RuH2(CO)(PPh3)3-catalyzed arylation of aromatic esters using arylboronates via C-H bond cleavages

Article abstract of DOI:10.1016/j.jorganchem.2010.01.022

The RuH₂(CO)(PPh₃)₃-catalyzed C-H functionalization of aromatic esters with 5,5-dimethyl-2-aryl-[1,3,2]dioxaborinanes (arylboronates) gave the ortho arylation products. This coupling reaction can be performed with various combinations of isopropyl benzoate derivatives and arylboronates. Introduction of CF₃ group in the aromatic ring increased the reactivity of the esters. Pinacolone effectively served as an acceptor of a hydride generated by C-H bond cleavage, and the amount of pinacolone used also affected the yield of the arylation product.

Full text of DOI:10.1016/j.jorganchem.2010.01.022

Journal of Organometallic Chemistry 695 (2010) 1163–1167
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
RuH2(CO)(PPh3)3-catalyzed arylation of aromatic esters using arylboronates
via C–H bond cleavages
Kentaroh Kitazawa a, Masashi Kotani b, Takuya Kochi a, Michael Langeloth b, Fumitoshi Kakiuchi a,
*
a Department of Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, Kanagawa 223-8522, Japan
b PRESTO, JST, 4-1-8 Honcho Kawaguchi, Saitama, Japan
a r t i c l e i n f o
a b s t r a c t
Article history:
The RuH2(CO)(PPh3)3-catalyzed C–H functionalization of aromatic esters with 5,5-dimethyl-2-aryl-
[1,3,2]dioxaborinanes (arylboronates) gave the ortho arylation products. This coupling reaction can be
performed with various combinations of isopropyl benzoate derivatives and arylboronates. Introduction
of CF3 group in the aromatic ring increased the reactivity of the esters. Pinacolone effectively served as an
acceptor of a hydride generated by C–H bond cleavage, and the amount of pinacolone used also affected
the yield of the arylation product.
Received 19 December 2009
Received in revised form 13 January 2010
Accepted 19 January 2010
Available online 25 January 2010
Keywords:
Ó 2010 Elsevier B.V. All rights reserved.
C–H arylation
Aromatic esters
Ruthenium
Biaryls
Arylboronates
2,6-Diarylbenzoic acid
1. Introduction
RuH2(CO)(PPh3)3-catalyzed coupling of aromatic esters and
arylboronates.
Construction of biaryl structures by transition metal-catalyzed
intermolecular C–H arylation has been extensively studied in order
to develop efficient alternatives of conventional cross-couplings
between preactivated arenes [1–7]. Since Catellani and Chiusoli re-
ported an interesting coupling of norbornene and aryl bromides
[2a], there have been developed a variety of C–H arylations such
as Ar–H/Ar–X (X = halides and pseudohalides) [3,4], Ar–H/Ar–me-
tal [5,6], and Ar–H/Ar–H [7,8] couplings. Directing groups have of-
ten been employed to achieve high regioselectivity and efficiency
for the arylation of benzene derivatives [4,6,8].
We have developed RuH2(CO)(PPh3)3-catalyzed ortho arylation
of aromatic ketones with 5,5-dimethyl-2-aryl-[1,3,2]dioxaborin-
anes (arylboronates) [6b,c]. In this coupling reaction, pinacolone
serves as both a solvent and a scavenger of hydride generated by
C–H bond cleavage. We envisioned that application of aromatic es-
ters in place of aromatic ketones to the arylation would provide an
efficient route to other important classes of functionalized biaryl
molecules. For example, 2,6-diarylbenzoic acids, which are widely
recognized as useful supporting ligands [9] and hydrogen-bonding
scaffolds [10], should be easily prepared from aromatic esters.
Herein, we describe catalytic synthesis of o-arylbenzoates by
2. Results and discussion
The arylation was first examined using several alkyl 2-meth-
ylbenzoate 1 and phenylboronate 2a (Table 1). When the reaction
of methyl ester 1a with 2a was performed with 5 mol% RuH2(CO)-
(PPh3)3 (3) in refluxing pinacolone for 7 h, ortho phenylation
product 4a was formed in 21% GC yield (entry 1). Use of ethyl ester
1b did not improve the yield significantly (entry 2). However, the
phenylation of isopropyl ester 1c gave the corresponding product
4c in 75% GC yield (entry 3). Increase of the steric bulk of the
directing group to tert-butoxycarbonyl group resulted in reduction
of the product yield (entry 4). To investigate the electronic effect of
the directing group, hexafluoroisopropyl ester 1e was used as a
substrate, but no desired product was observed (entry 5) [11].
Therefore, isopropyl esters were chosen as substrates for further
examination.
