cyclohexane–EtOAc, 8:1).
IR (neat): 1740 (C=O), 1644 (C=C) cm–1.
1H NMR (500 MHz, CDCl3): d = 2.07 (s, 3 H, COCH3), 3.87 (s, 3
H, OCH3), 4.82 (s, 2 H, CH2), 7.28–7.30 (m, 2 H, ArH), 7.46 (s, 1
H), 7.97 (s, 1 H).
13C NMR (125 MHz, CDCl3): d = 20.81, 52.45, 59.11, 127.28,
129.23, 129.67, 130.92, 131.44, 135.02, 135.93, 140.82, 166.43,
170.36.
Soleilhavoup, M.; Bertrand, G. Angew. Chem. Int. Ed. 2008,
47, 5224. (d) Li, G.; Huang, X.; Zhang, L. J. Am. Chem. Soc.
2008, 130, 6944. (e) Zhang, G.; Huang, X.; Li, G.; Zhang, L.
J. Am. Chem. Soc. 2008, 130, 1814. (f) Gorin, D. J.;
Waston, I. D. G.; Toste, F. D. J. Am. Chem. Soc. 2008, 130,
3736. (g) Shapiro, N.; Toste, F. D. J. Am. Chem. Soc. 2008,
130, 9244. (h) Bae, H. J.; Baskar, B.; An, S. E.; Cheong, J.
Y.; Thangadurai, D. T.; Hwang, I.-C.; Rhee, Y. H. Angew.
Chem. Int. Ed. 2008, 47, 2263.
MS (EI, 70 eV): m/z = 302 [M+], 304 [M+ + 2].
Anal. Calcd for C13H12Cl2O4: C, 51.51; H, 3.99. Found: C, 51.72; H,
3.96.
Methyl (2E)-2-(Acetoxymethyl)dec-2-enoate (2j)
Colorless liquid; Rf = 0.65 (cyclohexane–EtOAc, 8:1).
IR (neat): 1733 (C=O), 1651 (C=C) cm–1.
1H NMR (500 MHz, CDCl3): d = 0.88 (t, J = 6.5 Hz, 3 H), 1.27–1.47
(m, 10 H), 2.05 (s, 3 H, COCH3), 2.30 (q, J = 7.5 Hz, 2 H), 3.78 (s,
3 H, OCH3), 4.84 (s, 2 H), 7.06 (t, J = 7.5 Hz, 1 H).
13C NMR (125 MHz, CDCl3): d = 14.02, 20.87, 22.57, 28.58, 28.75,
29.02, 29.21, 31.69, 51.91, 58.02, 126.84, 149.88, 166.94, 170.79.
MS (EI, 70 eV): m/z = 256 [M+].
(3) For a review, see: Marison, N.; Nolan, S. P. Angew. Chem.
Int. Ed. 2007, 46, 2750.
(4) For recent examples concerning gold-catalyzed skeletal
rearrangement of propargylic esters, see: (a) Zhang, L.;
Wang, S. J. Am. Chem. Soc. 2006, 128, 1442. (b) Buzas,
A.; Gagosz, F. Org. Lett. 2006, 8, 515. (c) Buzas, A.;
Istrate, F.; Gagosz, F. Org. Lett. 2006, 8, 1957. (d) Wang,
S.; Zhang, L. J. Am. Chem. Soc. 2006, 128, 8414.
Anal. Calcd for C14H24O4: C, 65.60; H, 9.44. Found: C, 65.89; H,
9.38.
(e) Wang, S.; Zhang, L. Org. Lett. 2006, 8, 4585. (f) Buzas,
A.; Gagosz, F. J. Am. Chem. Soc. 2006, 128, 12614.
(g) Lemière, G.; Gandon, V.; Carioys, K.; Fukuyama, T.;
Dhimane, A.-L.; Fensterbank, L.; Malacria, M. Org. Lett.
2007, 9, 2207. (h) Yu, M.; Li, G.; Wang, S.; Zhang, L. Adv.
Synth. Catal. 2007, 349, 871. (i) Dudnik, A. S.; Schwier, T.;
Gevorgyan, V. Org. Lett. 2008, 10, 1465. (j) Li, G.; Zhang,
G.; Zhang, L. J. Am. Chem. Soc. 2008, 130, 3740.
(E)-2-(4-Chlorobenzylidene)cyclohex-3-enone (5a)
Colorless liquid; Rf = 0.60 (cyclohexane–EtOAc, 8:1).
IR (neat): 1687 (C=O), 1614 (C=C) cm–1.
