PAPER
Reactivity of Arylic Carbanions
2813
13C NMR: = 43.3, 117.8, 126.5, 126.6, 126.6, 126.6, 128.4, 128.7
130.5, 134.0, 134.1, 140.8, 141.9, 150.6.
ogy provides a simple and highly regioselective synthetic
route to polyphenyl derivatives, an important class of or-
ganic compounds which found useful applications as pre- Anal. Calcd for C20H19N (273.37): C, 87.87; H, 7.01; N, 5.12.
Found: C, 87.71; H, 7.06; N, 5.09.
cursor of pharmaceuticals, ligands, polymers, materials,
and liquid crystals.18
Reductive Cleavage of Phenyl-Substituted N,N-Dimethyla-
nilines 2a–d, and Reaction with Electrophiles; General Proce-
Boiling and melting points are uncorrected; the air bath tempera-
tures on bulb-to-bulb distillations are given as boiling points. Start-
ing materials were of the highest commercial quality and were used
without further purification. Li metal (30% wt dispersion in mineral
oil) was purchased from Fluka. THF was distilled from a Na/K alloy
under N2, immediately prior to use. Petroleum ether used has a bp
dure
A dispersion of Li metal in mineral oil (30% wt, 84.6 mg) was
washed with THF (3 × 10 mL) and placed under Ar in a 50 mL two-
necked flask, equipped with reflux condenser and magnetic stirrer
in THF (25 mL). A solution of the appropriate substrate 2a–d (1.83
mmol), dissolved in anhyd THF (5 mL), was added dropwise. After
stirring of this mixture at r.t. for the reported time (see Table 1), a
solution of the appropriate electrophile (5.49 mmol, 3 equiv) in
THF (5 mL) was added dropwise. After stirring for 2 h, the mixture
was quenched by slow dropwise addition of H2O (10 mL, caution)
and the resulting mixture extracted with Et2O (30 mL). The organic
phase was washed with brine (10 mL), dried (K2CO3) and the sol-
vent evaporated.
1
40–70 °C. H NMR spectra were recorded at 300 MHz, and 13C
NMR spectra were recorded at 75 MHz, in CDCl3 with TMS as in-
ternal standard. Elemental analyses were performed by the Mi-
croanalytical Laboratory of the Dipartimento di Chimica,
Università di Sassari.
2-Aminobiphenyl (1a) is commercially available (Aldrich). 4-Ami-
nobiphenyl (1b), and aminoterphenyls, 1c and 1d, were prepared by
the Suzuki cross-coupling reaction, as described below. The amino-
terphenyls 1c and 1d are known compounds, and were character-
ized by comparison with literature data.13 Methylation reactions
were performed according to a general procedure described in the
literature;11 2a and 2b are known compounds, and were character-
ized by comparison with literature data;20 4aa,21 4ab,22 4ac,23 4ba,24
4bb,22 4bc,23 4cb25 and 4db26 are known compounds and were char-
acterized by comparison with literature data.
Phenyl-[1,1 ;3 ,1 ]terphenyl-2 -yl-methanol (4ca)
Purified by flash chromatography (petroleum ether–EtOAc,
9.5:0.5); yield 60%; mp 144–146 °C (petroleum ether).
1H NMR: = 4.98 (d, 1 H, J = 9.6 Hz, OH), 5.95 (d, 1 H, J = 9.6
Hz), 6.78–7.86 (m, 2 H, ArH), 7.00–7.42 (m, 16 H, ArH).
13C NMR: = 72.4, 125.1, 125.9, 126.0, 127.0, 127.6, 127.8, 129.5,
130.4, 145.1, 138.9, 141.4, 142.8, 145.2.
Anal. Calcd for C25H20O (336.43): C, 89.25; H, 5.99; O, 4.76.
Found: C, 89.02; H, 5.96.
4-Aminobiphenyl (1b); Typical Procedure
To a solution of 3b (1.00 g, 5.81 mmol) in DME (50 mL) under N2,
were added a 2 M aq solution of Na2CO3 (9.4 mL, 18.88 mmol),
LiCl (0.74 g, 3 equiv, 17.43 mmol), phenylboronic acid (1.42 g, 2
equiv, 11.62 mmol), and Pd(PPh3)4 (0.34 g, 0.05 equiv, 0.29 mmol).
