Gold versus palladium: A regioselective cycloisomerization of aromatic enynes

Article abstract of DOI:10.1002/adsc.201300746

Aromatic enynes can be transformed into arylnaphthalenes or benzofulvenes depending on the reaction conditions. Under gold(I) catalysis, exclusive or major 6-endo-dig cyclization took place leading to arylnaphthalenes. However, a catalytic system based on

Full text of DOI:10.1002/adsc.201300746

FULL PAPERS
DOI: 10.1002/adsc.201300746
Gold versus Palladium: A Regioselective Cycloisomerization of
Aromatic Enynes
Jessy Aziz,a Gilles Frison,b Patrick Le Menez,a Jean-Daniel Brion,a
Abdallah Hamze,a,* and Mouad Alamia,*
a
Univ Paris-Sud, CNRS, BioCIS - UMR 8076, LabEx LERMIT, Laboratoire de Chimie Thꢀrapeutique, Facultꢀ de
Pharmacie, 5 rue J.-B. Clꢀment, F-92296 Chꢁtenay-Malabry, France
Fax : (+33)-1-4683-5828; phone: (+33)-1-4683-5498; e-mail: abdallah.hamze@u-psud.fr or mouad.alami@u-psud.fr
Laboratoire des Mꢀcanismes Rꢀactionnels, Department of Chemistry, Ecole polytechnique and CNRS, 91128 Palaiseau
b
Cedex, France
Received: August 17, 2013; Revised: October 4, 2013; Published online: November 14, 2013
Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/adsc.201300746.
Abstract: Aromatic enynes can be transformed into zation pattern, regardless of the electronic effects of
arylnaphthalenes or benzofulvenes depending on the the substituents. In the latter transformation, a mech-
reaction conditions. Under gold(I) catalysis, exclusive anistic study (kinetic isotopic effect, density function-
À
or major 6-endo-dig cyclization took place leading to al theory) involving a C H activation is suggested
arylnaphthalenes. However, a catalytic system based for the exclusive formation of benzofulvenes.
on palladium iodide/1,3-bis(diphenylphosphino)pro-
pane, in the presence of cesium carbonate as a base Keywords: aromatic enynes; cycloisomerization;
was necessary to furnish exclusively 5-exo-dig cycli- gold; palladium; regioselectivity
Introduction
(1)].[8b] However, the reaction took place only in the
presence of electron-donating groups, which seems to
In the past few decades, myriads of transition metal- be important for the 6-endo-dig cyclization process.
catalyzed carbon-carbon cross-coupling reactions The presence of a strongly electron-withdrawing ester
have been discovered and developed.[1] Among the group on the alkyne not only diminishes the reaction
extraordinary variety of the transformations reported, rate but also overturns this inherent bias furnishing
1,n-enynes cycloisomerizations are growing in impor- a 5-exo-dig ring closure fluorene derivative. Two years
tance as the most valuable strategies for the synthesis later, Shibata and co-workers[5a] reported a gold-cata-
of functionalized cyclic structures.[2] The significance lyzed cycloisomerization of aromatic enynes giving
of this process stems in part from the rapid increase mainly the 6-endo-dig ring closure products. The
in structural complexity, starting with relatively scope of this method was limited only to alkyl sub-
simple acyclic subunits containing ene and yne frag- stituents or neutral phenyl group. In 2008, Gevorgy-
ments,[3] and secondly, this procedure is inherently anꢃs team[7b,13] described an exclusive regio- and ste-
atom economic. In addition to that, intra- or intermo- reoselective formation of 9-benzylidene-9H-fluorene
lecular addition reactions to alkynes have been broad- derivatives catalyzed by PdACTHNUTRGNE(UNG OAc)2 and a ferrocene-
À
ly explored due to the recent significant advances in type ligand [Figure 1, Eq. (2)]. A C H activation
the development of transition metal complexes capa- mechanism was proposed, in opposition to the most
ble of catalyzing enyne cycloisomerizations, such common electrophilic activation process. In this case
as Ag(I),[4] Au(I),[5] Au(III),[6] Pd(II),[7] Pt(II),[2,8] also, the electronic effect of the substituents played
ACHTUNGTRENNUNG
Rh
N
a major role, since very good yields were obtained
Gold-catalyzed cycloisomerizations of enyne com- with substrates having electron-withdrawing groups
pounds leading to carbocycles and heterocycles have and a drop in the reaction yield was observed with
been actively investigated.[2,12] Recently, Fꢂrstner and those bearing electron-donating groups.
co-workers synthesized phenanthrenes by a transition
From the above observations, a complete control of
metal p-activation of ortho-alkynylated biaryl deriva- the regioselectivity of the intramolecular ring closure
tives via a 6-endo-dig cyclization [Figure 1, Eq. of aromatic enynes is still a challenge given that it de-
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Figure 1. Intramolecular cycloisomerization of 1,5-enynes.
pends on several parameters: the nature of the cata- the yield of 2a (entry 2). When (PPh3)AuCl complex
lyst, electronic effects of the substituents and the or AgOTf were used alone, they were unable to pro-
mechanism of the reaction.
mote the intramolecular ring closure, and the starting
In this paper, we wish to disclose our findings on material 1a was fully recovered (entries 3 and 4). We
the cycloisomerization of aromatic enynes 1 [Figure 1, were delighted to find that the use of a silver-free salt
[15]
Eq. (3)]. We were able to obtain under Au(I) catalysis complex Ph3PAuNTf2
(5 mol%) in THF gave the
mainly phenylnaphthalene derivatives 2 via a 6-endo- best result (entry 5). Changing the solvent sources
dig cyclization, and under Pd(II) catalysis benzoful- (CH2Cl2, toluene, 1,4-dioxane) did not affect the reac-
vene derivatives 3 via an exclusive 5-exo-dig cycliza- tion outcome. In agreement with the results obtained
tion, regardless of the electronic effects of the sub- by Fꢂrstner,[8b] PtCl2 and InCl3 salts also catalyze the
stituents. The mechanism of the Pd-catalyzed cycloi- intramolecular cyclization of 1a, providing the expect-
somerization of enynes 1 was studied to determine if ed substituted naphthalene 2a in 76% and 85% yields,
À
the reaction evolves either by p or by C H activa- respectively. A control experiment revealed that by
tion.
