K. Funabiki et al. / Journal of Molecular Catalysis A: Chemical 367 (2013) 116–120
117
7.24–7.37 (m, 5H); 13C NMR (CDCl3, 100 MHz) ı 25.7 (s), 67.8 (s),
128.3 (s), 128.46 (s), 128.52 (s), 134.9 (s), 166.6 (s); HRMS (EI)
227.9786 (C9H9O279Br requires 227.9787 (M+)).
mixture was stirred at room temperature for 4 h. Propanesultone
(3.175 g, 25.99 mmol) was then added and the mixture was stirred
at the same temperature for 2 h. After the solvent was removed
under reduced pressure, the obtained compounds were repeatedly
washed with ethanol, and subjected to evaporation under vacuum
at 60 ◦C. The obtained solid was washed with methanol and sub-
jected to evaporation under vacuum at room temperature to give
sodium 3,3ꢀ-(1H-imidazole-3-ium-1,3-diyl)dipropane-1-sulfonate
(1) (2.737 g, 82%).
2.3.2. Oxybis(methylene)dibenzene (6aa) [9]
Rf 0.38 (hexane:Et2O = 10:1); 1H NMR (CDCl3, 400 MHz) ı 4.54 (s,
4H), 7.25–7.37 (m, 10H); 13C NMR (CDCl3, 100 MHz) ı 71.7 (s), 127.2
(s), 127.4 (s), 128.0 (s), 137.9 (s); HRMS (EI) 198.1044 (C14H14O2
requires 198.1045 (M+)).
2.1.2. Sodium
2.3.3. Ethane-1,2-diyl bis(2-bromoacetate) (5ab) [6]
3,3ꢀ-(1H-imidazole-3-ium-1,3-diyl)dipropane-1-sulfonate (1)
Yield 82%; Mp 268.5–269.5 ◦C; IR (KBr) 1562 (C C), 1180 (SO),
Yield 68%; Rf 0.75 (hexane:EtOAc = 1:1); IR (KBr) 1738
(C O) cm−1 1H NMR (CDCl3, 400 MHz) ı 3.81 (s, 4H), 4.35 (s, 4H);
;
1045 (SO) cm−1 1H NMR (D2O, 400 MHz) ı 2.33 (quint, J = 7.24 Hz,
;
13C NMR (CDCl3, 100 MHz) ı 25.4 (s), 63.3 (s), 167.0 (s); HRMS (CI)
4H), 2.94 (t, J = 7.24 Hz, 4H), 4.38 (t, J = 7.24 Hz, 4H), 7.57 (d,
J = 1.69 Hz, 2H), 8.88 (s, 1H); 13C NMR (D2O, 100 MHz) ı 37.6
(s), 59.8 (s), 60.4 (s), 135.1 (s), 148.3 (s); HRMS (FAB+) 335.0345
(C9H16N2NaO6S2 requires 335.0347 (M−I)).
302.8868 (C6H9O479Br requires 302.8868 (M+H)).
2.3.4. (Z)-But-2-ene-1,4-diyl bis(2-bromoacetate) (5ac) [10]
Yield 76%; Rf 0.80 (hexane:EtOAc = 3:1); IR (KBr) 1738
To sodium 3,3ꢀ-(1H-imidazole-3-ium-1,3-diyl)dipropane-1-
sulfonate (1) (1.009 g, 3.018 mmol) in water (1 mL) was added
trifluoromethanesulfonic acid (1.154 g, 7.689 mmol) at 0 ◦C, and
the mixture was stirred at room temperature for 12 h and concen-
trated under vacuum. Precipitation of the obtained compounds
with a mixture of methanol and Et2O, filtration, and drying under
trifluoromethanesulfonate (2) (0.999 g, 72%).
(C O) cm−1 1H NMR (CDCl3, 400 MHz) ı 3.80 (s, 4H), 4.74 (d,
;
J = 4.10 Hz, 4H), 5.75 (m, 2H); 13C NMR (CDCl3, 100 MHz) ı 25.5 (s),
61.3 (s), 127.8 (s), 166.8 (s); HRMS (CI) 328.9032 (C8H11O479Br2
requires 328.9024 (M+H)).
2.3.5. 1-Phenylethyl 2-bromoacetate (5ad) [11]
Yield 37%; Rf 0.46 (hexane:CH2Cl2 = 2:1); IR (KBr) 1732
(C O) cm−1 1H NMR (CDCl3, 400 MHz) ı 1.50 (d, J = 6.64 Hz, 3H),
;
3.75 (s, 2H), 5.85 (q, J = 6.64 Hz, 1H), 7.20–7.33 (m, 5H); 13C NMR
(CDCl3, 100 MHz) ı 21.9 (s), 26.2 (s), 74.4 (s), 126.1 (s), 128.2 (s),
2.1.3. 1,3-Bis(3-sulfopropyl)-1H-imidazol-3-ium
trifluoromethanesulfonate (2) [7]
Yield 72%; Mp 284.0–284.3 ◦C; IR (KBr) 3151 (SO3H), 3098
128.5 (s), 140.6 (s), 166.4 (s); HRMS (EI) 241.9943 (C10
H11OBr
(SO3H), 1562 (C C), 1273 (SO), 1200 (SO), 1049 (SO) cm−1 1H
;
requires 241.9942 (M+)).
