Use of aryliron complexes [CpFe(CO)2Ar] as arylcarbonyl cation equivalents in the reactions with organolithium reagents to yield ketones

Article abstract of DOI:10.1021/om900558a

Treatment of aryliron complexes [CpFe(CO)₂Ar] with organolithium reagents RLi in THF affords the corresponding ketones RCOAr. The reaction, wherein the aryliron complexes serve as arylcarbonyl cation equivalents, would begin with nudeophilic ad

Full text of DOI:10.1021/om900558a

4872 Organometallics 2009, 28, 4872–4875
DOI: 10.1021/om900558a
Use of Aryliron Complexes [CpFe(CO)2Ar] as Arylcarbonyl Cation
Equivalents in the Reactions with Organolithium Reagents To Yield
Ketones
Shigeo Yasuda, Hideki Yorimitsu,* and Koichiro Oshima*
Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyoto-daigaku
Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
Received June 29, 2009
Summary: Treatment of aryliron complexes [CpFe(CO)2Ar]
with organolithium reagents RLi in THF affords the corre-
sponding ketones RCOAr. The reaction, wherein the aryliron
complexes serve as arylcarbonyl cation equivalents, would
begin with nucleophilic addition of RLi to one of the carbonyl
ligands to form acyliron [CpFe(CO)(RCO)Ar] without lithia-
tion of the Cp ring.
The reactions of [CpFe(CO)2Ar] with organometallic re-
agents are rare. The reaction of [CpFe(CO)2Ph] with excess
butyllithium in THF at -78 °C was reported, leading to the
lithiation of the cyclopentadienyl ring (eq 1).9,10 To our
surprise, a similar reaction at a higher reaction temperature
led to a completely different outcome. Treatment of
[CpFe(CO)2(4-tolyl)] (1a) with 2 equiv of butyllithium at
-20 °C afforded butyl 4-tolyl ketone (2a) in 59% yield
(Table 1, entry 1). Iron complex 1a thus behaved as an
arylcarbonyl cation equivalent, the utility of which we
describe here in detail.
Dicarbonylcyclopentadienylorganoiron complexes [CpFe-
(CO)2R] represent an important class of organometallic com-
pounds due to their rich coordination chemistry.1 The corre-
sponding aryliron complexes [CpFe(CO)2Ar] are fundamental
18-electron arylmetals, and several reliable methods for the
synthesis of the aryliron complexes have been reported.2 On
the other hand, the chemical reactivity of the aryliron com-
plexes has not been well investigated.3-8 Thanks to the ubi-
quity and abundance of iron as a transition metal, we have
envisioned that [CpFe(CO)2Ar] would serve as interesting
arylating agents in organic synthesis and have been studying
the reactivity and utility of [CpFe(CO)2Ar].2e,2f
Whereas bulky secondary and tertiary butyllithiums re-
acted with 1a to afford the corresponding ketones in modest
yields (entries 2 and 3), methylation proceeded smoothly
(entry 4). The reaction of 1a with phenyllithium furnished
phenyl 4-tolyl ketone (2e) in excellent yield (entry 5). The use
of a smaller amount, 1.2 equiv, of phenyllithium diminished
the yield of 2e (entry 6). Grignard reagents were ineffective
for the formation of ketone, even at an elevated temperature
(entry 7).
*Corresponding authors. E-mail: yori@orgrxn.mbox.media.
kyoto-u.ac.jp; oshima@orgrxn.mbox.media.kyoto-u.ac.jp.
(1) Kerber, R. C. In Comprehensive Organometallic Chemistry II;
Abel, E. W., Stone, F. G. A., Wilkinson, G., Eds.; Elsevier: Oxford, U.K.,
1995; Vol. 7, Chapter 2.
Other aryllithium reagents, prepared by bromine-lithium
exchange, also engaged in the reaction (entries 8-14). De-
spite their steric hindrance, bulky 2-tolyllithium and
1-naphthyllithium converted 1a smoothly to the correspond-
ing ketones in high yields (entries 8 and 9). Although
4-methoxyphenyllithium reacted efficiently (entry 10), elec-
tron-deficient aryllithium reagents were less reactive (entries
11-13).
The reactions of various aryliron complexes with phenyl-
lithium were investigated (Table 2). Sterically demanding
arylirons 1d and 1f were available for use (entries 3 and 5),
while the 1-naphthyl group of 1d retarded the reaction.
