Reactions of Arenesulfonyl Derivatives with Strong Bases
J . Org. Chem., Vol. 61, No. 4, 1996 1397
Lit h ia t ion R ea ct ion s of Ben zen esu lfon yl F lu or id e
(1a ). Rea ction w ith LTMP P r ep a r ed fr om n -Bu tyl-
lith iu m in THF or fr om Meth yllith iu m in Dieth yl Eth er .
A mixture of 2,2,6,6-tetramethylpiperidine (1.40 mL, 8.3 mmol)
and n-BuLi (5.2 mL, 8.3 mmol, 1.6 M in hexane) was prepared
at room temperature in 5 mL of THF and then added dropwise
to benzenesulfonyl fluoride (1 mL, 8.3 mmol) in dry THF at
-78 °C. The dark-red solution was stirred for 2 h at -78 °C
and then was allowed to stir at room temperature overnight,
whereupon the reaction was quenched with saturated aqueous
NH4Cl solution.
The yellow solid suspended in the hydrolysate was filtered
off, washed with CH2Cl2, and dried to afford the apparently
polymeric 7 (0.21 g): mp > 320 °C; IR (mineral oil, cm-1) 1150,
1320, 720; MS m/e 811, 667, 617, 502, 357, 325, 221, 159, 142,
146, 111, 81, 65. The IR bonds are consistent with the
presence of sulfone groups on aromatic nuclei. The MS peaks
are attributable to SO2H (65), PhSOH (126), PhSO2H (142),
PhSO3H2 (159), C6H4(SO2)2OH (221), (C6H4)3S2O2H (325),
(C6H5)3S2O4 (357), and higher oligomers.
The filtrate was concentrated under reduced pressure and
the residue extracted with CH2Cl2. The organic layer was
washed with water, dried with anhydrous MgSO4, filtered, and
concentrated. The residue was purified by flash chromatog-
raphy (silica gel, 50:1 hexanes/THF) to afford the butyl
benzenesulfonate 6 (0.1 g, 5.6% yield): 1H NMR (CDCl3) δ 7.5-
7.9 (m, 5H), 3.99-4.03 (t, 2H) 1.56-1.6 (m, 2H), 1.26-1.3 (m,
2H), 0.79-0.84 (m, 3H); 13C NMR (CDCl3) δ 135.90, 133.36,
128.91, 127.48, 70.32, 30.44, 18.23, 13.02. Benzenesulfonyl
fluoride (0.3 g, 22.6%) and 2,2,6,6-tetramethylpiperidine (0.03
g, 2.5%) were also recovered.
The aqueous extract was boiled to remove any traces of
organic solvent, cooled, and acidified with 1.0 N HCl.
The evolved SO2 gas was identified by its odor, its acidic
reaction to litmus, and the fact that it caused a white
precipitate when led into aqueous BaCl2 solution. That the
precipitate was BaSO3 was verified by its dissolution upon
adding dilute aqueous HCl. The acidic aqueous extract was
boiled to complete expulsion of the SO2 and then cooled and
treated with aqueous BaCl2 solution. The colorless precipitate
thereupon formed did not dissolve in aqueous HCl, and upon
heating in a crucible burned to leave a residue. It is therefore
concluded to be barium benzenesulfonate.
11: mp 183-184 °C; 1H NMR (CDCl3) δ 7.07-7.45 (m), 396
(s); 13C NMR (CDCl3) δ 145.28, 145.03, 143.50, 140.51, 132.44,
131.36, 129.56, 129.03, 128.54, 128.29, 128.04, 127.99, 127.84,
125.36, 93.82, 82.84; MS m/e 504 (M+), 422, 345, 241, 239, 105,
77, 32.
Rea ction w ith Lith iu m n -Bu toxid e in th e P r esen ce of
Meth yl Iod id e. Admixture of dry 1-butanol (0.76 mL, 8.3
mmol) and n-BuLi (5.2 mL, 8.3 mmol, 1.6 M in hexane) was
conducted at room temperature in 5 mL of THF to form lithium
n-butoxide, which was then added dropwise to benzenesulfonyl
fluoride (1 mL, 8.3 mmol) in dry THF at -78 °C. The reaction
mixture was stirred for 10 min at -78 °C, and then 3.53 g
(1.55 mL, 24.9 mmol) of methyl iodide was added. After being
allowed to warm to room temperature slowly, the resulting
slight yellow solution was treated with aqueous 6 N HCl and
then extracted with ether. The residue were separated by
means of flash chromatography (silica gel; gradient elution
with hexanes, then hexanes/THF (50:1)) to give n-butyl ben-
zenesulfonate (6) (1.10 g, 62%). The unreacted methyl iodide
and benzenesulfonyl fluoride (0.26 g, 20%) were recovered. No
o-methyl derivative of 1a or of 6 was detected.
Rea ction w ith Lith iu m n -Bu toxid e in th e P r esen ce of
Ben zop h en on e. Admixture of dry 1-butanol (0.76 mL, 8.3
mmol) and n-BuLi (5.2 mL, 8.3 mol, 1.6 M in hexane) was
conducted at room temperature in 5 mL of THF, and the
resulting lithium n-butoxide was then added dropwise to
benzenesulfonyl fluoride (1 mL, 8.3 mmol) and benzophenone
(1.51 g, 8.3 mmol) in 20 mL of THF at -78 °C. The reaction
mixture was allowed to warm to room temperature slowly. The
workup procedure was the same as given earlier. Flash
chromatography using 1:50 (THF/hexanes) on silica gel pro-
vided butyl benzenesulfonate 6 (0.6 g, 33.7%). The benzophe-
none and benzenesulfonyl fluoride were also recovered. None
of the cyclic ester 10 was detected among the reaction products.
