Palladium/norbornene catalysis: A versatile aryl C-H hydroxyalkylation, alkyl cinnamate formation

Article abstract of DOI:10.1016/j.tet.2012.10.013

Application of bromoalkylalcohol and acrylate partners in a palladium/norbornene catalyzed domino direct alkylation/alkenylation of iodoarenes provides a new strategy for construction of biologically interesting ortho-hydroxyalkyl cinnamic acid alkyl esters. This protocol is compatible with a vide variety of electron-donating and -withdrawing substituents and allows one-pot construction of highly functionalized primary alcohols in high yields.

Full text of DOI:10.1016/j.tet.2012.10.013

Tetrahedron 68 (2012) 10286e10292
Contents lists available at SciVerse ScienceDirect
Tetrahedron
journal homepage: www.elsevier.com/locate/tet
Palladium/norbornene catalysis: a versatile aryl CeH hydroxyalkylation, alkyl
cinnamate formation
*
Farnaz Jafarpour , Nafiseh Jalalimanesh
School of Chemistry, College of Science, University of Tehran, PO Box 14155-6455, Tehran, Iran
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 8 August 2012
Received in revised form 21 September 2012
Accepted 2 October 2012
Available online 10 October 2012
Application of bromoalkylalcohol and acrylate partners in a palladium/norbornene catalyzed domino
direct alkylation/alkenylation of iodoarenes provides a new strategy for construction of biologically
interesting ortho-hydroxyalkyl cinnamic acid alkyl esters. This protocol is compatible with a vide variety
of electron-donating and -withdrawing substituents and allows one-pot construction of highly
functionalized primary alcohols in high yields.
Ó 2012 Elsevier Ltd. All rights reserved.
Keywords:
Catalysis
Domino reaction
Norbornene
Palladium
Primary alcohols
1. Introduction
syntheses of 2-tetralone22 and isochroman23 derivatives (Scheme
1). Alkyl cinnamates are also used as regulator for the C1 domain
Isochroman derivatives are important backbones in a broad
range of biological and pharmaceutical interesting substances.1,2
These structural motifs are an important class of natural and syn-
thetic compounds,2e4 which exhibit various biological activities
including antihypertensive activities,5 treatment of migraine,6 and
Schizophrenia.7 Accordingly, their syntheses have been developed
extensively through the past years.8e12 Among various synthetic
routes used to build up these molecules, reactions of salicylic al-
of protein kinase C isoforms24a and UV screens for preventing the
photo-yellowing of lignin-rich pulps.24b
R1
R1
O
R1
H
I
R2
R2
R2
OH
+
Br
dehydes with a,b
-unsaturated carbonyl compounds13,14 and tran-
OH
O
sition metal catalyzed coupling reactions15e18 are very important
ones. However, these reactions often suffer from the need for
synthesis of complex starting materials, prior functionalization
reactions, harsh reaction conditions, and low yields.
Isochromans
R2
2-Tetralones
During the course of our study in palladium-catalyzed/
norbornene-mediated domino reactions19 based on the pioneer-
ing work of Catellani20 and its modifications by Lautens,21 to in-
crease its synthetic potential, we sought to develop a three-
component one-pot synthesis of alkyl cinnamates with an ortho-
primary alcohol tether attached. The resulting skeletons are highly
versatile building blocks in synthetic organic chemistry and pre-
cious intermediates in pharmaceutical applications. The versatility
of this reaction can be demonstrated by atom- and step-economic
Scheme 1. Strategy for the synthesis of cinnamic esters.
Main synthetic routes for construction of alkyl 3-(2-(2-
hydroxyalkylaryl))acrylates include reduction of ortho-haloaryl-
acetic acids followed by a Heck reaction23 and nickel-mediated
carboxylation to aryl alkynes bearing an ortho alkyl alcohol
tether.25 Recently a direct olefination of phenyl acetic acid has also
been disclosed.22 However, all mentioned methods require prior
functionalization of arenes and installment of primary alkyl alcohol
tethers, which is not feasible.
* Corresponding author. Tel.: þ98 21 61112480; fax: þ98 21 66495291; e-mail
address: jafarpur@khayam.ut.ac.ir (F. Jafarpour).
0040-4020/$ e see front matter Ó 2012 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.tet.2012.10.013

F. Jafarpour, N. Jalalimanesh / Tetrahedron 68 (2012) 10286e10292
10287
The value of primary alcohols in chemical and pharmaceutical
industries, has inspired many studies toward their synthesis. 2-
Phenylethanol for instance is an important ingredient in artificial
flavors, perfumery, and soaps. However, under popular hydro-
boration/oxidation conditions, styrene is a challenging substrate to
functionalize with high anti-Markovnikov selectivity. Very recently,
Grubbs reported the conversion of aryl-substituted terminal olefins
to primary alcohols using triple relay catalysis.26
Herein, we set out to explore the possibility of palladium-cata-
lyzed/norbornene-mediated ortho-alkylation based methodology
to construct these structural motifs for the first time. This meth-
odology is a versatile, simple, and effective way for synthesis of
selectively substituted biaryls and alkyl-aryls under the cooperative
control of palladium and norbornene, through sequential Cehalide
and CeH bond activation.
reactivity than PdCl2 (Table 1, entry 4). Replacing ACN with dime-
thoxy ethane (DME) even improved the yield of 4a to 65% (Table 1,
entry 5). Further optimizations on the equivalents of reactants
revealed that lowering the amount of base to 2 equiv, increased the
yield (Table 1, entries 6e9).
Finally, lowering the reaction temperature to 80 ꢀC was ac-
companied with a substantial product yield increase (Table 1, entry
10). Further lowering of the temperature decreased the yield. Under
the optimized reaction conditions of iodoarene 1a (1.0 equiv), 2a
(2.0 equiv), 3a (2.0 equiv), Pd(OAc)2 (10 mol %), PBu3 (20 mol %),
norbornene (3.0 equiv), and Cs2CO3 (2.0 equiv) at 80 ꢀC in DME, the
desired ester 4a was obtained in 78% yield (Table 1, entry 10).
Next, the scope of the reaction was investigated and a wide
range of acrylate Heck acceptors and iodoarenes were found to be
compatible with this domino alkylation/Heck reaction protocol
(Table 2). An ortho-substituent in the aryl iodide is necessary to
ensure alkyl migration on the arene instead of norbornene moiety
(ortho-effect).27 In addition to n-butyl acrylate, tert-butyl and ethyl
acrylates 3b and 3c were also tolerated under the reaction condi-
tions, resulted the corresponding products 4b and 4c in 63% and
65% yields, respectively (entries 2 and 3).