Next, we examined the arylation of 2-(trifluoromethyl)benzoate
5. The reaction of ester 5 with 2a for 7 h led to the formation of
ortho phenylation product 6a in 92% GC yield, which is higher than
the yield obtained with a substrate bearing a relatively electron-
donating (CH3) group (Table 1, entry 3). This indicates that the
presence of electron-withdrawing groups on the aromatic ring of
the ester substrates promotes the arylation, and a similar trend
* Corresponding author. Fax: +81 45 5661591.
E-mail address: kakiuchi@chem.keio.ac.jp (F. Kakiuchi).
0022-328X/$ - see front matter Ó 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2010.01.022

1164
K. Kitazawa et al. / Journal of Organometallic Chemistry 695 (2010) 1163–1167
Table 1
iPrO
iPrO
O
O
3
Phenylation of 2-methylbenzoate 1.
0.050 mmol
Ph
2a
+
pinacolone 1.0 mL
reflux ,3h
7
8
1.0 mmol
2.0 mmol
90% yield
Scheme 1.
Entry
Substrate
R
Time (h)
Product
GC yield (%)
Table 3
Arylation of unsubstituted benzoate 9.
1
2
3
4
5
1a
1b
1c
1d
1e
Me
7
7
7
7
3
4a
4b
4c
4d
–
21
23
75
32
ND
Et
iPr
tBu
CH(CF3)2
Table 2
Arylation of 2-(trifluoromethyl)benzoate 5.
Entry
Arylboronate
Yield of 10a
Yield of 11a
1
2
3
2a (R = Ph)
2b (R = 4-MeOC6H4)
2d (R = 4-MeC6H4)
10a
10b
10d
19%
27%
26%
11a
11b
11d
58%
37%
38%
a
Isolated yield.
Entry
Arylboronate
Pinacolone (mL)
Time
(h)
Product
Yield
(%)
Ph
O
Ph
O
conc. HBr 0.1 mL
OiPr
OH
1
2
3
4
5
6
2a (R = Ph)
2a
2a
2a
2b (R = 4-MeOC6H4)
2c (R = 2-MeC6H4)
0.5
0.5
1.0
2.0
1.0
1.0
7
2
2
3
3
3
6a
6a
6a
6a
6b
6c
92a
69b
83b
84b
78
AcOH 0.5 mL
120 °C, 65 h
Ph
Ph
in a sealed tube
11a
12
93% yield
0.2 mmol
74
Scheme 2.
a
GC yield.
Determined based on 1H NMR spectra of 6a isolated as a mixture with starting
b
material 5.
O
O
O
cat. 3
+
OR
Ar B
OR
pinacolone
was also observed for ortho alkylation of aromatic esters with al-
kenes catalyzed by 3 [12]. It is worthy to note that, in the arylation
of aromatic ketones, introduction of a CF3 group at an ortho posi-
tion of a substrate resulted in decrease of the yield, because in-
creased electrophilicity facilitated undesired reduction of the
substrate and the product and prevented the selective trapping
of hydrides by pinacolone [6c].
O
Ph
OR
OR
O
Ar B
O
OR
O
tBu
O
[Ru]
H
O
O
[Ru]
O
[Ru]
Ar
15
In order to improve the reaction rate, the amount of pinacolone
used was then investigated. As already mentioned above, pinaco-
lone is not only a solvent but also a reagent. Considering its func-
tion as a reagent, increase of the amount may improve the activity.
When the reaction was performed with 0.5 mL of pinacolone for
2 h, product 6a was obtained in 69% yield. Increase of the amount
of pinacolone to 1.0 mL actually improved the product yield to 83%.
The phenylation in 2.0 mL of pinacolone afforded a comparable
yield (84%) of 6a in 3 h. Based on the results, 1.0 mL of pinacolone
was used to explore the reaction of other substrates (see Table 2).
The arylation of ester 5 was also performed with other arylbo-
ronates. The reaction using 4-methoxyphenylboronate 2b provided
the corresponding product 6b in 78% yield. Ortho-substituted phe-
nylboronate 2c can be used for this reaction and product 6c was
obtained in 74% yield, even though the methyl substituent should
create severe steric congestion. As previously reported, arylboron-
ate 2c was also applicable for the arylation of aromatic ketones cat-
alyzed by 3 [6b,c].
O
O B
13
tBu
14
O
tBu
H
Scheme 3. Proposed mechanism of the arylation of aromatic esters.
Unsubstituted benzoate 9 has two ortho C–H bonds, and both
can be arylated in the reaction. The reaction of 9 with phenylbor-
onate 2a afforded 1:1 and 1:2 coupling products, 10a and 11a,
which was isolated in 19% and 58% yields, respectively (Table 3,
entry 1). The arylations of 9 with 2b and 2d also provided both
mono- and di-arylation products (entries 2 and 3). In all cases,
2,6-diaylated benzoate esters were the major products.
Removal of the isopropyl group was also examined. When ester
11a was treated with conc. HBr in AcOH [13] was performed in a
sealed tube at 120 °C for 65 h, hydrolysis took place cleanly, and
2,6-diphenylbenzoic acid (12) [14] was isolated in 93% yield (see
Scheme 2).