The mixture was stirred at reflux for 2 h. After chilling to r.t., a sec-
ond amount Pd(PPh3)4 (0.34 g) was added. The mixture was stirred
for 1 h at reflux. After cooling to r.t., the resulting suspension was
diluted with EtOAc (20 mL), the aqueous layer was extracted with
EtOAc (60 mL), and the combined organic layers washed with 10%
aqueous solution of NaOH (40 mL), brine (20 mL), and H2O (20
mL). The organic phase was dried (K2CO3), and concentrated. The
residue was purified by flash chromatography (petroleum ether–
CH2Cl2, 1:1) to afford 1b (0.79 g, 80% yield) as a pale yellow pow-
der; mp 53–55 °C (petroleum ether) (lit.19 51–52 °C).
Phenyl-[1,1 ;3 ,1 ]terphenyl-4 -yl-methanol (4da)
Purified by flash chromatography (petroleum ether–CH2Cl2, 1:1);
yield: 70%; mp 96–98 °C (petroleum ether)
1H NMR: = 2.18 (d, 1 H, J = 4.2 Hz, OH), 5.93 (d, 1 H, J = 4.2
Hz), 7.18–7.52 (m, 14 H, ArH), 7.56–7.66 (m, 4 H, ArH).
13C NMR: = 72.3, 126.5, 126.6, 127.1, 127.3, 127.3, 127.4, 127.7,
128.2, 128.3, 128.8, 129.4, 140.1, 140.2, 140.5, 140.8, 141.8, 143.8.
Anal. Calcd for C25H20O (336.43): C, 89.25; H, 5.99; O, 4.76.
Found: C, 89.13; H, 6.02.
4 -Butyl-[1,1 ;3 ,1 ]terphenyl (4dc)
Purified by flash chromatography (petroleum ether–EtOAc,
9.5:0.5); yield 34%; mp 168 °C (petroleum ether).
1H NMR: = 0.81 (t, 3 H, J = 7.5 Hz, CH3), 1.20–1.28 (m, 2 H,
CH2), 1.46–1.53 (m, 2 H, CH2), 2.61 (t, 2 H, J = 7.8, CH2), 7.32–
7.63 (m, 13 H, ArH).
1H NMR: = 3.66 (br s, 2 H, NH2), 6.72–6.78 (m, 2 H, ArH), 7.18–
7.72 (m, 7 H, ArH).
13C NMR: = 114.0, 117.4, 127.4, 129.0, 129.8, 136.6, 137.4,
147.2.
13C NMR: = 13.8, 22.5, 32.4, 33.5, 125.9, 126.8, 127.0, 127.1,
128.0, 128.7, 129.3, 129.7, 138.4, 139.5, 140.8, 141.9 142.3, 145.1.
2,6-Diphenyl-N,N-dimethylaniline (2c)
Purified by flash chromatography (petroleum ether–Et2O–Et3N,
9.8:0.2:0.2); yield: 75%; mp 93–95 °C (petroleum ether).
1H NMR: = 2.25 (s, 6 H, 2 × CH3), 7.08–7.15 (m, 1 H, ArH),
Anal. Calcd for C22H22 (286.41): C, 92.26; H, 7.74. Found: C,
92.20; H, 7.76.
7.21–7.45 (m, 12 H, ArH).
13C NMR: = 43.2, 122.8, 126.4, 128.1, 128.8 130.8, 139.1, 142.2,
148.3.
Acknowledgment
Financial support from Università di Sassari (ex-60% funds) is gra-
tefully acknowledged.
Anal. Calcd for C20H19N (273.37): C, 87.87; H, 7.01; N, 5.12.
Found: C, 87.63; H, 7.05; N, 5.15.
2,4-Diphenyl-N,N-dimethylaniline (2d)
Purified by flash chromatography (petroleum ether–EtOAc,
9.5:0.5); yield: 86%; mp 61–63 °C (petroleum ether).
1H NMR: = 2.58 [s, 6 H, (CH3)2N], 7.10 (d, 1 H, J = 9.0, ArH),
7.26–7.64 (m, 12 H, ArH).
References
(1) (a) Wakefield, B. J. In Organolithium Methods; Academic
Press: London, 1988. (b) Bartsch, R.; Drost, C.; Klingebiel,
U. In Synthetic Methods of Organometallic and Inorganic
Synthesis 2003, No. 18, 2811–2814 © Thieme Stuttgart · New York