C. Marshall et al. / Journal of Organometallic Chemistry 690 (2005) 3970–3975
3973
(NCH), 123.6 (NCH), 136.8 (N2CH); (ESI), 341.0 (12%,
[M ꢀ Br79]+), 339.0 (11%, [M ꢀ Br81]+), 129.9 (100%,
[M ꢀ 2Br]2+).
1.38 (2H, m, CH2CH2CH2), 1.54–1.60 (2H, m,
CH2CH2), 1.71–1.79 (2H, m, CH2CH2) 2.30–2.32 (2H,
m, CH), 3.54 (6H, s, NCH3), 3.84–3.90 (2H, dd, J 4.8
and 5.3, NCH2), 3.98–4.08 (2H, dd,J 5.3 and 4.8,
NCH2), 6.62 (2H, s, NCH), 6.82 (2H, s, NCH); dC
(62.9 MHz; CDCl3) 23.9 (CH2), 30.4 (CH2), 35.2
(NCH3), 43.1 (CH), 51.7 (NCH2), 117.5 (NCH), 117.7
(NCH), 162.3 (C@S; m/z (ESI) 323.1363 [M + H]+),
C15H22N4S2requires 323.1364, (ESI), 323.1 (100%,
[M + H]+).
(1R,2R)-1,2-Bis(1-methylimidazolium-3-methyl)-
cyclopentane dibromide [(1R, 2R)5a]
The procedure for the synthesis of (1S,2S)-5a was fol-
lowed using 1-methylimidazole (0.59 g, 3.9 mmol) and
(1R,2R)-1,2-Bis(bromomethyl)cyclopentane (0.5 g,
1.96 mmol) to give the dibromide salt (1.09 g, 100%) as
23
D
a light yellow glass; ½aꢁ 17.0 (c 0.02 in H2O).
(1R,2R)-1,2-bis(1-methylimidazol-2-thio-3-methyl)-
cyclopentane [(1R, 2R)6a]
4.2.2. (1S,2S)-1,2-Bis(1-cyclohexylimidazolium-3- methyl)-
cyclopentane dibromide [(1S, 2S)5b]
The procedure for the synthesis of (1S,2S )-5a was
followed using 1-cyclohexylimidazole (0.7 g, 4.66 mmol)
and (1S,2S)-1,2-Bis(bromomethyl)cyclopentane (0.6 g,
The procedure for the synthesis of [(1S, 2S) 6a] using
(1R,2R)-1,2-bis(1-methylimidazolium-3-methyl)cyclo-
pentane dibromide (0.77 g, 1.84 mmol), sulphur (0.18 g,
5.53 mmol), methanol (10 cm3), pyridine (0.9 g,
11.0 mmol) and 1,8-diazabicyclo[5.4.0]undec-7-ene
2.33 mmol) to give the dibromide salt (1.3 g, 100%) as
23
D
a light yellow glass; ½aꢁ 5.4 (c 0.02 in H2O); 3126
(1.21 g, 8.10 mmol) gave the dithione (0.45 g, 76%) as
25
colourless crystals; m.p. 154 ꢁC (from methanol); ½aꢁ
(CH), 3075 (CH), 3043 (CH), 2931 (CH), 2857 (CH),
1449 (CH), 1365 (CH); dH(250 MHz; DMSO) 1.08–
1.90 (22H, m, CH2), 2.06 (4H, m, CH2CH2), 2.20 (2H,
m, CH), 4.09 (2H, m, NCH), 4.25 (4H, m, NCH2),
7.90–7.93 (4H, d,J 7, NCH), 9.61 (2H, s, N2CH);
dC(62.9 MHz; DMSO) 23.4 (CH2), 24.4 (CyCH2), 24.5
(CyCH2), 29.2 (CH2), 32.4 (CyCH2), 42.4 (CH), 52.0
(NCH2), 58.6 (NCH), 121.2 (NCH), 122.3 (NCH),
135.1 (N2CH). (ESI), 477.2 (100%, [M ꢀ Br79]+), 475.2
(98%, [M ꢀ Br81]+).
D
ꢀ35.8 (c 1.0 in CH2Cl2).
