DEEPA ET AL.
3
12 mmol), acetone (13 mL) and i‐PrOH (17 mL) were
taken and p‐TsOH H2O (0.07 g, 0.37 mmol) was added
in the mixture. The resulting solution was stirred at 85 °
C for 5 h. The solvent in the round bottom flask was
removed under vacuum to give light brown oil. The oil
was diluted with MeOH (1.5 mL) and an ice‐cold
methanolic HCl solution (prepared from 1.3 mL of acetyl
chloride was added to ice‐cooled 5 mL Methanol.) was
added slowly. Later, Et2O (25 mL) was slowly added to
give white precipitate and further stirred for 30 min, fil-
tered and washed with Et2O (7 mL). The white solid dried
to give (5R)‐5‐benzyl‐2,2‐dimethyl‐3‐(2‐hydroxyethyl)‐
imidazolidin‐4‐one hydrochloride 5. Mp = 152.2 °C;
4.16(t, J = 6.8 Hz, 4H), 3.80 (s, 6H), 1.80 (quintet,
J = 6.8 Hz, 4H), 1.23 (quintet, J = 7.6 Hz, 2H,). 13C
NMR (DMSO‐d6, 100 MHz): δ = 137.0 (2C), 124.0 (2C),
122.7 (2C), 48.8 (2C), 36.3 (2C), 29.0 (2C), 22.3 ppm. IR
(ATR) ῡ = 3414, 3146, 2944, 1628, 1569, 1459, 1238,
▪
1166, 838, 745, 657 cm−1
.
2.2.6 | 3,3′‐(Pentane‐1,5‐diyl)bis(1‐methyl‐
1H‐imidazol‐3‐ium) boron tetrafluoride
(11b)
25
½αꢀD = − 51.3 (c 1.0, MeOH); 1H NMR (DMSO‐d6,
Compound 11a (1.18 g, 3.0 mmol) and NaBF4 (1.30 g,
12 mmol) was dissolved in mixture of 5 mL CH3OH/
H2O (1:1). Methanol was removed at reduced pressure
to give transparent solution. The aqueous phase
was decanted off and residue was dissolved in DCM.
The solvent was evaporated and residue was dried
under reduced pressure to afford compound 11b
(1.18 g, 97%).
400 MHz): δ = 7.42 (d, J = 7.6 Hz, 2H), 7.31 (d,
J = 7.6 Hz, 2H), 7.25–7.22 (m, 1H), 4.57 (brs, 1H), 3.54
(t, J = 5.2 Hz, 1H), 3.46 (t, J = 6.4 Hz, 2H), 3.27 (t,
J = 6.4 Hz, 2H), 3.23–3.19 (m, 2H), 1.67 (s, 3H), 1.48 (s,
3H) ppm. 13C NMR (DMSO‐d6, 100 MHz): δ = 167.7,
136.9, 129.9 (2C), 129.0 (2C), 127.4, 77.7, 58.9, 57.5, 42.7,
33.4, 24.6, 23.8 ppm. IR (ATR) ῡ = 3359, 2981, 1666,
1H NMR (DMSO‐d6, 400 MHz): δ = 9.32 (s, 2H), 7.83
(s, 2H), 7.72 (s, 2H), 4.16 (t, J = 7.1 Hz, 4H), 1.78 (quintet,
J = 7.2 Hz, 4H), 1.16 (quintet, J = 8 Hz, 2H) ppm. 13C
NMR (DMSO‐d6, 100 MHz): δ = 137.1 (2C), 123.7 (2C),
122.6 (2C), 48.7 (2C), 36.3 (2C), 28.8 (2C), 22.7 ppm. 19F
NMR (DMSO‐d6, 304 MHz) δ −147.86 ppm. IR (ATR)
ῡ = 3417, 3150, 2948, 1631, 1571, 1428, 1286, 1167,
1531, 1416, 1308, 1057, 745, 699, 666 cm−1
.
