Alkylation of Nitroaromatics
sources, and were used as such. Coloumn chromatography was
performed using 230-400 mesh silica gel.
CHART 2. Sp in Den sities
Typ ica l P r oced u r e for th e Alk yla tion of 1 (Syn th esis
of 2a , b, a n d g). A 56 mg (0.5 mmol) portion of K-t-OBu
dissolved in 5 mL of dry t-BuOH or THF was placed in a flame-
dried flask closed with rubber septum and purged with argon.
A 0.6 mL (0.6 mmol) portion of a 1 M solution of the borane in
THF was injected through the septum. The mixture was
stirred for 2 min, and 84 mg (0.5 mmol) of 1, dissolved in 1
mL of dry t-BuOH or THF was injected into the above solution.
The mixture was stirred for 5-10 min at room temperature.
The reaction was quenched with 5 mL of 3% hydrochloric acid
and was extracted using 20% methylene chloride in hexane
(5 mL, three times). The combined organic layers were washed
with water and dried over anhydrous sodium sulfate. The
solvent was then removed under reduced pressure. The crude
compound was purified by flash column chromatography over
1
silica gel. The compounds were characterized by their H NMR
as well as mass specta.
P r oced u r e for th e Syn th esis of Com p ou n d s 2c-f. The
corresponding boranes for these compounds were prepared in
situ in the following way: The respective cyclo-olefin (0.7
mmol) was dissolved in 2 mL of THF. One milliliter of a 0.5
M solution of 9-borabicyclononane (9-BBN) was injected into
the olefin/THF mixture which was heated at 50-60 °C for 6
h, under an atmosphere of argon. The mixture was then cooled
to room temperature and used for alkylation as in the above
procedure.
group, the differences in spin densities between the two
positions are the smallest, and indeed, in this case the
two products were obtained in a ratio of 5:1 in cor-
respondence with the respective spin densities.
All compounds except 2g are reported in the literature, and
Exp er im en ta l Section
their physical data have been reported.10 Compound 2g (oil)
1
was characterized on the basis of its H NMR and HRMS data.
The 1H NMR spectra were recorded on a 300 MHz spec-
trometer with CDCl3 as solvent and TMS as reference.
Chemical ionization mode was used for the high-resolution
mass spectra.
Ma ter ia ls. Analytical grade t-BuOH and tetrahydrofuran
(THF) were purified prior to use by the usual procedures.8
2,4,4′-Trinitrobiphenyl (Chart 1) was prepared by the reported
procedure (mp 176 °C, lit. 176 0 °C).9 All other chemicals were
of analytical grade, were obtained from various commercial
1H NMR data for 2g (300 MHz, CDCl3, TMS, δ ppm): 0.877
(d, 3H, 7.5 Hz), 1.17 (s, 3H), 1.12-1.15 (m, 1H), 1.30 (s, 3H),
1.84-1.95 (m, 2H), 2.04-2.09 (m, 2H), 2.40-2.57 (2H), 3.09-
3.15 (m, 1H), 7.46 (d, 2H, 9 Hz), 8.18 (d, 2H, 9 Hz).
13C NMR (75 MHz, CDCl3, TMS, δ ppm): 20.9, 23.0, 28.4,
35.0, 37.2, 39.2, 41.7, 45.0, 45.8, 47.9, 123.7, 129.1, 146.2, 157.3.
HRMS: calculated for (M + 1) ion 260.163216; observed
260.165054.
Su p p or tin g In for m a tion Ava ila ble: Archive files con-
taining energies and structures of the DFT computed radical
anions of Chart2 (S1) and 1H and 13C NMR for compound 2g
(S2). This material is available free of charge via the Internet
at http://pubs.acs.org.
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Chem. 2001, 624, 167. (c) For 2c and 2e: Hartmann, R. W.; Bartzl, C.
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