Rhodium catalyzed reaction of internal alkynes with organoborons under CO atmosphere: a product tunable reaction

Article abstract of DOI:10.1016/j.tet.2009.09.044

Alkynes react with organoborons under a CO atmosphere in the presence of a rhodium(I) catalyst to afford mainly 5-aryl-2(5H)-furanones, α,β-unsaturated ketones, and indanones. The product selectivity can be tuned by modifying the reaction conditions.

Full text of DOI:10.1016/j.tet.2009.09.044

Tetrahedron 65 (2009) 9125–9133
Contents lists available at ScienceDirect
Tetrahedron
journal homepage: www.elsevier.com/locate/tet
Rhodium catalyzed reaction of internal alkynes with organoborons under CO
atmosphere: a product tunable reaction
*
¨
¨
Levent Artok , Melih Kus¸, Ozge Aksın-Artok, Fatma Nurcan Dege, Fatma Yelda Ozkılınç
Department of Chemistry, Faculty of Science, Izmir Institute of Technology, Urla 35430, Izmir, Turkey
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 22 June 2009
Received in revised form 27 August 2009
Accepted 10 September 2009
Available online 15 September 2009
Alkynes react with organoborons under a CO atmosphere in the presence of a rhodium(I) catalyst to
afford mainly 5-aryl-2(5H)-furanones,
a,b-unsaturated ketones, and indanones. The product selectivity
can be tuned by modifying the reaction conditions.
Ó 2009 Elsevier Ltd. All rights reserved.
Keywords:
Carbonylation
Rhodium catalysis
Organoborons
1. Introduction
(4), indenone (5), and indanone (6) products (Scheme 2) and aimed
at the selective synthesis of each product by a suitable modification
of the reaction conditions.2b,f
We have shown in our preliminary studies that product selec-
tivity of the method could be made tunable by varying the exper-
imental conditions to favor formation of structures 3 or 4.2b,f In this
report we present additional scope and limitations of this method
and provide more insight into the reaction pathways.
Intra- and intermolecular carbonylative arylations of un-
saturated systems by in-situ formed acyl metal species under a CO
atmosphere are powerful methods for the synthesis of compounds
with carbonyl moieties, as well as a range of heterocycles.1,2
Palladium catalyzed carbonylation of aryl halides is a frequently
applied method to create acyl palladium species, which having
a considerable electrophilic character, are capable of reacting with
nucleophilic sites.1 However, it has been recently shown that
arylboronic reagents can also be carbonylated by rhodium catalysis
to give acyl rhodium species A (Scheme 1), which are amenable to
add unsaturated C–C bonds.2 These methods can be respected as
complementary to each other and the latter method providing
possible alternative routes as compared to their Pd catalyzed
counterparts.
2. Results and discussion
2.1. Synthesis of 5-aryl-2(5H)-furanones
The [Rh(cod)Cl]2 complex was the catalyst precursor of choice in
the synthesis of 3 in our preliminary study.2b Further exploration of
rhodium complexes for the carbonylation of the diphenylacetylene
and phenylboronic acid mixture at 80 ꢀC, in toluene and under
20 atm of CO pressure led us to attain somewhat better and more
reproducible results specifically with the [Rh(cod)OH]2 complex,
producing the corresponding furanone in an isolated yield of 86%
(Table 1, entries 1–6).
[Rh]
CO
ArB(OH)2
ArCO[Rh]
Ar[Rh]
A
Scheme 1. Formation of aroylrhodium species from arylboronic reagents.
The effect of CO pressure was also investigated with the use of
[Rh(cod)OH]2. It was observed that lower CO pressures resulted in
proportionally lower product yield (entries 7 and 8).
In this context, we disclosed recently that the rhodium catalyzed
carbonylation of an internal alkyne and arylboronic acid mixture
could yield the 5-aryl-2(5H)-furanone (3), a,b-unsaturated ketone
The methodology was particularly applicable with m- and
p-substituted phenylboronic acids, which tolerated both electron-
donating or withdrawing groups and afforded excellent yields
when reacted with diphenylacetylene under optimum reaction
conditions (Table 2). For instance, a carbonylative reaction of
* Corresponding author. Tel.: þ90 232 750 7529; fax: þ90 232 750 7509.
E-mail address: leventartok@iyte.edu.tr (L. Artok).
0040-4020/$ – see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2009.09.044

9126
L. Artok et al. / Tetrahedron 65 (2009) 9125–9133
R2
R1
R2
R1
O
O
R2
R1
Ar
R1
O
[Rh]
CO
R2
+
+
+
ArB(OH)2
O
+
R1
O
Ar
R2
1
2
R3
R3
3
6
4
5
Scheme 2. Rhodium catalyzed carbonylative reaction of alkynes with arylboronic acids.
Table 1
tentatively recognized to be 5-phenyl-3,4-dipropylfuran-2(3H)-one
by NMR spectroscopic analyses of the crude product. The product
3ba was isolated at a yield of 60% when the reaction was performed
with 0.88% rhodium (entry 1); however, it increased to a yield of
76% yield with the use of 2.63% rhodium (entry 2).
Effect of rhodium complex and CO pressure on the formation of 3,4,5-triphe-
nylfuran-2(5H)-one
Ph
Ph
Ph
B(OH)2
1% Rh, toluene (10 mL)
O
+
O
Ph
CO
80 °C, 16 h
Ph
1.2 mmol
1 mmol
Table 3
The synthesis of 5-aryl-2(5H)-furanones by the rhodium catalyzed carbonylative
reaction of phenylboronic acid with various alkynes
Entry
Complex
P (atm)
Conversion %
Yielda
%
1
2
3
4
5
6
7
8
[Rh(cod)Cl]2
[Rh(cod)OH]2
[Rh(C2H4)2Cl]2
[Rh(C2H4)2acac]2
Rh(cod)2BF4
[Rh(CO)2Cl]2
[Rh(cod)OH]2
[Rh(cod)OH]2
20
20
20
20
20
20
10
5
100
100
100
87
100
100
100
100
89 (78)
93 (86)
35
63
84
88
76
65
[Rh(cod)OH]2,
Ph
R1
Ph
R2
R2
O
O
toluene (10 mL)
+
B(OH)2
O
O
+
Ph
R1
CO (20 atm),
80 °C, 16 h
R2
R1
1.2 mmol
1 mmol
1
3'
2
3
Entry
R1
R2
Rh%
Isolated yield %
30
a
3
Determined by GC. Isolated yields are given in parentheses.
1
2
3
4
5
6
7
8
n-C3H7
n-C3H7
Ph
Ph
p-CH3COC6H4
p-CH3OC6H4
o-CH3OC6H4
p-CH3COC6H4
p-CH3OC6H4
o-CH3C6H4
o-CH3OC6H4
o-CH3OC6H4
n-C3H7
n-C3H7
n-C3H7
CH3
n-C4H9
n-C4H9
n-C4H9
Ph
0.88
2.63
2.63
2.63
0.88
1
60 (3ba)
76 (3ba)
35 (3ca)a
32 (3da)
24 (3ea)
36 (3fa)
11 (3ga)
45 (3ha)
29 (3ia)
30 (3ja)
26 (3ka)
23 (3la)a
d
d
Table 2
47 (3ca0)a
32 (3da0)
42 (3ea0)
44 (3fa0)
48 (3ga0)
36 (3ha0)
48 (3ia0)
42 (3ja0)
68 (3ka0)
63 (3la0)a
Carbonylative reaction of diphenylacetylene with arylboronic acids, leading to 5-
aryl-2(5H)-furanones
R
1% Rh, [Rh(cod)OH]2
toluene (10 mL)
Ph
B(OH)2
3
O
R
+
0.88
0.88
1
1
1
O
Ph
CO (20 atm)
80 °C, 16 h
9
Ph
Ph
Ph
Ph
1 mmol
1.2 mmol
Ph
10
11
12
1a
2
3a
p-CH3COC6H4
Isomeric ratio was determined by 1H NMR spectroscopy.
a
Entry
R
Isolated yield %
1
2
3
4
H
p-CH3
m-CH3
p-OCH3
p-COCH3
p-CF3
86 (3aa)
88 (3ab)
90 (3ac)
90 (3ad)
88 (3ae)
82 (3af)
41 (3ag)
In the case of non-symmetric alkynes, the methodology was
moderately regioselective. The relative formation of isomeric
products was influenced by electronic and steric variations on the
alkyne substrate. It can be deduced on the basis of the product
distribution that the aroylation step relatively favored the alkyl
substituted, more electrophilic, and less sterically congested
alkynyl carbon. Nevertheless, the method was not successful with
ester functionalized alkynes, yielding a complex mixture after the
reaction.
Regioisomeric 2(5H)-furanones could be separated in most
cases by column chromatography. The isomers of 3la and 3la0 could
not be separated and the relative proportions of 3ca and 3ca0 could
only be enriched by column chromatography. The regioisomeric
structures of furanones were elucidated via NOE measurements,
while that of 3ca was identified by comparison with the literature.3
5
6a
7a
o-CH3
a
3% Rh.
electron poor p-acetylphenylboronic acid with diphenylacetylene
resulted in an isolated yield of 88% of 3ae in the presence of 1%
rhodium (entry 5). In contrast, the reaction of 4-(trifluoromethyl)-
phenylboronic acid with diphenylacetylene required a higher Rh
concentration (3%) to afford a high yield of the corresponding fur-
anone (3af) (entry 6). A modest furanone product (3ag) can also be
recovered with sterically hindered o-tolylboronic acid (entry 7). It
must be noted, however, that o-tolylboronic acid had failed to
undergo carbonylative addition to diphenylacetylene when using
[Rh(cod)Cl]2 as shown in our previous study2b and that in general
better yields were also realized by using [Rh(cod)OH]2 instead of
[Rh(cod)Cl]2.
