Efficient indenones synthesis via iridium-catalyzed decarboxylative annulation between 2-oxo-2-phenylacetic acids and alkynes

Article abstract of DOI:10.1016/j.jorganchem.2018.09.011

Efficient iridium-catalyzed decarboxylative annulation reactions between 2-oxo-2-phenylacetic acids and alkyne derivatives has been achieved. [IrCp*Cl₂]₂ with a (CH₃OC₆H₄)₃P ligand, AgSbF₆ and Cu(OAc)₂ additives was the most efficient catalytic system for this transformation. This reaction is suitable for a broad range of alkynes and 2-oxo-2-phenylacetic acids and a variety of indenone derivatives were obtained in medium to high yields. This work provides an efficient approach for the construction of indenones by iridium–catalyzed decarboxylative annulation.

Full text of DOI:10.1016/j.jorganchem.2018.09.011

Accepted Manuscript
Efficient indenones synthesis via iridium-catalyzed decarboxylative annulation
between 2-oxo-2-phenylacetic acids and alkynes
Xiaobo Yu, Shudong Geng, Guanchen Liu, Weijie Guo, Jianhui Wang
PII:
S0022-328X(18)30498-4
10.1016/j.jorganchem.2018.09.011
JOM 20568
DOI:
Reference:
To appear in: Journal of Organometallic Chemistry
Received Date: 20 June 2018
Revised Date: 10 September 2018
Accepted Date: 17 September 2018
Please cite this article as: X. Yu, S. Geng, G. Liu, W. Guo, J. Wang, Efficient indenones synthesis via
iridium-catalyzed decarboxylative annulation between 2-oxo-2-phenylacetic acids and alkynes, Journal
of Organometallic Chemistry (2018), doi: https://doi.org/10.1016/j.jorganchem.2018.09.011.
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ACCEPTED MANUSCRIPT
Efficient Indenones Synthesis via Iridium-Catalyzed Decarboxylative
Annulation between 2-Oxo-2-phenylacetic acids and Alkynes
Xiaobo Yu,*a Shudong Geng,a Guanchen Liu,a Weijie Guo,b Jianhui Wang*b
a College of Materials Science and Engineering, Jilin Institute of Chemical Technology, Jilin City 132022, P. R.China.
b Department of Chemistry, College of Science, Tianjin University, Tianjin 300072, P. R. China.
Supporting Information Placeholder
ABSTRACT: Efficient iridium-catalyzed decarboxylative annulation reactions between 2-oxo-2-phenylacetic acids and alkyne
derivatives has been achieved. [IrCp*Cl2]2 with a (CH3OC6H4)3P ligand, AgSbF6 and Cu(OAc)2 additives was the most efficient
catalytic system for this transformation. This reaction is suitable for a broad range of alkynes and 2-oxo-2-phenylacetic acids and a
variety of indenone derivatives were obtained in medium to high yields. This work provides an efficient approach for the construc-
tion of indenones by iridium–catalyzed decarboxylative annulation.
Keywords: iridium-catalyzed; C–H bond activation; decarboxylative annulation; indenones
ligand, the yield of product 3aa decreased slightly to 70% and
72%.
INTRODUCTION
Transition metal-catalyzed C–H bond activations is a versa-
Based on these results, [IrCp*Cl2]2 as catalyst with AgSbF6
tile and efficient method of creating organic molecules and many
and Cu(OAc)2, (CH3OC6H4)3P was selected as the best ligand
appealing results have been produced.1,2 Although the activation
under air, for the production of indenone.
of C–H bond have obvious advantages, difficulties in selectivity
activation a specific C–H bond restrict the development of C–H
bond activation. To circumvent this problem, a directing group
Table 1: Optimization of Reaction Conditions for the Reac-
tion of 2-oxo-2-phenylacetic acid with Alkyne a
usually needs to be introduced. It is clear that the substance with
the directing group itself has the advantage of the activation of C-
H bonds. The carboxylic acid containing a removable type orient-
ed group can be subjected to a decarboxylation reaction to selec-
tively construct a new C-C bond in the region instead of the car-
boxylate carbon when CO or CO is extruded.3
Based on the above reasons, in recent years decarboxylation
cross-coupling reaction developed rapidly.4 we demonstrated
efficient decarboxylation annulation reactions between mandelic
acids and alkyne derivatives to obtain indenones via rhodium
catalyzed.5 In the process of studying the mechanism found that
mandelic acid is first oxidized to 2-oxo-2-phenylacetic acid in the
reaction conditions, and then react with alkynes to produce prod-
ucts. 2-oxo-2-phenylacetic acid is also a commercially available
material, for this reason, we next turn our attention to the reaction
of 2-oxo-2-phenylacetic acids and alkyne derivatives.