1-Naphthoate 7 also showed high reactivity for the arylation.
The reaction of ester 7 with 2a for 3 h afforded product 8, of which
a phenyl group was introduced selectively at 2-position, in 90%
yield (Scheme 1).
The arylation of aromatic esters described here is considered to
proceed via a similar mechanism to the previously-reported

K. Kitazawa et al. / Journal of Organometallic Chemistry 695 (2010) 1163–1167
1165
arylation of aromatic ketones [6b,c]. Coordination of the ester moi-
4.2.3. Compound 4c
ety of an ester substrate to a ruthenium center, followed by oxida-
tive addition of a C–H bond, leads to formation of five-membered
ruthenacycle 13. Hydroruthenation of the carbonyl group of pina-
colone results in alkoxyruthenium complex 14. Transmetalation
between 14 and arylboronates 2 gives intermediate 15. Reductive
elimination provides the coupling product and regenerates the cat-
alytically active ruthenium species (see Scheme 3).
Colorless liquid 1H NMR (270 MHz, CDCl3): d = 0.99 (d,
J = 6.2 Hz, 6H), 2.41 (s, 3H), 4.97 (septet, J = 6.2 Hz, 1H), 7.18–7.22
(m, 2H), 7.31–7.38 (m, 6H). 13C NMR (67.8 MHz, CDCl3): d = 19.7,
21.4, 68.5, 127.1, 127.2, 128.1, 128.4, 129.0, 129.1, 133.6, 135.0,
139.9, 140.8, 169.0. IR (neat): 3060, 3027, 2979, 2933, 1720,
1590, 1496, 1463, 1384, 1374, 1273, 1180, 1130, 1108, 1090,
1066, 917, 851, 794, 760, 701 cmÀ1. MS m/z (% relative intensity):
254 (M+, 50), 212 (60), 196 (13), 195 (85), 194 (100), 167 (14), 166
(17), 165 (50), 152 (32). Anal. Calc. for C17H18O2: C, 80.28; H, 7.13.
Found: C, 80.01; H, 7.10%.
3. Conclusion
In summary, aromatic esters were coupled with arylboronates
by a catalytic amount of RuH2(CO)(PPh3)3 to form ortho arylated
benzoate derivatives. Isopropyl esters particularly gave high yields
of the products. Introduction of electron-withdrawing CF3 group
increased the product yield, and the amount of pinacolone used
also affected the reaction rate. Finally, 2,6-diarylation product
11a was successfully hydrolyzed to the corresponding carboxylic
acid. The arylation method for aromatic esters reported here pro-
vides a new entry for convenient synthesis of functionalized biaryl
molecules including highly hindered benzoic acids.
4.2.4. Compound 4d
Colorless liquid 1H NMR (400 MHz, CDCl3): d = 1.27 (s, 9H), 2.42
(s, 3H), 7.14–7.24 (m, 2H), 7.28–7.40 (m, 6H). 13C NMR (100 MHz,
CDCl3): d = 19.5, 27.7, 81.5, 127.1, 127.1, 128.0, 128.7, 128.7, 129.0,
134.7, 134.8, 139.8, 141.0, 168.6. IR (neat): 2977, 2931, 1720, 1461,
1392, 1368, 1287, 1258, 1242, 1172, 1126, 1092, 1067, 848, 782,
760, 701 cmÀ1. MS m/z (% relative intensity): 268 (M+, 10), 213
(15), 212 (100), 195 (61), 194 (91), 166 (11), 165 (30), 152 (19),
57 (25). Anal. Calc. for C18H20O2: C, 80.56; H, 7.51. Found: C,
80.79; H, 7.57%.
4. Experimental
4.2.5. Compound 6a
Colorless liquid 1H NMR (270 MHz, CDCl3): d = 1.01 (d,
J = 6.2 Hz, 6H), 4.98 (septet, J = 6.2 Hz, 1H), 7.35–7.43 (m, 5H),
7.53–7.57 (m, 2H), 7.67–7.71 (m, 1H). 13C NMR (67.8 MHz, CDCl3):
d = 21.2, 69.6, 123.5 (q, J = 273 Hz), 124.8 (q, J = 4.5 Hz), 127.4 (q,
J = 32 Hz), 127.9, 128.2, 128.6, 129.2, 132.0 (q, J = 2.2 Hz), 133.3,
139.0, 141.1, 166.5. IR (neat) 2983, 1733, 1467, 1456, 1375, 1328,
4.1. General procedure for the arylation of aromatic esters
An apparatus consisting of a 10 mL two-necked round-bot-
tomed flask, a reflux condenser and a magnetic stirring bar was
flame-dried, and then cooled to room temperature under a flow
of nitrogen. Catalyst 3, arylboronate 2, ester and pinacolone were
added to the flask. The resulting mixture was refluxed (oil bath
temperature 135 °C) under nitrogen. After cooled to room temper-
ature, the reaction mixture was passed through a basic alumina
column (Merck, aluminum oxide 90 active basic (0.063–
0.200 mm), i.d. 30 mm, length 50 mm) with 2% ethyl acetate in
hexane to remove unreacted arylboronate. The arylation product
was isolated by silica gel column chromatography (Merck, silica
gel 60 (230–400 mesh ASTM)). Further purification of the product
was performed by GPC, if necessary.