Halophenylirons 1g-1i and electron-deficient aryliron 1j
underwent the reaction to afford the corresponding benzo-
phenone derivatives in high yields (entries 6-9). The reaction
of electron-rich 4-methoxyphenyliron 1k was slow, requiring
(2) (a) Butler, I. R.; Lindsell, W. E.; Preston, P. N. J. Chem. Res. (S)
1981, 185. (b) Artamkina, G. A.; Mil'chenko, A. Y.; Bumagin, N. A.;
Beletskaya, I. P.; Reutov, O. A. Organomet. Chem., USSR 1988, 1, 17–
20. (c) Nesmeyanov, A. N.; Chapovsky, Y. A.; Polovyanyuk, I. V.; Makarova,
L. G. J. Organomet. Chem. 1967, 7, 329–337. (d) Hunter, A. D.; Szigety, A.
B. Organometallics 1989, 8, 2670-2679, and references therein. (e) Yasuda,
S.; Yorimitsu, H.; Oshima, K. Organometallics 2008, 27, 4025–4027.
(f) Asada, Y.; Yasuda, S.; Yorimitsu, H.; Oshima, K. Organometallics
2008, 27, 6050–6052.
(3) Reaction with diphenylacetylene yielding indenone derivatives:
Butler, I. R.; Cullen, W. R.; Lindsell, W. E.; Preston, P. N.; Rettig, S. J. J.
Chem. Soc., Chem. Commun. 1987, 439–441.
(4) Insertion of unsaturated bonds into aryl-iron bonds: (a) Sever-
son, R. G.; Leung, T. W.; Wojcicki, A. Inorg. Chem. 1980, 19, 915–923.
(b) Su, S. R.; Wojcicki, A. Inorg. Chem. 1975, 14, 89–98. (c) Jacobson, S. E.;
Wojcicki, A. J. Am. Chem. Soc. 1973, 95, 6962–6970.
(5) Iron-carbon bond cleavage in strong carboxylic acids: De Luca,
N.; Wojcicki, A. J. Organomet. Chem. 1980, 193, 359–378.
(6) Reaction with HgX2 affording ArHgX: (a) Dizikes, L. J.;
Wojcicki, A. J. Am. Chem. Soc. 1977, 99, 5295–5303. (b) Reference 2c.
(7) Electrochemical behavior: Magdesieva, T. V.; Kukhareva, I. I.;
Artamkina, G. A.; Beletskaya, I. P.; Butin, K. P. Izv. Akad. Nauk, Ser.
Khim. 1996, 1812–1821.
(8) Photochemical behavior: (a) Nesmeyanov, A. N.; Chapovskii, Y.
A.; Polovyanyuk, I. V.; Makarova, L. G. Izv. Akad. Nauk, SSSR Ser.
Khim. 1968, 1628–1629. (b) Nesmeyanov, A. N.; Chapovskii, Y. A.;
Lokshin, B. V.; Polovyanyuk, I. V.; Makarova, L. G. Dokl. Akad. Nauk,
SSSR 1966, 166, 1125–1128. (c) References 2e and 2f.
(9) Orlova, T. Y.; Setkina, V. N.; Sizoi, V. F.; Kursanov, D. N. J.
Organomet. Chem. 1983, 252, 201–204.
(10) Similar Cp ring lithiation reactions of [CpFe(CO)2(SiR3)] were
reported: (a) Berryhill, S. R.; Clevenger, G. L.; Burdurlu, F. Y.
Organometallics 1985, 4, 1509–1515. (b) Berryhill, S. R.; Sharenow, B. J.
Organomet. Chem. 1981, 221, 143–146.
r
pubs.acs.org/Organometallics
Published on Web 07/30/2009
2009 American Chemical Society

Note
Organometallics, Vol. 28, No. 16, 2009 4873
Table 1. Reactions of [CpFe(CO)2(4-tolyl)] with Organolithium
Reagents
Scheme 1. Reaction of (Ethoxycarbonylphenyl)iron Complex 1l
entry
R
2
yield/%
1
2
3
4
Bu
2a
2b
2c
2d
2e
2e
2e
2f
2g
2h
2i
2j
2k
2l
59
37
36
63
91
68
4
71
75
65
52
47
46
79
s-Bu
t-Bu
Me
Ph
Ph
Ph
2-MeC6H4
1-naphthyl
4-MeOC6H4
4-FC6H4
4-CF3C6H4
4-ClC6H4
4-PhC6H4
Scheme 2. Draft Mechanism
5
6a
7b
8c
9c
10c
11c
12c,d
13c
14c
form acylferrate [CpFe(CO)(Ar0CO)Ar]Li (3).11 Acylferrate
3 might undergo reductive elimination to yield ketone 2.