RESULTS AND DISCUSSION
With the optimized reaction conditions in hand, the scope of
On the basis of previous research work, we further discussed
the reaction conditions for the preparation of indenone with 2-
oxo-2-phenylacetic acids and 1,2-diphenylacetylene. When
[RhCp*Cl2]2 with AgSbF6 and Cu(OAc)2 was used, the desired
annulation product 3aa was obtained in 52% yield (entry 1). The
catalyst was changed to [IrCp*Cl2]2, combined with AgSbF6 and
Cu(OAc)2, as a result, product 3aa was obtained in 55% yield
(entry 2). In order to further improve the yield of the product, the
effects of several phosphine ligands were studied. Phosphine lig-
ands PCy3 and (CH3OC6H4)3P significantly improved the reaction
efficiency and afforded the product 3aa in yields of 83% and 85%,
respectively (entries 3,4). Phosphine ligand P(C6F5)3 and 1,1'-
bis(diphenylphosphino)ferrocene (DPPF) gave lower yields of 64%
and 61%. This catalytic reaction was also examined under a nitro-
gen atmosphere. When PCy3 or (CH3OC6H4)3P was phosphine
the iridium-catalyzed decarboxylative annulation was investigated
and the results are shown in Table 2. When 1aa reacted with 1,2-
diphenylethyne (2aa), the desired product 3aa was obtained in 85%
yield. The 1,2-diphenylethyne with methyl group at para-position
was readily converted into the corresponding product (3ab) in 87%
yields. When 2-oxo-2-phenylacetic acid was reacted with 1,2-
diphenylethynes bearing methoxy or ethoxy groups at para-
position, the desired products 3ac and 3ad were also obtained in
81% and 80% yields. The 1,2-diphenylethyne with a tert-butyl
group also gave the desired product 3ae in 86% yield.

ACCEPTED MANUSCRIPT
Table 2: Decarboxylative Annulation Reactions of 2-Oxo-2-phenylacetic acids with Alkynesa
[IrCp*Cl2]2 10 mol%
O
O
O
AgSbF6 10 mol%
R2
R3
Cu(OAc)2 20 mol%
R1
+
COOH
R1
+
R2
R3
(CH3OC6H4)3P10 mol%
tolune, 120oC
R1
R3
R2
1
2
3'
3
O
O
O
O
O
OC2H5
tBu
OMe
OMe
OC2H5
tBu
3ab 87%
O
3aa 85%
O
3ac 81%
3ad 80%
3ae 86%
O
O
O
Br
CF3
Cl
OCF3
COOEt
Br
CF3
OCF3
Cl
COOEt
3ag 73%
3ai 71%
3aj 60%
3af 76%
3ah 75%
COOMe
O
O
O
O
O
OMe
MeOOC
3ak 79%(5:4)
O
3al 68%(5:6)
O
3am 62%
O
3an 55%
O
3ao 57%
O
Br
3ap 46%(6:7)
3ba 73%
3ca 70%
3da 66%
3ea 63%
The 1,2-diphenylethynes with electron withdrawing groups
also were applied to the catalytic reaction. 1,2-diphenylethynes
bearing -Cl or -Br groups can smoothly reacted with 2-oxo-2-
phenylacetic acid to obtain the desired products 3af and 3ag in 76%
and 73% yields. The 1,2-diphenylethynes with -CF3 or -OCF3
groups also gave the desired products 3ah and 3ai in 75% and 71%
yields, respectively. When 1aa reacted with 1,2-diphenylethyne
bearing –COOEt group, the desired product 3aj was obtained in
60% yield.
In addition, 1,2-diphenylethyne bearing one methoxy group
at meta-position gave the corresponding products 3ak in 79%
yields (The ratio of 3ak and 3ak’ is 5:4). Next, the 1,2-
diphenylethynes with groups at ortho-position were applied to the
annulation reaction. 1,2-diphenylethynes bearing methyl groups
gave the corresponding products 3al and 3am in 68% and 62%
yields, respectively. The reaction was also compatible with 1,2-
diphenylethynes with –COOMe group to afford the desired prod-
uct 3an in 55% yield. When 1,2-di(naphthalen-1-yl) ethyne was
used the catalytic reaction can also afford the desired product 3ao
in 57% yield. These results indicate the catalytic reaction is slight-
ly sensitive to steric effects of functional group. The reactivities of
substituted 2-oxo-2-phenylacetic acids were also investigated. The
2-oxo-2-phenylacetic acids bearing a methyl group reacted with
1,2-diphenylethyne can afford the product 3ba in 73% yield. A
phenyl group, or 1-naphthenyl group substituted 2-oxo-2-
phenylacetic acids reacted smoothly to obtain 3ca and 3da in 70%
and 66% yields, respectively. In addition, 2-oxo-2-phenylacetic
acid bearing a -Br group also reacted in the catalytic reaction to
providing 63% yield of the desired product 3ea.
Figure 1. Mechanism for the Decarboxylative Annulation
Reactions of 2-Oxo-2-phenylacetic acids with Alkynes.
The mechanism of the reaction is similar to that of the previ-
ous studies in Figure 1, the reaction is subjected to a mechanism
involving intramolecular C-H activation, decarboxylation, and
annulation to obtain the desired product.5
CONCLUSION
In summary, we have developed a iridium catalyzed decar-
boxylative annulation of 2-oxo-2-phenylacetic acids with alkynes.