1280, 1197, 1171, 1141, 1103, 1067, 1047, 809, 763, 702 cmÀ1
.
MS m/z (% relative intensity): 308 (M+, 45), 267 (11), 266 (72),
265 (12), 250 (18), 249 (100), 245 (17), 230 (14), 229 (74), 201
(47), 152 (21). Anal. Calc. for C17H15F3O2: C, 66.23; H, 4.90. Found:
C, 65.93; H, 4.83%.
4.2.6. Compound 6b
White solid; mp 63–64 °C. 1H NMR (400 MHz, CDCl3): d = 1.06
(d, J = 6.3 Hz, 6H), 3.84 (s, 3H), 5.02 (septet, J = 6.3 Hz, 1H), 6.93
(d, J = 8.8 Hz, 2H), 7.30 (d, J = 8.8 Hz, 2H), 7.47–7.58 (m, 2H),
7.61–7.71 (m, 1H). 13C NMR (100 MHz, CDCl3): d = 21.2, 55.3,
69.5, 113.7, 123.6 (q, J = 274 Hz), 124.6 (q, J = 5.0 Hz), 127.4 (q,
J = 32 Hz), 129.2, 129.9, 131.5, 132.1 (q, J = 2.1 Hz), 133.5, 140.1,
159.6, 166.8. IR (KBr): 1722, 1611, 1517, 1453, 1382, 1285,
1262, 1250, 1195, 1178, 1168, 1142, 1117, 1101, 1067, 1046,
1029, 826, 812 cmÀ1. MS m/z (% relative intensity): 339 (14), 338
(M+, 73), 297 (16), 296 (100), 279 (26), 259 (44), 139 (14).
HRMS–ESI: m/z [M + Na]+ calc. for C18H17F3NaO3: 361.1028; found
361.1021.
4.2. Analytical data
4.2.1. Compound 4a
Colorless liquid 1H NMR (400 MHz, CDCl3): d = 2.40 (s, 3H), 3.58
(s, 3H), 7.20–7.24 (m, 2H), 7.31–7.42 (m, 6H). 13C NMR (100 MHz,
CDCl3): d = 19.6, 51.7, 127.2, 127.3, 128.1, 128.2, 129.1, 129.4,
133.1, 135.4, 140.1, 140.9, 170.2. IR (neat): 2949, 1730, 1591,
1462, 1436, 1270, 1239, 1123, 1092, 1067, 797, 760, 701 cmÀ1
.
MS m/z (% relative intensity): 227 (13), 226 (M+, 73), 196 (15),
195 (100), 194 (48), 167 (17), 166 (15), 165 (49), 152 (34), 82
(16). Anal. Calc. for C15H14O2: C, 79.62; H, 6.24. Found: C, 79.64;
H, 6.25%.
4.2.7. Compound 6c
Colorless liquid 1H NMR (400 MHz, CDCl3): d = 0.87 (d,
J = 6.3 Hz, 3H), 1.01 (d, J = 6.3 Hz, 3H), 2.11 (s, 3H), 4.87 (septet,
J = 6.3 Hz, 1H), 7.10–7.21 (m, 2H), 7.21–7.31 (m, 2H), 7.42
(d, J = 7.6 Hz, 1H), 7.54 (dd, J = 7.6 Hz, 7.9 Hz, 1H), 7.69
(d, J = 7.9 Hz, 1H). 13C NMR (100 MHz, CDCl3): d = 20.1, 20.8,
21.2, 69.3, 123.6 (q, J = 274 Hz), 124.9 (q, J = 4.8 Hz), 125.2,
127.4 (q, J = 32 Hz), 128.3, 128.9, 129.6, 129.8, 132.6 (q,
J = 2.2 Hz), 133.4 (q, J = 1.2 Hz), 136.4, 138.2, 140.8, 166.2. IR
(neat): 2983, 1733, 1455, 1376, 1328, 1279, 1192, 1171, 1139,
1102, 1065, 1053, 810, 762 cmÀ1. MS (% relative intensity): 322
(M+, 21), 280 (28), 263 (43), 262 (100), 261 (11), 243 (15), 235
(15), 234 (57), 215 (27), 214 (11), 193 (11), 166 (21), 165 (76).
HRMS–ESI: m/z [M + Na]+ calc. for C18H17F3NaO2: 345.1078;
found 345.1079.