High yields of furanone products were also achieved by the
carbonylative reaction of 4-octyne and a number of non-symmetric
alkynes with phenylboronic acid in the presence of 0.88–3% Rh
(Table 3). GC and GC–MS analyses of the crude product recovered
from the reaction of 4-octyne and phenylboronic acid showed the
presence of the corresponding 2(5H)-furanone (3ba) product to-
gether with a regioisomer. The regioisomer readily underwent
isomerization to form 3ba during column separation, which is
R2
R1
O
H
R3
O
Eventually, the 1H NMR spectra of the 2(5H)-furanones syn-
thesized in this study and those from the literature demonstrate the
existence of a correlation between the chemical shift values of the
5H signals and diamagnetic field induced by the substituent at
position 4 of the ring. When both positions 4 and 5 of the ring were
occupied by aryl groups, a 5H resonance signal appeared at field

L. Artok et al. / Tetrahedron 65 (2009) 9125–9133
9127
strengths lower than 6 ppm (typically in the range of 6.0–6.5 ppm).
R
O
R
H+
-[Rh]
R
R
The corresponding signal shifted to higher fields, giving a reso-
nance signal in the range of 5.3–6.0 ppm, when position 4 on the
furanone ring was occupied with an alkyl group.1d,2b,3,4
Rh
H
Ar
Ar
O
B
4
A third isomer was also detected by GC and GC–MS analyses of
the crude products of the reactions performed with alkynes
substituted with both alkyl and aryl groups on the alkynyl carbons
(entries 3–7), which converted to isomer 30 during purification
work-up and their structures were tentatively assigned to be 4-
alkyl-2(3H)-furanone as determined by 1H NMR spectroscopic
analysis of the crude products.
Under the established optimum conditions, the reaction of di-
phenylacetylene (1.5 mmol, 1a) with several arylboronic acids
(3 mmol) in the presence of [Rh(C2H4)2Cl]2 complex (3% Rh),
CF3COOH (2 mmol), and water (0.1 mL) as additives in methanol
(9.9 mL) solvent, yielded mixtures of both Z- and E-isomers of the
corresponding enones (4a), which can be isolated separately by
flash chromatography on silica gel along with the following by-
products: furanones (3a), indenones (5a), indanones (6a), and
a methoxycarbonylated product of diphenylacetylene, methyl 2,3-
diphenylacrylate (8a) (Table 4).
Isomers of 4a were identified or estimated by comparing with IR
carbonyl frequencies and melting points from the literature. It has
been reported that existence of steric inhibition of the enone res-
onance in Z-enones results in the appearance of their carbonyl
absorption bands at relatively higher wavenumbers than those of
the E-isomers.5
The reaction of arylboronic acid 2a with alkyne 1a afforded the
isolated products E- and Z-4aa in overall yield of 58% and pro-
duced by-products at 30% yield (entry 1). Arylboronic acids, 2b
and 2d, which have methyl and methoxy groups, respectively, at
the p-position of the phenyl ring, gave the corresponding
hydroacylation products in yields of 70% yields for both the E- and
Z-4ab and 76% for both the E- and Z-4ad isomers (entries 2 and 3).
Lower amounts of by-products (16 and 11%, respectively) were
generated when using these arylboronic acids. Furthermore,
a partial deboronylation was also observed with electron-rich
boronic acids. The reaction with m-tolylboronic acid, 2c, pro-
ceeded to give the corresponding enones (E- and Z-4ac) in an
overall yield of 61%, along with formation of the by-products at
a yield of 24% (entry 4).
Ar
O
O
Alk
Alk(Ar)
No traces of 4-aryl-2(3H)-furanone isomeric forms were detec-
ted from the reactions of alkyl-aryl or diaryl substituted acetylene
reagents. Probably, more extended
p electron conjugation of
4-aryl-2(5H)-furanones as compared to 4-alkyl-2(5H)-furanones
facilitated the isomerization of 4-aryl-2(3H)-furanones to structure 3.
The 1H NMR spectrum of the product 3ja revealed the existence
of two methyl hydrogen singlets at 2.02 and 2.39 ppm in a respective
ratio of 1:2 and an enlarged 5H signal. 2-D NMR studies indicated
that furanone 3ja exists as an atropisomeric mixture (entry 10).
O
O
O
O
3ja
H3C
H3C
In light of the findings given above, the formed aroylrhodium(I)
species A should subsequently undergo 1,2-addition to the car-
bon–carbon triple bond (Scheme 3). Insertion of CO into the
The hydroacylation reaction could also be realized with a mod-
erately electron poor p-chlorophenylboronic acid, giving rise to the
corresponding enones (E- and Z-4ah) in modest yield (entry 5).
However, the reactions involving o-tolylboronic or p-(trifluoro-
methyl)phenylboronic acids with alkyne 1a resulted in corre-
spondingly low enone yields, a marked increase in the amount of
side products, and even yielded significant amounts of the corre-
sponding hydroarylation products, triarylacetylene structures.
These results indicate that enone formation is responsive to the
steric and electronic nature of arylboronic acids. Low reactivity of
these reagents should be due to a decreased ability of the corre-
sponding electron poor arylrhodium species to undergo CO in-
sertion at lower CO pressures, because these boronic reagents were
shown to successfully yield the furanones when a higher CO
pressure was applied under optimum conditions, albeit requiring
a higher Rh concentration (see Section 2.1).
resulting
b-aroyl alkenylrhodium(I) complex (B) followed by a ring
closure could form a
s
-furanoyl complex (C). Displacement of Rh
from the cyclic complex and subsequent protonation leads to
a 5-aryl-2(3H)-furanone molecule (7), which then should undergo
isomerization to a more stable structure, 5-aryl-2(5H)-furanone
molecule (3).
R
R
R
R
CO
R
[Rh]
Ar
A
+
[Rh]
Ar
O
R
O
O
B
-
R
R
R
R
R
R
R
R
As determined by NOE studies,2f hydroaroylation proceeded
exclusively with syn-selectivity for other alkynes, which have only
one aryl substituent or none, yielding only the E-isomer of the
corresponding enones (Table 5).
-[Rh]
H+
Ar
[Rh]
Ar
Ar
O
Ar
O
O
O
O
7
O
O
3
O
C
Scheme 3. The proposed mechanisms for the formation of 2(5H)-furanone (3).
The carbonylative reaction of 4-octyne (1b) with 2a pro-
ceeded with a relatively low isolated yield of E-4ba (30%) (entry 1).
Better yields of E-4bb and E-4bd were obtained via the reaction of
1b with the arylboronic acids 2b and 2d at yields of 53% and 57%,
respectively (entries 2 and 3). Reactions were also regioselective
for those alkynes that had been activated with an ester function-
2.2. Synthesis of a,b-unsaturated ketones
A
prompt protodemetalation of the alkenylrhodium in-
termediate (B), before the insertion of CO, which leads to the
product 3 should be responsible for the formation of the -un-
a
,b
ality. The aroyl group was introduced selectively at the b-position
saturated ketone (4), and hence, we have considered that the
presence of an acidic additive and a protic solvent medium would
promote the protodemetalation step provided that the catalyst
retains its activity.
with respect to the electron-withdrawing group (entries 4–6).
High regioselectivity was also observed with 1-phenylpropyne
(1d), the aroyl group primarily introduced at the methyl sub-
stituted acetylenic carbon (entries 7–9). However, the presence of

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L. Artok et al. / Tetrahedron 65 (2009) 9125–9133
Table 4
The synthesis of enones (4a) by carbonylative addition of various arylboronic acids (2) to alkyne 1a
R
[Rh(C2H4)2Cl]2 (3% Rh)
Ph
Ph
Ph
Ph
Ph
O
COOCH3
Ph
O
Ph
CO (5 atm)
B(OH)2
Ph
+
+
+
+
+
O
Ph
O
CF3COOH (2 mmol)
CH3OH:H2O
O
R
Ph
1a
Ph
2
R
Ph
(9.9:0.1) mL
R
R
1.5 mmol
3 mmol
80 °C, 16h
6a
8a
4a
5a
3a
Entry
R
Yield (%)
4aaa
3abb
5abb
6abb
8abb
1
2
3
4
5
H
p-CH3
p-OCH3
m-CH3
p-Cl
4aa (33 Z, 25 E)
4ab (55 Z, 16 E)
4ad (45 Z, 31 E)
4ac (29 Z, 32 E)
4ah (20 Z, 17 E)
3aa (11)
3ab (8)
3ad (5)
3ac (7)
3ah (4)
5aa (3)
6aa (12)
6ab (5)
6ad (1)
6ac (9)
6ah (5)
(4)
(2)
(3)
(5)
(14)
5ab (<1)
5ad (2)
5ac (3)
5ah (3)
a
Isolated yield.
Determined by GC.
b
Table 5
The synthesis of enones (4) by carbonylative addition of various arylboronic acids (2) to alkynes (1)
R1
R2
[Rh(C2H4)2Cl]2 (3% Rh)
R2
R1
R2
B(OH)2
CO (5 atm)
+
R3
+
R1
O
O
CF3COOH (2 mmol)
CH3OH:H2O
R3
R3
(9.9:0.1) mL
80 °C, 16 h
1
2
1.5 mmol
3 mmol
4
4'
1m: R1 = n-C4H9, R2 = CO2CH3
1n: R1= CH3, R2= CO2CH3
1b: R1 = R2 = n-C3H7
2a: R3 = H
1c: R1 = n-C3H7, R2 = Ph
2b R3 = CH3
1o: R1 = n-C4H9, R2 = 2-C5H5N
1p: R1 = n-C4H9, R2 = 2-thienyl
1d: R1 = CH3, R2 = Ph
2d: R3 = OCH3
1g: R1 = n-C4H9, R2 = o-CH3OC6H4
Entry
Yield (%)
1
2
4a
40
1
2
3
4
5
6
7
8
1b
1b
1b
1m
1m
1n
1d
1d
1d
1c
2a
2b
2d
2b
2d
2d
2a
2b
2d
2d
2b
2d
2d
4ba (30)
4bb (53)
4bd (57)
4mb (52)
4md (64)
4nd (54)
4da (42)
4db (75)
4dd (74)
4cd (41)
4gb (39)
4od (16)c
4pd (42)
d
d
d
(2)b
(<1)b
(2)b
(3)b
(2)b
(6)b
(13)a
(7)b
(16)c
(10)b
9
10
11
12
13
1g
1o
1p
a
Isolated yield.
b
c
Determined by GC.