1H NMR (500 MHz, CDCl3): d = 2.59–2.69 (m, 4 H), 6.16–6.20 (m,
1 H), 6.84–6.87 (m, 1 H), 7.34–7.36 (m, 5 H).
(k) Correa, A.; Marion, N.; Fensterbank, L.; Malacria, M.;
Synthesis 2009, No. 7, 1170–1174 © Thieme Stuttgart · New York

1174
Y. Liu et al.
PAPER
Nolan, S. P.; Cavallo, L. Angew. Chem. Int. Ed. 2008, 47,
718.
(11) Garrido, N. M.; Garcia, M.; Díez, D.; Sánchez, F. S.; Urones,
J. G. Org. Lett. 2008, 10, 1687.
(5) For rearrangements of allylic esters involving gold catalysts,
see: (a) Marion, N.; Gealageas, R.; Nolan, S. P. Org. Lett.
2007, 9, 2653. (b) Buzas, A. K.; Istrate, F. M.; Gagosz, F.
Org. Lett. 2007, 9, 985.
(6) For rearrangements of allylic esters involving other
transition-metal catalysts, see: (a) Henry, P. M. J. Chem.
Soc. D 1971, 328. (b) Henry, P. M. J. Am. Chem. Soc. 1972,
94, 5200. (c) Overman, L. E.; Campbell, C. B.; Knoll, F. M.
J. Am. Chem. Soc. 1978, 100, 4822. (d) Overman, L. E.;
Knoll, F. M. Tetrahedron Lett. 1979, 4, 321.
(12) Basavaiah, D.; Muthukumaran, K.; Sreenivasulu, B.
Synthesis 2000, 545.
(13) (a) Shanmugan, P.; Rajasingh, P. Synlett 2001, 1314.
(b) Shanmugan, P.; Rajasingh, P. Tetrahedron 2004, 60,
9283.
(14) Mason, P. H.; Emslie, W. D. Tetrahedron 1994, 50, 12001.
(15) Foucaud, A.; El Guemmout, F. Bull. Soc. Chim. Fr. 1989,
403.
(16) Park, J. B.; Ko, S. H.; Kim, B. G.; Hong, W. P.; Lee, K.-J.
Bull. Korean Chem. Soc. 2004, 25, 27.
(e) Mukhopadhyay, M.; Reddy, M. M.; Maikap, G. C.; Iabal,
J. J. Org. Chem. 1995, 60, 2670. (f) Shull, B. K.; Sakai, T.;
Koreeda, M. J. Am. Chem. Soc. 1996, 118, 11690.
(g) Krishna, P. R.; Kannan, V.; Sharma, G. V. M. Synth.
Commun. 2004, 34, 55. (h) Shekhar, S.; Trantow, B.;
Leitner, A.; Hartwig, J. F. J. Am. Chem. Soc. 2006, 128,
11770.
(17) (a) Liu, Y. K.; Li, J.; Zheng, H.; Xu, D. Q.; Xu, Z. Y.; Zhang,
Y. M. Synlett 2005, 2999. (b) Liu, Y. K.; Xu, X. S.; Zheng,
H.; Xu, D. Q.; Xu, Z. Y.; Zhang, Y. M. Synlett 2006, 571.
(c) Liu, Y. K.; Zheng, H.; Xu, D. Q.; Xu, Z. Y.; Zhang, Y.
M. Synlett 2006, 2492. (d) Liu, Y. K.; Xu, D. Q.; Xu, Z. Y.;
Zhang, Y. M. Zhejiang Univ. SCIENCE B 2006, 7, 393.
(e) Liu, Y. K.; Xu, D. Q.; Xu, Z. Y.; Zhang, Y. M. Synlett
2007, 1671. (f) Liu, Y. K.; Zheng, H.; Xu, D. Q.; Xu, Z. Y.;
Zhang, Y. M. Org. Prep. Proced. Int. 2007, 39, 190.
(g) Liu, Y. K.; Mao, D. J.; Xu, D. Q.; Xu, Z. Y.; Zhang, Y.
M. Synth. Commun. 2007, 37, 4389. (h) Liu, Y. K.; Xu, D.
Q.; Xu, Z. Y.; Zhang, Y. M. Heteroat. Chem. 2008, 19, 188.
(18) Dar, A.; Moss, K.; Cottrill, S. M.; Parish, R. V.; McAuliffe,
C. A.; Pritchard, R. G.; Beagley, B.; Sandbank, J. J. Chem.
Soc., Dalton Trans. 1992, 1907.
(7) (a) Baylis, A. B.; Hillman, M. E. D. German Patent 2155113,
1972; Chem. Abstr. 1972, 77, 34174q. (b) Ciganek, E. Org.