Various substituted indenones were obtained in medium to high
yields under the standard reaction conditions. The catalytic meth-

ACCEPTED MANUSCRIPT
od provide a straight-forward synthetic pathway for various in-
denones from 2-oxo-2-phenylacetic acids and alkynes.
80%). 1H NMR (CDCl3, 400 MHz): δ 7.57 (d, J = 7.48 Hz, 1H),
7.36 (d, J = 8.64 Hz, 3H), 7.29-7.24 (m, 3H), 7.19 (d, J = 7.20 Hz,
1H), 6.94 (d, J = 8.76 Hz, 2H), 6.82 (d, J = 8.84 Hz, 2H), 4.12-
4.02 (m, 4H), 1.49-1.41 (m, 6H); 13C NMR (CDCl3, 100 MHz): δ
196.97, 159.70, 158.47, 153.73, 153.73, 145.52, 133.18, 131.24,
131.06, 130.15, 128.53, 124.98, 123.29, 122.64, 120.92, 114.65,
114.17, 63.52, 63.33, 14.82, 14.79; IR (KBr): ν 3579, 2977, 2925,
2360, 1701, 1604, 1468, 1346, 1289, 1178, 1075, 1042, 919, 823,
764, 667 cm-1; Analytical Data. Found (calcd) for: C25H22O3 C,
81.07 (81.06); H, 5.98 (5.99).
EXPERIMENTAL SECTION
General information: 1H NMR, 13C NMR and 19F NMR were
recorded on Bruker AV 400 spectrometers with CDCl3 as the solvent.
Infrared spectra were recorded on a Perkin-Elmer Model 1600 FT-IR
spectrophotometer and Nicolet Magna 550 FT-IR spectrophotometer.
High resolution mass spectra (HRMS) were obtained on a JEOL JMS-
DX303 instrument. Elemental analyses were performed by the Ele-
mental Analysis Section of Tianjin University.
Materials and Methods: Unless otherwise noted, all reactions
were performed under an atmosphere of air with oven-dried glassware.
Reactions were monitored by analytical thin layer chromatography on
0.20 mm silica gel plates, spots were detected by flash chromatog-
raphy through UV-absorption. Silica gel (200-300 mesh) (from Yantai
Huagong Chem. Company, Ltd.). The starting materials various 2-
oxo-2-phenylacetic acids and 1,2-diphenylethynes were synthesized
and purified according to the literature procedures.5,6 Other chemicals
or reagents were obtained from commercial sources.
2,3-bis(4-tert-butylphenyl)-1H-inden-1-one (3ae): Purified by
column chromatography to provide a red solid (33.9 mg, yield:
86%). 1H NMR (CDCl3, 400 MHz): δ 7.60 (d, J = 7.20 Hz, 1H),
7.47 (d, J = 8.52 Hz, 2H), 7.40-7.33 (m, 4H), 7.32-7.28 (m, 4H),
7.19 (d, J = 7.24 Hz, 1H), 1.41 (s, 9H), 1.35 (s, 9H); 13C NMR
(CDCl3, 100 MHz): δ 196.86, 154.63, 152.37, 150.47, 145.55,
133.21, 131.74, 130.87, 129.85, 129.53, 128.60, 128.24, 127.87,
125.54, 124.93, 122.67, 121.21, 34.81, 34.55, 31.23, 31.17; IR
(KBr): ν 3456, 2525, 1634, 1415, 1390, 1167, 1106, 1054, 1026,
945, 891, 750 cm-1; Analytical Data. Found (calcd) for: C29H30O
C, 88.29 (88.28); H, 7.66 (7.66).
General Experimental Procedure for the Preparation of In-
denones.
To an oven-dried screwed vial were added substituted 2-oxo-2-
phenylacetic acid (0.1 mmol), substituted alkyne (0.11 mmol),
[IrCp*Cl2]2 (0.01 mmol, 7.97 mg), (CH3OC6H4)3P (0.01 mmol, 3.52
mg), AgSbF6 (0.01 mmol, 3.44 mg), Cu(OAc)2 (0.02 mmol, 3.99 mg),
2,3-bis(4-chlorophenyl)-1H-inden-1-one (3af): Purified by col-
umn chromatography to provide a red solid (26.6 mg, yield: 76%).
1H NMR (CDCl3, 400 MHz): δ 7.61 (d, J = 7.00 Hz, 1H), 7.45-
7.40 (m, 3H), 7.34 (d, J = 8.28 Hz, 3H), 7.29-7.27 (m, 2H), 7.22
(d, J = 7.56 Hz, 2H), 7.14 (d, J = 8.64 Hz, 1H); 13C NMR (CDCl3,
100 MHz): δ 195.77, 154.28, 144.63, 135.52, 134.03, 133.67,
133.65, 131.52, 131.18, 130.85, 130.48, 129.83, 129.34, 129.32,
128.53, 123.27, 121.16; IR (KBr): ν 3535, 2962, 2871, 2354,
1723, 1607, 1457, 1389, 1283, 1120, 1082, 1013, 960, 866, 721,
661 cm-1; Analytical Data. Found (calcd) for: C21H12Cl2O C,
71.80 (71.81); H, 3.45 (3.44).
o
and toluene (1 mL ). The mixture was vigorously stirred at 120 C
under air to the end of the reaction. Organic solvents were removed in
vacuo, and then the residue was purified by a silica gel column chro-
matography to give the desired product.