Isomeric ratio was determined by 1H NMR spectroscopy.
a larger alkyl group on the alkynyl carbon somewhat reduced its
regioselectivity, probably due to increased steric hindrance (entry
10). The presence of an electron-donating methoxy group on the
o-position of 1-phenylpentyne had a modest effect on regiose-
lectivity (entry 11). The overall yield of by-products was nearly
30% for the reaction of 1b with 2a, whereas it was less than 10% for
other reactions as determined by GC.
Hydroaroylation reactions were also performed with hetero-
aryl substituted alkynes. A complex mixture of products was
obtained for the reaction of 2-(pent-1-ynyl)pyridine (entry 12).
The corresponding enone products were isolated as a 1:1 ratio of
regio-isomers, whereas a higher yield and better regioselec-
tivity could be attained when using 2-(pent-1-ynyl)thiophene
(entry 13).
Surprisingly, a 2(5H)-furanone product (3rd) and its hydrated
compound 9rd were isolated from the carbonylative reaction of
4,4-dimethylpent-2-yne (1r) with 2d under the general conditions
applied for enone synthesis. The latter product was formed by
conversion of an isomer of 3rd (its structure hitherto not assigned)
during silica gel column chromatography and determined by GC–
MS. The factors that led alkyne 1r to its being converted to the
furanone structures rather than the expected enone products are
not known currently. It must also be noted that the alkyne 1r had
failed to yield furanones under the typical conditions applied for
synthesis of the 2(5H)-furanones.
Demetalation of vinylrhodium via protonation should play
a role in the formation of E-enones. A control reaction performed
using the pure E-isomer of 4ad under the general reaction

L. Artok et al. / Tetrahedron 65 (2009) 9125–9133
9129
H3CO
H3CO
B(OH)2
conditions of Table 5
O
O
+
+
O
O
HO
H3CO
1r
2d
9rd (11%)
3rd (42%)
protocols but in the absence of arylboronic acid brought about its
isomerization to the Z-configuration in a yield of approximately
25%. Although this result shows that E-enones formed from
diphenylacetylene can isomerize partly during the course of the
carbonylative arylation reactions, it cannot account for the Z:E
ratios given in Table 4. Probably the intermediate B can also un-
dergo isomerization, which is facilitated by extended conjugation
when the alkenyl carbons are substituted with two aryl groups
(Scheme 4).
2-enone) were obtained as by-products at an overall yield
of 20%.
Lower amounts of inda(e)none products were formed when
using either m- or p-methoxy substituted phenylboroxine re-
agents. However, nearly 50% of overall inda(e)none products
could be achieved with m- or p-tolylboroxine reagents (entries
2 and 5). The reaction of diphenylacetylene with p-CF3 sub-
stituted phenylboroxine produced the corresponding indenone
and indanone products only at an overall yield of 20% (entry 6).
The reaction, however, yielded a significant amount of an
indene product 11 (42% yield). The formation of this type of
indene structure was shown and well discussed for the rho-
dium catalyzed reaction of 4-octyne and phenylboroxine by
Hayashi et al. previously.6 However, the reaction conditions and
the use of diphenylacetylene in our case led to the hydro-
demetalation of a cyclic alkylrhodium intermediate instead of
Ar
O
Ar
O
Ar
Ph
Ph
H+
-[Rh]
Ph
Ph
O
Ph
Ph
[Rh]
[Rh]
H
Z-3a
B
Scheme 4. Isomerization of b-aroyl alkenylrhodium(I) complex.
a
-hydrogen elimination during the last step of the reaction
cycle.
2.3. Synthesis of inda(e)nones
Ph
Ph
Ph
Ph
Ph
[Rh]
The next stage of our efforts in the reactions of alkynes and
organoborons under a CO atmosphere was to promote the selective
formation of indenone (5) and indanone (6) (inda(e)nones) prod-
ucts since they are also reagents of high value.
Ph
Ph
H
-[Rh]
Ph
First, optimum conditions were established by thoroughly
studying the effect of many variables, such as Rh complexes, sol-
vents, additives, organoboron types, CO pressure, and temperature.
Then the scope of the method was examined for a number of
alkynes and organoborons. To this end, alkynes (1 mmol), and
arylboroxines (1 mmol) were reacted in 10 mL of methanol in the
presence of 1.5% of Rh(cod)2BF4 under 1 atm of CO pressure, and at
120 ꢀC. The results are given in Table 6.
F3C
F3C
11
AM1 calculations indicated that the dihedral angles of the
ring hydrogens in the cis- and trans-6aa isomers are <1ꢀ and
z124ꢀ, respectively. On the basis of coupling constants of the
ring hydrogens in the 1H NMR spectra, the indanones produced
should be in trans-isomeric form.
Table 6
The synthesis of inda(e)nones by rhodium catalyzed reactions of alkynes with arylboroxines under CO atmospherea
R1
R1
R1
R1
R1
R1
1.5% Rh(cod)2BF4
R1
O
O
O
R1
+
CO (1 atm)
R1
Ar
+
+
+
(ArBO)
R1
3
Ar
R2
R2
CH3OH (10 mL)
120 °C, 16 h
6
Z-,E-
5
10
4
Entry
R1
Arylboroxine
Yield (%)
4b
5b
6a
10b
1
2
3
4
5
6
7
8
Ph
Ph
Ph
Ph
Ph
Ph
p-CH3O
p-CF3
(PhBO)3
4aa (10)
4ad (15)
4ab (25)
4ac (6)
4ai (<1)
4af (2)
5aa (7)
5ad (7)a
5ab (8)
5ac (4)
5ai (<1)
5af (7)
6aa (43)
6ad (26)
6ab (41)
6ac (43)
6ai (24)
6af (13)
6sa (26)
6ta (30)
10aa (9)
10ad (3)
10ab (7)
10ac (15)
10ai (13)
10af (7)
(p-OCH3C6H4BO)3
(p-CH3C6H4BO)3
(m-CH3C6H4BO)3
(m-OCH3C6H4BO)3
(p-CF3C6H4BO)3
(PhBO)3
4sa (18)
4ta (3)
5sa (15)
5ta (6)
10sa (20)a
10ta (9)a
(PhBO)3
a
Isolated yield.
GC yield.
b
The reaction of diphenylacetylene with (PhBO)3 yielded 43%
The presence of an electron-donating methoxy group at the
of indanone 6aa and 7% of indenone 5aa as isolated products
(entry 1). The corresponding Z- and E-enones, a hydroaryla-
tion product (1,1,2-triphenylacetylene), and an intermolecular
Pauson Khand reaction product (2,3,4,5-tetraphenylcyclopent-
p-position on both of the phenyl groups of the alkyne led to an in-
creased amount of indenone product (entry 7). p-CF3 substitution
on both ends of the diphenylacetylene substrate, however, also
rendered the indene (12) formation in significant quantity (entry 8).

9130
L. Artok et al. / Tetrahedron 65 (2009) 9125–9133
CF3
4. Experimental section
CF3
35% (12)
4.1. General
F3C
The alkynes 1e–l,o,p were synthesized by the Sonogashira
method.8 The alkynes 1s,t were synthesized as described else-
where.9 Arylboroxines were synthesized by azeotropic removal of
water from the refluxing benzene solution of arylboronic acids.10
The products were analyzed by GC and GC–MS (Varian Star
3400CX/Saturn 2000 or HP 6890/5973N) and isolated by column
chromatography. High-resolution mass spectral analyses were
performed at Dortmund University of Technology Mass Spec-
CF3
The reaction with trimethyl(2-phenylethynyl)silane proceeded
in a regioselective manner, affording a desilylated indanone prod-
uct (6ua) together with a hydrophenylated product (10ua).
trometry Laboratory on a Thermo Electron system. 1H, 13C, and 19
F
O
Si(CH3)3
Si(CH3)3
NMR spectra were recorded on a Varian VnmrJ 400 spectrometer.
19F NMR spectra were recorded in the presence of CF3COOH as
standard. 19F signal of the acid was set to ꢁ76.55 ppm. Melting
points were determined using an Electrothermal Melting Point
Apparatus 9200. Infrared spectra were obtained using Perkin–
Elmer Spectrum 100 by ATR or KBr pellet methods.
conditions of Table 6
Ph
+
(PhBO)3
+
Ph
Ph
Ph
34%
13%
6ua
10ua
Under the general conditions of inda(e)none synthesis, the
reactions of alkyl or ester functionalized alkynes produced low
amounts of inda(e)nones and increased amounts of by-
products.
4.2. Carbonylation reactions
Reaction conditions for the synthesis of 3 and 4 are given else-
where.2b,f Typical reaction conditions for the synthesis of 5 and 6:
The regioisomeric structures of products 5 and 6 imply that the
reaction mechanisms involve a rhodoarylation step, analogous to
the carbonylative reaction of o-halo arylboronic acids with alkynes,
which gives rise to indenones as was reported by Chatani et al.7
This is unlike the reactions yielding furanones and enones, in which
rhodoaroylation of the alkyne is the key step. The reaction mech-
anisms should involve the formation of an alkenylrhodium in-
termediate (D), which undergoes oxidative addition to a C–H bond
on the o-position of the aryl ring that is contributed by the aryl-
boroxine reagent to generate the Rh(III) species (E) (Scheme 5). The
insertion of CO followed by reductive elimination produces 5.