However, there are two issues to be addressed. While the
mechanism in Scheme 2 should require only 1 equiv of PhLi
in principle, the higher yield of 2e was obtained when 2 equiv
of PhLi was used (Table 1, entry 5 vs entry 6). It is also worth
noting that no further nucleophilic attack of organolithium
to ketone 2 was observed despite the use of 2 equiv of
organolithium.
a 1.2 equiv of PhLi. b Instead of PhLi, PhMgBr was used at 25 °C.
c The aryllithium reagent was prepared from 2 equiv of the corresponding
aryl bromide and 4 equiv of tert-butyllithium at -20 °C. d The aryllithium
reagent was prepared at -78 °C and reacted with 1a at -20 °C.
Table 2. Scope of Aryliron Complexes
To gain more information about the reaction mechanism,
we examined the following experiment. Treatment of 1a with
2 equiv of PhLi in THF at -20 °C for 1 h was followed by an
addition of 4-isopropylbenzaldehyde (5, 1.0 equiv)
(Scheme 3). After quenching with water, the reaction af-
forded (4-isopropylphenyl)(phenyl)methanol (6) in 27%
yield along with an 80% yield of 2e and a 30% recovery of
the aldehyde 5. The formation of 6 and the absence of
triarylmethanol 7 suggest that ketone 2e is protected from
the nucleophilic attack of organolithium during the reaction.
We presume that ketone 2e exists in the resonance of 8 and 80
(Scheme 4).12 The (η2-ketone)iron complex would be formed
via nucleophilic migration of the reactive Ar anion to the acyl
carbonyl.13 The η2 complexation is not robust, and liberation
of ketone 2 would take place upon addition of water.
The formation of 6 clarifies that 1.7 equiv of phenyllithium
was consumed before the addition of 5 and suggests that 0.7
equiv of aryllithium might attack the second carbonyl ligand
to yield diacylferrate 9 (Scheme 4). The Ar group of the
higher order ferrate 9 would be more reactive than that of 3
and undergo smoother migration to yield a hybrid of 10 and
100. The subsequent protonolysis would afford 2.14
entry
Ar
1
2
yield/%
1
4-PhC6H4
2-naphthyl
1-naphthyl
4-t-BuC6H4
2-MeC6H4
4-ClC6H4
1b
1c
1d
1e
1f
1g
1h
1i
2m
2n
2o
2p
2q
2r
2s
2t
2u
2v
74
86
65
91
76
85
83
68
89
59
2
3a
4
5
6
7
8
4-FC6H4
4-BrC6H4
3-CF3C6H4
4-MeOC6H4
9
1j
1k
10b
a Performed at 25 °C. b Performed at 0 °C.
a higher temperature to obtain 2v in moderate yield (entry 10).
The methoxy group lowered the electrophilicity of 1k.
The reaction of iron complex 1l, bearing an ester group,
with 2.5 equiv of phenyllithium resulted in selective nucleo-
philic addition at the ester moiety, providing iron complex
1m (Scheme 1). The reactivity of the carbonyl ligands proved
to be lower than that of the ester carbonyl. With 4 equiv of
phenyllithium, the aryliron moiety acted as an arylcarbonyl
cation equivalent to yield ketone 2w.
(12) Complexes having an open structure such as 800 are also con-
ceivable.
We had initially proposed a draft mechanism as shown in
Scheme 2. The reaction would begin with nucleophilic addi-
tion of Ar0Li to the carbonyl group of [CpFe(CO)2Ar] 1 to
(11) Nucleophilic attack of hydride to the carbonyl ligand of
[CpFe(CO)2R]: (a) Kubo, K.; Nakazawa, H.; Nakahara, S.; Yoshino,
K.; Mizuta, T.; Miyoshi, K. Organometallics 2000, 19, 4932–4934.
(b) Tobita, H.; Shiozawa, R.; Ogino, H. Chem. Lett. 1997, 26, 805–806.
(c) Shiozawa, R.; Tobita, H.; Ogino, H. Organometallics 1998, 17, 3497–
3504.
(13) The conventional reductive elimination process may provide the
same complex.
(14) Although the protonolysis is likely to yield aldehyde Ar0CHO,
none of the aldehyde was detected. Prior to the protonolysis of the
(arylcarbonyl)iron moiety Ar0C(dO)Fe, decarbonylation could occur to
yield Ar0Fe(CO), which then undergoes protonolysis.