4.2.2. Compound 4b
Colorless liquid 1H NMR (400 MHz, CDCl3): d = 0.96 (t, J = 7.3 Hz,
3H), 2.41 (s, 3H), 4.05 (q, J = 7.3 Hz, 2H), 7.19–7.24 (m, 2H), 7.30–
7.40 (m, 6H). 13C NMR (100 MHz, CDCl3): d = 13.6, 19.6, 60.8,
127.2, 127.3, 128.2, 128.4, 129.1, 129.3, 133.4, 135.4, 140.2,
141.0, 169.7. IR (neat): 3060, 2980, 2932, 1724, 1590, 1462,
1445, 1365, 1266, 1238, 1173, 1124, 1092, 1067, 1015, 797, 760,
701 cmÀ1. MS m/z (% relative intensity): 241 (11), 240 (M+, 65),
196 (16), 195 (100), 194 (48), 167 (14), 166 (14), 165 (42), 152
(29). Anal. Calc. for C16H16O2: C, 79.97; H, 6.71. Found: C, 80.05;
H, 6.72%.

1166
K. Kitazawa et al. / Journal of Organometallic Chemistry 695 (2010) 1163–1167
4.2.8. Compound 8
NMR (100 MHz, CDCl3): d = 21.2, 55.3, 68.4, 113.6, 128.5, 128.9,
129.7, 133.0, 133.5, 139.7, 159.1, 168.9. IR (KBr): 1722, 1609,
1515, 1460, 1291, 1270, 1245, 1175, 1101, 1059, 1032, 1020,
827, 802, 775, 568 cmÀ1. MS m/z (% relative intensity): 377 (26),
376 (M+, 100), 335 (13), 334 (58), 333 (11), 318 (13), 317 (49),
Colorless liquid 1H NMR (400 MHz, CDCl3): d = 1.03 (d,
J = 6.3 Hz, 6H), 5.12 (septet, J = 6.3 Hz, 1H), 7.34–7.46 (m, 3H),
7.46–7.61 (m, 5H), 7.87–7.92 (m, 1H), 7.92–7.97 (m, 1H), 7.97–
8.02 (m, 1H). 13C NMR (100 MHz, CDCl3): d = 21.4, 69.0, 124.9,
126.2, 127.4, 127.4, 127.5, 128.1, 128.3, 128.8, 129.6, 129.9,
130.5, 132.3, 137.9, 141.0, 168.9. IR (neat): 3058, 2979, 1718,
1495, 1464, 1447, 1375, 1284, 1238, 1181, 1167, 1143, 1105,
1086, 1029, 1012, 916, 836, 823, 762, 747, 702 cmÀ1. MS (% relative
intensity): 291 (16), 290 (M+, 77), 249 (12), 248 (70), 247 (26), 232
(22), 231 (100), 203 (36), 202 (72), 201 (14), 200 (13), 101 (11).
Anal. Calc. for C20H18O2: C, 82.73; H, 6.25. Found: C, 83.01; H,
6.35%.
202 (13). HRMS–ESI: m/z [M
399.1572; found 399.1585.
+
Na]+ calc. for C24H24NaO4:
4.2.14. Compound 11d
White solid; mp 92.5–93 °C. 1H NMR (400 MHz, CDCl3): d = 0.85
(d, J = 6.3 Hz, 6H), 2.38 (s, 6H), 4.78 (septet, J = 6.3 Hz, 1H), 7.15–
7.22 (m, 4H), 7.28–7.35 (m, 6H), 7.42–7.48 (m, 1H). 13C NMR
(100 MHz, CDCl3): d = 21.0, 21.1, 68.4, 128.4, 128.6, 128.8, 129.0,
133.3, 137.0, 137.7, 140.1, 168.8. IR (KBr): 2976, 1727, 1515,
1454, 1280, 1265, 1101, 1063, 819, 800 cmÀ1. MS m/z (% relative
intensity):345 (21), 344 (M+, 79), 303 (11), 302 (53), 301 (33),
286 (27), 285 (100), 271 (15), 242 (24), 241 (15), 238 (13).
HRMS–ESI: m/z [M + Na]+ calc. for C24H24NaO2: 367.1674; found
367.1684.
4.2.9. Compound 10a
Colorless liquid 1H NMR (400 MHz, CDCl3): d = 1.01(d, J = 6.3 Hz,
6H), 4.97 (septet, J = 6.3 Hz, 1H), 7.28–7.44 (m, 7H), 7.47–7.54 (m,
1H), 7.77–7.83 (m, 1H). 13C NMR (100 MHz, CDCl3): d = 21.3, 68.5,
127.0, 127.0, 127.9, 128.4, 129.5, 130.5, 130.8, 131.9, 141.5, 142.2,
168.4. IR (neat): 2980, 1718, 1476, 1451, 1373, 1283, 1243, 1132,
1108, 1047, 748, 700 cmÀ1. MS m/z (% relative intensity): 240
(M+, 48), 198 (45), 197 (39), 182 (20), 181 (100), 153 (25), 152
(41), 151 (11). Anal. Calc. for C16H16O2: C, 79.97; H, 6.71. Found:
C, 79.72; H, 6.76%.