Indanone should form through protonation of intermediate (F). The
notion that hydrogenation of 5 to 6 was invalidated since a control
experiment conducted using the rhodium catalyst in the presence
of a preformed indenone produced no hydrogenation product and
the starting material was recovered in high yield.
a
mixture of alkyne (1 mmol), arylboroxine (0.5 mmol),
Rh(cod)2BF4 (1.5 mol % Rh), and 10 mL of degassed CH3OH (pre-
dried over Mg turnings and stored on molecular sieve 4 Å) was
added to a 50 mL stainless steel autoclave containing a glass insert
tube. Then, the sealed autoclave was evacuated and purged with
5 atm CO twice, successively. Subsequently, the reactor was pres-
surized to 1 atm with CO and the mixture was stirred magnetically
in an oil bath preheated at 120 ꢀC. After cooling, the reaction
mixture was recovered with ethyl acetate. Physical and spectro-
metric characteristics of the samples are reported or given
elsewhere.2b,f
4.2.1. 3,4-Diphenyl-5-m-tolylfuran-2(5H)-one (3ac). Hexane/ethyl
acetate; yellow paste; 1H NMR (400 MHz, CDCl3)
d
: 2.21 (s, 3H), 6.13
(s, 1H), 6.98–7.41 (m, 14H); 13C NMR (100 MHz, CDCl3)
d: 20.3, 82.7,
123.8, 125.7, 127.1, 127.3, 127.5, 127.6, 127.7, 127.8, 128.4, 128.5, 128.8,
R
R
R
[Rh]
129.1, 130.1, 133.6, 137.7, 158.3, 171.5; MS (EI, m/z): 326 (61, Mþ), 207
R
R
R
(54), 179 (100), 119 (100); FTIR (ATR) n
(cmꢁ1) CO: 1746; HRMS (m/z,
[Rh]
CO
R'
[Rh]
R
R'
R'
Mþ): 326.1327 (calculated), 326.1303 (found).
H
D
E
4.2.2. 5-(4-Acetylphenyl)-3,4-diphenylfuran-2(5H)-one (3ae). Hexane/
ethyl acetate; yellow paste; 1H NMR (400 MHz, CDCl3)
d
: 2.25 (s,
R
5
R
3H), 6.34 (s, 1H), 7.00–7.90 (m, 14H); 13C NMR (100 MHz, CDCl3)
d
:
R
-[Rh]-H
26.9, 83.1, 126.7, 127.1, 127.9 (2C), 128.5 (2C), 128.7, 128.9, 129.1,
R'
[Rh]
O
129.1, 129.3, 129.6, 130.4, 131.0, 137.9, 159.5, 172.6, 197.9; MS (EI, m/
R'
R
R
z): 354 (22, Mþ), 281 (29), 207 (100), 179 (91); FTIR (ATR)
n )
(cmꢁ1
H
H
O
H
-[Rh]
CO: 1748; HRMS (m/z, Mþ): 354.1256 (calculated), 354.1241
R
R
[Rh]
O
R'
R'
(found).
O
6
F
4.2.3. 3,4-Diphenyl-5-o-tolylfuran-2(5H)-one (3ag). Hexane/ethyl
acetate; light yellow solid; mp: 140.7–142.6 ꢀC; 1H NMR (400 MHz,
Scheme 5. The mechanisms of indenone and indanone formation.
CDCl3)
(100 MHz, CDCl3) d: 19.5, 81.0,126.8,127.8,127.9,128.4,128.8, 129.0,
d
: 2.5 (s, 3H), 6.5 (s, 1H), 7.08–7.5 (m, 14H); 13C NMR
3. Conclusions
129.1, 129.5, 129.6, 130.1, 130.3, 131.3, 131.6, 133.1, 137.7, 159.3, 172.7;
In summary, we have shown here that internal alkynes and
organoborons react under a CO atmosphere in the presence of
MS (EI, m/z): 326 (68, Mþ), 207 (68), 179 (100), 119 (52), 91 (16);
FTIR (ATR)
n
(cmꢁ1) CO: 1741; calculated for C23H18O2: C, 84.6; H,
a rhodium complex to yield 5-aryl-2(5H)-furanone, an
a,b-un-
5.6; found: C, 84.2; H, 5.7.
saturated ketone, and inda(e)none products mainly. The insertion of
an in-situ generated aroylrhodium complex to an alkyne was a key
step in formation of the former two products, while indanone or
indenone formation involved a rhodoarylation step. The product se-
lectivity can be controlled by modifying the experimental conditions.
4.2.4. 4,5-Diphenyl-3-propylfuran-2(5H)-one (3ca) and 3,5-di-
phenyl-4-propylfuran-2(5H)-one (3ca0). Hexane/ethyl acetate, only
the isomer 3ca0 could be enriched by column chromatography;
(3ca): 1H NMR (400 MHz, CDCl3)
d: 0.97 (t, J¼7.4 Hz, 3H), 1.61–1.75

L. Artok et al. / Tetrahedron 65 (2009) 9125–9133
9131
(m, 2H), 2.44–2.51 (m, 2H), 6.13 (s, 1H), 7.0–7.39 (m, 10H); MS (EI,
m/z): 278 (58, Mþ), 260 (46), 25 (33), 173 (82), 105 (100); HRMS (m/
z, Mþ): 278.1301 (calculated), 278.1300 (found); (3ca0): colorless
ethyl acetate; (3ga): light yellow solid; mp: 141.5–145.2 ꢀC; 1H NMR
(400 MHz, CDCl3)
: 0.85 (t, J¼7.2 Hz, 3H), 1.29 (sext, J¼7.6 Hz, 2H),
1.45–1.64 (m, 2H), 2.39 (t, J¼7.6 Hz, 2H), 3.81 (s, 3H), 6.36 (s, 1H),
6.80–7.30 (m, 9H); 13C NMR (100 MHz, CDCl3)
: 13.9, 22.8, 24.5,
d
oil; 1H NMR (400 MHz, CDCl3)
d
: 0.87 (t, J¼7.4 Hz, 3H),1.29–1.52 (m,
d
2H), 2.08 (ddd, J¼14.4, 9.5, 5.4 Hz,1H), 2.58 (ddd, J¼14.4, 9.6, 6.8 Hz,
30.2, 55.6, 83.9, 111.2, 120.8, 120.9, 126.9, 128.7, 128.8, 129.2, 130.1,
1H), 5.85 (s, 1H), 7.17–7.49 (m, 10H); MS (EI, m/z): 278 (47, Mþ), 235
130.9, 135.7, 155.6, 159.3, 174.6; MS (EI, m/z): 322 (14, Mþ), 251 (15),
(100), 105 (23); FTIR (ATR)
n
(cmꢁ1) CO: 1749; HRMS (m/z, Mþ):
217 (100), 121 (30); FTIR (ATR)
322.1600 (calculated), 322.1600 (found); (3ga0): yellow paste; 1H
NMR (400 MHz, CDCl3)
: 0.74 (t, J¼7.2 Hz, 3H), 1.0–1.4 (m, 4H), 1.98
(ddd, J¼14.5, 9.1, 6 Hz, 1H), 2.31 (ddd, J¼15.6, 9.2, 6.8 Hz, 1H), 3.85
(s, 3H), 5.9 (s, 1H), 6.9–7.4 (m, 9H); 13C NMR (100 MHz, CDCl3)
n
(cmꢁ1) CO: 1746; HRMS (m/z, Mþ):
278.1301 (calculated), 278.1302 (found).
d
4.2.5. 3-Methyl-4,5-diphenylfuran-2(5H)-one (3da) and 4-methyl-3,5-
diphenylfuran-2(5H)-one (3da0). Hexane/dichloromethane; (3da):
d
:
colorless oil; 1H NMR (400 MHz, CDCl3)
d
: 2.15 (d, J¼1.6, 3H), 6.18 (d,
13.9, 22.7, 27.6, 30.2, 55.8, 84.3, 111.4, 119.4,120.8, 125.1, 127.6, 129.2,
J¼2.0, 1H), 7.20–7.40 (m, 10H); 13C NMR (100 MHz, CDCl3)
d
: 10.5,
129.6, 130.4, 131.2, 135.3, 157.5, 164.4, 173.2; MS (EI, m/z): 322 (70,
77.6, 77.3, 76.9, 83.9, 124.4, 127.7, 128.3, 128.9, 129.0, 129.4, 129.9,
Mþ), 265 (90), 121 (100); FTIR (ATR) (cmꢁ1) CO: 1750; HRMS (m/z,
n
131.7, 135.3, 158.6, 174.7; MS (EI, m/z): 250 (61, Mþ), 235 (5), 222 (19),
Mþ): 322.1600 (calculated), 322.1559 (found).
145 (100), 115 (88); FTIR (ATR)
250.0994 (calculated), 250.0995 (found); (3da0): colorless oil; 1H
NMR (400 MHz, CDCl3) : 2.00 (s, 3H), 5.74 (s, 1H), 7.25–7.56 (m,
10H); 13C NMR (100 MHz, CDCl3)
: 13.6, 76.97, 77.3, 77.6, 85.1, 126.7,
n
(cmꢁ1) CO: 1747; HRMS (m/z, Mþ):
4.2.9. 4-(4-Acetylphenyl)-3,5-diphenylfuran-2(5H)-one (3ha) and
3-(4-acetylphenyl)-4,5-diphenylfuran-2(5H)-one (3ha0). Hexane/
dichloromethane; (3ha): light yellow solid; mp: 78.9–80.1 ꢀC; 1H
d
d
127.2, 128.77, 128.83, 129.1, 129.2, 129.3, 129.7, 130.1, 135.01, 160.6,
NMR (400 MHz, CDCl3)
d
: 2.51 (s, 3H), 6.28 (s, 1H), 7.29 (d, J¼8.8 Hz,
173.0; MS (EI, m/z): 250 (69, Mþ), 235 (23), 207 (38), 145 (41), 117
2H), 7.33–7.47 (m, 10H), 7.79 (d, J¼8.4 Hz, 2H); 13C NMR (100 MHz,
(100), 115 (86); FTIR (ATR)
n
(cmꢁ1) CO: 1748; HRMS (m/z, Mþ):
CDCl3) d: 26.9, 83.8, 127.8, 128.5, 128.8, 128.9, 129.3, 129.5, 129.6,
250.0994 (calculated), 250.0983 (found).