4874 Organometallics, Vol. 28, No. 16, 2009
Scheme 3. Attempt To Trap PhLi with Aldehyde 5
Yasuda et al.
1
[using C6H6 (for H, δ = 7.15 ppm) and C6D6 (for 13C, δ =
128.6 ppm) as an internal standard]. IR spectra were determined
on a JASCO IR-810 spectrometer. Mass spectra (EI unless
otherwise noted) were determined on a JEOL Mstation 700
spectrometer. Elemental analyses were carried out at the Ele-
mental Analysis Center of Kyoto University.
Scheme 4. Detailed Plausible Reaction Mechanism
Unless otherwise noted, materials obtained from commercial
suppliers were used without further purification. [CpFe-
(CO)2Ar] was synthesized by palladium-catalyzed transmetala-
tion between [CpFe(CO)2I] and arylmetal reagents according to
the methods reported previously.2e,2f THF was purchased from
Kanto Chemical Co., stored under nitrogen, and used as is.
Organolithium reagents were commercially available or pre-
pared as described below. Silica gel (Wakogel 200 mesh) was
used for column chromatography.
Typical Procedure for Reactions of [CpFe(CO)2Ar] with Or-
ganolithium Reagents (Tables 1, 2 and Scheme 1). Dicar-
bonylcyclopentadienyl(4-methylphenyl)iron (1a, 80 mg,
0.30 mmol) and THF (1.5 mL) were added in a 20 mL reaction
flask under argon. The mixture was cooled to -20 °C, and then
phenyllithium (1.1 M cyclohexane/Et2O solution, 0.55 mL,
0.60 mmol) was added. After being stirred for 1 h at -20 °C,
saturated ammonium chloride solution (0.13 mL) was added to
the reaction mixture. The mixture was filtered through a pad of
silica gel, and the filtrate was concentrated. Silica gel column
purification (eluent: hexane/ethyl acetate, 40:1) of the crude
product provided phenyl 4-tolyl ketone (2e, 53 mg, 0.27 mmol,
91% yield).
Typical Procedure for Reactions of [CpFe(CO)2(4-tolyl)] with
Aryllithium Reagents Generated in Situ by Br/Li Exchange
Reactions (Table 1, entry 14 as a representative). 4-Bromobiphe-
nyl (140 mg, 0.60 mmol) and THF (1.0 mL) were added in a
20 mL reaction flask under argon. The mixture was cooled
to -20 °C, and then tert-butyllithium (1.6 M pentane solution,
0.75 mL, 1.2 mmol) was added. After being stirred for 30 min
at -20 °C, dicarbonylcyclopentadienyl(4-methylphenyl)iron
(1a, 80 mg, 0.30 mmol) in THF (1.0 mL) was added to the
reaction mixture. After being stirred for 1 h at -20 °C, saturated
ammonium chloride solution (0.26 mL) was added to the
reaction mixture. The mixture was filtered through a pad of
silica gel, and the filtrate was concentrated. Silica gel column
purification (eluent: hexane/ethyl acetate, 40:1) of the crude
product provided 4-biphenylyl phenyl ketone (2l, 65 mg,
0.24 mmol, 79% yield).
The following experiments verified that the lithiation of
the Cp ring by the excess amount of RLi9,10 did not occur
under the present reaction conditions. Treatment of 1a with
only 1.0 equiv of PhLi was followed by quenching with D2O
(eq 2). The reaction afforded 2e in 62% yield, and 1a was
recovered in 25% yield. The recovered 1a had only the
natural abundance of deuterium. The use of 1.0 equiv of
BuLi at -20 °C also resulted in no deuterium incorporation
(47% of 2a and 37% of 1a). Given that the lithiation of the
Cp ring is irreversible, the lithiation would predominate
kinetically at -78 °C and the nucleophilic attack would
occur under kinetic control at -20 °C.
In summary, [CpFe(CO)2Ar] complexes have emerged as
arylcarbonyl cation equivalents in the reaction with organo-
lithium reagents. In contrast to the previous report on the
reaction of [CpFe(CO)2Ar] with organolithium, no metala-
tion of the Cp ring was observed. This finding represents a
new chemical reactivity of [CpFe(CO)2Ar] toward organo-
metallic reagents and will be applicable to organic synthesis.