heating enyne 1a in THF at 708C for 12 h in the ab-
sence of any catalyst (entry 8) no ring closure product
was observed, clearly suggesting that the cycloisome-
rization reaction is not just a thermal electrocycliza-
tion process but definitely requires assistance by
Results and Discussion
We began our investigations by testing the reactivity a soft Lewis acid. The whole set of experiments (en-
of enyne 1a in the presence of Au(I) or AuACTHNUGTRNEUNG(III) cata- tries 1–7) showed a pronounced preference for the 6-
lysts (Table 1).[14] Treatment of 1a with AuCl3/AgOTf endo-dig cyclization giving 2a over the conceivable 5-
(5 mol%) in THF at 708C gave phenylnaphthalene 2a exo-dig mode. Not more than 12% of benzofulvene
in 74% yield, together with a small amount of benzo- 3a were formed.
fulvene 3a (9%, Table 1, entry 1). Switching from
In continuation of this study, we investigated
AuCl3 to (PPh3)AuCl resulted in a slight increase of whether 3a could be exclusively formed, reversing the
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Gold versus Palladium: A Regioselective Cycloisomerization of Aromatic Enynes
Table 1. Effect of Lewis acids on the hydroarylation of the
enyne 1a.[a]
zation assays with respect to the base revealed that
Cs2CO3 is the best base (entries 10–12). Among other
palladium sources examined (entries 10, 13 and 14),
PdI2 proved to be the catalyst of choice, providing ex-
clusively the 5-exo-dig cyclization product 3a in
a good 77% yield (entry 14). Finally, screening of
phosphine ligands (entries 14–19) demonstrated the
supremacy of the bidentate ligand dppp (entry 14) in
comparison to ferrocene (entries 16–18) or biaryl-type
ligand (entry 19). Also, we found that the use of Ge-
vorgyan conditions with enyne 1 were neither stereo-
nor regioselective (entry 17), as a mixture of com-
pounds 2a and 3a was obtained and the benzofulvene
compound was obtained as a mixture of E and Z iso-
mers (70/30 E/Z). It should be noted that our new
palladium-catalyzed cycloisomerization conditions of
1a (entry 14) are stereoselective, giving exclusively
the (E)-isomer 3a, as was determined by 2D NMR
(NOESY experiments).
Once the influence of the nature of the catalyst as
well as the reaction conditions on the regioselectivity
of the cycloisomerization of 1a were defined, we used
the above optimized conditions (entries 5 and 14)
with different substitution patterns on the aromatic
enynes 1 (Table 2 and Table 3).
Au Catalysis (Table 2)
The examples compiled in Table 2 show the generality
of this cycloisomerization reaction catalyzed by the
PPh3AuNTf2 complex. Various substituted naphtha-
lene derivatives 2 were formed with isolated yields up
to 98% (compounds 2a–j). The reaction worked se-
lectively towards the 6-endo-dig cyclization pattern
regardless of the electronic effects of the substituents
on the aromatic nucleus of the alkene moiety.
Aromatic substituents on the alkyne moiety had
somewhat more effect on the cycloisomerization reac-
tion selectivity. In fact, the presence of electron-rich
or electron-neutral aromatic groups on the alkyne
provided exclusively the corresponding 6-endo-dig
ring closure products 2e–i. However, the presence of
electron-poor aromatic groups slightly diminished the
yields of the 6-endo-dig ring closure compounds 2a–d,
and 2j in favor of the corresponding 5-exo-dig prod-
[a]
Unless otherwise noted, reaction conditions are for en-
tries 1–8: enyne 1a (0.6 mmol), catalyst (5 mol%),
AgOTf when used (5 mol%), THF (1 mL) at 708C for
3 h under argon. For entries 9–19: enyne 1a (0.6 mmol),
Pd (10 mol%), ligand (20 mol%), base (1 equiv.), 1,4-di-
oxane (2 mL) in a sealed tube at 1508C for 15 h.
Yield of isolated product.
1a was completely recovered.
Reaction conducted in toluene at 908C.
Reaction time=6 h.
1a was completely recovered when the reaction was con-
ducted without ligand and/or base.
[b]
[c]
[d]
[e]
[f]
[g]
Reaction was conducted in toluene at 1208C for 3 h,
a mixture of E- and Z-isomers of 3a was obtained in
a 70/30 E/Z ratio.
regioselectivity observed with gold, platinum or ucts 3a–d, and 3j, but with yields never exceeding
indium catalysts. For these reasons, we turned our at- 10%. These results clearly demonstrated that elec-
tention to the use of palladium complexes (Table 1, tronic effects on the alkyne moiety play a crucial role
entries 9–19).
in the regioselectivity outcome.[16] The substituentꢃs
First, when PdCl2ACHTNUTRGENNUG(MeCN)2 was employed at 1508C position was studied as well, and very good yields
for 6 h, no reaction occurred and 1a was completely were also obtained with aromatic enyne substrates
recovered (Table 1, entry 9).[14] After several assays, having various groups, such as OMe, Me, CF3, CN in
we determined that the addition of 1,3-bis(diphenyl- meta-, ortho- and para-positions.
phosphino)propane (dppp) as a ligand, under basic
conditions (Cs2CO3) and heating at 1508C for 15 h af-
forded exclusively 3a in 66% yield (entry 10). Optimi-
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Table 2. Intramolecular cycloisomerization of aromatic enynes 1 under Au catalysis.
[a]
Reaction conditions: enyne 1 (0.6 mmol), (PPh3)AuNTf2 (5 mol%), THF (1 mL) at 708C for 3 h under argon.
Isolated yields.
[b]
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Gold versus Palladium: A Regioselective Cycloisomerization of Aromatic Enynes
Table 3. Intramolecular hydroarylation of aromatic enynes 1 under Pd catalysis.
[a]
Reactions conditions: enyne 1 (0.6 mmol), PdI2 (10 mol%), Dppp (20 mol%), Cs2CO3 (1 equiv.), 1,4-dioxane
(2 mL) at 1508C for 15 h in a sealed tube.
Isolated yields.