2,3-diphenyl-1H-inden-1-one （ 3aa ） : Purified by column
1
chromatography to provide a red solid (24.0 mg, yield: 85%). H
NMR (CDCl3, 400 MHz): δ 7.61 (d, J = 6.96 Hz, 1H), 7.46-7.37
(m, 6H), 7.33-7.27 (m, 6H), 7.17 (d, J = 7.20 Hz, 1H); 13C NMR
(CDCl3, 100 MHz): δ 196.37, 155.23, 145.11, 133.36, 132.61,
132.27, 131.51, 130.65, 129.90, 129.22, 128.87, 128.71, 128.42,
127.99, 127.66, 122.87, 121.18; IR (KBr): ν 3739, 3446, 3062,
2921, 2360, 1708, 1609, 1450, 1349, 1183, 1075, 919, 840, 734,
695 cm-1; Analytical Data. Found (calcd) for: C21H14O C, 89.35
(89.34); H, 5.00 (5.00).
2,3-bis(4-bromophenyl)-1H-inden-1-one (3ag): Purified by
column chromatography to provide a red solid (31.9 mg, yield:
1
73%). H NMR (CDCl3, 400 MHz): δ 7.62-7.56 (m, 2H), 7.46-
7.39 (m, 4H), 7.35-7.27 (m, 4H), 7.16-7.12 (m, 2H); 13C NMR
(CDCl3, 100 MHz): δ 195.61, 154.28, 144.52, 133.63, 132.27,
132.09, 131.46, 131.43, 130.43, 130.01, 129.88, 129.80, 129.32,
123.78, 123.25, 122.35, 121.15; IR (KBr): ν 3059, 2925, 2851,
1709, 1602, 1456, 1342, 1263, 1179, 1069, 1010, 921, 827, 760,
673 cm-1; Analytical Data. Found (calcd) for: C21H12Br2O C,
57.31 (57.31); H, 2.74 (2.75).
2,3-dip-tolyl-1H-inden-1-one (3ab): Purified by column chroma-
1
tography to provide a red solid (27.0 mg, yield: 87%). H NMR
(CDCl3, 400 MHz): δ 7.59 (d, J = 7.00 Hz, 1H), 7.39-7.30 (m,
4H), 7.25-7.18 (m, 5H), 7.12 (d, J = 7.80 Hz, 2H), 2.43 (s, 3H),
2.35 (s, 3H); 13C NMR (CDCl3, 100 MHz): δ 196.67, 154.71,
145.38, 139.26, 137.44, 133.23, 131.96, 130.86, 129.83, 129.78,
129.74, 129.39, 129.34, 128.76, 128.65, 128.42, 127.91, 123.83,
122.70, 121.06, 120.94, 21.45, 21.28; IR (KBr): ν 3620, 2925,
1709, 1604, 1507, 1460, 1346, 1186, 1071, 1018, 818, 736 cm-1;
Analytical Data. Found (calcd) for: C23H18O C, 89.01 (89.00); H,
5.84 (5.85).
2,3-bis(4-(trifluoromethyl)phenyl)-1H-inden-1-one (3ah): Puri-
fied by column chromatography to provide a red solid (31.4 mg,
yield: 75%). 1H NMR (CDCl3, 400 MHz): δ 7.75 (d, J = 8.08 Hz,
2H), 7.66 (d, J = 6.92 Hz, 1H), 7.55 (dd, J = 7.44, 6.68 Hz, 4H),
7.45 (t, J = 7.68 Hz, 1H), 7.40-7.37 (m, 3H), 7.14 (d, J = 7.52 Hz,
1H); 13C NMR (CDCl3, 100 MHz): δ 195.28, 155.01, 144.30,
135.92, 133.89, 133.80, 131.55 (q, J=32 Hz), 130.20, 129.76,
128.81, 126.09 (q, J=3.72 Hz), 125.21 (q, J=3.72 Hz), 123.97 (q,
J=271 Hz), 123.73 (q, J=272 Hz), 123.61, 121.43; 19F NMR (376
MHz, CDCl3): δ – 62.77 (s, 3F)，-62.86 (s, 3F); IR (KBr): ν
3626, 2921, 2363, 1712, 1603, 1459, 1343, 1272, 1183, 1072,
1026, 915, 849, 757, 694 cm-1; Analytical Data. Found (calcd) for:
C23H12F6O C, 66.06 (66.04); H, 2.88 (2.89).