Characterization Data. The product 2p showed spectra iden-
tical to that of the commercially available authentic sample. The
spectral data of the products 1a,2e 1b,2e 1d,2f 1f-1l,2e,2f 2a,15
2b,15 2c,16 2d,17 2e,15 2f,15 2g,17 2h,15 2i,15 2k,17 2m,18 2n,17 2o,16
2q,17 2r,16 2s,17 2t,17 and 2v16 can be found in the literature.
Dicarbonylcyclopentadienyl(2-naphthyl)iron (1c): IR (Nujol)
2342, 2021, 1998, 1970, 1944, 1574, 1456, 1419, 813, 745, 644,
1
628 cm-1; H NMR (CDCl3) δ 4.90 (s, 5H), 7.28 (dd, J=7.5,
Experimental Section
(15) Fausett, B. W.; Liebeskind, L. S. J. Org. Chem. 2005, 70, 4851–
4853.
(16) Goossen, L. J.; Rudolphi, F.; Oppel, C.; Rodrıguez, N. Angew.
1
General Procedures. H NMR (500 and 300 MHz) and 13C
NMR (125.7 and 75.3 MHz) spectra were taken on a Varian
UNITY INOVA 500 spectrometer and a Varian Gemini 300
spectrometer. 1H NMR and 13C NMR spectra were obtained in
CDCl3 [using tetramethylsilane (for 1H, δ = 0.00 ppm) and
CDCl3 (for 13C, δ = 77.2 ppm) as an internal standard] or C6D6
Chem., Int. Ed. 2008, 47, 3043–3045.
(17) Rao, M. L. N.; Venkatesh, V.; Banerjee, D. Tetrahedron 2007,
63, 12917–12926.
(18) Li, B.-J.; Li, Y.-Z.; Lu, X.-Y.; Liu, J.; Guan, B.-T.; Shi, Z.-J.
Angew. Chem., Int. Ed. 2008, 47, 10124–10127.

Note
Organometallics, Vol. 28, No. 16, 2009 4875
7.0 Hz, 1H), 7.36 (dd, J=8.0, 7.0 Hz, 1H), 7.44 (d, J=8.5 Hz,
1H), 7.55-7.59 (m, 2H), 7.69 (d, J=8.0 Hz, 1H), 7.93 (s, 1H);
13C NMR (CDCl3) δ 86.14, 124.08, 125.51, 125.53, 125.94,
127.73, 131.09, 134.20, 143.07, 143.30, 143.90, 216.27. Anal.
Found: C, 67.11; H, 3.94. Calcd for C17H12FeO2: C, 67.14;
H, 3.98. Mp: 94-95 °C.
Dicarbonylcyclopentadienyl (4-tert-butylphenyl)iron (1e): IR
(Nujol) 2002, 1966, 1945, 1917, 1479, 1464, 1362, 1116, 1004,
809, 729, 632, 594 cm-1; 1H NMR (CDCl3) δ 1.27 (s, 9H), 4.86
(s, 5H), 7.02 (d, J=7.5 Hz, 2H), 7.35 (d, J=7.5 Hz, 2H); 13C
NMR (CDCl3) δ 31.44, 33.80, 85.70, 124.83, 139.89, 144.45,
145.60, 216.21. Anal. Found: C, 65.57; H, 5.75. Calcd for
C17H18FeO2: C, 65.83; H, 5.85. Mp: 106-107 °C.
88.29; H, 5.94. Calcd for C20H16O: C, 88.20; H, 5.92. Mp: 122-
124 °C.
Phenyl 3-trifluoromethylphenyl ketone (2u): IR (Nujol) 1654,
1337, 1266, 1170, 1118, 1073, 725, 715, 691, 660 cm-1; 1H NMR
(CDCl3) δ 7.50-7.54 (m, 2H), 7.62-7.65 (m, 2H), 7.79-7.81 (m,
2H), 7.85 (d, J=7.5 Hz, 1H), 7.98 (d, J=7.5 Hz, 1H), 8.07 (s,
1H); 13C NMR (CDCl3) δ 123.91 (q, JC-F=271.1 Hz), 126.90
(q, JC-F=3.9 Hz), 128.78, 129.03 (q, JC-F=3.4 Hz), 129.16,
130.23, 131.22 (q, JC-F = 32.3 Hz), 133.22, 133.32, 136.98,
138.51, 195.41. Anal. Found: C, 67.24; H, 3.37. Calcd for
C14H9F3O: C, 67.20; H, 3.63; HRMS (m/z) obsd 250.0603
(Δ=-1.0 ppm); calcd for C14H9F3O 250.0605. Mp: 48-49 °C.