[b]
Pd Catalysis (Table 3)
isomers.[18] Various groups, such as CN, F, CF3 and
OMe, were perfectly tolerated under the optimized
With the optimized conditions in hand (Table 1, conditions. Finally, the substituentꢃs position had little
entry 14), we next explored the generality of this effect on the reaction outcome; the para position fa-
transformation. In contrast to the PPh3AuNTf2 com- cilitated the reaction course giving 3a in 77%, while
plex, the PdI2/dppp catalytic system triggered the ex- the yields were slightly lower with substrates possess-
clusive 5-endo-dig cyclization leading to the benzoful- ing a CN group at the ortho- and meta-positions, lead-
vene derivatives 3a–j in good to excellent yields, re- ing to 3b and 3c in yields of 60% and 57%, respec-
gardless of the electronic nature of the aromatic sub- tively. One can note that aromatic enynes having an
stituent on the alkene and the alkyne moieties alkyl substituent on the alkyne or the alkene moieties
(Table 3).[17] Importantly, the cyclization of all aromat- did not provide any cyclization products under our
ic enynes 1a–j proceeded in a trans-stereoselective Pd-optimized conditions.[19]
manner producing benzofulvenes 3a–j as single (E)-
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Mechanistic Investigations for Exclusive 5-exo-dig
Cyclization of Aromatic Enynes under Palladium
Catalysis
path I). In this pathway, the palladium catalyst acts as
a Lewis acid. It initiates the reaction by coordination
to the triple bond (complex A); the resulting activat-
ed alkyne could undergo nucleophilic attack by the
Even if cycloisomerization of enyne derivatives based alkene moiety to form alkenylpalladium species B,
on Au catalysis has grown into a major field of experi- which would produce the final product and regenerate
mental as well as theoretical research,[20] mechanistic the catalyst.
investigations for palladium catalyzed 5-exo-dig cycli-
In order to better understand this transformation,
zation of enynes were not extensively undertaken. At we performed a kinetic study in order to examine
this stage of the study, we are not able to confirm if whether the (E)-isomer is the only product formed
the Pd-catalyzed cycloisomerization of enynes during the reaction. To this end, the cyclization of 1a
À
1 evolves either by p or by C H activation.
was conducted under optimized conditions and the re-
In contrast to the previous work of Gevorgyan[7b] action progress was followed depending on the reac-
on the cyclization of o-alkynylbiphenyls, which pro- tion time. As illustrated in Scheme 2, at the beginning
ceeds with a cis-selectivity, our study on the cycliza- of this transformation (90 min), in addition to the ex-
tion of aromatic enynes 1 showed that the reaction pected benzofulvene E-3a,
a significant amount
formally occurred with a trans-selectivity. On the (20%) of its isomer Z-3a was formed, which then dis-
basis of the stereochemistry of compounds 3 formed appeared at the end of the reaction (15 h).
(Table 2) and the literature reports,[8,16a] it seems that
This result suggests that Z-3a is unstable under the
the formation of 3 may be rationalized via an electro- optimized conditions and isomerizes to the thermody-
philic cyclization of aromatic enynes 1 (Scheme 1, namically more stable isomer E-3a.[21] The existence
Scheme 1. Proposed mechanism for the 5-exo-dig cyclization of aroamtic enynes under palladium catalysis.
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Gold versus Palladium: A Regioselective Cycloisomerization of Aromatic Enynes
matic enyne 1a, together with its deuterated analogue
2d-1a under our standard conditions revealed a sub-
stantial intermolecular kinetic isotope effect (kH/kD =
2.5). These data are in a range of the isotope effects
observed for the reactions proceeding via the Pd-cata-
À
lyzed aromatic C H activation.
À
In order to support this C H activation path, we
then realized a computational study.
Computational Studies
The mechanism of the cyclization reaction of enyne
1h, catalyzed by palladium, was studied computation-
ally at the DFT level. We first estimated the cycliza-
tion barrier following both electrophilic activation
Scheme 2. E/Z distribution of 3a during the cyclization reac-
tion.
À
(path I) and C H activation (path II) pathways envi-
sioned in Scheme 1.[22] Various coordination spheres
around Pd have been studied {[Pd]=PdI2PMe3,
+
PdI
(PMe3)2 , Pd
E
(PMe3)2 and Pd
N
explore a large set of catalytic species. Among them,
Pd(CO3)PMe3 gives the lowest cyclization transition
AHCTUNGTRENNUNG
state for the electrophilic activation pathway. An even
lower energy transition state is obtained for the 5-
À
exo-dig cyclization following the C H activation path-
way with the same Pd complex. With this catalytic
À
system, the whole reaction mechanism for the C H
activation pathway has been investigated to confirm
its reliability (Scheme 4). Our calculations indicate
À
that the activation of C H bond to form intermediate
6 (C in Scheme 1) could be decomposed in three
steps: (i) first coordination of the catalyst to the
double bond (4); (ii) intramolecular deprotonation of
the CH2 terminal group by the carbonate ligand, via
transition state TS1, which produces intermediate 5;
(iii) formation of the palladium p complex 6. Next,
the 5-exo-dig cyclization step leads easily to inter-
mediate 7 (D in Scheme 1), which can isomerize to 8
via transition state TS3. Finally, intramolecular protio-
depalladation of 8 leads to E-benzofulvene 3h. This
DFT study shows that the limiting step clearly is TS1
Scheme 3. 1H/2H intermolecular kinetic isotope effect ex-
periments.
À
(C H activation), this is in complete agreement with
the experimental results.
of both E/Z isomers of compound 3a at the early
stage of the reaction strongly suggests that the path-
way II (Scheme 1) might be considered more likely Conclusions
À
involving the following steps: (i) activation of C H
bond to form s-alkenylpalladium intermediate C, (ii) In conclusion, we report a general approach for con-
migratory insertion to the triple bond would form verting aromatic enynes into phenylnaphthalenes 2 or
species D, and (iii) protiodepalladation of D gives Z- benzofulvenes 3 depending on the nature of the cata-
benzofulvene 3 which then isomerizes into its E- lytic system used. In fact, we were able to control the
isomer. One can note isomerization may also occur regioselectivity of aromatic enyne cycloisomerization
between alkenylpalladium species D and E as illus- process. Ph3PAuNTf2 was the best catalyst to promote,
trated in Scheme 1.
via an electrophilic activation, mainly 6-endo-dig cy-
clization leading to a variety of phenylnaphthalene
With the aim to support this suggested mechanism,
ACHTUNGTRENNUNG
kinetic isotope effect studies were performed derivatives. Moreover, a fine tuning of other Lewis
(Scheme 3). Intermolecular competition between aro- acids, ligands and reaction conditions led us to discov-
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Scheme 4. Gibbs free energies for the Pd-catalyzed cyclization of aromatic enyne 1h.