2.2.4 | (S)‐5‐Benzyl‐3‐(2‐hydroxyethyl)‐2,2‐
dimethylimidazolidin‐4‐one (1)
Compound 5 (1 g, 3.5 mmol) was dissolved in CH2Cl2 and
then add saturated NaOH solution dropwise (maintain
pH 9). Extract the solution in CH2Cl2 (3x25 mL). Evapo-
rated CH2Cl2 to get the desired compound 1 as yellowish
1056, 841, 750, 651 cm−1
.
viscous liquid (0.850 g, 98%). ½αꢀ2D5 = − 51.3 (c 1.0, MeOH);
1H NMR (CDCl3, 400 MHz): δ = 7.29 (t, J = 7.1 Hz, 2H),
7.26–7.18 (m, 3H), 3.82 (t, J = 5.4 Hz, 1H), 3.78–3.69 (m,
1H), 3.68–3.59 (m, 1H), 3.41 (dq, J = 14.6, 3.5 Hz, 1H),
3.19–3.09 (m, 1H), 3.07 (d, J = 5.4 Hz, 2H), 1.26 (s, 3H),
1.10 (s, 3H). 13C NMR (CDCl3, 100 MHz) 176.3, 136.7,
129.6 (2C), 128.7 (2C), 127.1, 76.7, 62.5, 58.8, 44.2, 37.0,
27.7, 26.5 ppm. IR (ATR) ῡ = 3359, 2981, 1666, 1531,
2.2.7 | 3,3′‐(Pentane‐1,5‐diyl)bis(1‐methyl‐
1H‐imidazol‐3‐ium) phosphorus
hexafluoride (11c)
Compound 11a (1.18 g, 3.0 mmol) and KPF6 (2.21 g,
12 mmol) was dissolved in mixture of 5 mL CH3OH/
H2O (1:1). Methanol was removed at reduced pressure
to give transparent solution. The aqueous phase was
decanted off and residue was dissolved in DCM. The sol-
vent was evaporated and residue was dried under reduced
pressure to afford compound 11c (1.52 g, 97). mp = 72.2 °
1416, 1308, 1057, 745, 699, 666 cm−1
.
2.2.5 | 3,3′‐(Pentane‐1,5‐diyl)bis(1‐methyl‐
1H‐imidazol‐3‐ium) bromide (11a)
1
C H NMR (DMSO‐d6, 400 MHz): δ = 9.00 (s, 2H), 7.68–
7.67 (m, 2H), 7.63–7.62 (m, 2H), 4.11 (t, J = 8 Hz, 4H),
3.80 (s, 6H), 1.78 (quintet, J = 8 Hz, 4H), 1.19 (quintet,
J = 7.6 Hz, 2H), ppm. 13C NMR (DMSO‐d6, 100 MHz):
δ = 137.0 (2C), 124.1 (2C), 122.7 (2C), 48.9 (2C), 36.2
(2C), 29.1 (2C), 22.5 ppm. 19F NMR (DMSO‐d6,
304 MHz): δ = −70.34 (d, J = 644.5 Hz) ppm, 31P NMR
1,5‐Dibromo pentane (2 mL, 14.6 mmol) and N‐methyl
imidazole (3 ml, 36.6 mmol) was heated at 100 °C for
1.5 h after that reaction mixture was cooled to room tem-
perature and then washed with diethyl ether to remove
excess of N‐methyl imidazole. Decant off ether. The com-
pound was dried under reduced pressure to afford ionic
(DMSO‐d6, 162 MHz):
J = 748.7 Hz) ppm. IR (ATR) ῡ = 3170, 2954, 1575,
1463, 1172, 1109, 812, 740, 648, 617, 551 cm−1
δ
=
−143.63 (septet,
1
liquid 11a (5.16 g, 90%). H NMR (DMSO‐d6, 400 MHz):
δ = 9.90 (s, 2H), 7.63–7.61 (m, 2H), 7.25–7.20 (m, 2H),
.