4.3. Synthesis of 12
An apparatus consisting of a 10 mL Schlenk tube, a glass stopper
and a magnetic stirring bar was flame-dried, and then cooled to
room temperature under a flow of nitrogen. Ester 11a (63.1 mg,
0.20 mmol), acetic acid (0.50 mL) and hydrobromic acid (48 wt%,
0.10 mL) were added to the tube. The resulting mixture was heated
at 120 °C for 65 h under nitrogen atmosphere. After cooled to room
temperature, the reaction mixture was dissolved in potassium
hydroxide solution and the mixture was extracted with diethyl
ether. The water layer was then acidified with dilute hydrochloric
acid and the mixture was extracted with diethyl ether. The organic
layer was washed with brine and dried over Na2SO4. Compound 12
was isolated by silica gel column chromatography (eluent: 25%
ethyl acetate in hexane).
4.2.10. Compound 10b
Colorless liquid 1H NMR (400 MHz, CDCl3): d = 1.06 (d,
J = 6.3 Hz, 6H), 3.84 (s, 3H), 4.94 (septet, J = 6.3 Hz, 1H), 6.98 (d,
J = 8.8 Hz, 2H), 7.24 (d, J = 8.8 Hz, 2H), 7.32–7.47 (m, 2H), 7.49–
7.59 (m, 1H), 7.65–7.74 (m, 1H). 13C NMR (100 MHz, CDCl3):
d = 21.4, 55.3, 68.5, 113.5, 126.7, 129.4, 129.6, 130.6, 130.8, 131.9,
133.9, 141.7, 159.0, 168.6. IR (neat): 2980, 2935, 1714, 1612,
1518, 1480, 1466, 1444, 1373, 1284, 1248, 1179, 1132, 1107,
1085, 1047, 1037, 833, 764 cmÀ1. MS m/z (% relative intensity):
271 (17), 270 (M+, 95), 229 (15), 228 (100), 227 (17), 212 (14),
211 (63), 168 (21), 167 (11), 140 (15), 139 (27), 106 (12). Anal. Calc.
for C17H18O3: C, 75.53; H, 6.71. Found: C, 75.24; H, 6.76%.
Acknowledgements
4.2.11. Compound 10d
Colorless liquid. 1H NMR (400 MHz, CDCl3): d = 1.05(d,
J = 6.3 Hz, 6H), 2.39 (s, 3H), 4.99 (septet, J = 6.3 Hz, 1H), 7.16–7.23
(m, 4H), 7.31–7.41 (m, 2H), 7.45–7.53 (m, 1H), 7.74–7.80 (m,
1H). 13C NMR (100 MHz, CDCl3): d = 21.1, 21.4, 68.5, 126.9, 128.3,
128.7, 129.4, 130.5, 130.8, 131.9, 136.8, 138.6, 142.2, 168.5. IR
(neat): 3024, 2979, 2935, 1714, 1599, 1518, 1480, 1467, 1446,
1386, 1373, 1350, 1334, 1287, 1245, 1182, 1132, 1108, 1046,
918, 854, 820, 761, 709 cmÀ1. MS m/z (% relative intensity): 255
(16), 254 (M+, 86), 213 (12), 212 (82), 211 (47), 196 (22), 195
(100), 181 (20), 167 (18), 166 (18), 165 (46), 152 (37). Anal. Calc.
for C17H18O2: C, 80.28; H, 7.13. Found: C, 80.56; H, 7.18%.
This work was supported, in part, by a Grant-in-Aid for Scien-
tific Research (21350056) from MEXT and by a Grant for Private
Education Institute Aid from MEXT.
Reference
[1] (a) Recent reviews: M. Catellani, Synlett (2003) 298;
(b) L.-C. Campeau, K. Fagnou, Chem. Commun. (2006) 1253;
(c) K. Godula, D. Sames, Science 312 (2006) 67;
(d) O. Daugulis, V.G. Zaitsev, D. Shabashov, Q.-N. Pham, A. Lazareva, Synlett
(2006) 3382;
(e) T. Satoh, M. Miura, Chem. Lett. 36 (2007) 200;
(f) D. Alberico, M.E. Scott, M. Lautens, Chem. Rev. 107 (2007) 174;
(g) L. Ackermann, Synlett (2007) 507;
(h) S. Pascual, P. de Mendoza, A.M. Echavarren, Org. Biomol. Chem. 5 (2007)
2727;
(i) A. Mori, A. Sugie, Bull. Chem. Soc. Jpn 81 (2008) 548;
(j) B.-J. Li, S.-D. Yang, Z.-J. Shi, Synlett (2008) 949;
(k) F. Kakiuchi, T. Kochi, Synthesis (2008) 3013;
(l) X. Chen, K.M. Engle, D.-H. Wang, J.-Q. Yu, Angew. Chem., Int. Ed. 48 (2009)
5094.