1514, 1498, 1462, 1288, 1244, 1177, 1110, 1033 cmÀ1
;
1H NMR (300 MHz, CDCl3): d=8.05 (d, J=1.5 Hz, 1H),
7.96 (t, J=6.8 Hz, 2H), 7.84 (d, J=8.4 Hz, 2H), 7.76 (d, J=
8.4 Hz, 2H), 7.64 (d, J=1.9 Hz, 1H), 7.60–7.41 (m, 4H),
7.07 (d, J=8.7 Hz, 2H), 3.92 (s, 3H); 13C NMR (75 MHz,
CDCl3): d=159.3 (C), 145.4 (C), 141.2 (C), 135.9 (C), 134.1
(C), 132.7 (2CH), 132.6 (C), 131.7 (C), 131.1 (2CH), 128.9
(CH), 128.0 (2CH), 126.9 (CH), 126.7 (CH), 126.1 (C), 125.9
(CH), 125.8 (CH), 119.0 (C), 114.0 (2CH), 111.0 (C), 55.5
(OCH3); HR-MS (ESI): m/z=358.1188, calculated for
C24H17NNaO (M+Na)+: 358.1202 found .
er that PdI2/dppp as a catalytic system guided an ex-
clusive 5-exo-dig cyclization pattern and a subsequent
formation of (E)-benzofulvenes. These results were
obtained regardless of the electronic nature of sub-
stituents on alkene and alkyne moieties. KIE and
DFT studies led us to propose a C H activation
mechanism for this palladium-catalyzed transforma-
tion.
À
2-[4-(4-Methoxyphenyl)naphthalen-2-yl]benzonitrile (2b):
The crude residue was purified by flash chromatography on
silica gel (cyclohexane/EtOAc 90/10) to give 2b as a yellow
oil; yield: 90 mg (0.26 mmol; 87%); M=335.4 g·molÀ1; Rf =
0.61 (cyclohexane/EtOAc 70/30); IR (film): n=2224, 1609,
Experimental Section
General Procedure for the Gold(I)-Catalyzed
Cyclization
1
1514, 1288, 1245, 1179, 1108, 1032 cmÀ1; H NMR (300 MHz,
To a solution of the corresponding enyne (1 equiv.) in 3 mL
of anhydrous THF under argon was added 0.05 equiv. of
PPh3AuNTf2. The reaction mixture was stirred at reflux
until total conversion (3 h). Then, the solvent was evaporat-
ed under reduced pressure to give the crude product which
was purified by flash chromatography on silica gel.
4-[4-(4-Methoxyphenyl)naphthalen-2-yl]benzonitrile (2a):
The crude residue was purified by flash chromatography on
silica gel (cyclohexane/EtOAc 90/10) to give 2a as a colorless
oil; yield: 90 mg (0.27 mmol; 89%); M=335.4 g·molÀ1; Rf =
0.72 (cyclohexane/EtOAc 70/30); IR (film): n=2224, 1602,
CDCl3): d=8.06–7.96 (m, 3H), 7.81 (dd, J=7.7, 0.8 Hz,
1H), 7.67 (d, J=3.8 Hz, 3H), 7.63 (d, J=1.8 Hz, 1H), 7.60–
7.42 (m, 4H), 7.07 (d, J=8.7 Hz, 2H), 3.91 (s, 3H);
13C NMR (75 MHz, CDCl3): d=159.3 (C), 145.5 (C), 140.7
(C), 135.1 (C), 133.9 (CH), 133.9 (C), 132.9 (CH), 132.7 (C),
131.7 (C), 131.3 (2CH), 130.4 (CH), 129.0 (CH), 127.7 (CH),
127.6 (CH), 127.5 (CH), 126.9 (CH), 126.6 (CH), 126.1
(CH), 118.9 (C), 114.0 (2CH), 111.7 (C), 55.5 (OCH3); HR-
MS (ESI): m/z=358.1191, calculated for C24H17NNaO (M+
Na)+: 358.1202.
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Gold versus Palladium: A Regioselective Cycloisomerization of Aromatic Enynes
3-[4-(4-Methoxyphenyl)naphthalen-2-yl]benzonitrile (2c):
The crude residue was purified by flash chromatography on
silica gel (cyclohexane/EtOAc 90/10) to give 2c as a yellow
oil; yield: 70 mg (0.22 mmol; 73%); M=335.4 g·molÀ1; Rf =
0.72 (cyclohexane/EtOAc 70/30); IR (film): n=3372, 2228,
2037, 1609, 1575, 1515, 1464, 1401, 1288, 1245, 1178, 1034,
126.8 (CH), 126.3 (CH), 126.1 (CH), 126.1 (CH), 125.2
(CH), 113.9 (2CH), 55.4 (OCH3); HR-MS (ESI): m/z=
311.1435, calculated for C23H19O (M+H)+: 311.1436.
4-[3-(4-Methoxyphenyl)naphthalen-1-yl]benzonitrile (2g):
The crude residue was purified by flash chromatography on
silica gel (cyclohexane/EtOAc 90/10) to give 2g as an oil;
yield: 90 mg (0.27 mmol; 90%); M=335.40 g·molÀ1; Rf =
0.82 (cyclohexane/EtOAc 70/30); IR (film): n=2225, 1607,
908 cmÀ1 1H NMR (300 MHz, CDCl3): d=8.06–8.00 (m,
;
2H), 7.96 (m, 3H), 7.70–7.52 (m, 4H), 7.51–7.40 (m, 3H),
7.07 (d, J=8.7 Hz, 2H), 3.92 (s, 3H); 13C NMR (75 MHz,
CDCl3): d=159.3 (C), 142.3 (C), 141.2 (C), 135.6 (C), 134.2
(C), 132.6 (C), 131.7 (CH), 131.6 (C), 131.2 (2CH), 131.0
(CH), 130.8 (CH), 129.7 (CH), 128.8 (CH), 126.8 (CH),
126.7 (CH), 126.1 (CH), 125.9 (CH), 125.5 (CH), 118.9 (C),
114.0 (2CH), 113.1 (C), 55.5 (OCH3); HR-MS (ESI): m/z=
358.1194, calculated for C24H17NNaO (M+Na)+: 358.1202.
1-(4-Methoxyphenyl)-3-[4-(trifluoromethyl)phenyl]naph-
thalene (2d): The crude residue was purified by flash chro-
matography on silica gel (cyclohexane/EtOAc 95/5) to give
2d as a yellow oil; yield: 70 mg (0.18 mmol; 70%); M=
1513, 1286, 1244„ 1179, 1031 cmÀ1 1H NMR (300 MHz,
;
CDCl3): d=8.07 (s, 1H), 7.97 (d, J=8.1 Hz, 1H), 7.78 (t, J=
7.1 Hz, 3H), 7.70 (s, 1H), 7.68–7.60 (m, 4H), 7.55 (t, J=
7.0 Hz, 1H), 7.46 (dd, J=11.1, 4.1 Hz, 1H), 7.04 (d, J=
8.7 Hz, 2H), 3.88 (s, 3H); 13C NMR (75 MHz, CDCl3): d=
159.6 (C), 145.7 (C), 138.8 (C), 137.7 (C), 134.3 (C), 132.9
(C), 132.2 (2CH), 130.9 (2CH), 129.9 (C), 128.8 (CH), 128.5
(2CH), 126.6 (CH), 126.6 (CH), 126.5 (CH), 125.7 (CH),
125.1 (CH), 119.0 (C), 114.5 (2CH), 111.3 (C), 55.5 (OCH3);
HR-MS (ESI): m/z=336.1386, calculated for C24H18NO
(M+H)+: 336.1388.