Lith ia tion Rea ction s w ith P h en yl Ben zen esu lfon a te
(1d ). The LTMP (5.3 mmol) in 5 mL of THF was added
dropwise to phenyl benzenesulfonate (0.62 g, 2.65 mmol) in
10 mL of dry THF at -78 °C, whereupon the reaction mixture
immediately turned yellow. Stirring was continued for 2 h at
-78 °C, after which time the mixture was allowed to warm to
room temperature slowly. The resulting dark-brown solution
was treated with water, the THF was evaporated, and the
residue was dissolved in ether and extracted by aqueous KOH.
A similar reaction was carried out with the LTMP that was
prepared from 2,2,6,6-tetramethylpiperidine and CH3Li (1.4
M in Et2O). The workup procedure was the same as that
described previously; flash chromatography separation gave
ethyl benzenesulfonate (8) in 4% yield: 1H NMR (CDCl3) δ
7.53-7.93 (m, 5H), 4.10-4.17 (q, 2H), 1.26-1.33 (t, 3H); 13C
NMR (CDCl3) δ 136.0, 133.61, 129.19, 127.80, 66.99, 14.72.
Rea ction w ith LTMP in th e P r esen ce of Ben zop h e-
n on e. The LTMP (8.3 mmol) in 5 mL of THF was added
dropwise over 5 min to a rapidly stirred solution of benzene-
sulfonyl fluoride (1 mL, 8.3 mmol) and benzophenone (1.51 g,
8.3 mmol) in dry THF at -78 °C. The solution was stirred at
-78 °C for 2 h and then was allowed to warm to room
temperature slowly overnight. To the resulting red solution
was added, with stirring, 10 mL of aqueous NH4Cl solution
followed by 10 mL of aqueous NH4Cl. It was extracted with
ether (3 × 50 mL), dried (MgSO4), and concentrated under
reduced pressure. The 3,3-diphenyl-1,2-benzoxathiole 1,1-
dioxide (10) (0.35 g, 13%) and two other products, 6 (0.1 g,
5.6%) and 11 (0.15 g, 3.6%), were isolated by flash chroma-
tography (silica gel, gradient elution with hexanes/THF (50:
1), hexanes/CH2Cl2 (1:1), and then CHCl3); benzophenone was
also recovered (0.21 g, 14%). The novel products were identi-
fied by NMR spectroscopy and mass spectrometry. 10: mp
The ether layer was dried over MgSO4 and concentrated
under reduced pressure. Purification by flash chromatography
on silica gel afforded 6 (0.01 g, 1.8%).
The aqueous layer was acidified by 6 N HCl and extracted
with ether. The extract was dried (MgSO4) and evaporated
to give phenol (0.01 g, 4%).
Rea ction w ith LTMP in th e P r esen ce of Ben zop h e-
n on e. The LTMP (8.3 mmol) in 5 mL of THF was added
dropwise to a rapidly stirred solution of phenyl benzene-
sulfonate (1.94 g, 8.3 mmol) and benzophenone (1.51 g, 8.3
mmol) in 10 mL of THF at -78 °C. After being stirred at -78
°C for 2 h, the solution was allowed to warm to room
temperature slowly. After the usual workup procedure and
purification by flash chromatography on silica gel (1:1 hexanes/
CH2Cl2), 0.21 g (7.8%) of 10 was isolated. In addition, 0.99 g
of a mixture of phenyl benzenesulfonate and benzophenone
was also recovered.
Lith ia tion Rea ction s of N-Meth yl-N-p h en ylben zen e-
su lfon a m id e (1e). Rea ction w ith LTMP . To a solution of
1.0 g (4.05 mmol) of N-methyl-N-phenylbenzenesulfonamide
in 10 mL of THF at -78 °C was added dropwise LTMP (8.10
mmol) in 5 mL of THF. The yellow solution was stirred for 2
h at -78 °C and then allowed to warm to room temperature
slowly. The resulting dark-red solution was treated with water
and then extracted with ether. The organic layer was dried
over anhydrous MgSO4 and concentrated. The residue was
separated by means of flash chromatography (silica gel;
gradient elution with hexanes/THF (50:1), then hexanes/CH2-
Cl2 (1:1)) to give 6 (0.04 g, 4.5%) and 9 (0.05 g, 5%). Some
N-methyl-N-phenylbenzenesulfonamide was also recovered
1
161-162 °C (lit.18 mp 163-164 °C); H NMR (CDCl3) δ 7.8-
7.9 (m), 7.7-7.6 (m), 7.4-7.3 (m); 13C NMR (CDCl3) δ 141.5,
140.1, 133.5, 132.2, 130.2, 129.2, 128.6, 127.7, 125.9, 122.1,
96; IR (film, cm-1) 1440, 1350, 1200, 900, 820; MS m/e 322
(M+), 257.245, 239, 152, 105, 77.
(17) Tipson, R. S. J . Org. Chem. 1944, 9, 235.
(18) Watanabe, H.; Schwarz, R. A.; Hauser, C. R. Can. J . Chem.
1969, 47, 1543.
1
(0.05 g, 5%). 9: mp 136-137 °C; H NMR (CDCl3) δ 7.89-
7.83 (m), 7.53-7.38 (m), 6.74-6.72 (t), 6.64-6.62 (d), 6.39 (s,