4.2.12. Compound 11a
White solid; mp 125–125.5 °C. 1H NMR (270 MHz, CDCl3):
d = 0.83 (d, J = 6.2 Hz, 6H), 4.75 (septet, J = 6.2 Hz, 1H), 7.34–7.49
(m, 13H). 13C NMR (67.8 MHz, CDCl3): d = 21.1, 65.6, 127.4, 128.1,
128.5, 128.7, 129.0, 133.3, 140.1, 140.4, 168.5. IR (KBr):3059,
2976, 1723, 1584, 1571, 1495, 1454, 1441, 1372, 1282, 1267,
1129, 1099, 1065, 1028, 919, 809, 773, 761, 699 cmÀ1. MS m/z (%
relative intensity): 317 (13), 316 (M+, 55), 274 (38), 273 (28), 258
(30), 257 (100), 229 (19), 228 (30), 227 (12), 226 (16). Anal. Calc.
for C22H20O2: C, 83.51; H, 6.37. Found: C, 83.36; H, 6.34%.
[2] (a) M. Catellani, G.P. Chiusoli, J. Organomet. Chem. 286 (1985) C13;
(b) M. Catellani, B. Marmiroli, M.C. Fagnola, D. Acquotti, J. Organomet. Chem.
507 (1996) 157;
(c) N. Della Ca, G. Sassi, M. Catellani, Adv. Synth. Catal. 350 (2008) 2179;
(d) M. Catellani, E. Motti, N. Della Ca, Acc. Chem. Res. 41 (2008) 1512.
[3] (a) D.E. Ames, D. Bull. Tetrahedron 38 (1982) 383;
(b) N. Nakamura, Y. Tajima, K. Sakai, Heterocycles 17 (1982) 235;
M. Miura, S. Pivsa-Art, G. Dyker, J. Heiermann, T. Satoh, M. Nomura, Chem.
Commun. (1998) 1889;
4.2.13. Compound 11b
White solid; mp 113–114 °C. 1H NMR (400 MHz, CDCl3):
d = 0.88 (d, J = 6.3 Hz, 6H), 3.83 (s, 6H), 4.80 (septet, J = 6.3 Hz,
1H), 6.89–6.94 (m, 4H), 7.28–7.37 (m, 6H), 7.41–7.48 (m, 1H). 13C
(d) M. Lafrance, C.N. Rowley, T.K. Woo, K. Fagnou, J. Am. Chem. Soc. 128 (2006)
8754;
(e) S. Proch, R. Kempe, Angew. Chem., Int. Ed. 46 (2007) 3135.

K. Kitazawa et al. / Journal of Organometallic Chemistry 695 (2010) 1163–1167
1167
[4] (a) G. Dyker, Angew. Chem., Int. Ed. 31 (1992) 1023;
(g) R. Li, L. Jiang, W. Lu, Organometallics 25 (2006) 5973;
(h) D.R. Stuart, K. Fagnou, Science 316 (2007) 1172;
(i) T.A. Dwight, N.R. Rue, D. Charyk, R. Josselyn, B. DeBoef, Org. Lett. 9 (2007)
3137;
(b) D.D. Hennings, S. Iwasa, V.H. Rawal, J. Org. Chem. 62 (1997) 2;
(c) T. Satoh, Y. Kawamura, M. Miura, M. Nomura, Angew. Chem., Int. Ed. 36
(1997) 1740;
(d) T. Satoh, Y. Kametani, Y. Terao, M. Miura, M. Nomura, Tetrahedron Lett. 40
(1999) 5345;
(e) Y. Kametani, T. Satoh, M. Miura, M. Nomura, Tetrahedron Lett. 41 (2000)
2655;
(f) S. Oi, Y. Ogino, S. Fukita, Y. Inoue, Org. Lett. 4 (2002) 1783;
(g) S. Oi, E. Aizawa, Y. Ogino, Y. Inoue, J. Org. Chem. 70 (2005) 3113;
(h) D. Kalyani, N.R. Deprez, L.V. Desai, M.S. Sanford, J. Am. Chem. Soc. 127
(2005) 7330;
(j) D.R. Stuart, E. Villemure, K. Fagnou, J. Am. Chem. Soc. 129 (2007) 12072.
[8] (a) K.L. Hull, E.L. Lanni, M.S. Sanford, J. Am. Chem. Soc. 128 (2006) 14047;
(b) K.L. Hull, M.S. Sanford, J. Am. Chem. Soc. 129 (2007) 11904;
(c) J.-B. Xia, S.-L. You, Organometallics 26 (2007) 4869;
(d) B.-J. Li, S.-L. Tian, Z. Fang, Z.-J. Shi, Angew. Chem., Int. Ed. 47 (2008) 1115;
(e) S. Oi, H. Sato, S. Sugawara, Y. Inoue, Org. Lett. 10 (2008) 1823;
(f) G. Brasche, J. García-Fortanet, S.L. Buchwald, Org. Lett. 10 (2008) 2207;
(g) X. Guo, G. Deng, C.-J. Li, Adv. Synth. Catal. 351 (2009) 2071.