2. Results and discussion
The approach involved the use of iodoarenes, acrylates, and
bromoalkylalcohols so that an intermolecular alkenylation can
follow ortho-alkylation of iodoarene, forming two carbonecarbon
bonds in one-pot. This reaction has remarkably broad substrate
scope, with varied functionalities on the benzenoid ring. Further-
more, olefination and tether installment occur in one-pot, and
though the Pd-catalyzed oxidation of primary alcohols to corre-
sponding aldehydes is well known, we do not observe aldehyde
formation using unprotected primary bromoalkylalcohols under
optimized reaction conditions.
A preliminary investigation to explore whether this reaction is
feasible, examined the reaction of 2-iodotoluene 1a, 2-
bromoethanol 2a (2.0 equiv), butylacrylate 3a (2.0 equiv), PdCl2
(10 mol %), Cs2CO3 (3.0 equiv), and norbornene (3.0 equiv) in ACN
(0.1 M) at 100 ꢀC for 20 h. The use of phosphine ligands in the
Catellani reaction was developed by Lautens to achieve greater
functional group tolerance. So we also applied conventional tri-
arylphosphine ligands such as TFP and PPh3 at our beginning ex-
periments. However, the desired cinnamic ester 4a was obtained in
only 30% and 28% yields, respectively (Table 1, entries 1 and 2). Next
we modified the catalyst using tri-alkylphosphine ligand PBu3.
Pleasingly, the electron-rich tributylphosphine ligand proved to be
particularly useful and the desired product was obtained in 46%
yield (Table 1, entry 3). Pd(OAc)2 was also found to exhibit higher
We further investigated the scope of the reaction using 3-
bromopropanol 2b as alkylating agent. Gratifyingly, 4d was con-
structed in 78% yield (Table 2, entry 4). tert-Butyl and methyl ac-
rylates 3b and 3d, also afforded the corresponding products 4e and
4f in high yields with the same alcohol (entries 5 and 6).
Next more sterically encumbered substrates were employed. 2-
Iodonaphthalene 1b was successfully converted to the corre-
sponding cinnamic esters 4ge4m, in high yields (entries 7e13).
Furthermore, we studied the scope and limitations of the
domino alkylation/Heck reaction with other iodoarenes containing
electron-donating and -withdrawing groups. While strongly
electron-donating methoxy group resulted 4n in only 38% yield,
moderate to good yields were obtained with iodoarenes containing
nitro substituents at the 2- and 4-position (entries 14e16).
The reaction also tolerated arene containing fluoride sub-
stitution, offering an opportunity for further functionalizations and
facilitating practical synthesis of highly functionalized molecules.
The latter substrate furnished 4q in moderate yield (entry 17).
The mechanism of this reaction is proposed to involve a pallada-
cycle.28 Next, the oxidative addition of the bromoalkylalcohol leads
to the Pd(IV) species, which on reductive elimination, generates the
Table 1
Screening of the reaction conditions for construction of cinnamic ester 4aa
Entry
[Pd]
L
Solv.
2a (equiv)
3a (equiv)
Base (equiv)
Norbornene (equiv)
Yieldb (%)
1
2
3
4
5
6
7
8
9
PdCl2
PdCl2
PdCl2
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
Pd(OAc)2
TFP
ACN
ACN
ACN
ACN
DME
DME
DME
DME
DME
DME
2
2
2
2
2
3
3
2
2
2
2
2
2
2
2
2
3
2
2
2
3
3
3
3
3
3
3
2
2
2
3
3
3
3
3
3
3
3
4
3
30
28
46
57
65
60
63
69
66
78c
PPh3
PBu3
PBu3
PBu3
PBu3
PBu3
PBu3
PBu3
PBu3
10
a
All reactions were run under the following conditions: n-butyl acrylate, 2-bromoethanol, catalyst (10 mol %), ligand (20 mol %) in solvent (0.1 M) were heated in a sealed
tube at 100 ꢀC for 20 h.
b
Isolated yields.
The reaction mixture was heated at 80 ꢀC.
c

10288
F. Jafarpour, N. Jalalimanesh / Tetrahedron 68 (2012) 10286e10292
Table 2
Scope of domino alkylation/Heck reactiona
Entry
1
Iodoarene
Bromoalcohol
Acrylate
Product
Yielda (%)
78
2
3
1a
1a
2a
2a
63
65
4
5
6
7
1a
1a
1a
3a
3b
78
71
70
75
2b
2b
2a
3a
3b
3c
3a
8
1b
1b
1b
2a
2a
2b
73
70
69
9
10
11
1b
2b
3b
78

F. Jafarpour, N. Jalalimanesh / Tetrahedron 68 (2012) 10286e10292
10289
Table 2 (continued )
Entry
Iodoarene
Bromoalcohol
Acrylate
Product
Yielda (%)
12
13
1b
2b
2b
3c
76
71
1b
3d
14
15
2a
2a
3a
3a
38
65
16
2b
2b
3b
3b
58
50
17
a
All reactions were run under the following conditions: iodoarene (0.20 mmol, 1 equiv), bromoalkylalcohol (0.4 mmol, 2 equiv), acrylate (0.4 mmol, 2 equiv), Pd(OAc)2
(10 mol %), PBu3 (20 mol %), norbornene (0.6 mmol, 3 equiv), and Cs2CO3 (0.4 mmol, 2 equiv) in dry DME (0.1 M) were heated in a sealed tube at 80 ꢀC for 20 h.
ortho-alkylated arylpalladium(II) intermediate. Finally an in-
4.2. Synthesis of functionalized alkyl cinnamates
termolecular Heck reaction yields the corresponding ester.
4.2.1. (E)-Butyl 3-(2-(2-hydroxyethyl)-6-methylphenyl)acrylate (4a).