2,3-bis(4-methoxyphenyl)-1H-inden-1-one (3ac): Purified by
column chromatography to provide a red solid (27.7 mg, yield:
81%). 1H NMR (CDCl3, 400 MHz): δ 7.57 (d, J = 6.92 Hz, 1H),
7.48-7.37 (m, 3H), 7.30-7.25 (m, 3H), 7.19 (d, J = 7.24 Hz, 1H),
6.96 (d, J = 8.76 Hz, 2H), 6.84 (d, J = 8.76 Hz, 2H), 3.88 (s, 3H),
3.82 (s, 3H); 13C NMR (CDCl3, 100 MHz): δ 196.91, 160.29,
159.09, 153.75, 145.49, 133.22, 131.25, 131.03, 130.15, 128.58,
127.11, 125.13, 123.43, 122.68, 120.92, 114.20, 113.66, 55.29,
55.17; IR (KBr): ν 3450, 2925, 2360, 1703, 1606, 1507, 1459,
1403, 1294, 1249, 1175, 1029, 788 cm-1; Analytical Data. Found
(calcd) for: C23H18O3 C, 80.69 (80.68); H, 5.30 (5.30).
2,3-bis(4-(trifluoromethoxy)phenyl)-1H-inden-1-one
(3ai):
Purified by column chromatography to provide a red solid (31.9
1
mg, yield: 71%). H NMR (CDCl3, 400 MHz): δ 7.63 (d, J =
6.92 Hz, 1H), 7.46-7.41 (m, 3H), 7.37-7.30 (m, 5H), 7.17-7.14 (m,
3H); 13C NMR (CDCl3, 100 MHz): δ 195.76, 154.26, 149.34 (q,
J=102Hz), 144.59, 133.73, 131.45, 131.37, 130.85, 130.35,
130.13, 129.44, 128.93, 123.36, 121.66, 120.59, 120.38 (q, J=258
2,3-bis(4-ethoxyphenyl)-1H-inden-1-one (3ad): Purified by
column chromatography to provide a red solid (29.6 mg, yield:

ACCEPTED MANUSCRIPT
Hz); 19F NMR (376 MHz, CDCl3): δ – 57.73 (s, 6F); IR (KBr):
ν 3567, 2922, 2361, 1715, 1611, 1408, 1346, 1267, 1173, 1021,
926, 837, 744, 692 cm-1; Analytical Data. Found (calcd) for:
C23H12F6O3 C, 61.36 (61.34); H, 2.68 (2.69).
(m, 1H), 7.32-7.27 (m, 2H), 7.23-7.06 (m, 6H), 6.96 (d, J = 7.56
Hz, 1H), 6.90 (d, J = 7.12 Hz, 1H), 2.17 (s, 3H), 2.11 (s, 3H); 13
C
NMR (CDCl3, 100 MHz): δ 196.20, 157.57, 157.51, 145.87,
137.06, 135.91, 135.78, 133.47, 132.27, 130.97, 130.69, 130.53,
130.22, 128.84, 128.10, 125.77, 125.35, 122.84, 121.44, 20.62,
20.13; IR (KBr): ν 3563, 2920, 1711, 1606, 1457, 1341, 1261,
1176, 1070, 1033, 925, 849, 752 cm-1; Analytical Data. Found
(calcd) for: C23H18O C, 88.98 (89.00); H, 5.86 (5.85).
diethyl 4,4'-(1-oxo-1H-indene-2,3-diyl)dibenzoate (3aj): Puri-
fied by column chromatography to provide a red solid (25.6 mg,
yield: 60%). 1H NMR (CDCl3, 400 MHz): δ 8.12 (d, J = 8.44 Hz,
2H), 7.96 (d, J = 8.52 Hz, 2H), 7.65 (d, J = 7.0 Hz, 1H), 7.47-7.42
(m, 3H), 7.38-7.33 (m, 3H), 7.15 (d, J = 8.28 Hz, 1H), 4.46-4.35
(m, 4H), 1.46-1.38 (m, 6H); 13C NMR (CDCl3, 100 MHz): δ
194.35, 165.87, 155.49, 151.20, 144.54, 140.78, 136.91, 134.94,
133.78, 131.43, 130.15, 129.83, 129.58, 129.34, 128.44, 123.45,
121.43, 61.29, 60.98, 14.31; IR (KBr): ν 3578, 2928, 2367, 1718,
1606, 1459, 1368, 1277, 1180, 1070, 1021, 927, 836, 771, 711
cm-1; Analytical Data. Found (calcd) for: C27H22O5 C, 76.02
(76.04); H, 5.21 (5.20).