378.4 g·molÀ1
; Rf =0.65 (cyclohexane/EtOAc 80/20); IR
3-(4-Methoxyphenyl)-1-(3,4,5-trimethoxyphenyl)-naphtha-
lene (2i): The crude residue was purified by flash chroma-
tography on silica gel (cyclohexane/EtOAc 90/10) to give 2i
as a yellow oil; yield: 100 mg (0.24 mmol; 98%); M=
(film): n=3493, 3454, 3433, 3416, 3316, 3267, 3172, 2331,
2278, 2171, 2130, 2060, 2043, 2021, 1938, 1612, 1514, 1324,
1288, 1246, 1165, 1126, 1109, 1071, 1034 cmÀ1 1H NMR
;
400.47 g·molÀ1
;
Rf =0.55 (cyclohexane/EtOAc 70/30);
(300 MHz, CDCl3): d=8.06 (d, J=1.2 Hz, 1H), 7.96 (t, J=
8.1 Hz, 2H), 7.86 (d, J=8.1 Hz, 2H), 7.73 (d, J=8.2 Hz,
2H), 7.67 (d, J=1.8 Hz, 1H), 7.58–7.41 (m, 4H), 7.07 (d, J=
8.6 Hz, 2H), 3.91 (s, 3H); 13C NMR (101 MHz, CDCl3): d=
159.3 (C), 144.7 (C), 141.1 (C), 136.7 (C), 134.2 (C), 132.9
1H NMR (300 MHz, CDCl3): d=8.02 (s, 1H), 7.95 (d, J=
8.6 Hz, 2H), 7.71 (dd, J=5.5, 2.9 Hz, 3H), 7.48 (m, 2H),
7.04 (d, J=8.6 Hz, 2H), 6.77 (s, 2H), 3.98 (s, 3H), 3.90 (s,
6H), 3.88 (s, 3H); 13C NMR (75 MHz, CDCl3): d=159.3
(C), 153.0 (2C), 140.7 (C), 137.5 (C), 137.3 (C), 136.4 (C),
134.2 (C), 133.1 (C), 130.5 (C), 128.5 (CH), 128.4 (2CH),
126.2 (2CH), 125.9 (CH), 125.8 (CH), 124.6 (CH), 114.3
(2CH), 107.2 (2CH), 60.9 (OCH3), 56.11 (2OCH3), 55.2
(OCH3); HR-MS (ESI): m/z=401.1751, calculated for
C26H25O4 (M+H)+: 401.1753.
2
(C), 131.6 (C), 131.2 (2CH), 129.6 (C, JC,F =32.5 Hz), 128.8
(CH), 127.8 (2CH), 126.7 (CH), 126.6 (CH), 126.3 (CH),
126.2 (CH), 125.9 (2CH, 3JC,F =3.6 Hz), 125.8 (CH), 124.5
(C, 1JC,F =271.9 Hz), 114.0 (2CH), 55.6 (OCH3); 19F NMR
(188 MHz, CDCl3): d=À60.4, À60.5, À60.6; HR-MS (ESI):
m/z=379.1308, calculated for C24H18F3O (M+H)+:
379.1310.
4-[4-(3,4,5-Trimethoxyphenyl)naphthalen-2-yl]benzonitrile
(2j): The crude residue was purified by flash chromatogra-
phy on silica gel (cyclohexane/EtOAc 90/10) to give 2j as
1-(4-Methoxyphenyl)-3-p-tolylnaphthalene
(2e):
The
crude residue was purified by flash chromatography on
silica gel (cyclohexane/EtOAc 90/10) to give 2e as an oil;
yield: 90 mg (0.28 mmol; 90%); M=324.42 g·molÀ1; Rf =
0.86 (cyclohexane/EtOAc 70/30); IR (film): n=1609, 1513,
a
yellow oil; yield: 70 mg (0.18 mmol; 73%); M=
395.45 g·molÀ1; Rf =0.58 (cyclohexane/EtOAc 70/30); IR
(film): n=3462, 3411, 3356, 3301, 3208, 3127, 2861, 2485,
2362, 2306, 2195, 2102, 2034, 1962, 1604, 1508, 1399, 1336,
1287, 1243, 1178, 1034 cmÀ1 1H NMR (300 MHz, CDCl3):
;
1181, 1127, 1007 cmÀ1; H NMR (300 MHz, CDCl3): d=8.08
1
d=8.05 (d, J=1.4 Hz, 1H), 7.96 (dd, J=8.0, 4.3 Hz, 2H),
7.71 (d, J=1.9 Hz, 1H), 7.68 (d, J=8.0 Hz, 2H), 7.57–7.39
(m, 4H), 7.31 (d, J=8.0 Hz, 2H), 7.08 (d, J=8.7 Hz, 2H),
3.92 (s, 3H), 2.44 (s, 3H); 13C NMR (75 MHz, CDCl3): d=
159.1 (C), 140.5 (C), 138.0 (C), 138.0 (C), 137.1 (C), 134.4
(C), 133.1 (C), 131.2 (2CH), 131.0 (C), 129.6 (2CH), 128.6
(CH), 127.3 (2CH), 126.6 (CH), 126.1 (CH), 126.0 (CH),
125.9 (CH), 124.8 (CH), 113.8 (2CH), 55.2 (OCH3), 21.1
(CH3); HR-MS (ESI): m/z=325.1590, calculated for
C24H21O (M+H)+: 325.1592.
(d, J=1.5 Hz, 1H), 8.02–7.94 (m, 2H), 7.87 (d, J=8.6 Hz,
2H), 7.78 (d, J=8.4 Hz, 2H), 7.68 (d, J=1.9 Hz, 1H), 7.54
(m, 2H), 6.74 (s, 2H), 3.96 (s, 3H), 3.89 (s, 6H); 13C NMR
(75 MHz, CDCl3): d=153.3 (2C), 145.4 (C), 141.6 (C), 137.7
(C), 135.9 (C), 135.9 (C), 134.1 (C), 132.7 (2CH), 131.6 (C),
128.9 (CH), 128.1 (2CH), 127.1 (CH), 126.8 (CH), 126.2
(CH), 126.1 (CH), 125.7 (CH), 119.0 (C), 111.1 (C), 107.3
(2CH), 61.1 (OCH3), 56.3 (2OCH3); HR-MS (ESI); m/z=
396.1598, calculated for C26H22NO3 (M+H)+: 396.1600.