A vial equipped with a stir bar was charged with 1-iodo-2-
methylbenzene (0.044 g, 0.20 mmol), 2-bromoethanol (0.050 g,
0.40 mmol), n-butyl acrylate (0.051 g, 0.40 mmol), Pd(OAc)2 (10 mol
%), PBu3 (20 mol %), norbornene (0.056 g, 0.60 mmol), and Cs2CO3
(0.130 g, 0.40 mmol). Dry DME (0.1 M) was added and the vial was
capped and degassed. The resulting mixture was heated in an oil
bath at 80 ꢀC for 20 h, cooled then filtered through a short plug of
silica, and the solvent was removed under vacuo. Purification of the
crude product by flash column chromatography (10% EtOAc/hexane)
afforded the corresponding product 4a (0.041 g, 78%) as yellow oil.
Found: C, 73.42; H, 8.57. C16H22O3 requires C, 73.25; H, 8.45%. nmax
3. Summary and conclusions
In summary, we have applied some aliphatic alcohols in
palladium-catalyzed norbornene-mediated domino ortho-alkyl-
ation/Heck reactions. Using unprotected bromo alkylalcohols suc-
cessfully produced not easily accessible alkyl cinnamates with ortho-
primaryalcohol substituents, which can be usedtoyieldisochromans
and tetralones. Expansion of the derived methodology to heterocy-
cles and their subsequent annulation are under investigation.
4. Experimental section
1169, 1715, 2957, 3441 cmꢁ1
; dH (500 MHz, CDCl3) 0.98 (3H, t, J
4.1. General remarks
6.9 Hz, CH2Me), 1.43e1.45 (2H, m, CH2Me), 1.70e1.72 (2H, m,
CH2CH2Me), 2.35 (3H, s, CMe), 2.95 (2H, t, J 6.5 Hz, CH2CH2OH), 3.81
(2H, t, J 6.5 Hz, CH2OH), 4.23 (2H, t, J 6.3 Hz, OCH2), 6.07 (1H, d, J
16.3 Hz, ]CH), 7.12e7.20 (3H, m, Ph), 7.87 (1H, d, J 16.3 Hz, CH]); dC
(100 MHz, CDCl3) 13.7, 19.2, 21.2, 30.7, 36.8, 63.0, 64.6, 124.7, 127.7,
128.3, 128.9, 130.9, 134.5, 136.6, 143.2, 166.6; m/z (EI) 262 (Mþ, 21%),
189 (64), 158 (32), 143 (100), 130 (79), 115 (44), 105 (14).
Anhydrous solvents were used. DME was distilled under nitro-
gen from CaH2 and immediately used or stored under 4 A molecular
ꢀ
sieves. Other reagents, palladium catalysts, and ligands (TFP, PPh3,
and PBu3) were commercially available and used as received. These
reactions were carried out in a sand bath using microwave vials
(2e5 mL). 1H and 13C NMR spectra were recorded at room tem-
perature on 500 MHz spectrometers using CDCl3 as the NMR sol-
vent. 1H NMR spectra are referenced to tetramethylsilane
(0.00 ppm) and 13C NMR spectra are referenced from the solvent
central peak (77.23 ppm). Chemical shifts are given in parts per
million. IR is reported as characteristic bands (cmꢁ1) in their
maximal intensity.
4.2.2. (E)-tert-Butyl 3-(2-(2-hydroxyethyl)-6-methylphenyl)acrylate
(4b). Following the procedure described above treatment of 1-
iodo-2-methylbenzene (0.044 g, 0.20 mmol), 2-bromoethanol
(0.050 g, 0.40 mmol), and tert-butyl acrylate (0.051 g, 0.40 mmol)
gave the title compound 4b (0.033 g, 63%) as yellow oil. Found: C,
73.47; H, 8.58. C16H22O3 requires C, 73.25; H, 8.45%. nmax 1149, 1708,

10290
F. Jafarpour, N. Jalalimanesh / Tetrahedron 68 (2012) 10286e10292
2929, 3398 cmꢁ1
;
dH (500 MHz, CDCl3) 1.55 (9H, s, CMe3), 2.35 (3H,
iodonaphthalene (0.051 g, 0.20 mmol), 2-bromoethanol (0.050 g,
0.40 mmol), and n-butyl acrylate (0.051 g, 0.40 mmol) gave the
title compound 4g (0.045 g, 75%) as yellow oil. Found: C, 76.69; H,
7.55. C19H22O3 requires C, 76.48; H, 7.43%. nmax 1170, 1710, 2959,
s, CMe), 2.95 (2H, t, J 6.9 Hz, CH2CH2OH), 3.81 (2H, t, J 6.9 Hz,
CH2OH), 5.99 (1H, d, J 16.3 Hz, ]CH), 7.11e7.20 (3H, m, Ph), 7.77 (1H,
d, J 16.3 Hz, CH]); dC (125 MHz, CDCl3) 21.2, 28.2, 36.8, 63.0, 80.8,
126.3,127.6,128.1,128.8,134.7,136.6,136.7,142.0,165.9; m/z (EI) 262
(Mþ, 32%), 206 (16), 188 (29), 176 (35), 143 (82), 130 (55), 57 (100).
3350 cmꢁ1
; dH (500 MHz, CDCl3) 1.00 (3H, t, J 7.4 Hz, CH2Me),
1.44e1.47 (2H, m, CH2Me), 1.72e1.75 (2H, m, CH2CH2Me), 3.10 (2H,
t, J 6.9 Hz, CH2CH2OH), 3.88 (2H, t, J 6.9 Hz, CH2OH), 4.26 (2H, t, J
6.7 Hz, OCH2), 6.24 (1H, d, J 16.3 Hz, ]CH), 7.40 (1H, d, J 8.4 Hz,
CH), 7.47e7.50 (2H, m, Ph), 7.78 (1H, d, J 8.4 Hz, CH), 7.82 (1H, d, J
7.6 Hz, CH), 8.04 (1H, d, J 8.1 Hz, CH), 8.21 (1H, d, J 16.3 Hz, CH]);
dC (100 MHz, CDCl3) 13.7, 19.1, 30.6, 37.0, 63.0, 64.6, 124.9, 125.5,
126.1, 126.5, 127.9, 128.2, 128.7, 131.3, 131.7, 132.3, 134.3, 142.4,
166.6; m/z (EI) 298 (Mþ, 28%), 280 (20), 225 (89), 179 (100),
165 (90).
4.2.3. (E)-Ethyl
3-(2-(2-hydroxyethyl)-6-methylphenyl)acrylate
(4c). Following the procedure described above treatment of 1-iodo-
2-methylbenzene (0.044 g, 0.20 mmol), 2-bromoethanol (0.050 g,
0.40 mmol), and ethyl acrylate (0.040 g, 0.40 mmol) gave the title
compound 4c (0.030 g, 65%) as yellow oil. Found: C, 71.99; H, 7.84.
