PAPER
Synthesis of (p-Nitroaryl)diarylmethanes via Vicarious Nucleophilic Substitution of Hydrogen
1239
[(4-Chlorophenyl)phenylmethyl]-4-chlorophenyl Sulfide (2b)
Orange oil, LSIMS(+) HR: calcd for C19H13S35Cl2 (M-H)+:
343.01150. Found: 343.01182.
1H NMR (200 MHz, CDCl3) d = 8.27 (d, 1H, J = 2.4), 8.02 (dd, 1H,
J = 8.5, 2.4), 7.01-7.34 (m, 11H,), 5.99 (s, 1H).
3-Methoxy-4-(diphenylmethyl)nitrobenzene (3h)
Reaction of Nitroarenes with 2a or 2b; General Procedure
t-BuOK (560 mg, 5 mmol) was dissolved in dry DMF (8 mL) under
Ar and the solution was cooled to -40 °C. A solution of a nitroarene
1 (1 mmol) and a sulfide 2 (1 mmol) in DMF (2 mL) was added over
1.5 h. The reaction mixture was stirred at -40 °C to -50 °C for 4 h,
then the reaction mixture was poured into ice-cooled dilute HCl
(10%, 20 mL). After extraction with CH2Cl2 (4 x 10 mL), the com-
bined organic layers were washed with aq NaOH (10%, 40 mL) to
remove p-chlorothiophenol. The organic layer was dried (MgSO4)
and filtered through silica gel. Products were purified either by re-
crystallization from EtOH or by column chromatography on silica
gel (hexane/EtOAc, 50:1), and then additionally recrystallized from
EtOH.
Purified by recrystallization to give yellow crystals, mp: 95-96 °C.
1H NMR (500 MHz, CDCl3) d = 7.75 (dd, 1H, J = 8.4, 2.2), 7.68 (d,
1H, J = 2.2), 7.26-7.30 (m, 4H), 7.20-7.24 (m, 2H), 7.04-7.07 (m,
4H), 7.01 (d, 1H, J = 8.4), 5.93 (s, 1H), 3.81 (s, 3H).
4-[(4-Chlorophenyl)phenylmethyl]-3-methoxynitrobenzene (3i)
Purified by column chromatography to give white crystals, mp: 85-
86 °C (Lit.5 orange oil).
1H NMR (200 MHz, CDCl3) d = 7.70-7.79 (m, 2H), 7.23-7.32 (m,
5H), 6.95-7.08 (m, 5H), 5.89 (s, 1H), 3.83 (s, 3H).
3-Cyano-4-(diphenylmethyl)nitrobenzene (3j)
Purified by recrystallization to give yellow crystals, mp: 97-98 °C.
1H NMR (200 MHz, CDCl3) d = 8.51 (d, 1H, J = 2.4), 8.33 (dd, 1H,
J = 8.8, 2.5), 7.05-7.40 (m, 11H), 6.03 (s, 1H).
4-(Diphenylmethyl)nitrobenzene (3a)
Purified by recrystallization to give pale yellow crystals, mp: 93-
94 °C (Lit.5 95-97 °C).
4-(Diphenylmethyl)-1-nitronaphthalene (3k)
Purified by recrystallization to give pale yellow crystals, mp: 125-
127 °C.
1H NMR (200 MHz, CDCl3) d: 8.55 (d, 1H, J = 8.7), 8.14 (d, 1H,
J = 8.5), 8.06 (d, 1H, J = 8.1), 7.72-7.48 (m, 2H), 7.36-7.25 (m,
6H), 7.13-7.04 (m, 5H), 6.31 (s, 1H).
2-Fluoro-4-(diphenylmethyl)nitrobenzene (3b)
Purified by column chromatography to give pale yellow crystals,
mp: 58-59 °C (EtOH), (Lit.5 59-60 °C).
1H NMR (200 MHz, CDCl3) d = 7.98 (dd, 1H, J = 8.9, 8.0), 7.35-
7.27 (m, 6H), 7.12-7.02 (m, 6H), 5.59 (s, 1H).
2-Chloro-4-(diphenylmethyl)nitrobenzene (3c)
Purified by recrystallization to give yellow crystals, mp: 82-83 °C.
1H NMR (200 MHz, CDCl3) d = 7.81 (d, 1H, J = 8.4), 7.05-7.35
(m, 12H), 5.57 (s, 1H).