dimethyl 2,2'-(1-oxo-1H-indene-2,3-diyl)dibenzoate (3an):
Purified by column chromatography to provide a red solid (21.9
1
mg, yield: 55%). H NMR (CDCl3, 400 MHz): δ 8.09-8.06 (m,
1H), 8.00-7.97 (m, 1H), 7.57 (d, J = 8.48 Hz, 1H), 7.45-7.42 (m,
2H), 7.33-7.28 (m, 3H), 7.25-7.23 (m, 2H), 7.06-7.04 (m, 1H),
6.72 (d, J = 7.16 Hz, 1H), 3.84 (s, 3H), 3.72 (s, 3H); 13C NMR
(CDCl3, 100 MHz): δ 195.14, 167.60, 167.15, 155.02, 146.26,
134.80, 134.13, 133.44, 132.71, 132.26, 131.70, 131.42, 131.15,
130.39, 130.24, 130.00, 128.83, 128.34, 127.81, 123.04, 119.95,
52.26, 52.14; IR (KBr): ν 3667, 2951, 2363, 1721, 1668, 1437,
1344, 1269, 1187, 1074, 1042, 927, 853, 761, 681 cm-1; Analyti-
cal Data. Found (calcd) for: C25H18O5 C, 75.34 (75.37); H, 4.56
(4.55).
2-(3-methoxyphenyl)-3-phenyl-1H-inden-1-one (3ak): Purified
by column chromatography to provide a red solid (13.7 mg, yield:
44%). 1H NMR (CDCl3, 400 MHz): δ 7.61 (d, J = 6.72 Hz, 1H),
7.42-7.33 (m, 3H), 7.31-7.28 (m, 5H), 7.21 (d, J = 6.76 Hz, 1H),
7.01-6.96 (m, 2H), 6.93-6.92 (m, 1H), 3.74 (s, 3H); 13C NMR
(CDCl3, 100 MHz): δ 196.43, 159.71, 155.14, 145.17, 133.97,
133.43, 132.48, 130.73, 130.70, 129.92, 129.90, 128.92, 128.03,
127.74, 122.94, 121.28, 120.81, 115.12, 113.72, 55.19; IR (KBr):
ν 3678, 3060, 2933, 2836, 2361, 1711, 1596, 1456, 1345, 1284,
1249, 1176, 1042, 755, 696 cm-1; Analytical Data. Found (calcd)
for: C22H16O2 C, 84.56 (84.59); H, 5.17 (5.16).
2,3-di(naphthalen-1-yl)-1H-inden-1-one (3ao): Purified by col-
umn chromatography to provide a red solid (21.8 mg, yield: 57%).
1H NMR (CDCl3, 400 MHz): δ 7.97 (d, J = 8.32 Hz, 1H), 7.89-
7.70 (m, 6H), 7.57-7.34 (m, 7H), 7.28-7.07 (m, 3H), 6.86-6.76 (m,
1H); 13C NMR (CDCl3, 100 MHz): δ 196.18, 146.20, 141.27,
137.01, 135.04, 133.65, 133.50, 133.50, 130.49, 129.40, 129.07,
128.53, 128.20, 127.76, 126.21, 126.19, 126.10, 126.05, 126.01,
125.97, 125.94, 125.88, 125.81, 125.77, 125.76, 125.57, 125.53,
125.49, 123.03, 122.17; IR (KBr): ν 3534, 2925, 1709, 1596,
1458, 1326, 1258, 1176, 1082, 1018, 964, 773, 697 cm-1; Analyti-
cal Data. Found (calcd) for: C29H18O C, 91.08 (91.07); H, 4.73
(4.74).
3-(3-methoxyphenyl)-2-phenyl-1H-inden-1-one (3ak’): Purified
by column chromatography to provide a red solid (11.0 mg, yield:
35%). 1H NMR (CDCl3, 400 MHz): δ 7.59 (d, J = 7.04 Hz, 1H),
7.42-7.36 (m, 6H), 7.31-7.27 (m, 1H), 7.19-7.13 (m, 2H), 6.89 (d,
J = 7.68 Hz, 1H), 6.81-6.79 (m, 2H), 3.64 (s, 3H); 13C NMR
(CDCl3, 100 MHz): δ 196.31, 159.08, 155.54, 145.16, 133.42,
132.74, 132.17, 131.93, 130.71, 129.26, 129.04, 128.98, 128.77,
128.44, 122.94, 122.47, 121.27, 114.87, 114.08, 54.99; IR (KBr):
ν 3678, 3060, 2933, 2836, 2361, 1711, 1596, 1456, 1345, 1284,
1249, 1176, 1042, 755, 696 cm-1.
5-methyl-2,3-diphenyl-1H-inden-1-one (3ba): Purified by col-
umn chromatography to provide a red solid (21.6 mg, yield: 73%).
1H NMR (CDCl3, 400 MHz): δ 7.51 (d, J = 7.24 Hz, 1H), 7.45-
7.44 (m, 3H), 7.41-7.38 (m, 2H), 7.29-7.27 (m, 5H), 7.10 (d, J =
7.28 Hz, 1H), 6.96 (s, 1H), 2.38 (s, 3H); 13C NMR (CDCl3, 100
MHz): δ 196.16, 154.93, 145.72, 144.38, 132.90, 132.81, 130.88,
129.97, 129.14, 128.91, 128.77, 128.51, 128.38, 128.01, 127.65,
123.05, 122.51, 22.08; IR (KBr): ν 3572, 2920, 2361, 1704, 1603,
1469, 1357, 1275, 1188, 1070, 1031, 922, 839, 732, 695 cm-1;
Analytical Data. Found (calcd) for: C22H16O C, 89.13 (89.16); H,
5.45 (5.44).