C14H18O3 requires C, 71.77; H, 7.74%. nmax 1171,1711, 2936, 3410 cmꢁ1
;
dH (500 MHz, CDCl3) 1.35 (3H, t, J 7.1 Hz, CH2Me), 2.34 (3H, s, CMe),
2.95 (2H, t, J 6.9 Hz, CH2CH2OH), 3.81 (2H, t, J 6.9 Hz, CH2OH), 4.28
(2H, q, J 7.1 Hz, OCH2), 6.07 (1H, d, J 16.3 Hz, ]CH), 7.13e7.21 (3H, m,
Ph), 7.87 (1H, d, J 16.3 Hz, CH]); dC (125 MHz, CDCl3) 14.2, 21.2, 36.8,
60.6, 63.0, 124.7, 127.7, 128.3, 128.9, 134.5, 136.6, 136.7, 143.2, 166.5;
m/z (EI) 234 (Mþ, 1%), 209 (2), 134 (23), 92 (81), 76 (100).
4.2.8. (E)-tert-Butyl 3-(2-(2-hydroxyethyl)naphthalen-1-yl)acrylate
(4h). Following the procedure described above treatment of 1-
iodonaphthalene (0.051 g, 0.20 mmol), 2-bromoethanol (0.050 g,
0.40 mmol), and tert-butyl acrylate (0.051 g, 0.40 mmol) gave the
title compound 4h (0.043 g, 73%) as yellow oil. Found: C, 76.25; H,
7.32. C19H22O3 requires C, 76.48; H, 7.43%, nmax 1147, 1706, 2975,
4.2.4. (E)-Butyl
3-(2-(3-hydroxypropyl)-6-methylphenyl)acrylate
(4d). Following the procedure described above treatment of 1-
iodo-2-methylbenzene (0.044 g, 0.20 mmol), 3-bromopropanol
(0.056 g, 0.40 mmol), and n-butyl acrylate (0.051 g, 0.40 mmol)
gave the title compound 4d (0.043 g, 78%) as yellow oil. Found: C,
74.05; H, 8.84. C17H24O3 requires C, 73.88; H, 8.75%. nmax 1168, 1714,
3458 cmꢁ1
; dH (500 MHz, CDCl3) 1.59 (9H, s, CMe3), 3.11 (2H, t, J
6.9 Hz, CH2CH2OH), 3.88 (2H, t, J 6.9 Hz, CH2OH), 6.19 (1H, d, J
16.3 Hz, ]CH), 7.39 (1H, d, J 8.4 Hz, CH), 7.45e7.55 (2H, m, Ph), 7.77
(1H, d, J 8.4 Hz, CH), 7.82 (1H, d, J 8.5 Hz, CH), 8.06 (1H, d, J 8.5 Hz,
CH), 8.12 (1H, d, J 16.3 Hz, CH]); dC (125 MHz, CDCl3) 28.1, 37.0,
63.0, 80.9, 125.2, 125.4, 126.4, 127.7, 127.9, 128.1, 128.5, 131.3, 131.8,
132.3, 134.2, 141.3, 165.8; m/z (EI) 298 (Mþ, 7%), 217 (29), 167 (61),
143(100), 129(46).
2926, 3454 cmꢁ1
; dH (500 MHz, CDCl3) 0.98 (3H, t, J 7.2 Hz, CH2Me),
1.43e1.45 (2H, m, CH2Me), 1.69e1.71 (2H, m, CH2CH2Me), 1.82e1.83
(2H, m, CH2CH2OH), 2.06 (1H, br s, OH), 2.35 (3H, s, CMe), 2.76 (2H,
t, J 7.5 Hz, CH2(CH2)2OH), 3.67 (2H, t, J 6.2 Hz, CH2OH), 4.23 (2H, t, J
6.6 Hz, OCH2), 6.07 (1H, d, J 16.3 Hz, ]CH), 7.10e7.17 (3H, m, Ph),
7.88 (1H, d, J 16.3 Hz, CH]); dC (125 MHz, CDCl3) 13.7, 19.2, 21.2,
29.9, 30.7, 33.8, 62.2, 64.5, 124.2, 127.1, 128.3, 128.4, 133.8, 136.4,
140.4, 143.2, 166.8; m/z (EI) 276 (Mþ, 15%), 242 (48), 214 (27), 183
(46), 143 (100), 119 (73), 105 (39).
4.2.9. (E)-Ethyl 3-(2-(2-hydroxyethyl)naphthalen-1-yl)acrylate (4i).
Following the procedure described above treatment of 1-
iodonaphthalene (0.051 g, 0.20 mmol), 2-bromoethanol (0.050 g,
0.40 mmol), and ethyl acrylate (0.040 g, 0.40 mmol) gave the title
compound 4i (0.038 g, 70%) as yellow oil. Found: C, 75.77; H, 6.82.
C17H18O3 requires C, 75.53; H, 6.71%. nmax 1164, 1710, 2926,
4.2.5. (E)-tert-Butyl 3-(2-(3-hydroxypropyl)-6-methylphenyl)acry-
late (4e). Following the procedure described above treatment of 1-
iodo-2-methylbenzene (0.044 g, 0.20 mmol), 3-bromopropanol
(0.056 g, 0.40 mmol), and tert-butyl acrylate (0.051 g, 0.40 mmol)
gave the title compound 4e (0.039 g, 71%) as yellow oil. Found: C,
73.62; H, 8.64. C17H24O3 requires C, 73.88; H, 8.75%. nmax 1150, 1710,
3454 cmꢁ1
; dH (500 MHz, CDCl3) 1.38 (3H, t, J 7.1 Hz, CH2Me), 3.10
(2H, t, J 6.9 Hz, CH2CH2OH), 3.88 (2H, t, J 6.9 Hz, CH2OH), 4.32 (2H,
q, J 7.1 Hz, OCH2), 6.26 (1H, d, J 16.3 Hz, ]CH), 7.39 (1H, d, J 8.4 Hz,
CH), 7.45e7.51 (2H, m, Ph), 7.77e7.83 (2H, m, Ph), 8.03 (1H, d, J
8.3 Hz, CH), 8.2 (1H, d, J 16.3 Hz, CH]); dC (125 MHz, CDCl3) 14.2,
36.9, 63.0, 64.5, 124.9, 125.5 126.1, 126.5, 127.9, 128.2, 128.7, 131.3,
131.7, 132.3, 134.3, 142.4, 166.5; m/z (EI) 270 (Mþ, 35%), 252 (19),
240 (13), 225 (36), 207 (12), 179 (100), 165 (96), 152 (17), 115 (13),
43 (13).