[9] (a) H.J. Callot, F. Metz, Tetrahedron 41 (1985) 4495;
(b) D. Lee, S.J. Lippard, J. Am. Chem. Soc. 120 (1998) 12153;
(c) J.R. Hagadorn, L. Que Jr., W.B. Tolman, J. Am. Chem. Soc. 120 (1998) 13531;
(d) W.B. Tolman, L. Que Jr., J. Chem. Soc., Dalton Trans. (2002) 653;
(e) E.Y. Tshuva, S.L. Lippard, Chem. Rev. 104 (2004) 987;
(f) S.V. Kryatov, E.V. Rybak-Akimova, Chem. Rev. 105 (2005) 2175.
[10] (a) C.-T. Chen, J.S. Siegel, J. Am. Chem. Soc. 116 (1994) 5959;
(b) Y. Tanaka, H. Katagiri, Y. Furusho, E. Yashima, Angew. Chem., Int. Ed. 44
(2005) 3867;
(i) D. Shabashov, O. Daugulis, Org. Lett. 8 (2006) 4947;
(j) H.A. Chiong, Q.-N. Pham, O. Daugulis, J. Am. Chem. Soc. 129 (2007) 9879.
[5] H. Kawai, Y. Kobayashi, S. Oi, Y. Inoue, Chem. Commun. (2008) 1464;
(b) L. Ackermann, S. Barfüßer, Synlett (2009) 808.
[6] S. Oi, S. Fukita, Y. Inoue, Chem. Commun. (1998) 2439;
(b) F. Kakiuchi, S. Kan, K. Igi, N. Chatani, S. Murai, J. Am. Chem. Soc. 125 (2003)
1698;
(c) F. Kakiuchi, Y. Matsuura, S. Kan, N. Chatani, J. Am. Chem. Soc. 127 (2005)
5936;
(d) R. Giri, N. Maugel, J.-J. Li, D.-H. Wang, S.P. Breazzano, L.B. Saunders, J.-Q. Yu,
J. Am. Chem. Soc. 129 (2007) 3510;
(c) M. Ikeda, Y. Tanaka, T. Hasegawa, Y. Furusho, E. Yashima, J. Am. Chem. Soc.
128 (2006) 6806;
(e) S. Yang, B. Li, X. Wan, Z. Shi, J. Am. Chem. Soc. 129 (2007) 6066;
(f) Z. Shi, B. Li, X. Wan, J. Cheng, Z. Fang, B. Cao, C. Qin, Y. Wang, Angew. Chem.,
Int. Ed. 46 (2007) 5554;
(g) J. Norinder, A. Matsumoto, N. Yoshikai, E. Nakamura, J. Am. Chem. Soc. 130
(2008) 5858;
(d) T. Maeda, Y. Furusho, S.-I. Sakurai, J. Kumaki, K. Okoshi, E. Yashima, J. Am.
Chem. Soc. 130 (2008) 7938.
[11] For all the entries on Table 1 except for entry 3, more than 44% of recovered
starting esters were detected by GC analyses.
[12] (a) M. Sonoda, F. Kakiuchi, A. Kamatani, N. Chatani, S. Murai, Chem. Lett. 25
(1996) 109;
(h) D.-H. Wang, T.-S. Mei, J.-Q. Yu, J. Am. Chem. Soc. 130 (2008) 17676.
[7] (a) R. van Helden, G. Verberg, Rec. Trav. Chim. Pays-Bas 84 (1965) 1263;
J.M. Davidson, C. Triggs, Chem. Ind. (1966) 457;
(b) F. Kakiuchi, H. Ohtaki, M. Sonoda, N. Chatani, S. Murai, Chem. Lett. 30
(2001) 918;
(c) L. Eberson, L. Gomez-Gonzalez, Acta Chim. Scand. 27 (1973) 1249;
(d) H. Yoshimoto, H. Itatani, Bull. Chem. Soc. Jpn 46 (1973) 2490;
(e) K. Masui, H. Ikegami, A. Mori, J. Am. Chem. Soc. 126 (2004) 5074;
(f) M. Takahashi, K. Masui, H. Sekiguchi, N. Kobayashi, A. Mori, M. Funahashi,
N. Tamaoki, J. Am. Chem. Soc. 128 (2006) 10930;
(c) F. Kakiuchi, S. Murai, Acc. Chem. Res. 35 (2002) 826.
[13] S. Merlet, M. Birau, Z.Y. Wang, Org. Lett. 4 (2002) 2157.
[14] D. Tilley, S.S. Samanta, A.-S. Castanet, A. De, J. Mortier, Eur. J. Org. Chem. (2006)
174. see also Ref. [4g,j]..