Synthesis and NMR assignment of substituted sulfinyl monomers 937
and KF (788 mg, 13.587 mmol) were dissolved in a mixture of
water (20 ml) and toluene (20 ml). PdꢀPPh3ꢁ4 (115 mg) was added
as a catalyst. After refluxing the mixture for 23 h, extraction
with CHCl3 ꢀ3 ð 30 mlꢁ was performed and the combined organic
phases were dried over MgSO4. The crude reaction product was
purified by column chromatography (silica, CHCl3). Yield, 74%
General procedure for the synthesis of sulfoxides
5a and 5b
All the commercially available substrates were purchased from
Acros or Aldrich and were used without further purification.
Thin-layer chromatographic (TLC) analyses were made on Merck
aluminium sheets, 20 ð 20 cm, covered with silica gel 60 F254
.
Cž
°
(2.1 g, 5.0481 mmol); m.p., 54.1–55.4 C; MS (EI, m/z), 416 (M ),
255 [MCž ꢀ S(O)C8H17]; UV–vis, ꢂmax at 208 nm; FT-IR (ꢃ, cmꢀ1),
2954 (s), 2926 (s), 2855 (s), 1478 (m), 1418 (w), 1371 (m), 1080 (s), 1047
(s), 888 (w), 851 (w), 695 (s).
Synthesis of 1,4-dibromomethyl-2,5-dichlorobenzene (2a)
In a three-necked flask, 2,5-dichloro-p-xylene (1) (17.5 g, 0.1 mol) was
dissolved in benzene (100 ml). After NBS (N-bromosuccinimide)
(35.6 g, 0.2 mol) and DBP (dibenzoyl peroxide) (0.01 g, 0.041 mol) as
initiator had been added, the mixture was refluxed under nitrogen
and lit with a 200 W lamp. After 24 h, the succinimide was filtered
off and the solvent was evaporated. The product was dissolved
in CHCl3, extraction with CHCl3 ꢀ3 ð 50 mlꢁ was performed, the
combined organic layers were washed with NaHCO3 solution
and with water, dried over MgSO4 and the solvent was partially
evaporated. The flask was placed in a refrigerator and the crystals
that were formed were filtered off. Yield, 36% (12.1 g, 0.0364 mol);
Synthesis of 1-chloromethyl-2-(30-thienyl)-4-(n-octylsulfinyl)methyl-
5-chlorobenzene (5b)
The preparation of 5b is analogous to that described for 5a but here
3-thiopheneboronic acid was used. YielCdž, 71% (2.0 g, 4.8077 mmol);
m.p., 57.0–57.8 C; MS (EI, m/z), 416 (M ), 255 [MCž ꢀ S(O)C8H17];
°
UV–vis, ꢂmax at 208 nm; FT-IR (ꢃ, cmꢀ1), 2954 (s), 2926 (s), 2855 (s),
1478 (m), 1411 (w), 1368 (m), 1079 (s), 1047 (s), 888 (w), 832 (w), 813
(w), 770 (m), 636 (w).
Cž
°
m.p., 123.0–125.4 C; MS [electron ionization (EI), m/z], 332 (M ),
252 (MCž ꢀ Br), 172 (MCž ꢀ 2 Br); 1H NMR, 7.46 (s, 2H), 4.48 (s, 4H).
Acknowledgements
A. Henckens is indebted to the IWT (Vlaams Instituut voor de
Bevordering van het Wetenschappelijk-Technologisch Onderzoek
in de Industrie) for a PhD grant. The Inter University Attraction
Pole (IUAP-P4/11) supported by the Belgian government, EFRO
(Europees Fonds voor Regionale Ontwikkeling) and the FWO (Fonds
voor Wetenschappelijk Onderzoek) are acknowledged for financial
support.
Synthesis of 1,4-dichloromethyl-2,5-dichlorobenzene (2b)
(a) A mixture of 1,4-dibromomethyl-2,5-dichlorobenzene (2a) (12 g,
0.03614 mol) and LiCl (15.18 g, 0.3614 mol) in acetone (150 ml)
was refluxed for 24 h. Water was added and extraction with
CHCl3 ꢀ3 ð 50 mlꢁ was performed, the combined organic layers
were dried over MgSO4 and the solvent was evaporated, which
yielded 2b as white crystals. Yield, 94% (8.2 g, 0.03388 mol).
(b) To a solution of 2,5-dichloro-p-xylene (1) (10 g, 57.14 mmol) in
CCl4 (20 ml), sulfuryl chloride (4.58 ml, 57.14 mmol) and a catalytic
amount of benzoyl peroxide (BPO) was added. The solution was
refluxed for 12 h, after which the solvent was removed in vacuo. The
crude reaction product was purified by column chromatography
(silica, n-hexane), which yielded 2b as white crystals. YieCldž, 36%
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Bradley DDC,
Brown AR,
Marks RN,
°
(5 g, 20.661 mmol); m.p., 98.9–99.9 C; MS (EI, m/z), 242 (M ), 207
(MCž ꢀ Cl), 172 (MCž ꢀ 2 Cl), 137 (MCž ꢀ 3 Cl), 102 (MCž ꢀ 4 Cl);
1H NMR, 7.51 (s, 2H), 4.62 (s, 4H).
Synthesis of
1-chloromethyl-4-(n-octylsulfinyl)methyl-2,5-dichlorobenzene (4)
A mixture of 1,4-dichloromethyl-2,5-dichlorobenzene (2b) (850 mg,
3.5124 mmol) in toluene (10 ml), NaOH (365 mg, 9.1322 mmol) in
H2O (10 ml) and a catalytic amount of the phase-transfer catalyst,
trioctylmethylammonium chloride (Aliquat 336) was stirred at room
temperature. A solution of 1-octanethiol (513 mg, 3.5124 mmol) in
toluene (5 ml) was added dropwise and stirred for 5 h. After extrac-
tion with CHCl3 ꢀ3 ð 20 mlꢁ, drying over MgSO4 and evaporation
of the solvent, the product was oxidized by adding dioxane (15 ml),
H2O2 (0.42 ml), TeO2 (35 mg) and three drops of concentrated HCl.
The reaction was followed on TLC and proceeded until traces of
overoxidation were visible, then it was quenched by adding brine
(20 ml) and subsequently extracted with CHCl3 ꢀ3 ð 20 mlꢁ. The
combined organic layers were dried over MgSO4 and concentrated.
After column chromatographic purification [silica, CHCl3 –Et2O
(8 : 2)], compound 4 was obtained as a white solid. Yield, 46%
°
(600 mg, 1.6304 mmol); m.p., 53.0–54.8 C; MS [chemical ionization
(CI), m/z], 369 (MCž), 333 (MCž ꢀ Cl); 1H NMR, 7.56 (s, 1H), 7.46 (s,
1H), 4.62 (s, 2H), 4.10 (dd, 2J D 12.9 Hz, 2H), 2.73 (m, 2H), 1.79 (m,
2H), 1.43 (m, 2H), 1.25 (m, 8H), 0.86 (t, 3H).
Synthesis of 1-chloromethyl-2-(20-thienyl)-4-(n-octylsulfinyl)methyl-
5-chlorobenzene (5a)
2-Thiopheneboronic acid (2.0 g, 15.625 mmol), 1-chloromethyl-4-
(n-octylsulfinyl)methyl-2,5-dichlorobenzene (4) (2.5 g, 6.7935 mmol)
Copyright 2004 John Wiley & Sons, Ltd.
Magn. Reson. Chem. 2004; 42: 931–937