2927, 3458 cmꢁ1
; dH (500 MHz, CDCl3) 1.55 (9H, s, CMe3), 1.81e1.83
(2H, m, CH2CH2OH), 2.35 (3H, s, CMe), 2.75 (2H, t, J 7.8 Hz,
CH2(CH2)2OH), 3.67 (2H, t, J 6.4 Hz, CH2OH), 5.98 (1H, d, J 16.3 Hz, ]
CH), 7.09e7.16 (3H, m, Ph), 7.78 (1H, d, J 16.3 Hz, CH]); dC
(125 MHz, CDCl3) 21.3, 28.2, 29.7, 33.8, 62.2, 80.7, 125.9, 127.2, 128.1,
128.4, 130.9, 133.9, 136.4, 142.1, 166.1; m/z (EI) 277 (Mþþ1, 7%), 220
(20), 202 (21), 57 (100), 41 (53).
4.2.10. (E)-Butyl
3-(2-(3-hydroxypropyl)naphthalen-1-yl)acrylate
(4j). Following the procedure described above treatment of 1-
iodonaphthalene (0.051 g, 0.20 mmol), 3-bromopropanol (0.056 g,
0.40 mmol), and n-butyl acrylate (0.051 g, 0.40 mmol) gave the title
compound 4j (0.043 g, 69%) as yellow oil. Found: C, 76.65; H, 7.62.
C20H24O3 requires C, 76.89; H, 7.74%. nmax 1171, 1709, 2956,
4.2.6. (E)-Methyl 3-(2-(3-hydroxypropyl)-6-methylphenyl)acrylate
(4f). Following the procedure described above treatment of 1-iodo-
2-methylbenzene (0.044 g, 0.20 mmol), 3-bromopropanol (0.056 g,
0.40 mmol), and methyl acrylate (0.034 g, 0.40 mmol) gave the title
compound 4f (0.033 g, 70%) as yellow oil. Found: C, 71.56; H, 7.63.
C14H18O3 requires C, 71.77; H, 7.74%. nmax 1263, 1720, 2954,
3466 cmꢁ1
; dH (500 MHz, CDCl3) 1.00 (3H, t, J 7.2 Hz, CH2Me),
1.45e1.50 (2H, m, CH2Me), 1.73e1.76 (2H, m, CH2CH2Me), 1.90e1.93
(2H, m, CH2CH2OH), 2.93 (2H, t, J 7.8 Hz, CH2(CH2)2OH), 3.70 (2H, t, J
6.4 Hz, CH2OH), 4.29 (2H, t, J 6.7 Hz, OCH2), 6.26 (1H, d, J 16.3 Hz, ]
CH), 7.39 (1H, d, J 8.4 Hz, CH), 7.47e7.50 (2H, m, Ph), 7.78 (1H, d, J
8.4 Hz, CH), 7.82e7.84 (1H, m, Ph), 8.06 (1H, d, J 8.3 Hz, CH), 8.21
(1H, d, J 16.3 Hz, CH]); dC (125 MHz, CDCl3) 13.7, 19.2, 30.1, 30.7,
33.9, 62.1, 64.7, 124.9, 125.1, 125.4, 126.5, 127.7, 128.2, 128.8, 130.8,
131.3, 132.2, 137.8, 142.5, 166.6; m/z (EI) 312 (Mþ, 71%), 193(50),
179(53), 165(100).
3468 cmꢁ1
; dH (500 MHz, CDCl3) 1.83e1.86 (2H, m, CH2CH2OH),
2.31 (3H, s, CMe), 2.71 (2H, t, J 7.8 Hz, CH2(CH2)2OH), 3.70 (2H, t, J
6.1 Hz, CH2OH), 3.80 (3H, s, OMe), 6.03 (1H, d, J 16.3 Hz, ]CH),
7.05e7.08 (2H, m, Ph), 7.13e7.16 (2H, m, Ph), 7.86 (1H, d, J 16.3 Hz,
CH]); dC (125 MHz, CDCl3) 21.2, 29.6, 33.8, 62.2, 65.0, 123.8, 127.1,
128.3, 128.4, 130.9, 133.8, 136.4, 143.6, 167.1; m/z (EI) 234 (Mþ, 4%),
223 (12), 203 (12), 149 (100).
4.2.11. (E)-tert-Butyl 3-(2-(3-hydroxypropyl)naphthalen-1-yl)acry-
late (4k). Following the procedure described above treatment of 1-
iodonaphthalene (0.051 g, 0.20 mmol), 3-bromopropanol (0.056 g,
4.2.7. (E)-Butyl 3-(2-(2-hydroxyethyl)naphthalen-1-yl)acrylate (4g).
Following the procedure described above treatment of 1-

F. Jafarpour, N. Jalalimanesh / Tetrahedron 68 (2012) 10286e10292
10291
0.40 mmol), and tert-butyl acrylate (0.051 g, 0.40 mmol) gave the
title compound 4k (0.049 g, 78%) as yellow oil. Found: C, 76.69; H,
7.65. C20H24O3 requires C, 76.89; H, 7.74%. nmax 1149, 1707, 2933,
1.41e1.46 (2H, m, CH2Me), 1.69e1.72 (2H, m, CH2CH2Me), 2.41 (3H,
s, CMe), 2.98 (2H, t, J 6.6 Hz, CH2CH2OH), 3.86 (2H, t, J 6.6 Hz,
CH2OH), 4.23 (2H, t, J 6.7 Hz, OCH2), 6.11 (1H, d, J 16.4 Hz, ]CH),
7.79 (1H, d, J 16.4 Hz, CH]), 7.96 (1H, s, CH), 8.00 (1H, s, CH); dC
(125 MHz, CDCl3) 13.6, 19.1, 21.2, 30.6, 36.4, 62.3, 65.0, 122.2, 123.1,
126.5, 138.2, 138.9, 141.3, 141.4, 147.0, 165.9; m/z (EI) 307 (Mþ, 2%),
234 (4), 223 (9), 149 (90), 129 (77), 41 (100).