Reaction of 4-Bromo-2-fluoronitrobenzene with 2a
t-BuOK (560 mg, 5 mmol) was dissolved in dry DMF (8 mL) under
Ar and the solution was cooled to -40 °C. A solution of a 4-bromo-
2-fluoronitrobenzene (220 mg, 1 mmol) and 2a (1 mmol) in DMF
(2 mL) was added over 1.5 h. The reaction mixture was stirred at
-40 °C to -50 °C for 4 h and then was poured into ice-cooled dilut-
ed HCl (10%, 20 mL). After extraction with CH2Cl2 (4 x 10 mL),
the combined organic layers were washed with aq NaOH (10%, 40
mL) to remove p-chlorothiophenol. The organic layer was dried
(MgSO4). The products were separated from tars by column chro-
matography on silica gel (hexane) to give a mixture of 3 substances
as an orange oil (168 mg). According to TLC and EIMS, these prod-
ucts were identified as 3b, 3f and 3l.
2-Methoxy-4-(diphenylmethyl)nitrobenzene (3d)
Purified by recrystallization to give pale yellow crystals, mp: 139-
140 °C (Lit.5 142-144 °C).
1H NMR (200 MHz, CDCl3) d** = 7.78 (d, 1H, J = 8.4), 7.23-7.34
(m, 10H), 6.83 (d, 1H, J = 1.5), 6.76 (dd, 1H, J = 8.4, J = 1.7), 5.58
(s, 1H), 3.80 (s, 1H).
2-Iodo-4-(diphenylmethyl)nitrobenzene (3e)
Purified by recrystallization to give pale yellow crystals, mp: 109-
110 °C.
1H NMR (500 MHz, CDCl3) d = 7.81 (dd, 1H, J = 1.9, 0.6), 7.79 (d,
1H, J = 8.4), 7.31-7.35 (m, 4H), 7.25-7.29 (m, 2H), 7.19 (ddd, 1H,
J = 8.4, 1.9, 0.6), 7.06–7.09 (m, 4H), 5.54 (s, 1H).
5-(Diphenylmethyl)-2-nitrophenyl 4-chlorophenyl Sulfide (3l)
Compound 3j (307 mg, 1 mmol) was stirred with 4-chlorothiophe-
nol (144 mg, 1 mmol) and K2CO3 (630 mg, 5 mmol) in acetone (10
mL) at ambient temperature for 12 h. The workup was as for sul-
fides 2a and 2b.
The product was purified by column chromatography to give an or-
ange oil, yield 328 mg, 76%.
1H NMR (200 MHz, CDCl3) d = 8.15 (d, 1H, J = 8.5), 7.19-7.26
(m, 10H), 7.00-7.07 (m, 1H), 6.84-6.91 (m, 4H), 6.75 (d, 1H,
J = 1.8), 5.40 (s, 1H).
2-tert-Butoxy-4-(diphenylmethyl)nitrobenzene (3f)
To a solution of 2-tert-butoxynitrobenzene (195 mg, 1 mmol) and
2a (311 mg, 1 mmol) in DMF (8 mL) cooled to -40 °C t-BuOK
(250 mg, 2,2 mmol) dissolved in DMF (2 mL) was added over 1.5
h. The mixture was stirred at -40 °C to -50 °C for 4 h and then
poured into cold water. After extraction with CH2Cl2 (4 x 10 mL),
the combined organic layers were dried (MgSO4) and filtered
through silica gel. Products were purified via column chromatogra-
phy (hexane) to give yellow crystals, mp: 86-87 °C.
References
(1) Casiraghi, G.; Casanti, G.; Cornia, M. Tetrahedron Lett. 1973,
679.
1H NMR (200 MHz, CDCl3) d = 7.66 (d, 1H, J = 8.9), 7.20-7.37
(m, 6H), 7.05-7.12 (m, 4H), 6.86-6.92 (m, 2H), 5.55 (s, 1H), 1.28
(s, 9H).
(2) Pindur, U.; Flo, C. J. Heterocycl. Chem. 1989, 26, 1563.
(3) Ungnade, H. E.; Crandell, E. W. J. Am. Chem. Soc. 1949, 71,
2209.
(4) Snyder, H. R.; Knoecky, M. S. J. Am. Chem. Soc. 1958, 80,
4388.
(5) Katritzky, A. R.; Toader, D. J. Org. Chem. 1997, 62, 4137.
3-Chloro-4-(diphenylmethyl)nitrobenzene (3g)
Purified by recrystallization to give pale yellow crystals, mp: 86-
87 °C.
Synthesis 2000, No. 9, 1237–1240 ISSN 0039-7881 © Thieme Stuttgart · New York