129.8, 158.3, 172.3, 197.5; MS (EI, m/z): 354 (71, Mþ), 281 (29), 249
(51), 207 (77), 176 (27), 105 (57); FTIR (ATR)
n
(cmꢁ1) CO: 1749;
4.2.6. 4-(4-Acetylphenyl)-3-butyl-5-phenylfuran-2(5H)-one (3ea) and
3-(4-acetylphenyl)-4-butyl-5-phenylfuran-2(5H)-one (3ea0). Hexane/
calculated for C24H18O3 C, 81.3; H, 5.1; found: C, 81.0; H, 5.3; HRMS
(m/z, Mþ): 354.1256 (calculated), 354.1241 (found); (3ha0): pale
dichloromethane; (3ea): colorless oil; 1H NMR (400 MHz, CDCl3)
d:
yellow solid; mp: 105.2–108.7; 1H NMR (400 MHz, CDCl3)
d: 2.60 (s,
0.91 (t, J¼7.3, 3H), 7.17 (m, 2H), 6.15 (s, 1H), 2.53 (s, 3H), 2.50 (m, 2H),
3H), 6.29 (s, 1H), 7.08 (d, J¼8.4 Hz, 2H), 7.20–7.34 (m, 8H), 7.59 (d,
1.63 (m, 2H),1.38 (sext, 2H), 7.28 (m, 5H), 7.92 (d, J¼8.8, 2H); 13C NMR
J¼8.8 Hz, 2H), 7.93 (d, J¼8.8 Hz, 2H); 13C NMR (100 MHz, CDCl3)
d:
(100 MHz, CDCl3)
d: 14.0, 22.9, 24.5, 26.8, 31.0, 83.9, 127.5, 128.3,
26.9, 84.1, 126.1, 128.8, 128.7, 129.1, 129.2, 129.7, 129.9, 130.5, 130.9,
128.9,129.2, 129.6,130.5, 134.8,136.3, 137.7, 157.9, 173.8,197.4; MS (EI,
134.6, 134.9, 137.2, 161.1, 172.1, 197.9; MS (EI, m/z): 354 (69, Mþ), 281
m/z): 334 (20, Mþ), 289 (31), 247 (13), 185 (14), 105 (33), 43 (100);
(46), 249 (60), 221 (100), 207 (97), 105 (52); FTIR (ATR) n
(cmꢁ1) CO:
FTIR (ATR)
lated), 334.1559 (found); (3ea0): colorless oil; 1H NMR (400 MHz,
CDCl3)
n
(cmꢁ1) CO: 1747; HRMS (m/z, Mþ): 334.1569 (calcu-
1751; calculated for C24H18O3: C, 81.3, H, 5.1, found: C, 80.8; H, 5.4;
HRMS: 354.1256 (calculated), 354.1240 (found).
d
: 0.80 (t, J¼7.2, 3H), 1.45–1.49 (m, 1H), 1.34–1.38 (m, 1H),
1.21–1.29 (m, 2H), 2.13 (ddd, J¼5.6, 9.8, 14.4, 1H), 2.56–2.62 (m, 1H),
2.63 (s, 1H), 5.89 (s, 1H), 7.29 (m, 3H), 7.43 (m, 4H), 7.52 (dd, J¼3.0,
4.2.10. 4-(4-Methoxyphenyl)-3,5-diphenylfuran-2(5H)-one (3ia) and
3-(4-methoxyphenyl)-4,5-diphenylfuran-2(5H)-one (3ia0). Hexane/
ethyl acetate; (3ia): light yellow solid; mp: 139.3–142.9 ꢀC; 1H
6.8, 1H), 7.61 (m, 3H), 8.03 (m, 3H); 13C NMR (100 MHz, CDCl3)
d:
13.8, 22.8, 26.9, 27.2, 30.2, 84.1, 126.1, 127.3, 128.7, 128.72,129.5, 129.9,
NMR (400 MHz, CDCl3) d: 3.73 (s, 3H), 6.24 (s, 1H), 6.70 (d,
134.6, 135.0, 137.1, 166.6, 172.6, 197.9; MS (EI, m/z): 334 (16, Mþ), 289
J¼4.8 Hz, 2H), 7.09 (d, J¼8.8 Hz, 2H), 7.30–7.51 (m, 10H); 13C NMR
(31), 247 (13), 185 (15), 145 (12), 105 (34), 43 (100); FTIR (ATR)
n
(100 MHz, CDCl3) d: 55.4, 83.7, 114.3, 123.4, 125.7, 128.0, 128.88,
(cmꢁ1) CO: 1750; HRMS (m/z, Mþ): 334.1569 (calculated), 334.1559
128.96, 129.34, 129.6, 129.7, 130.3, 130.7, 135.5, 158.8, 161.0, 172.9;
MS (EI, m/z): 342 (100), 237 (60); FTIR (ATR)
(cmꢁ1) CO: 1741;
HRMS: 342.1247 (calculated), 342.1250 (found); (3ia0): light yellow
paste; 1H NMR (400 MHz, CDCl3)
: 3.74 (s, 3H), 6.14 (s, 1H), 6.80
(found).
n
4.2.7. 3-Butyl-4-(4-methoxyphenyl)-5-phenylfuran-2(5H)-one (3fa) and
4-butyl-3-(4-methoxyphenyl)-5-phenylfuran-2(5H)-one (3fa0). Hexane/
ethyl acetate; (3fa): white solid; mp: 66.7–70.5 ꢀC; 1H NMR (400 MHz,
d
(d, J¼8.8 Hz, 2H), 7.02–7.05 (m, 2H), 7.12–7.25 (m, 8H), 7.37 (d,
J¼9.2, 2H); 13C NMR (100 MHz, CDCl3)
d: 55.5, 83.9, 114.2, 122.2,
126.5, 127.9, 128.5, 128.9, 129.1, 129.5, 129.9, 131.0, 131.7, 135.1,
CDCl3)
2H), 2.51–2.56 (m, 2H), 3.77 (s, 3H), 6.12 (s, 1H), 6.85 (d, J¼8.8 Hz, 2H),
7.17–7.20 (m, 4H), 7.26–7.29 (m, 3H); 13C NMR (100 MHz, CDCl3)
: 14.1,
d: 0.94 (t, J¼7.4 Hz, 3H), 1.42 (sext, J¼7.4 Hz, 2H), 1.54–1.73 (m,
158.1, 160.2, 173.0; FTIR (ATR)
n
(cmꢁ1) CO: 1751; MS (EI, m/z): 342
d
(100, Mþ), 237 (22), 165 (24), 105 (35); calculated for C23H18O3: C,
80.7; H, 5.3, found C, 80.0; H, 5.4; HRMS (m/z, Mþ): 342.1247
(calculated), 342.1254 (found).
23.1, 24.6, 30.6, 55.5, 83.7, 114.5, 124.0, 127.4, 127.7, 129.0, 129.3, 129.6,
135.7,158.3,160.7,174.7; MS (EI, m/z): 322 (22, Mþ), 255 (100),105 (31);
FTIR (ATR)
322.1567 (found); (3fa0): light yellow, solid; mp: 84.1–86.5 ꢀC; 1H NMR
(400 MHz, CDCl3)
n
(cmꢁ1) CO: 1726; HRMS (m/z, Mþ): 322.1563 (calculated),
4.2.11. 3,5-Diphenyl-4-o-tolylfuran-2(5H)-one (3ja) and 4,5-diphenyl-
3-o-tolylfuran-2(5H)-one (3ja0). Hexane/ethyl acetate; (3ja): light
d
: 0.83 (t, J¼7.2 Hz, 3H), 1.20–1.50 (m, 4H), 2.08 (ddd,
J¼14.0, 9.6, 5.4 Hz, 1H), 2.61 (ddd, J¼15.2, 9.0, 6.2 Hz, 1H), 3.84 (s, 3H),
5.83 (s,1H), 6.98 (d, J¼8.8 Hz, 2H), 7.26–7.30 (m, 2H), 7.38–7.42 (m, 3H),
yellow solid; mp: 138.0–141.9 ꢀC; 1H NMR (400 MHz, CDCl3)
d
: 2.02
and 2.39 (s, in a ratio of 1:2, 3H), 6.41 (br s, 1H), 7.10–7.40 (m, 14H);
13C NMR (100 MHz, CDCl3)
: 19.9 (CH3), 20.0 (CH3), 83.9, 126.6,
128.0, 128.5, 128.9, 129.3, 129.7, 130.4, 130.9, 135.6, 159.2; MS (EI, m/
z): 326 (60, Mþ), 282 (100), 236 (33), 105 (22); FTIR (ATR) (cmꢁ1
CO: 1750; HRMS (m/z, Mþ): 326.1301 (calculated), 326.1304
(found); (3ja0): yellow paste; 1H NMR (400 MHz, CDCl3)
: 1.70 (s,
3H), 6.11 (s, 1H), 6.9–7.46 (m, 14H); 13C NMR (100 MHz, CDCl3)
7.46 (d, J¼8.8 Hz, 2H); 13C NMR (100 MHz, CDCl3)
d: 13.9, 22.9, 27.1,
d
30.2, 55.6, 88.8, 114.2, 122.4, 126.3, 127.4, 129.3, 129.6, 130.5, 135.2,
160.0, 163.6, 173.5; MS (EI, m/z): 322 (100, Mþ), 217 (60), 105 (70); FTIR
n
)
(ATR) n
(cmꢁ1) CO: 1732; calculated for C21H22O3: C, 78.2; H, 6.0; found:
C, 77.8, H, 6.2; HRMS (m/z, Mþ): 322.1563 (calculated), 322.1553
d
(found).