3418 cmꢁ1
; dH (500 MHz, CDCl3) 1.59 (9H, s, CMe3), 1.91e1.92 (2H,
m, CH2CH2OH), 2.93 (2H, t, J 7.7 Hz, CH2(CH2)2OH), 3.69 (2H, t, J
6.3 Hz, CH2OH), 6.18 (1H, d, J 16.3 Hz, ]CH), 7.38 (1H, d, J 8.4 Hz,
CH), 7.44e7.50 (2H, m, Ph), 7.76 (1H, d, J 8.4 Hz, CH), 7.82 (1H, d, J
7.8 Hz, CH), 8.1 (1H, d, J 8.2 Hz, CH), 8.11 (1H, d, J 16.3 Hz, CH]); dC
(125 MHz, CDCl3) 28.2, 30.0, 33.9, 62.1, 80.9, 125.1, 125.3, 126.4,
127.6, 127.7, 128.2, 128.6, 131.0, 131.4, 132.2, 137.8, 141.3, 165.9; m/z
(EI) 312 (Mþ, 62%), 256 (54), 239 (41), 165 (89), 57 (100), 41 (45).
4.2.16. (E)-tert-Butyl 3-(2-(2-hydroxyethyl)-6-nitrophenyl)acrylate
(4p). Following the procedure described above treatment of 1-
iodo-2-nitrobenzene (0.050 g, 0.20 mmol), 2-bromoethanol
(0.050 g, 0.40 mmol), and tert-butyl acrylate (0.051 g, 0.40 mmol)
gave the title compound 4p (0.036 g, 58%) as yellow oil. Found: C,
62.72; H, 6.98; N, 4.68. C16H21NO5 requires C, 62.53; H, 6.89; N,
4.56%. nmax 1051, 1152, 1316, 1353, 1452, 1527, 1712, 2930,
4.2.12. (E)-Ethyl
3-(2-(3-hydroxypropyl)naphthalen-1-yl)acrylate
(4l). Following the procedure described above treatment of 1-
iodonaphthalene (0.051 g, 0.20 mmol), 3-bromopropanol (0.056 g,
0.40 mmol), and ethyl acrylate (0.040 g, 0.40 mmol) gave the title
compound 4l (0.043 g, 76%) as yellow oil. Found: C, 76.26; H, 7.21.
C18H20O3 requires C, 76.03; H, 7.09%. nmax 1171, 1263, 1711, 2945,
3348 cmꢁ1
; dH (500 MHz, CDCl3) 1.52 (9H, s, CMe3), 1.91e1.93 (2H,
m, CH2CH2OH), 2.81 (2H, t, J 7.5 Hz, CH2(CH2)2OH), 3.66 (2H, t, J
6.5 Hz, CH2OH), 5.87 (1H, d, J 16.2 Hz, ]CH), 7.39e7.41 (1H, m, Ph),
7.50 (1H, d, J 7.4 Hz, CH), 7.72 (1H, d, J 7.8 Hz, CH), 7.81 (1H, d, J
16.2 Hz, CH]); dC (125 MHz, CDCl3) 27.6, 29.1, 32.8, 61.1, 80.8, 121.4,
126.0, 128.1, 129.2, 133.1, 137.8, 142.2, 148.9, 164.3; m/z (EI) 307 (Mþ,
2%), 216 (16), 188 (16), 57 (100), 41 (93).
3353 cmꢁ1
; dH (500 MHz, CDCl3) 1.38 (3H, t, J 7.2 Hz, CH2Me),
1.87e1.88 (2H, m, CH2CH2OH), 2.43 (1H, br s, OH), 2.91 (2H, t, J
7.9 Hz, CH2(CH2)2OH), 3.68 (2H, t, J 6.2 Hz, CH2OH), 4.33 (2H, q, J
7.2 Hz, CH2Me), 6.25 (1H, d, J 16.3 Hz, ]CH), 7.37 (1H, d, J 8.4 Hz,
CH), 7.45e7.47 (2H, m, Ph), 7.76 (1H, d, J 8.4 Hz, CH), 7.81 (1H, d, J
7.6 Hz, CH), 8.04 (1H, d, J 8.2 Hz, CH), 8.20 (1H, d, J 16.3 Hz, CH]); dC
(125 MHz, CDCl3) 14.2, 30.0, 33.9, 60.7, 61.9, 124.9, 125.3, 125.7,
126.4, 127.6, 128.2, 128.7, 130.7, 131.3, 132.1, 137.9, 142.5, 166.6; m/z
(EI) 284 (Mþ, 20%), 270 (43), 193 (46), 179 (47), 165 (100).
4.2.17. (E)-tert-Butyl 3-(2-fluoro-6-(3-hydroxypropyl)phenyl)acry-
late (4q). Following the procedure described above treatment of 1-
fluoro-2-iodobenzene (0.044 g, 0.20 mmol), 3-bromopropanol
(0.056 g, 0.40 mmol), and tert-butyl acrylate (0.051 g, 0.40 mmol)
gave the title compound 4q (0.028 g, 50%) as yellow oil. Found: C,
68.78; H, 7.66. C16H21FO3 requires C, 68.55; H, 7.55%. nmax 1057,
4.2.13. (E)-Methyl 3-(2-(3-hydroxypropyl)naphthalen-1-yl)acrylate
(4m). Following the procedure described above treatment of 1-
iodonaphthalene (0.051 g, 0.20 mmol), 3-bromopropanol (0.056 g,
0.40 mmol), and methyl acrylate (0.034 g, 0.40 mmol) gave the title
compound 4m (0.038 g, 71%) as yellow oil. Found: C, 75.29; H, 6.59.
C17H18O3 requires C, 75.53; H, 6.71%. nmax 1171, 1711, 2945,
1152, 1250, 1710, 2928, 3457 cmꢁ1
CMe3), 1.82e1.84 (2H, m, CH2CH2OH), 2.87 (2H, t,
;
dH (500 MHz, CDCl3) 1.53 (9H, s,
7.2 Hz,
J
CH2(CH2)2OH), 3.63 (2H, t, J 6.5 Hz, CH2OH), 6.53 (1H, d, J 16.2 Hz, ]
CH), 6.94e6.96 (1H, m, Ph), 7.03 (1H, d, J 7.4 Hz, CH), 7.20e7.22 (1H,
m, Ph), 7.71 (1H, d, J 16.2 Hz, CH]); dC (125 MHz, CDCl3) 27.6, 29.1,
33.5, 61.3, 80.2, 113.4, 113.6, 125.1, 125.3, 129.6, 129.7, 134.2, 143.7,
162.8; m/z (EI) 280 (Mþ, 2%), 262(3), 57 (100), 41 (87).