2-(2,6-dimethylphenyl)-3-phenyl-1H-inden-1-one (3al): Puri-
fied by column chromatography to provide a red solid (12.3 mg,
yield: 40%). 1H NMR (CDCl3, 400 MHz): δ 7.62 (d, J = 5.76 Hz,
1H), 7.37 (d, J = 6.48 Hz, 3H), 7.32-7.27 (m, 4H), 7.19-7.13 (m,
3H), 6.86 (d, J = 7.04 Hz, 1H), 2.39 (s, 3H), 2.05 (s, 3H); 13C
NMR (CDCl3, 100 MHz): δ 196.68, 156.09, 146.02, 135.63,
133.63, 132.43, 131.27, 130.73, 130.36, 129.62, 129.02, 128.83,
128.04, 127.67, 122.64, 121.23, 21.00, 19.35; IR (KBr): ν 3453,
2926, 2857, 1712, 1598, 1493, 1456, 1343, 1264, 1174, 1081,
1028, 815, 759, 697 cm-1; Analytical Data. Found (calcd) for:
C23H18O C, 89.01 (89.00); H, 5.84 (5.85).
2,3,6-triphenyl-1H-inden-1-one (3ca): Purified by column
chromatography to provide a red solid (25.1 mg, yield: 70%). 1H
NMR (CDCl3, 400 MHz): δ 7.89 (d, J = 1.72 Hz, 1H), 7.67-7.63
(m, 3H), 7.52-7.41 (m, 7H), 7.36-7.29 (m, 7H); 13C NMR (CDCl3,
100 MHz): δ 196.29, 155.39, 144.00, 142.26, 139.92, 132.81,
131.67, 131.57, 130.79, 129.97, 129.35, 128.94, 128.82, 128.51,
128.10, 127.90, 127.78, 126.78, 121.95, 121.61; IR (KBr): ν
3362, 2925, 1707, 1605, 1466, 1346, 1260, 1077, 969, 846, 768,
730, 696 cm-1; Analytical Data. Found (calcd) for: C27H18O C,
90.44 (90.47); H, 5.07 (5.06).
3-(2,6-dimethylphenyl)-2-phenyl-1H-inden-1-one (3al’): Puri-
fied by column chromatography to provide a red solid (8.8 mg,
yield: 28%). 1H NMR (CDCl3, 400 MHz): δ 7.60 (d, J = 6.84 Hz,
1H), 7.38-7.33 (m, 3H), 7.31-7.27 (m, 2H), 7.25-7.24 (m, 2H),
7.20-7.11 (m, 3H), 6.84 (d, J = 7.80 Hz, 1H), 2.37 (s, 3H), 2.02 (s,
3H); 13C NMR (CDCl3, 100 MHz): δ 196.71, 156.11, 146.04,
135.65, 133.64, 132.51, 132.45, 132.29, 131.28, 130.74, 130.38,
129.63, 129.03, 128.83, 128.16, 128.05, 127.68, 122.66, 121.24,
21.00, 19.35; IR (KBr): ν 3453, 2926, 2857, 1712, 1598, 1493,
1456, 1343, 1264, 1174, 1081, 1028, 815, 759, 697cm-1.
6-(naphthalen-1-yl)-2,3-diphenyl-1H-inden-1-one (3da): Puri-
fied by column chromatography to provide a red solid (26.9 mg,
yield: 66%). 1H NMR (CDCl3, 400 MHz): δ 7.94-7.88 (m, 3H),
7.77 (d, J = 1.12 Hz, 1H), 7.56-7.53 (m, 3H), 7.51-7.44 (m, 7H),
7.34-7.28 (m, 6H); 13C NMR (CDCl3, 100 MHz): δ 196.35,
155.34, 144.12, 141.86, 138.94, 134.74, 133.84, 132.77, 132.68,
131.28, 130.98, 130.76, 129.97, 129.44, 129.36, 128.84, 128.61,
128.51, 128.43, 128.21, 128.10, 127.78, 126.74, 126.35, 125.97,
2,3-dim-tolyl-1H-inden-1-one (3am): Purified by column chro-
matography to provide a red solid (19.2 mg, yield: 62%). 1H
NMR (CDCl3, 400 MHz): δ 7.60 (d, J = 7.76 Hz, 1H), 7.39-7.35

ACCEPTED MANUSCRIPT
125.56, 125.37, 124.87, 121.23; IR (KBr): ν 2926, 2847, 1728,
1517–1522; (h) Li, H.-J.; Li, P.-H.; Zhao, Q.; Wang, L. Chem.
Commun. 2013, 49, 9170–9172.
1602, 1460, 1378, 1260, 1162, 1033, 808, 781, 749 cm-1;
Analytical Data. Found (calcd) for C31H20O: 91.13 (91.15); H,
4.95 (4.94).