d:
19.3, 84.3, 126.0, 126.3, 126.4, 128.0, 128.3, 128.36, 128.39, 128.4,
128.6, 128.8, 129.96, 129.06, 129.13, 129.2, 129.6, 129.9, 130.7, 131.0,
134.2, 135.4, 161.6, 172.4; MS (EI, m/z): 326 (70, Mþ), 194 (100), 105
4.2.8. 3-Butyl-4-(2-methoxyphenyl)-5-phenylfuran-2(5H)-one (3ga) and
4-butyl-3-(2-methoxyphenyl)-5-phenylfuran-2(5H)-one (3ga0). Hexane/

9132
L. Artok et al. / Tetrahedron 65 (2009) 9125–9133
(65); FTIR (ATR)
n
(cmꢁ1) CO: 1752; HRMS (m/z, Mþ): 326.1301
FTIR (ATR) n
(cmꢁ1) CO: 1642; HRMS (m/z, Mþ): 236.1196 (calcu-
(calculated), 326.1295 (found).
lated), 236.1194 (found).
4.2.12. 4-(2-Methoxyphenyl)-3,5-diphenylfuran-2(5H)-one (3ka) and 3-
(2-methoxyphenyl)-4,5-diphenylfuran-2(5H)-one (3ka0). Hexane/ethyl
acetate; (3ka): light yellow solid; mp: 67.7–69.1 ꢀC; 1H NMR
4.2.17. (E)-2-(2-Methoxybenzylidene)-1-p-tolylhexan-1-one
(4gb). Hexane/ethyl acetate; yellow oil; 1H NMR (400 MHz, CDCl3)
d
: 0.87 (t, J¼7.2 Hz, 3H), 1.35 (sext, J¼7.6 Hz, 2H), 1.49 (pent,
(400 MHz, CDCl3)
6.78–6.84 (m, 2H), 7.18–7.30 (m, 9H), 7.44–7.47 (m, 2H); 13C NMR
(100 MHz, CDCl3) : 55.5, 83.9, 111.5, 120.8, 121.0, 127.2, 127.3, 128.4,
d: 3.68 (s, 3H), 6.49 (s, 1H), 6.72 (t, J¼7.6 Hz, 1H),
J¼7.6 Hz, 2 H), 2.40 (s, 3H), 2.65 (t, J¼7.2 Hz, 2H), 3.76 (s, 3H), 6.87
(d, J¼8.0 Hz, 1H), 6.98 (t, J¼7.6 Hz, 1H), 7.18 (s, 1H), 7.24 (d, J¼8.0 Hz,
2H), 7.30 (t, J¼7.6 Hz, 1H), 7.36 (d, J¼7.6 Hz, 1H), 7.78 (d, J¼8.0 Hz,
d
128.7, 128.8, 129.1, 129.2, 130.46, 130.50, 131.3, 135.3, 156.8, 159.5,
2H); 13C NMR (100 MHz, CDCl3)
d: 13.9, 21.6, 22.9, 27.8, 30.9, 55.4,
172.9; MS (EI, m/z): 342 (86, Mþ), 237 (50), 209 (53), 91 (86); FTIR
110.5, 120.2, 125.1, 128.8, 129.5, 129.6, 130.1, 135.9, 136.0, 141.9,
(ATR)
n
(cmꢁ1) CO: 1744; calculated for C23H18O3: C, 80.7; H, 5.3;
142.6, 157.3, 199.0; MS (EI, m/z): 308 (57, Mþ), 277 (100), 119 (75);
found: C, 80.4; H, 5.4; (3ka0): light yellow solid; mp: 142.0–
FTIR (ATR)
n
(cmꢁ1) CO: 1656; HRMS (m/z, Mþ): 308.1771 (calcu-
145.7 ꢀC; 1H NMR (400 MHz, CDCl3)
d: 3.61 (s, 3H), 6.34 (s, 1H), 6.94
lated), 308.1775 (found).
(d, J¼8.4 Hz, 1H), 7.02 (t, J¼7.6 Hz, 1H), 7.1–7.4 (m, 12H); 13C NMR
(100 MHz, CDCl3)
d: 55.6, 83.9, 111.7, 120.0, 121.2, 125.2, 128.08,
4.2.18. (E)-Methyl 4-(4-p-tolyl)-3-butyl-4-oxobut-2-enoate (4mb). Hex-
128.12, 128.6, 129.2, 129.5, 130.0, 130.6, 131.2, 131.9, 135.8, 157.5,
ane/ethyl acetate, yellow oil; 1H NMR (400 MHz, CDCl3)
d: 0.9 (t,
159.5, 172.8; MS (EI, m/z): 342 (100, Mþ), 297 (14), 237 (29), 105
J¼7.4 Hz, 3H), 1.36–1.51 (m, 4H), 2.40 (s, 3H), 2.98 (t, J¼7.8 Hz, 2H), 3.76
(13); FTIR (ATR) n
(cmꢁ1) CO: 1745; calculated for C23H18O3: C, 80.7;
(s, 3H), 6.0 (s, 1H), 7.27 (d, J¼8.0 Hz, 2H), (d, J¼8.0 Hz, 2H), 7.73 (d,
H, 5.3; found: C, 80.0; H, 5.2; HRMS (m/z, Mþ): 342.1256 (calcu-
J¼8.0 Hz, 2H); 13C NMR (100 MHz, CDCl3)
d: 13.8, 21.7, 22.9, 28.9, 30.5,
lated), 342.1242 (found).
51.5, 122.9, 129.3, 130.0, 133.5, 144.3, 157.5, 166.1, 197.6; MS (EI, m/z): 260
(25, Mþ), 245 (29), 229 (65), 214 (46), 119 (100); FTIR (ATR)
n
(cmꢁ1):
4.2.13. 4-(4-Acetylphenyl)-3-(2-methoxyphenyl)-5-phenylfuran-
2(5H)-one (3la0). Hexane/ethyl acetate; this isomer was isolated in
part from the isomeric mixture; yellow paste; 1H NMR (400 MHz,
1659 (CO), 1724 (COOCH3); HRMS (m/z, Mþ): 260.1407 (calculated),
260.1406 (found).
CDCl3)
d
: 3.60 (s, 3H), 2.48 (m, 3H), 6.36 (s, 1H), 6.92–7.40 (m, 11H),
4.2.19. (E)-1-(4-Methoxyphenyl)-2-((thiophen-2-yl)methylene)-
7.36 (m, 7H), 7.73 (d, J¼8.4 Hz, 2H); 13C NMR (100 MHz, CDCl3)
d:
hexan-1-one (4pd). Hexane/ethyl acetate; yellow oil; 1H NMR
26.5, 55.3, 83.6, 111.4, 119.1, 121.1, 126.5, 127.8, 128.0, 128.1, 128.2,
129.1, 129.5, 130.8, 130.9, 135.0,136.2, 137.4, 157.1, 158.0, 172.1,198.2;
MS (EI, m/z): 385 (68, Mþ), 280 (100), 237 (40), 105 (74); FTIR (ATR)
(400 MHz, CDCl3)
d
: 0.96 (t, J¼7.2 Hz, 3H), 1.48 (pent, J¼6.8 Hz, 2H),
1.53–1.61 (m, 2H), 2.86 (t, J¼7.2 Hz, 2H), 3.88 (s, 3H), 6.95 (d,
J¼9.2 Hz, 2H), 7.08 (dd, J¼3.6, 5.2 Hz 1H), 7.15 (d, J¼3.6 Hz, 1H), 7.19
(s, 1H), 7.47 (d, J¼5.2 Hz, 1H), 7.75 (d, J¼9.2 Hz, 2H); 13C NMR
n
(cmꢁ1) CO: 1748; HRMS (m/z, Mþ): 384.1356 (calculated),
384.1355 (found).