3353 cmꢁ1
; dH (500 MHz, CDCl3) 1.87e1.89 (2H, m, CH2CH2OH),
2.90 (2H, t, J 7.8 Hz, CH2(CH2)2OH), 3.68 (2H, t, J 6.5 Hz, CH2OH),
3.87 (3H, s, Me), 6.26 (1H, d, J 16.3 Hz, ]CH), 7.37 (1H, d, J 8.4 Hz,
CH), 7.45e7.50 (2H, m, Ph), 7.75e7.82 (2H, m, Ph), 8.03 (1H, d, J
8.2 Hz, CH), 8.22 (1H, d, J 16.3 Hz, CH]); dC (125 MHz, CDCl3) 30.0,
33.9, 51.8, 61.9, 124.8, 125.3, 126.4, 127.6, 128.1, 128.7, 130.5, 131.2,
132.0, 137.9, 142.8, 166.9; m/z (EI) 270 (Mþ, 13%), 239 (29), 193 (42),
178 (46), 165 (100).
Acknowledgements
We gratefully acknowledge the financial support of the Iran
National Science Foundation (INSF) and the University of Tehran.
Supplementary data
4.2.14. (E)-Butyl 3-(2-(2-hydroxyethyl)-6-methoxyphenyl)acrylate
(4n). Following the procedure described above treatment of 1-
iodo-2-methoxybenzene (0.047 g, 0.20 mmol), 2-bromoethanol
(0.050 g, 0.40 mmol), and n-butyl acrylate (0.051 g, 0.40 mmol)
gave the title compound 4n (0.021 g, 38%) as yellow oil. Found: C,
69.30; H, 8.09. C16H22O4 requires C, 69.04; H, 7.97%. nmax 1161, 1262,
Experimental procedures and characterization for all new
compounds. Supplementary data associated with this article can be
found in the online version, at http://dx.doi.org/10.1016/
j.tet.2012.10.013. These data include MOL files and InChiKeys of the
most important compounds described in this article.
1711, 2929, 3305 cmꢁ1
; dH (500 MHz, CDCl3) 0.93 (3H, t, J 7.3 Hz,
CH2Me), 1.42e1.44 (2H, m, CH2Me), 1.67e1.69 (2H, m, CH2CH2Me),
3.04 (2H, t, J 6.9 Hz, CH2CH2OH), 3.80 (2H, t, J 6.9 Hz, CH2OH), 3.86
(3H, s, OMe), 4.19 (2H, t, J 6.7 Hz, OCH2), 6.69 (1H, d, J 16.1 Hz, ]CH),
6.82 (1H, d, J 8.2 Hz, CH), 6.89e6.91 (1H, m, Ph), 7.18e7.20 (1H, m,
Ph), 7.86 (1H, d, J 16.1 Hz, CH]); dC (125 MHz, CDCl3) 13.5,19.1, 30.7,
37.0, 55.4, 63.0, 64.3, 109.3, 122.6, 123.0, 124.0, 130.1, 138.1, 140.0,
159.1, 168.3; m/z (EI) 278 (Mþ, 27%), 233 (19%), 203 (100), 179 (67).
References and notes
1. Ellis, G. P.; Lockhart, I. M. The Chemistry of Heterocyclic Compounds, Chromenes,
Chromanones, and Chromones; John Wiley & Sons: New York, NY, 2007.
2. Shen, H. C. Tetrahedron 2009, 65, 3931e3952.
3. Nicolaou, K. C.; Pfefferkorn, J. A.; Barluenga, S.; Mitchell, H. J.; Roecker, A. J.; Cao,
G.-Q. J. Am. Chem. Soc. 2000, 122, 9968e9976.
4. Trost, B. M.; Shen, H. C.; Dong, L.; Surivet, J.-P.; Sylvain, C. J. Am. Chem. Soc. 2004,
126, 11966e11983.
5. (a) McCall, J. M.; McCall, R. B.; TenBrink, R. E.; Kamdar, B. V.; Humphrey, S. J.;
Sethy, V. H.; Harris, D. W.; Daenzar, C. J. Med. Chem. 1982, 25, 75e81; (b) Von
Voigtlander, P. F.; Lahti, R. A.; Tang, A. H.; Sethy, V. H. Arch. Int. Pharmacodyn.
Ther. 1983, 266, 23e37.
6. Ennis, M. D.; Ghazal, N. B.; Hoffman, R. L.; Smith, M. W.; Schlachter, S. K.;
Lawson, C. F.; Im, W. B.; pregenzer, J. F.; Svensson, K. A.; Lewis, R. A.; Hall, E. D.;
Sutter, D. M.; Harris, L. T.; McCall, R. B. J. Med. Chem. 1998, 41, 2180e2183.
7. Kesten, S. R.; Heffner, T. G.; Johnson, S. J.; Pugsley, T. A.; Wright, J. L.; Wise, L. D. J.
Med. Chem. 1999, 42, 3718e3725.
4.2.15. (E)-Butyl
3-(2-(3-hydroxypropyl)-6-methyl-4-nitrophenyl)
acrylate (4o). Following the procedure described above treatment
of 1-iodo-2-methyl-4-nitrobenzene (0.053 g, 0.20 mmol), 3-
bromopropanol (0.056 g, 0.40 mmol), and n-butyl acrylate
(0.051 g, 0.40 mmol) gave the title compound 4o (0.040 g, 65%) as
yellow oil. Found: C, 62.74; H, 6.70; N, 4.70. C16H21NO5 requires C,
62.53; H, 6.89; N, 4.56%. nmax 1040, 1174, 1344, 1517, 1716, 2959,
8. van Lingen, H. L.; Zhuang, W.; Hansen, T.; Rutjes, F. P. J. T.; Jorgensen, K. A. Org.
Biomol. Chem. 2003, 1, 1953e1958.
3455 cmꢁ1
; dH (500 MHz, CDCl3) 0.97 (3H, t, J 7.4 Hz, CH2Me),

10292
F. Jafarpour, N. Jalalimanesh / Tetrahedron 68 (2012) 10286e10292
9. Zu, L.; Zhang, S.; Xie, H.; Wang, W. Org. Lett. 2009, 11, 1627e1630.
10. Hong, L.; Wang, L.; Sun, W.; Wong, K.; Wang, R. J. Org. Chem. 2009, 74,
6881e6884.