React. 1997, 51, 201. (c) Basavaiah, D.; Rao, P. D.; Hyma,
R. S. Tetrahedron 1996, 52, 8001. (d) Basavaiah, D.; Rao,
A. J.; Satyanarayana, T. Chem. Rev. 2003, 103, 811.
(8) For recent examples, see: (a) Ranu, B. C.; Chattopadhyay,
K.; Jana, R. Tetrahedron Lett. 2007, 48, 3847. (b) Shatiq,
Z.; Liu, L.; Liu, Z.; Wang, D.; Chen, Y.-J. Org. Lett. 2007,
9, 2525. (c) Basavaiah, D.; Aravindu, K. Org. Lett. 2007, 9,
2453. (d) Srihari, P.; Singh, A. P.; Basak, A.-K.; Yadav, J. S.
Tetrahedron Lett. 2007, 48, 5999. (e) Das, B.; Chowdhury,
N.; Damondar, K.; Banerjee, J. Chem. Pharm. Bull. 2007,
55, 1274. (f) Cha, M. J.; Song, Y. S.; Han, E.-G.; Lee, K.-J.
J. Heterocycl. Chem. 2008, 45, 235. (g) Kim, S. H.; Kim, K.
H.; Kim, H. S.; Kim, J. N. Tetrahedron Lett. 2008, 49, 1948.
(h) Basavaiah, D.; Reddy, R. J. Org. Biomol. Chem. 2008, 6,
1034. (i) Kim, H. S.; Gowrisankar, S.; Kim, S. H.; Kim, J. N.
Tetrahedron Lett. 2008, 49, 3858. (j) Jiang, Y.-Q.; Shi,
Y.-L.; Shi, M. J. Am. Chem. Soc. 2008, 130, 7202.
(9) (a) Basavaiah, D.; Padmaja, K.; Satyanarayana, T. Synthesis
2000, 1662. (b) Lee, K. Y.; Gowrisankar, S.; Kim, J. N. Bull.
Korean Chem. Soc. 2004, 25, 413. (c) Basavaiah, D.;
Sharada, D. S.; Veerendhar, A. Tetrahedron Lett. 2004, 45,
3081.
(19) For an excellent review on ligand effects in homogeneous
gold catalysis, see: Grorin, D. J.; Sherry, B. D.; Toste, F. D.
Chem. Rev. 2008, 108, 3351.
(20) For silver salt additives in gold catalysis, see, for example:
(a) Nieto-Oberhuber, C.; Muñoz, M. P.; Buñuel, E.; Nevado,
C.; Cárdenas, D. J.; Echavarren, A. M. Angew. Chem. Int.
Ed. 2004, 43, 2402. (b) Watanabe, T.; Oishi, S.; Fujii, N.;
Ohno, H. Org. Lett. 2007, 9, 4821. (c) Lemière, G. G.;
Gandon, V.; Agenet, N.; Goddard, J.-P.; de Kozak, A. D.;
Aubert, C.; Fensterbank, L.; Malacria, M. C. Angew. Chem.
Int. Ed. 2006, 45, 7596. (d) Shi, Z.; He, C. J. Am. Chem.
Soc. 2004, 126, 5964.
(21) Shafiq, Z.; Liu, L.; Liu, Z.; Wang, D.; Chen, Y. J. Org. Lett.
2007, 9, 2025.
(22) A referee commented that the loss of 1,3-diaxial repulsion
between the methoxycarbonyl or R group and the acetal
oxygens may be another factor why intermediate 7 is not
destabilized so much (see Scheme 5).
(23) (a) Hoffman, H. M. R.; Rabe, J. Angew. Chem., Int. Ed. Engl.
1983, 22, 795. (b) Lee, K. Y.; GowriSankar, S.; Kim, J. N.
Tetrahedron Lett. 2004, 45, 5485. (c) David, H. O.;
Kenneth, M. N. J. Org. Chem. 2003, 68, 6427.
(10) Cinnamyl alcohols are important building blocks in organic
synthesis. See: (a) Shanmugam, P.; Rajasigh, P. Chem. Lett.
2002, 1212. (b) Raubo, P.; Giuliano, C.; Hill, A. W.;
Huscroft, L. T.; London, C.; Reeve, A.; Seward, E. M.;
Swain, C. G.; Kulagowski, J. J. Synlett 2006, 600.
(c) Gowrisankar, S.; Lee, K. Y.; Kim, J. N. Bull. Korean
Chem. Soc. 2006, 27, 929. (d) Xian, M.; Alaux, S.; Sagot,
E.; Gefflant, T. J. Org. Chem. 2007, 72, 7560.
Synthesis 2009, No. 7, 1170–1174 © Thieme Stuttgart · New York