1-(4-Methoxyphenyl)-3-phenylnaphthalene
(2f):
The
crude residue was purified by flash chromatography on
silica gel (cyclohexane/EtOAc 90/10) to give 2f as an oil;
yield: 92 mg (0.30 mmol; 92%); M=310.4 g·molÀ1; Rf =0.72
(cyclohexane/EtOAc 70/30); IR (film): n=1513, 1244, 1179,
General Procedure for the Pd(II)-Catalyzed
Cyclization
In a sealed tube and under argon inlet, the enyne (1 equiv.),
PdI2 (0.1 equiv.), Dppp (0.2 equiv.) and Cs2CO3 (1 equiv.)
were mixed in 2 mL of dioxane. The reaction vessel was
then capped with a pressure screw cap and the reaction mix-
ture was stirred at 1508C for 15 h. The crude reaction mix-
ture was allowed to cool to room temperature. EtOAc was
added to the mixture, which was filtered through celite.
1032 cmÀ1 1H NMR (300 MHz, CDCl3): d=8.07 (d, J=
;
1.5 Hz, 1H), 8.01–7.94 (m, 2H), 7.79 (dd, J=8.3, 1.3 Hz,
2H), 7.73 (d, J=1.9 Hz, 1H), 7.58–7.37 (m, 7H), 7.08 (d, J=
8.8 Hz, 2H), 3.93 (s, 3H); 13C NMR (75 MHz, CDCl3): d=
159.2 (C), 141.1 (C), 140.6 (C), 138.2 (C), 134.4 (C), 133.2
(C), 131.3 (2CH), 129.0 (2CH), 128.7 (CH), 127.5 (2CH),
Adv. Synth. Catal. 2013, 355, 3425 – 3436
ꢄ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
3433

Jessy Aziz et al.
FULL PAPERS
Then, the solvent was evaporated under reduced pressure to
give the crude product which was purified by flash chroma-
tography on silica gel.
70/30); IR (film): n=3456, 3198, 2971, 2153, 1606, 1502,
1462, 1419, 1321, 1249, 1177, 1162, 1124, 1108, 1066, 1033,
1015, 931 cmÀ1 1H NMR (300 MHz, CDCl3): d=7.80–7.56
;
(E)-4-{[3-(4-Methoxyphenyl)-1H-inden-1-ylidene]methyl}-
benzonitrile (3a): The crude residue was purified by flash
chromatography on silica gel (cyclohexane/EtOAc 95/5) to
give 3a as a yellow oil; yield: 80 mg (0.23 mmol; 77%); M=
335.40 g·molÀ1; Rf =0.74 (cyclohexane/EtOAc 70/30); IR
(film): n=3468, 3453, 3434, 3407, 3391, 3377, 3338, 3275,
3229, 3111, 3063, 3047, 2999, 2947, 2930, 2542, 2271, 2189,
2172, 2132, 2091, 2052, 2030, 2010, 1984, 1928, 1605, 1501,
(m, 8H), 7.45 (s, 1H), 7.38–7.29 (m, 2H), 7.02 (d, J=8.8 Hz,
2H), 6.98 (s, 1H), 3.88 (s, 3H); 13C NMR (75 MHz, CDCl3):
d=160.1 (C), 148.6 (C), 141.4 (C), 141.3 (C), 140.9 (C),
1
138.8 (C), 130.3 (2CH), 130.0 (C), 124.3 (C, JC,F
=
271.7 Hz), 129.6 (C), 129.0 (2CH), 128.0 (CH), 125.9 (CH),
125.7 (2CH, 3JC,F =3.8 Hz), 125.3 (CH), 121.4 (CH), 120.7
(CH), 119.7 (CH), 114.3 (2CH), 55.5 (OCH3); 19F NMR
(188 MHz, CDCl3): d=À60.4, À60.5, À60.6; HR-MS (ESI):
m/z=401.1135, calculated for C24H17F3NaO (M+Na)+:
401.1129.
1342, 1287, 1251, 1178, 1032 cmÀ1
;
1H NMR (300 MHz,
CDCl3): d=7.78–7.68 (m, 5H), 7.65 (d, J=8.8 Hz, 2H),
7.61–7.54 (m, 1H), 7.38 (s, 1H), 7.36–7.28 (m, 2H), 7.02 (d,
J=8.8 Hz, 2H), 6.93 (s, 1H), 3.88 (s, 3H); 13C NMR
(75 MHz, CDCl3): d=160.2 (C), 149.3 (C), 142.2 (C), 142.0
(C), 141.2 (C), 138.7 (C), 132.5 (2CH), 130.6 (2CH), 129.0
(2CH), 128.3 (CH), 127.8 (C), 126.1 (CH), 124.5 (CH),
121.1 (CH), 120.9 (CH), 119.8 (CH), 119.0 (C), 114.4
(2CH), 111.3 (C), 55.5 (OCH3); HR-MS (ESI): m/z=
358.1182, calculated for C24H17NNaO (M+Na)+: 358.1202.
(E)-2-{[3-(4-methoxyphenyl)-1H-inden-1-ylidene]methyl}-
benzonitrile (3b): The crude residue was purified by flash
chromatography on silica gel (cyclohexane/EtOAc 95/5) to
give 3b as a yellow oil; yield: 60 mg (0.17 mmol; 60%); M=
335.40 g·molÀ1; Rf =0.61 (cyclohexane/EtOAc 70/30); IR
(film): n=3440 3416, 3400, 3378, 3352, 3296, 3268, 3241,
3217, 3142, 3121, 3036, 2990, 2946, 2702, 2361, 2234, 2184,
(E)-3-(4-Methoxyphenyl)-1-(4-mehylbenzylidene)-1H-
indene (3e): The crude residue was purified by flash chro-
matography on silica gel (cyclohexane/EtOAc 90/10) to give
3e as a yellow oil; yield: 80 mg (0.25 mmol; 80%); M=
324.42 g·molÀ1; Rf =0.85 (cyclohexane/EtOAc 70/30); IR
(film): n=3401, 3302, 3279, 3252, 3232, 2839, 2556, 2386,
2324, 2303, 2285, 2154, 2109, 2076, 2036, 2015, 2580, 1547,
1503, 1458, 1412, 1342, 1300, 1236, 1182, 1127, 1074,
1007 cmÀ1 1H NMR (300 MHz, CDCl3): d=7.79–7.71 (m,
;
1H), 7.64 (d, J=8.7 Hz, 2H), 7.55 (d, J=7.9 Hz, 3H), 7.45
(s, 1H), 7.31- 7.19 (m, 4H),7.08 (s, 1H), 6.99 (d, J=8.7 Hz,
2H), 3.85 (s, 3H), 2.39 (s, 3H); 13C NMR (75 MHz, CDCl3):
d=159.9 (C), 146.8 (C), 140.9 (C), 139.3 (C), 138.6 (C),
138.6 (C), 134.5 (C), 130.4 (2CH), 129.6 (2CH), 129.0
(2CH), 128.6 (C), 127.8 (CH), 127.3 (CH), 125.5 (CH),
122.3 (CH), 120.4 (CH), 119.3 (CH), 114.3 (2CH), 55.5
(OCH3), 21.5 (CH3); HR-MS (ESI): m/z=325.1577, calcu-
lated for C24H21O (M+H)+: 325.1587.