NMR (DMSO, 400 MHz) ı 2.08 (quint, J = 7.06 Hz, 4H), 2.40 (t,
J = 7.06 Hz, 4H), 4.28 (t, J = 7.06 Hz, 4H), 7.78 (d, J = 1.45, 2H), 9.15
(s, 1H); 13C NMR (D2O, 100 MHz) ı 38.3 (s), 60.5 (s), 61.1 (s),
132.2 (q, J = 269.3 Hz), 135.8 (s), 149.0 (s); HRMS (FAB+) 313.0532
(C9H17N2O9S2 requires 313.0528 (M−CF3SO3)).
2.3.6. 1,1ꢀ-Oxybis(ethane-1,1-diyl)dibenzene (6bb) [12]
Yield 38%; Rf 0.60 (hexane:CH2Cl2 = 1:1); 1H NMR (CDCl3,
400 MHz) ı 1.31 (d, J = 6.52 Hz, 6H), 1.39 (d, J = 6.52 Hz, 6H), 4.18
(q, J = 6.52 Hz, 2H), 4.46 (q, J = 6.52 Hz, 2H), 7.13–7.31 (m, 20H); 13
NMR (CDCl3, 100 MHz) ı 23.9 (s), 25.6 (s), 75.3 (s), 75.5 (s), 127.1
(s), 127.2 (s), 128.0 (s), 128.3 (s), 129.1 (s), 129.4 (s),145.0 (s), 145.1
(s); MS (EI) m/z 226 (M, 32.5%).
C
2.2. Adsorption of 1,3-bis(3-sulfopropyl)-1H-imidazol-3-ium
trifluoromethanesulfonate 2 onto silica gel
To
1,3-bis(3-sulfopropyl)-1H-imidazol-3-ium
trifluo-
2.3.7. Benzyl 2-bromopropanoate (5ba) [13]
romethanesulfonate (2) (0.069 g, 0.150 mmol) in methanol (20 mL)
was added silica gel (Wakogel C-200, 100–200 mesh, 75–150 m)
(30 mg), and the mixture was stirred at room temperature for
30 min. The obtained solid was dried under vacuum at room
temperature for 5 h.
Yield 74%; Rf 0.60 (hexane:Et2O = 2:1); IR (KBr) 1740
(C O) cm−1
;
1H NMR (CDCl3, 400 MHz) ı 1.83 (d, J = 7.00 Hz,
3H), 4.41 (q, J = 7.00 Hz, 1H), 5.20 (s, 2H), 7.28–7.44 (m, 5H);
13C NMR (CDCl3, 100 MHz) ı 22.3 (s), 40.7 (s), 68.2 (s), 128.8
(s), 129.1 (s), 129.3 (s), 135.8 (s), 170.8 (s); HRMS (EI) 241.9949
(C10H11O279Br requires 241.9942 (M+)). Enantiomer separation of
(R)-5ba: CHIRAL GC (GL Sciences, CP-CHIRALCEL-DEX CB column,
temperature: 80–180 ◦C (4 ◦C/min), muscle: 74.4 kPa, total flow:
26.0 mL/min, column flow: 0.89 mL/min, liner velocity: 25.7 cm/s,
purge flow: 3.0 mL/min, sprit fraction: 24.8), t1 (S) = 22.6 min, t2
(R) = 22.7 min.
2.3. Typical procedure for the silica gel-adsorbed acid 2-catalyzed
esterification of carboxylic acids with alcohols
A
mixture of the silica gel-adsorbed acid 2 (0.033 g), 2-
bromoacetic acid (3a) (0.137 g, 0.988 mmol), and phenylmethanol
(4a) (0.108 g, 1.000 mmol) under argon was stirred at 80 ◦C for 24 h.
After the reaction mixture was cooled to room temperature, the
addition of diethyl ether (5 mL × 5) and decantation resulted in
complete separation of the organic layer and the silica gel-adsorbed
acid 2. After the solvent was removed under reduced pressure,
the product was purified by column chromatography on silica
gel with hexane/EtOAc (v/v = 10/1) to give benzyl 2-bromoacetate
(5aa) (0.189 g, 83%). The silica gel-adsorbed acid 2 was dried under
vacuum at room temperature, and recovered as a white powder
(0.033 g, 99%).
2.3.8. Benzyl 2-(benzyloxycarbonylamino)acetate (8) [14]
Yield 88%; Mp 69.0–69.5 ◦C; Rf 0.17 (CH2Cl2); IR (KBr) 1717
(C O), 1735 (C O) cm−1 1H NMR (CDCl3, 400 MHz) ı 3.99 (d,
;
J = 5.31 Hz, 2H), 5.11 (s, 2H), 5.16 (s, 2H), 5.35 (br, 1H), 7.33–7.37
(m, 10H); 13C NMR (CDCl3, 100 MHz) ı 42.7 (s), 67.0 (s), 67.1 (s),
128.0 (s), 128.1 (s), 128.3 (s), 128.5 (s), 128.6 (s), 135.1 (s), 136.1
(s), 156.2 (s), 169.9 (s); HRMS (EI) 299.1156 (C17H17NO4 requires
299.1158 (M+)).
2.3.1. Benzyl 2-bromoacetate (5aa) [8]
2.3.9. Benzyl 2-methoxyacetate (10)
Yield 82%; Rf 0.52 (hexane:EtOAc = 10:1); IR (KBr) 1738
Yield 65%; Rf 0.45 (hexane:EtOAc = 10:1); IR (KBr) 1755
(C O) cm−1
;
1H NMR (CDCl3, 400 MHz) ı 3.85 (s, 2H), 5.19 (s, 2H),
(C O) cm−1 1H NMR (CDCl3, 400 MHz) ı 3.42 (s, 3H), 4.04 (s, 2H),
;