(100 MHz, CDCl3) d: 14.0, 23.2, 28.6, 30.4, 55.4, 113.6, 127.3, 128.9,
131.6, 131.8, 138.6, 139.2, 162.7, 197.8; MS (EI, m/z): 300 (62, Mþ),
4.2.14. 3-tert-Butyl-5-(4-methoxyphenyl)-4-methylfuran-2(5H)-one
(3rd) and 3-tert-butyl-5-hydroxy-5-(4-methoxyphenyl)-4-methyl-
furan-2(5H)-one (9rd). Hexane/ethyl acetate; (3rd): beige solid;
269 (19),135 (100), 203 (16); FTIR (ATR) n
(cmꢁ1): 1636; HRMS (m/z,
Mþ): 300.1179 (calculated), 300.1178 (found).
mp: 97–102 ꢀC; 1H NMR (400 MHz, CDCl3)
d
: 1.39 (s, 9H), 1.91 (s,
3H), 3.81 (s, 3H), 5.37 (s, 1H), 6.89 (d, J¼9.2, 2H), 7.11 (d, J¼9.2, 2H);
13C NMR (100 MHz, CDCl3)
: 14.1, 29.3, 33.3, 55.3, 84.2, 114.3, 127.1,
128.5, 156.2, 160.3, 173.3; MS (EI, m/z): 260 (72, Mþ), 245 (30), 135
(100), 108 (71); FTIR (ATR)
(cmꢁ1) CO: 1740; HRMS (m/z, Mþ):
260.1407 (calculated), 260.1412 (found); (9rd): 1H NMR (400 MHz,
4.2.20. 2,3-Dihydro-2,3-diphenylinden-1-one (6aa). Hexane/ethyl
acetate; orange paste; 1H NMR (400 MHz, CDCl3)
d: 3.81 (d,
d
J¼4.8 Hz, 1H), 4.57 (d, J¼4.8 Hz, 1H), 7.07–7.13 (m, 4H), 7.23–7.82
(m, 7H), 7.48 (t, J¼7.4 Hz, 1H), 7.64 (dt, J¼1.0, 7.6 Hz, 1H), 7.89 (d,
n
J¼8 Hz, 1H); 13C NMR (100 MHz, CDCl3)
d: 55.1, 64.9, 124.3, 126.9,
127.4, 127.4, 128.1, 128.5, 128.6, 129.1, 129.2, 135.7, 136.4, 138.8, 142.8
CDCl3)
d
: 1.34 (s, 9H), 1.95 (s, 3H), 3.56 (s, 1H), 3.81 (s, 3H), 6.89 (d,
156.4, 205.5; MS (EI, m/z): 284 (100, Mþ), 206 (20), 178 (25); FTIR
J¼8.8, 2H), 7.34 (d, J¼8.8, 2H); 13C NMR (100 MHz, CDCl3)
d:12.3,
(ATR) n
(cmꢁ1) CO: 1711; HRMS (m/z, Mþ): 284.1196 (calculated),
29.3, 33.2, 55.3, 104.3, 113.9, 127.1, 129.2, 133.1, 156.8, 160.2, 171.4;
284.1206 (found).
MS (EI, m/z): 276 (76, Mþ), 258 (9), 243 (17), 231 (100), 220 (26);
FTIR (ATR)
lated), 276.1351 (found).
n
(cmꢁ1) CO: 1763; HRMS (m/z, Mþ): 276.13656 (calcu-
4.2.21. 2,3-Dihydro-6-methoxy-2,3-diphenylinden-1-one (6ad) and
6-methoxy-2,3-diphenyl-1H-inden-1-one (5ad). Hexane/ethyl ace-
tate; (6ad): white solid; mp: 137.1–146.8 ꢀC; 1H NMR (400 MHz,
4.2.15. (E,Z)-1-(4-Chlorophenyl)-2,3-diphenylprop-2-en-1-one
CDCl3)
d
: 3.80 (d, J¼4.4 Hz, 1H), 3.88 (s, 3H), 4.5 (d, J¼4.4 Hz, 1H),
(4ah). Hexane/ethyl acetate; (E-4ah): yellow paste; 1H NMR
7.06–7.34 (m, 14H); 13C NMR (100 MHz, CDCl3)
d
: 54.5, 56.0, 65.6,
(400 MHz, CDCl3)
m/z): 318 (100, Mþ), 283 (27), 178 (55), 139 (52), 111 (25), 75 (13), 50
(10); FTIR (ATR)
(cmꢁ1) CO: 1645; HRMS (m/z, Mþ): 318.0806
(calculated), 318.0804 (found); (Z-4ah): yellow paste; 1H NMR
(400 MHz, CDCl3)
: 7.14–7.45 (m, 13H), 7.91 (d, J¼10.4, 2H); MS (EI,
m/z): 318 (100, Mþ), 283 (48),178 (75),139 (82),111 (51), 75 (35), 50
(25); FTIR (ATR)
(cmꢁ1) CO: 1665; HRMS (m/z, Mþ): 318.0806
d
: 7.05–7.45 (m, 13H), 7.78 (d, J¼8.4, 2H); MS (EI,
105.2, 125.1, 127.36, 127.43, 127.7. 128.0, 128.6, 129.1, 129.1, 137.7,
138.9, 143.0, 149.3, 160.3, 205.5; MS (EI, m/z): 314 (100, Mþ), 223
n
(10); FTIR (ATR)
n
(cmꢁ1) CO: 1698; HRMS (m/z, Mþ): 314.1301
(calculated), 314.1290 (found); (5ad): red paste; 1H NMR (400 MHz,
d
CDCl3)
d
: 3.85 (s, 3H), 6.80 (dd, J¼2.2 Hz, J¼8.0 Hz, 1H), 7.04 (d,
J¼8.0,1H), 7.17–7.26 (m, 6H), 7.34–7.43 (m, 4H); 13C NMR (100 MHz,
n
CDCl3) d: 55.8, 110.6, 116.3, 122.2, 127.5, 128.0, 128.4, 128.7, 129.3,
(calculated), 318.0805 (found).
129.8, 131.0, 131.4, 133.0, 136.9, 156.4, 161.1, 196.2; MS (EI, m/z): 312
(Mþ); 270.
4.2.16. (E)-2-Methyl-3-phenyl-1-p-tolylprop-2-en-1-one (4db). Hexane/
ethyl acetate; yellow oil; 1H NMR (400 MHz, CDCl3)
d: 2.26 (d,
4.2.22. 2,3-Dihydro-6-methyl-2,3-diphenylinden-1-one (6ab). Hexane/
J¼1.6 Hz, 3H), 2.42 (s, 3H), 7.15 (d, J¼1.6 Hz, 1H), 7.27 (d, J¼8.0 Hz,
ethyl acetate; white solid; mp: 67.4–74.8 ꢀC; 1H NMR (400 MHz,
2H), 7.30–7.42 (m, 5H), 7.68 (d, J¼8.0 Hz, 2H); 13C NMR (100 MHz,
CDCl3)
d
: 2.46 (s, 3H), 3.79 (d, J¼4.8 Hz, 1H), 4.53 (d, J¼4.8 Hz, 1H),
CDCl3)
d
: 14.6, 21.6, 128.5, 128.9, 129.7, 129.8, 135.6, 135.9, 137.0,
7.05–7.11 (m, 4H), 7.19 (d, J¼7.6 Hz, 1H), 7.23–7.33 (m, 6H), 7.46 (dd,
141.3, 142.4, 199.2; MS (EI, m/z): 236 (100, Mþ), 219 (12), 119 (25);
J¼1.4 Hz, J¼7.8, 1H), 7.69 (s, 1H); 13C NMR (100 MHz, CDCl3)
d: 21.4,

L. Artok et al. / Tetrahedron 65 (2009) 9125–9133
9133
54.8, 65.2, 124.2, 126.6, 127.3, 127.4, 128.1, 128.6, 129.02, 129.06,
136.6, 136.9, 138.6, 139.0, 143.0, 153.9, 205.6; MS (EI, m/z): 298 (100,
Mþ), 208 (10); HRMS (m/z, Mþ): 298.1352 (calculated), 298.1341
(found).
135.6–136.9 ꢀC; 1H NMR (400 MHz, CDCl3)
d
: 3.84 (d, J¼5.6 Hz, 1H),
4.63 (d, J¼5.6 Hz, 1H), 7.20–7.33 (m, 5H), 7.52–7.72 (m, 6H), 7.93 (d,
J¼7.6 Hz, 1H); MS (EI, m/z): 420 (100, Mþ), 401 (15), 351 (10), 275
(30), 261 (18); FTIR (KBr)
n
(cmꢁ1) CO: 1705; HRMS (m/z, Mþ):
420.0943 (calculated), 420.0934 (found); 19F NMR (375.9 MHz,
4.2.23. 2,3-Dihydro-5-methyl-2,3-diphenylinden-1-one (6ac). Hexane/
CDCl3)
(400 MHz, CD2Cl2)
d
: ꢁ63.7, ꢁ63.5; (12): white solid; mp: 229–234 ꢀC; 1H NMR
ethyl acetate; pale yellow solid; mp: 113.9–117.5 ꢀC; 1H NMR
d
: 3.56 (d, J¼12.4 Hz,1H), 3.98 (d, J¼12.8 Hz,1H),
(400 MHz, CDCl3)
J¼4.8 Hz, 1H), 7.06–7.12 (m, 5H), 7.2–7.34 (m, 7H), 7.78 (d, J¼7.6 Hz,
1H); 13C NMR (100 MHz, CDCl3)
: 22.2, 54.8, 64.7, 123.9, 126.9, 127.1,
127.9, 123.0, 128.8, 128.9 129.6, 134.0, 138.8, 142.7, 146.8, 156.7; MS (EI,
d: 2.40 (s, 3H), 3.79 (d, J¼4.8 Hz, 1H), 4.51 (d,
6.36 (d, J¼7.6 Hz, 2H), 6.69 (d, J¼8.0 Hz, 2H), 6.90–6.94 (m, 1H), 7.00
(d, J¼8.0 Hz, 2H), 7.10 (d, J¼8.0 Hz, 2H), 7.17–7.27 (m, 5H), 7.45–7.60
(m, 6H); MS (EI, m/z): 706 (8, Mþ), 687 (5), 547 (100), 401 (12);
HRMS (m/z, Mþ): 706.153 (calculated), 706.143 (found). 19F NMR
d
m/z): 298 (100, Mþ), 221 (40), 178 (23); FTIR (ATR)
n
(cmꢁ1) CO: 1696;
(375.9 MHz, CD2Cl2)
d: ꢁ63.5, ꢁ63.3, ꢁ63.2, ꢁ63.17.
HRMS (m/z, Mþ): 298.1352 (calculated), 298.1340 (found).