2157, 2121, 2061, 2034, 2019, 1988, 1964, 1253 cmÀ1
;
1H NMR (300 MHz, CDCl3): d=7.83 (dd, J=9.7, 5.0 Hz,
2H), 7.73 (d, J=8.4 Hz, 1H), 7.61 (m, 5H), 7.46–7.29 (m,
3H), 7.01 (d, J=8.8 Hz, 2H), 6.87 (s, 1H), 3.87 (s, 3H);
13C NMR (75 MHz, CDCl3): d=160.2 (C), 149.4 (C), 143.0
(C), 141.3 (C), 140.6 (C), 138.5 (C), 133.3 (CH), 132.76
(CH), 131.00 (CH), 129.02 (2CH), 128.37 (CH), 128.10
(CH), 127.82 (C), 126.2 (CH), 121.9 (CH), 121.1 (CH), 120.8
(CH), 120.2 (CH), 117.9 (C), 114.3 (2CH), 113.0 (C), 55.5
(OCH3); HR-MS (ESI): m/z=358.1189, calculated for
C24H17NNaO (M+Na)+: 358.1202.
(E)-1-Benzylidene-3-(4-methoxyphenyl)-1H-indene (3f):
The crude residue was purified by flash chromatography on
silica gel (cyclohexane/EtOAc 95/5) to give 3f as a yellow
oil; yield: 90 mg (0.27 mmol; 88%); M=310.39 g·molÀ1; Rf =
0.72 (cyclohexane/EtOAc 80/20); IR (film): n=2999, 2838,
2218, 1648, 1605, 1582, 1530, 1502, 1456, 1416, 1374, 1338,
1315, 1251, 1226, 1205, 1177, 1158, 1129, 1051, 1034,
1
951 cmÀ1; H NMR (300 MHz, CDCl3): d=7.79 (dd, J=5.7,
(E)-3-{[3-(4-Methoxyphenyl)-1H-inden-1-ylidene]methyl}-
benzonitrile (3c): The crude residue was purified by flash
chromatography on silica gel (cyclohexane/EtOAc 95/5) to
give 3c as a yellow oil; yield: 70 mg (0.21 mmol; 57%); M=
335.40 g·molÀ1; Rf =0.69 (cyclohexane/EtOAc 70/30); IR
(film): n=3484, 3462, 3440, 3336, 3254, 3225, 2956, 2278,
2208, 1607, 1593, 1513, 1441, 1342, 1287, 1249, 1178, 1107,
2.9 Hz, 1H), 7.68 (d, J=8.7 Hz, 4H), 7.64–7.57 (m, 1H),
7.47 (dd, J=14.6, 7.4 Hz, 3H), 7.37 (d, J=7.4 Hz, 1H), 7.33
(d, J=3.3 Hz, 2H), 7.11 (s, 1H), 7.03 (d, J=8.8 Hz, 2H),
3.89 (s, 3H); 13C NMR (75 MHz, CDCl3): d=159.9 (C),
147.3 (C), 141.1 (C), 139.4 (C), 139.2 (C), 137.4 (C), 130.4
(2CH), 129.0 (2CH), 128.9 (2CH), 128.4 (C), 128.3 (CH),
127.6 (CH), 127.5 (CH), 125.6 (CH), 122.2 (CH), 120.5
(CH), 119.5 (CH), 114.3 (2CH), 55.5 (OCH3); HR-MS
(ESI): m/z=311.1428, calculated for C23H19O (M+H)+:
311.1430.
(E)-4-[1-(4-Methoxybenzylidene)-1H-inden-3-yl]benzoni-
trile (3g): The crude residue was purified by flash chroma-
tography on silica gel (cyclohexane/EtOAc 95/5) to give 3g
as a yellow oil; yield: 80 mg (0.24 mmol; 81%); M=
335.40 g·molÀ1; Rf =0.80 (cyclohexane/EtOAc 70/30); IR
(film): n=3457, 3426, 3206, 2226, 2167, 2053, 2034, 1597,
1033 cmÀ1 1H NMR (300 MHz, CDCl3): d=7.89 (s, 1H),
;
7.83 (d, J=7.7 Hz, 1H), 7.77–7.71 (m, 1H), 7.66 (d, J=
8.8 Hz, 2H), 7.59 (m, 2H), 7.53 (t, J=7.7 Hz, 1H), 7.39–7.27
(m, 3H), 7.02 (d, J=8.8 Hz, 2H), 6.92 (s, 1H), 3.88 (s, 3H);
13C NMR (75 MHz, CDCl3): d=160.2 (C), 149.0 (C), 141.5
(C), 141.2 (C), 138.7 (C), 138.6 (C), 134.2 (CH), 133.3 (CH),
131.2 (CH), 129.6 (CH), 129.1 (2CH), 128.2 (CH), 127.8
(C), 126.0 (CH), 124.0 (CH), 120.9 (CH), 120.8 (CH), 119.7
(CH), 118.6 (C), 114.3 (2CH), 113.2 (C), 55.5 (OCH3); HR-
MS (ESI): m/z=358.1198, calculated for C24H17NNaO (M+
Na)+: 358.1202.