11. Leibeling, M.; Koester, D. C.; Pawliczek, M.; Schild, S. C.; Werz, D. B. Nat. Chem.
Biol. 2010, 6, 199e201.
12. Gowrisankar, S.; Lee, H. S.; Kim, J. N. Bull. Korean Chem. Soc. 2007, 28,
2501e2504.
13. Shi, Y.-L.; Shi, M. Org. Biomol. Chem. 2007, 5, 1499e1504.
14. Liu, K.; Chougnet, A.; Woggon, W.-D. Angew. Chem., Int. Ed. 2008, 47, 5827e5829.
15. Fukamizu, K.; Miyake, Y.; Nishibayashi, Y. J. Am. Chem. Soc. 2008, 130,
10498e10499.
21. For some related examples see: (a) Liu, H.; El-Salfiti, M.; Chai, D. I.; Auffret, J.;
Lautens, M. Org. Lett. 2012,14, 3648e3651; (b) Lautens, M.; Blanchot, M.; Candito,
D. A.; Larnaud, F. Org. Lett. 2011, 13, 1486e1489; (c) Candito, D. A.; Lautens, M.
Angew. Chem., Int. Ed. 2009, 48, 6713e6716; (d) Zhao, Y. B.; Mariampillai, B.;
Candito, D. A.; Laleu, B.; Li, M. Z.; Lautens, M. Angew. Chem., Int. Ed 2009, 48,
1849e1852; (e) Thansandote, P.; Gouliaras, C.; Turcotte-Savard, M. O.; Lautens,
M. J. Org. Chem. 2009, 74, 1791e1793; (f) Blaszykowski, C.; Aktoudianakis, E.;
Alberico, D.; Bressy, C.; Hulcoop, D. G.; Jafarpour, F.; Joushaghani, A.; Laleu, B.;
Lautens, M. J. Org. Chem. 2008, 73, 1888e1897; (g) Thansandote, P.; Raemy, M.;
Rudolph, A.; Lautens, M. Org. Lett. 2007, 9, 5255e5258; (h) Alberico, D.; Rudolph,
A.; Lautens, M. J. Org. Chem. 2007, 72, 775e781; (i) Jafarpour, F.; Lautens, M. Org.
Lett. 2006, 8, 3601e3604; (j) Pache, S.; Lautens, M. Org. Lett. 2003, 5, 4827e4830.
22. Wang, D.-H.; Engle, K. M.; Shi, B.-F.; Yu, J.-Q. Science 2010, 327, 315e319.
23. TenBrink, R. E.; Ennis, M. D.; Lahti, R. A. U.S. Patent 5,877,317, 1999.
24. (a) Mamidi, N.; Gorai, S.; Sahoo, J.; Manna, D. Chem. Phys. Lipids 2012, 165,
320e330; (b) Castellan, A.; Noutary, C.; Davidson, R. S. J. Photochem. Photobiol.,
A: Chem. 1994, 84, 317e326.
16. Yamamoto, Y.; Itonaga, K. Org. Lett. 2009, 11, 717e720.
17. Wegner, H. A.; Ahles, S.; Neuburger, M. Chem.dEur. J. 2008, 14, 11310e11313.
18. Hashmi, A. S. K.; Rudolph, M.; Bats, J. W.; Frey, W.; Rominger, F.; Oeser, T. Chem.d
Eur. J. 2008, 14, 6672e6678.
19. (a) Jafarpour, F.; Ashtiani, P. T. J. Org. Chem. 2009, 74,1364e1366; (b) Jafarpour, F.;
Hazrati, H. Adv. Synth. Catal. 2010, 352, 363e367.
20. (a) Catellani, M.; Frignani, F.; Rangoni, A. Angew. Chem., Int. Ed. 1997, 36,
119e122; (b) Tietze, L. F.; Brasche, G.; Gericke, K. Domino Reactions in Organic
Synthesis; John Wiley: New York, NY, 2006; For reviews on Catellani reaction
see: (c) Chiusoli, G. P.; Catellani, M.; Costa, M.; Motti, E.; Della Ca’, N.; Maestri,
G. Coord. Chem. Rev. 2010, 254, 456e469; (d) Martins, A.; Mariampillai, B.;
Lautens, M. Top. Curr. Chem. 2010, 292, 1e33; (e) Sehnal, P.; Taylor, R. J. K.;
Fairlamb, I. J. S. Chem. Rev. 2010, 110, 824e889; (f) Muniz, K. Angew. Chem., Int.
Ed. 2009, 48, 9412e9423; (g) Catellani, M.; Motti, E.; Della Ca, N. Acc. Chem. Res.
2008, 41, 1512e1522; (h) Lautens, M.; Alberico, D.; Bressy, C.; Fang, Y.-Q.; Ma-
riampillai, B.; Wilhelm, T. Pure Appl. Chem. 2006, 78, 351e361; (i) Dick, A. R.;
Sanford, M. S. Tetrahedron 2006, 62, 2439e2463.
25. Shimizu, K.; Takimoto, M.; Mori, M. Org. Lett. 2003, 5, 2323e2325.
26. Dong, G.; Teo, P.; Wickens, Z. K.; Grubbs, R. H. Science 2011, 333, 1609e1612.
27. Larraufie, M.-H.; Maestri, G.; Beaume, A.; Derat, E.; Ollivier, C.; Fensterbank, L.;
Courillon, C.; Lacote, E.; Catellani, M.; Malacria, M. Angew. Chem., Int. Ed. 2011,
50, 12253e12256 and references cited therein.
28. For some recent computational studies see: (a) Maestri, G.; Motti, E.; Della Ca,
N.; Malacria, M.; Derat, E.; Catellani, M. J. Am. Chem. Soc. 2011, 133, 8574e8585;
(b) Vicente, J.; Arcas, A.; Juli-Hernndez, F.; Bautista, D. Angew. Chem., Int. Ed.
2011, 50, 6896e6899; (c) Maestri, G.; Larraufie, M. H.; Derat, E.; Ollivier, C.;
Fensterbank, L.; Lacte, E.; Malacria, M. Org. Lett. 2010, 12, 5692e5695; (d)
Livendahl, M.; Echavarren, A. M. Isr. J. Chem. 2010, 50, 630e651.