4.2.4. (1S,2S)-1,2-bis(1-cyclohexylimidazol-2-thio-3-
methyl) cyclopentane [(1S, 2S)6b]
The procedure for the synthesis of [(1S, 2S) 6a] using
(1S,2S)-1,2-bis(1-cyclohexylimidazolium-3-methyl)cyclo-
pentane dibromide (1.18 g, 2.12 mmol), sulphur (0.20 g,
6.35 mmol), methanol (15 cm3), pyridine (1.5 g,
19 mmol)
and
1,8-diazabicyclo[5.4.0]undec-7-ene
(1R,2R)-1,2-bis(1-cyclohexylimidazolium-3-methyl)-
cyclopentane dibromide [(1R, 2R)5b]
The procedure for the synthesis of (1S,2S)-5a was fol-
lowed using 1-cyclohexylimidazole (0.59 g, 3.9 mmol)
and (1R,2R)-1,2-bis(bromomethyl)cyclopentane (0.5 g,
(1.41 g, 9.42 mmol) gave the residue, which was purified
by column chromatography (SiO2, ethyl acetate: petro-
leum ether-1:1, loaded as a dichloromethane solution)
to give the dithione (0.90 g, 93%) as a colourless solid;
24
m.p. 86 ꢁC; ½aꢁ 31.42 (c 1.5 in CH2Cl2); mmax (KBr)/
D
1.96 mmol) to give the dibromide salt (1.09 g, 100%) as
cmꢀ1 2927 (CH), 2854 (CH); dH(250 MHz; CDCl3)
1.06–1.94 (26H, m, CH2), 2.22–2.30 (2H, m, CH),
3.78–4.03 (4H, dddd, J 6, 7.5 and 11, NCH2), 4.54–
4.63 (2H, m, NCH), 6.62 (2H, d,J 2.3, NCH), 6.78
(2H, d,J 2.3, NCH); dC(62.9 MHz; CDCl3) 23.77
(CH2), 25.3 (CyCH2), 25.4 (CyCH2), 30.3 (CH2), 32.5
(CyCH2), 42.3 (CH), 50.9 (NCH2), 56.1 (NCH), 113.7
(NCH), 117.6 (NCH), 160.8 (C@S); m/z (ESI)
459.2616 ([M + H]+, C25H38N4S2requires 459.2616),
(FAB), 481.4 (23%, [M + Na]+), 459.4 (100%, [M +
H]+), 458.4 (76%, [M]+).
23
D
a light yellow glass; ½aꢁ ꢀ5.6 (c 0.02 in H2O).
4.2.3. (1S,2S)-1,2-bis(1-methylimidazol-2-thio-3-methyl)-
cyclopentane [(1S, 2S)6a]
A mixture of (1S,2S)-1,2-bis(1-methylimidazolium-3-
methyl)cyclopentane dibromide (1.44 g, 3.4 mmol), sul-
phur (0.33 g, 10.3 mmol), methanol (20 cm3), pyridine
(1.8 g, 22.8 mmol) and 1,8-diazabicyclo[5.4.0]undec-7-
ene (2.27 g, 15.2 mmol) was heated at 65 ꢁC for 6 h.
Once cooled to room temperature the mixture was
opened to water (100 cm3) and extracted with dichloro-
methane (3 · 30 cm3). The combined extracts were
washed with 8% (aq) HCl (2 · 50 cm3) before being
dried over magnesium sulphate, filtered and concen-
trated under reduced pressure to leave an orange
residue. The residue was purified by column chromatog-
raphy (SiO2, ethyl acetate, loaded as a dichloromethane
solution) to give the dithione (0.87 g, 79%) as a colour-
(1R,2R)-1,2-bis(1-cyclohexylimidazol-2-thio-3-methyl)-
cyclopentane [(1R, 2R)6b]
The procedure for the synthesis of [(1S, 2S) 6a]
using (1R,2R)-1,2-bis(1-cyclohexylimidazolium-3-methyl)
cyclopentane dibromide (1.03 g, 1.86 mmol), sulphur
(0.18 g, 5.53 mmol), methanol (10 cm3), pyridine (0.9 g,
11.13 mmol) and 1,8-diazabicyclo[5.4.0]undec-7-ene
(1.23 g, 8.11 mmol) gave the residue, which was purified
by column chromatography (SiO2, ethyl acetate: petro-
leum ether-1:1, loaded as a dichloromethane solution)
less solid which was recrystallised from methanol to give
colourless crystals; m.p. 152 ꢁC (from methanol); ½aꢁ
23
D
36.4 (c 2.5 in CH2Cl2); mmax (KBr)/cmꢀ1 2956 (CH),
2928 (CH), 2867 (CH); dH(250 MHz; CDCl3) 1.34–
to give the dithione (0.81 g, 95%) as a colourless solid;
25
D
m.p. 86 ꢁC; ½aꢁ ꢀ30.23 (c 1.2 in CH2Cl2).