(4) (a) Voutchkova, A.; Coplin, A.; Leadbeater, N. E.; Crabtree, R.
H. Chem. Commun. 2008, 6312–6314; (b) Goossen, L. J.; Rodriguez,
N.; Goossen, K. Angew. Chem. Int. Ed. 2008, 47, 3100–3120; (c)
Cornella, J.; Lu, P.-F.; Larrosa, I. Org. Lett. 2009, 11, 5506–5509; (d)
Wang, C.-Y.; Piel I.; Glorius, F. J. Am. Chem. Soc. 2009, 131, 4194–
4195; (e) Zhang, F.-Z.; Greaney, M.-F. Angew. Chem. Int. Ed. 2010,
49, 2768-2771; (f) Xie, K.; Yang, Z.-Y.; Zhou, X.-J.; Li, X.-J.; Wang,
S.-Z.; Tan, Z.; An, X.-Y.; Guo, C.-C. Org. Lett. 2010, 12, 1564–1567;
(g) Wang, S.-S.; Chen, X.-Z.; Ao, Q.-Q.; Wang, H.-F.; Zhai, H.-B.
Chem. Commun. 2016, 52, 9454–9457; (h) Liu, Z.-J.; Lu, X.; Wang,
G.; Lei, L.; Jiang, W.-T.; Wang, Y.-D.; Xiao, B.; Fu, Y. J. Am. Chem.
Soc. 2016, 138, 9714–9719; (i) Cruz, F. A.; Chen, Z.-W.; Kurtoic, S.
I.; Dong, V. M. Chem. Commun. 2016, 52, 5836–5839.
5-bromo-2,3-diphenyl-1H-inden-1-one (3ea): Purified by col-
umn chromatography to provide a red solid (22.7 mg, yield: 63%).
1H NMR (CDCl3, 400 MHz): δ 7.46-7.42 (m, 5H), 7.37-7.34 (m,
2H), 7.27-7.26 (m, 6H); 13C NMR (CDCl3, 100 MHz): δ 195.18,
154.15, 147.28, 133.40, 132.19, 131.62, 130.27, 129.98, 129.56,
129.35, 129.00, 128.36, 128.14, 128.08, 124.69, 124.07; IR
(KBr): ν 3561, 3059, 2957, 2926, 2852, 1713, 1601, 1485, 1445,
1350, 1262, 1063, 1029, 786 cm-1; Analytical Data. Found (calcd)
for: C21H13BrO, C 69.80 (69.82); H, 3.64 (3.63).
(5) Yu, X. –B.; Duan, Y. –L.; Guo, W. –J.; Wang, T.; Xie, Q. –X.;
Wu, S. –T.; Jiang, C. –G.; Fan, Z. –X.; Wang, J. –H.; Liu, G. –Y.
Organometallics 2017, 36, 1027−1034.
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ASSOCIATED CONTENT
Supporting Information
The Supporting Information is available free of charge on the
ACS Publications website.
NMR Spectra of Products (PDF)
AUTHOR INFORMATION
Corresponding Author
* Email: yuxiaobo1972@126.com
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENT
This work was supported by grants from the NSFC21572155,
JJKH20180554KJ.
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Transition metal-catalyzed C–H bond activations is a versatile and efficient method of
creating organic molecules and many appealing results have been produced. Although the
activation of C–H bond has made significant progress, the selectivity activation of a designated C–
H bond is difficult, which restricts the development of C–H bond activation. To circumvent this
problem, a directing group usually needs to be introduced. It is clear that the substance with the
directing group itself has the advantage of the activation of C-H bonds. The carboxylic acid
containing a removable type oriented group is prone to decarboxylation to selectively construct a
new C-C bond, which replace the original carboxylate carbon and extrude CO or CO .
Based on the above reasons, in recent years decarboxylation cross-coupling reaction
developed rapidly. We demonstrated efficient decarboxylation annulation reactions between
mandelic acids and alkyne derivatives to obtain indenones via rhodium catalyzed. In the process
of studying the mechanism, we found that mandelic acid was first oxidized to
2-oxo-2-phenylacetic acid in the reaction conditions, and then it reacted with alkynes to produce
products. 2-oxo-2-phenylacetic acid is also a commercially available material, for this reason, we
next turn our attention to the reaction of 2-oxo-2-phenylacetic acids and alkyne derivatives.
We have obtained the following research results after research. Efficient iridium-catalyzed
decarboxylative annulation reactions between 2-oxo-2-phenylacetic acids and alkyne derivatives
has been achieved. [IrCp*Cl2]2 with a (CH3OC6H4)3P ligand, AgSbF6 and Cu(OAc)2 additives
was the most efficient catalytic system for this transformation. This reaction is suitable for a broad
range of alkynes and 2-oxo-2-phenylacetic acids and a variety of indenone derivatives were
obtained in medium to high yields. This work provides an efficient approach for the construction
of indenones by iridium–catalyzed decarboxylative annulation.