4.2.28. 2,3-Dihydro-3-phenylinden-1-one (6ua). Hexane/ethyl ace-
4.2.24. 2,3-Dihydro-5-methoxy-2,3-diphenylinden-1-one (6ai). Hexane/
tate; yellow solid; mp: 72.8–75.7 ꢀC; 1H NMR (400 MHz, CDCl3)
d:
ethyl acetate; white solid; mp: 139–142 ꢀC; 1H NMR (400 MHz, CDCl3)
2.69 (dd, J¼19.2, 4.0 Hz, 1H), 3.23 (dd, J¼19.2, 8.0 Hz, 1H), 5.57 (dd,
d
: 3.78 (d, J¼4.8 Hz, 1H), 3.80 (s, 3H), 4.49 (d, J¼4.8 Hz, 1H), 6.69 (d,
J¼8.0, 3.6 Hz, 1H), 7.10–7.14 (m, 2H), 7.20–7.33 (m, 4H), 7.41 (t,
J¼1.2 Hz, 1H), 7.0 (dd, J¼8.4, 2.4 Hz,1H), 7.09 (d, J¼7.6 Hz, 4H), 7.22–7.34
J¼7.4 Hz, 1H), 7.81 (d, J¼8.0 Hz, 1H); 13C NMR (100 MHz, CDCl3)
d:
(m, 6H), 7.82 (d, J¼8.4 Hz, 1H); 13C NMR (100 MHz, CDCl3)
d: 55.0, 55.8,
44.4, 46.8, 123.4, 126.9, 127.0, 127.6, 127.9, 128.9, 135.1, 136.7, 143.7,
64.8, 109.6, 116.5, 125.8, 127.1, 127.2, 127.9, 128.3, 128.8, 128.9, 129.6,
158.0, 206.1; MS (EI, m/z): 208 (100, Mþ), 193 (13), 178 (25), 165
139.0, 142.6, 159.2, 165.9, 203.4; MS (EI, m/z): 314 (100, Mþ), 238 (30),
(20), 130 (10); FTIR (ATR) n
(cmꢁ1) CO: 1705; HRMS (m/z, Mþ):
165 (20); FTIR (ATR)
n
(cmꢁ1) CO: 1702; HRMS (m/z, Mþ): 314.1301
208.0883 (calculated), 208.0874 (found).
(calculated), 314.1287 (found).
Acknowledgements
4.2.25. 2,3-Dihydro-2,3-bis(4-methoxyphenyl)inden-1-one (6sa) and
2,3-bis(4-methoxyphenyl)-1H-inden-1-one (5sa). Hexane/ethyl ac-
etate; (6sa): orange-red solid; mp: 115.0–118.9; 1H NMR (400 MHz,
This work was supported by the Scientific and Technical Re-
search Council of Turkey (TBAG-106T385), National Boron Research
Institute (BOREN-2006-14-C, 13-09), and IZTECH (2007-IYTE-14).
We thank Prof. M. Balcı of Middle East Technical University for AM1
calculations, Ms. N. Meszaros of Dortmund University of Technol-
CDCl3)
d
: 3.71 (d, J¼4.8 Hz, 1H), 3.78 (s, 3H), 3.79 (s, 3H), 4.47 (d,
J¼4.8 Hz, 1H), 6.83 (d, J¼2.0 Hz, 2H), 6.86 (d, J¼2.8 Hz, 2H), 7.0
(d, J¼4.8 Hz, 2H), 7.02 (d, J¼4.4 Hz, 2H), 7.29 (d, J¼8.0 Hz, 1H), 7.46
(t, J¼7.4 Hz, 1H), 7.62 (t, J¼7.4 Hz, 1H), 7.86 (d, J¼7.4 Hz, 1H); 13C
¨
ogy for HRMS analyses, Mrs. I. Ozçelik for the measurement of NMR
¨
NMR (100 MHz, CDCl3) d: 54.3, 55.3, 114.3, 123.9, 126.6, 128.2, 128.9,
spectra, Dr. H. Ozgener for elemental analyses, and Dr. R. Eanes for
129.4,134.5,135.3,136.1; 156.2,158.7, 205.7; FTIR (KBr) n
(cmꢁ1) CO:
proofreading.
1709; MS (EI, m/z): 344 (97, Mþ), 237 (100), 208 (40), 166 (40), 122
(35), 73 (63); HRMS (m/z, Mþ): 344.1407 (calculated), 344.1406
References and notes
(found); (5sa): red paste; 1H NMR (400 MHz, CDCl3)
d: 3.79 (s, 3H),
1. Pd catalyzed reactions: (a) Vizer, S. A.; Yerzhanov, K. B.; Quntar, A. A. A. A.;
Dembitsky, V. M. Tetrahedron 2004, 60, 5499 and references therein; (b) Cao, H.;
McNamee, L.; Alper, H. Org. Lett. 2008, 10, 5281; (c) Ardizzoia, G. A.; Beccalli, E.
M.; Borsini, E.; Brenna, S.; Broggini, G.; Rigamonti, M. Eur. J. Org. Chem. 2008,
5590; (d) Cope´ret, C.; Sugihara, T.; Wu, W.; Shimoyama, I.; Negishi, E.-i. J. Am.
Chem. Soc. 1995, 117, 3422; (e) Negishi, E.-i.; Cope´ret, C.; Ma, S.; Mita, T.; Sugi-
hara, T.; Tour, J. M. J. Am. Chem. Soc. 1996, 118, 5904; (f) Ahmed, M. S. M.; Ko-
bayashi, K.; Mori, A. Org. Lett. 2005, 7, 4487; (g) Kadnikov, D. V.; Larock, R. C. J.
Org. Chem. 2004, 69, 6772; (h) Duan, X.-H.; Guo, L.-N.; Bi, H.-P.; Liu, X.-Y.; Liang,
Y.-M. Org. Lett 2006, 8, 3053; (i) Okuro, K.; Furuune, M.; Miura, M.; Nomura, M.
J. Org. Chem. 1992, 57, 4754; (j) Okuro, K.; Alper, H. J. Org. Chem. 1997, 62, 1566.
2. Rh catalyzed reactions: (a) Sauthier, M.; Castanet, Y.; Mortreux, A. Chem.
3.85 (s, 3H), 6.82 (d, J¼9.2 Hz, 2H), 6.94 (d, J¼8.8 Hz, 2H), 7.16 (d,
J¼7.2 Hz,1H), 7.21–7.28 (m, 3H), 7.31–7.37 (m, 3H), 7.55 (d, J¼6.8 Hz,
1H); 13C NMR (100 MHz, CDCl3)
d: 55.1, 55.2, 113.7, 114.2, 120.9,
122.7,123.4,125.1,128.6,130.2,131.0,131.2,133.2,134.9,145.5,153.8,
159.1, 160.3, 196.9; MS (EI, m/z): 342 (100, Mþ); HRMS (m/z, Mþ):
342.1250 (calculated), 342.1244 (found).
4.2.26. 6-(Trifluoromethyl)-2,3-dihydro-2,3-diphenylinden-1-one
(6af) and 1-benzyl-5-(trifluoromethyl)-1,2,3-triphenyl-1H-indene
(11). Hexane; (6af) pale yellow solid; mp: 81.6–83.3 ꢀC; 1H NMR
¨
Commun. 2004, 1520; (b) Aksın, O.; Dege, N.; Artok, L.; Tu¨ rkmen, H.; Çetinkaya,
B. Chem. Commun. 2006, 3187; (c) Chochois, H.; Sauthier, M.; Maerten, E.;
Castanet, Y.; Mortreux, A. Tetrahedron 2006, 62, 11740; (d) Menard, F.; Weise, C.
F.; Lautens, M. Org. Lett. 2007, 9, 5335; (e) Dheur, J.; Sauthier, M.; Castanet, Y.;
(400 MHz, CDCl3)
d
: 3.89 (d, J¼5.2 Hz, 1H), 4.62 (d, J¼5.2 Hz, 1H),
7.06–7.11 (m, 4H), 7.28–7.37 (m, 6H), 7.45 (d, J¼7.6 Hz, 1H), 7.80 (d,
J¼8.0 Hz, 1H), 8.16 (s, 1H); FTIR (KBr)
n
(cmꢁ1) CO: 1725; MS (EI, m/
¨
Mortreux, A. Adv. Synth. Catal. 2007, 349, 2499; (f) Kus¸, M.; Aksın-Artok, O.;
z): 352 (100, Mþ), 274 (28), 246 (12), 205 (14); HRMS (m/z, Mþ):
Ziyanak, F.; Artok, L. Synlett 2008, 2587; (g) Sautjier, M.; Lamotte, N.; Dheur, J.;
Castanet, Y.; Mortreux, A. New J. Chem. 2009, 33, 969.
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Q.; Yu, G. A.; Liu, S. L. Tetrahedron Lett. 2007, 48, 7129.
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352.1075 (calculated), 352.1070 (found); 19F NMR (375.9 MHz,
CDCl3)
(400 MHz, CDCl3)
d
: ꢁ63.5; (11): white solid; mp: 138–140 ꢀC; 1H NMR
d
: 3.57 (d, J¼12.4 Hz, 1H), 3.96 (d, J¼12.4 Hz, 1H),
6.35 (d, J¼7.2 Hz, 2H), 6.74 (d, J¼8.4 Hz, 2H), 6.89 (t, J¼7.6 Hz, 2H),
6.98–7.05 (m, 6H), 7.2 (s, 1H), 7.28–7.46 (10H); MS (EI, m/z): 502 (4,
Mþ), 483 (6), 411 (100), 334 (25), 91 (27); HRMS (m/z, Mþ):
502.1908 (calculated), 502.1890 (found). 19F NMR (375.9 MHz,
CDCl3)
d
: ꢁ63.4.
4.2.27. 2,3-Bis(4-(trifluoromethyl)phenyl)-2,3-dihydroinden-1-one (6ta)
and 1-(4-(trifluoromethyl)benzyl)-1,2,3-tris(4-(trifluoromethyl)phenyl)-
1H-indene (12). Hexane/ethyl acetate; (6ta): light yellow solid; mp:
10. Chen, F.-X.; Kina, A.; Hayashi, T. Org. Lett. 2006, 8, 341.