(E)-3-(4-Methoxyphenyl)-1-[4-(trifluoromethyl)benzyli-
dene]-1H-indene (3d): The crude residue was purified by
flash chromatography on silica gel (cyclohexane/EtOAc 95/
5) to give 3d as a yellow oil; yield: 79 mg (0.21 mmol;
(79%); M=378.39 g·molÀ1; Rf =0.77 (cyclohexane/EtOAc
1511, 1462, 1446, 1343, 1304, 1256, 1174, 1031, 910 cmÀ1
;
1H NMR (300 MHz, CDCl3): d=7.83–7.69 (m, J=8.3 Hz,
5H), 7.63 (d, J=8.6 Hz, 2H), 7.56 (s, 1H), 7.53 (d, J=
3.1 Hz, 1H), 7.32 (dd, J=5.5, 3.1 Hz, 2H), 7.23 (s, 1H), 7.00
(d, J=8.8 Hz, 2H), 3.88 (s, 3H); 13C NMR (75 MHz,
CDCl3): d=160.5 (C), 144.7 (C), 140.7 (C), 139.5 (C), 139.0
(C), 136.9 (C), 132.6 (2CH), 132.1 (2CH), 130.3 (CH), 129.6
3434
asc.wiley-vch.de
ꢄ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2013, 355, 3425 – 3436

Gold versus Palladium: A Regioselective Cycloisomerization of Aromatic Enynes
(C), 128.3 (2CH), 127.3 (CH), 125.9 (CH), 125.1 (CH),
120.0 (CH), 119.5 (CH), 119.1 (C), 114.6 (2CH), 111.3 (C),
55.5 (OCH3); HR-MS (ESI): m/z=358.1196, calculated for
C24H17NNaO (M+Na)+: 358.1202.
The validity of this level of calculation has been demonstrat-
ed in previous studies on Pd(II) complexes.[26] Zero-point vi-
brational energy corrections and thermal corrections to
Gibbs free energy were evaluated at the B3LYP/BS1 level
at 423.15 K according to experimental conditions. Energies
(E)-1-(4-Methoxybenzylidene)-3-(3,4,5-trimethoxyphe-
nyl)1H-indene (3i): The crude residue was purified by flash
chromatography on silica gel (cyclohexane/EtOAc 95/5) to
give 3i as a yellow oil; yield: 100 mg (0.25 mmol; 72%); M=
400.47 g·molÀ1; Rf =0.53 (cyclohexane/EtOAc 70/30); IR
(film): n=2934, 2836, 2221, 1602, 1573, 1510, 1498, 1463,
1448, 1414, 1351, 1304, 1255, 1235, 1175, 1126, 1060, 1032,
were evaluated with the M06 method,[27] 6–311+ +G
ACHTUNGTRENNUNG(2d,2p)
basis set for all main group elements and the aug-cc-pVTZ-
PP pseudo-potential and its associated triple-z basis set for
Pd and I (BS2 basis set). The solvation free energy correc-
tions were computed at the B3LYP/BS2 level with the
IEFPCM model on gas-phase optimized geometries, and
1,4-dioxane was chosen as solvent for consistency with the
experiment.
1007 cmÀ1 1H NMR (300 MHz, CDCl3): d=7.81–7.76 (m,
;
1H), 7.65 (d, J=8.8 Hz, 2H), 7.62–7.57 (m, 1H), 7.49 (s,
1H), 7.32 (dd, J=6.1, 2.4 Hz, 2H), 7.13 (s, 1H), 6.99 (d, J=
8.8 Hz, 2H), 6.91 (s, 2H), 3.94 (s, 6H), 3.93 (s, 3H), 3.87 (s,
3H); 13C NMR (75 MHz, CDCl3): d=160.2 (C), 153.6 (2C),
146.9 (C), 140.5 (C), 139.2 (C), 138.3 (C), 137.3 (C), 131.9
(2CH), 131.7 (C), 129.9 (C), 128.4 (CH), 127.1 (CH), 125.5
(CH), 122.8 (CH), 120.3 (CH), 119.3 (CH), 114.5 (2CH),
105.1 (2CH), 61.1 (OCH3), 56.4 (2OCH3), 55.5 (OCH3);
HR-MS (ESI): m/z=401.1728, calculated for C26H25O4 (M+
H)+: 401.1747.
Acknowledgements
The CNRS is gratefully acknowledged for financial support
of this research. Our laboratory BioCIS UMR 8076 is
a member of the Laboratory of Excellence LERMIT sup-
ported by a grant from ANR (ANR-10-LABX-33). We thank
the Lebanese University for the award of a research fellow-
ship to J. A. This work was granted access to the HPC re-
sources of CINES under the allocation 2012-086894 made by
GENCI (Grand Equipement National de Calcul Intensif).
(E)-4-{[3-(3,4,5-Trimethoxyphenyl)-1H-inden-1-ylidene]-
methyl}benzonitrile (3j): The crude residue was purified by
flash chromatography on silica gel (cyclohexane/EtOAc 95/
5) to give 3j as a yellow oil; yield: 80 mg (0.23 mmol; 76%);
M=395.45 g·molÀ1; Rf =0.58 (cyclohexane/EtOAc 70/30);
IR (film): n=3470, 3411, 3395, 3373, 3356, 3329, 3281, 3262,
3120, 3076, 3058, 2877, 2604, 2566, 2408, 2299, 2271, 2160,
2121, 2032, 2015, 1995, 1974, 1953, 1938, 1601, 1576, 1500,
1448, 1415, 1351, 1238, 1126, 1007, 909 cmÀ1 1H NMR
;
References
(300 MHz, CDCl3): d=7.79–7.74 (m, 1H), 7.72 (s, 4H), 7.58
(dd, J=6.1, 2.1 Hz, 1H), 7.44 (d, J=0.6 Hz, 1H), 7.39–7.31
(m, 2H), 6.94 (d, J=0.6 Hz, 1H), 6.88 (s, 2H), 3.93 (s, 6H),
3.92 (s, 3H); 13C NMR (75 MHz, CDCl3): d=153.7 (2C),
149.8 (C), 141.9 (C), 141.8 (C), 141.1 (C), 138.9 (C), 138.6
(C), 132.6 (2CH), 130.9 (C), 130.6 (2CH), 128.4 (CH), 126.3
(CH), 125.4 (CH), 121.8 (CH), 120.8 (CH), 119.9 (CH),
118.9 (C), 111.5 (C), 105.1 (2CH), 61.1 (OCH3), 56.5
(2OCH3); HR-MS (ESI): m/z=418.1394, calculated for
C26H21NNaO3 (M+Na)+: 418.1414.
[1] a) E. J. G. Anctil, V. Snieckus, in: Metal-Catalyzed
Cross-Coupling Reactions, Wiley-VCH, Weinheim,
2008, pp 761–813; b) H. Bçnnemann, W. Brijoux, in:
Transition Metals for Organic Synthesis, (Eds.: M.
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3436
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