4-(Hydroxydiphenylmethyl)phenyl phenyl ketone (2w): IR
(neat) 3444, 1658, 1599, 1447, 1405, 1318, 1279, 764, 732, 701,
680 cm-1; 1H NMR (C6D6) δ 2.51 (s, 1H), 7.06-7.19 (m, 9H),
7.33 (d, J=7.5 Hz, 4H), 7.38 (d, J=9.0 Hz, 2H), 7.71-7.75 (m,
4H); 13C NMR (C6D6) δ 82.55, 128.19, 128.53, 128.71, 128.93,
128.97, 130.51, 130.79, 132.64, 137.43, 138.83, 147.68, 152.12,
196.01. Anal. Found: C, 85.67; H, 5.66. Calcd for C26H20O2: C,
85.69; H, 5.53.
Dicarbonylcyclopentadienyl (4-(hydroxydiphenylmethyl)phenyl)-
iron (1m): IR (Nujol) 3548, 2022, 1970, 1957, 1448, 1157, 998,
818, 757, 700 cm-1; 1H NMR (C6D6) δ 2.41 (s, 1H), 4.01 (s, 5H),
7.03-7.06 (m, 2H), 7.09-7.11 (m, 6H), 7.42 (d, J=8.5 Hz, 2H),
7.45 (d, J=7.5 Hz, 4H); 13C NMR (C6D6) δ 82.67, 86.27, 127.67,
128.57, 128.91, 129.14, 143.46, 144.97, 145.23, 148.85, 217.27.
Anal. Found: C, 71.31; H, 4.52. Calcd for C26H20FeO3: C, 71.58;
H, 4.62. Mp: 116-117 °C.
(4-Isopropylphenyl)(phenyl)methanol (6): 1H NMR (CDCl3) δ
1.22 (d, J=7.0 Hz, 6H), 2.29 (d, J=8.0 Hz, 1H), 2.88 (sept,
J=7.0 Hz, 1H), 5.79 (d, J=8.0 Hz, 1H), 7.18 (d, J=8.0 Hz, 2H),
7.23-7.26 (m, 1H), 7.27 (d, J=8.0 Hz, 2H), 7.30-7.33 (m, 2H),
7.37 (d, J = 7.5 Hz, 2H); 13C NMR (CDCl3) δ 24.17, 33.99,
76.33, 126.67, 126.77, 126.79, 127.64, 128.62, 141.47, 144.08,
148.47.
4-Tolyl 4-trifluoromethylphenyl ketone (2j): IR (Nujol) 1647,
1605, 1407, 1329, 1171, 1136, 1110, 1067 cm-1 1H NMR
;
(CDCl3) δ 2.46 (s, 3H), 7.30-7.32 (m, 2H), 7.71-7.73 (m,
2H), 7.75 (d, J = 7.5 Hz, 2H), 7.87 (d, J = 7.5 Hz, 2H); 13C
NMR (CDCl3) δ 22.07, 124.04 (q, JC-F=271 Hz), 125.63 (q,
JC-F=3.9 Hz), 129.58, 130.36, 130.69, 133.83 (q, JC-F=32.5
Hz), 134.40, 141.46, 144.44, 195.64. Anal. Found: C, 68.13; H,
4.35. Calcd for C15H11F3O: C, 68.18; H, 4.20. Mp: 136-137 °C.
4-Biphenylyl 4-tolyl ketone (2l): IR (Nujol) 1644, 1604, 1275,
933, 855, 826, 776, 739, 691 cm-1; 1H NMR (CDCl3) δ 2.46 (s,
3H), 7.30 (d, J=8.0 Hz, 2H), 7.39-7.42 (m, 1H), 747-7.50 (m,
2H), 7.65 (d, J=8.0 Hz, 2H), 7.70 (d, J=8.0 Hz, 2H), 7.76 (d,
J=8.0 Hz, 2H), 7.88 (d, J=9.0 Hz, 2H); 13C NMR (CDCl3) δ
22.01, 127.25, 127.64, 128.47, 129.30, 129.35, 130.60, 130.95,
135.37, 136.94, 140.40, 143.54, 145.33, 196.47. Anal. Found: C,
Acknowledgment. This work was supported by
Grants-in-Aid for Scientific Research and for GCOE
Research from MEXT and JSPS. S.Y. acknowledges
JSPS for financial support. H.Y. thanks The Kurata
Memorial Hitachi Science and Technology Foundation
and Mizuho Foundation for the Promotion of Sciences
for financial support.