2-[2-(1,3-Dihexyl-2-methyl-2,3-dihydro-1H-benzo[d]imidazol-2-
yl)ethyl]-1,3-dihexyl-2-methyl-2,3-dihydro-1H-benzo[d]imidazole
7. Dimer 7 was prepared from N,N-dihexyl-1,2-benzenediamine
(1.21 g, 4.38 mmol), acetonylacetone (0.25 g, 2.19 mmol) and
p-toluenesulphonic acid (83.0 mg, 0.44 mmol) in toluene (20 mL).
The solution was refluxed under nitrogen for 20 h using a flask
provided with a condenser and a Dean–Stark trap. The toluene was
removed under reduced pressure and dichloromethane (30 mL)
was added. The solution was washed with NaHCO3 (saturated
solution, 2 ¥ 20 mL), water (2 ¥ 20 mL), dried over MgSO4,
filtered and concentrated in vacuo to give a black oil. This
oil was purified by column chromatography (neutral alumina,
hexane–ethyl acetate, 99 : 1) to afford green crystals which were
recrystallised from hot methanol, precipitating the d◦esired product
was neutralised with glacial acetic acid until the pH was weakly
basic to litmus. A brown solid precipitated out during this time.
The solid was filtered, washed with water and dried under reduced
pressure to yield the desired amine. The crude material was
purified by column chromatography (neutral alumina, hexane–
dichloromethane, 60 : 40) to afford the desi◦red product as◦a light-
1
brown solid (20.8 g, 66%). M.p. 102–103 C (Lit.,30 101 C); H
NMR (400 MHz; CDCl3) d 2.81 (6 H, s), 5.40 (2 H, br s), 6.52
(2 H (H 2 & 7), br dd, J = 7.3, 1.0 Hz), 7.18 (2 H (H 4 & 5), br dd,
J = 8.3, 1.5 Hz), 7.24 (2 H (H 3 & 6), br dd, J = 8.0, 7.6 Hz); 13
C
NMR (100 MHz; CDCl3) d 32.3 (C-1¢, q), 106.6 (C-2, d), 117.1
(C-8a, s), 119.3 (C-4, d), 126.6 (C-3, d), 137.0 (C-1, s), 147.9 (C-8a,
s); MS m/z (EI) 186 (M+, 100), 168 (83) 154 (57), 143 (23), 127 (38),
115 (46); Anal. Calcd for C12H14N2: C, 77.38; H, 7.58; N, 15.04.
Found C, 77.52; H, 7.60; N, 14.75; IR (ATR) nmax/cm-1 3354
(aromatic secN–H), 3052 (aromatic C–H), 2902 (aliphatic C–H),
1300 (secamine), 1585, 806 & 752 (1,2,3-trisubstituted aromatic).
1
as fine white crystals (1.09 g, 79%). M.p. 83–84 C; H NMR
(400 MHz; CDCl3) d 0.83 (12 H, t, J = 6.8 Hz), 1.12 (6 H, s),
1.25 (28 H, br m), 1.54 (4 H, s), 1.61 (8 H, m), 2.90 (8 H, m),
6.03 (4 H, dd, J = 3.1, 3.4 Hz), 6.41 (4 H, dd, J = 3.2, 3.2 Hz));
13C NMR (100 MHz; CDCl3) d 14.1 (C-6¢, 4q), 22.8 (C-5¢, 4t),
24.1 (C-1, 4q), 27.3 (C-4¢, 4t), 29.0 (C-3¢, 4t), 31.0 (C-¢2, 2t), 31.8
(C-2¢, 4t), 43.6 (C-1¢, 4t), 88.3 (C-2, 2 s), 101.7 (C-4, -7, 2d), 116.7
(C-5, -6, 2d), 140.6 (C-3a, -7a, 4 s); MS m/z (EI) 631 (M+, 2), 313
(32), 301 (100) 145 (9), 133 (8); HRMS found 630.5609, C42H70N4
requires 630.5601; Anal. Calcd for C42H70N4: C, 79.94; H, 11.18;
N, 8.88. Found C, 80.48; H, 11.13; N, 9.11; IR (ATR) nmax/cm-1
2925 (C–H), 1300 (tertamine) & 1159, 1119, 870 (1,2-disubstituted
benzene).
2,2-Diethyl-1,3-dimethyl-2,3-dihydro-1H-perimidine. To a so-
lution of N,N¢-dimethyl-1,8-naphthalenediamine (0.62 g,
3.33 mmol) and pentan-3-one (0.32 g, 0.37 mmol) in toluene
(10 mL) was added p-toluenesulphonic acid (63.3 mg, 0.33 mmol)
in a flask under nitrogen with stirring. The solution was refluxed
˚
for 20 h in the presence of 4 A molecular sieves. The toluene was
removed under reduced pressure and dichloromethane (20 mL)
was added. The solution was washed with NaHCO3 (saturated
solution, 2 ¥ 15 mL), water (2 ¥ 15 mL), dried over MgSO4,
filtered and concentrated under reduced pressure to give a brown
solid. This solid was purified by column chromatography (neutral
alumina, hexane–dichloromethane, 80 : 20) to afford the desired
product as a white solid (0.75 g, 80%). M.p. 97–98 ◦C.
2-[2-(1,3-Diethyl-2-methyl-2,3-dihydro-1H-benzo[d]imidazol-2-
yl)ethyl]-1,3-diethyl-2-methyl-2,3-dihydro-1H -benzo[d]imida-
zole. The dimer was prepared from N,N-diethyl-1,2-benzenedi-
amine (1.45 g, 8.84 mmol), acetonylacetone (0.50 g, 4.42 mmol)
and p-toluenesulphonic acid (168.0 mg, 0.88 mmol) in toluene
(15 mL). The solution was refluxed under nitrogen for 20 hours us-
ing a flask provided with a condenser and a Dean–Stark trap. The
toluene was removed under reduced pressure and dichloromethane
(30 mL) was added. The solution was washed with NaHCO3
(saturated solution, 2 ¥ 20 mL), brine (2 ¥ 20 mL), dried over
MgSO4, filtered and concentrated under reduced pressure to give
a black oil. This oil was purified by column chromatography
(neutral alumina, hexane–dichloromethane, 85:15) to afford the
desired product as a blue solid. This blue powder was◦recrystallised
from isopropyl alcohol (1.53 g, 85%). M.p. 140–142 C; 1H NMR
(400 MHz; CDCl3) d 1.19 (6 H, s), 1.23 (12 H, t, J = 7.0), 1.72 (4
H, s), 2.98 - 3.19 (8 H, m), 6.16 (4 H, dd, J = 3.4, 2.9 Hz), 6.49 (4
H, dd, J = 3.4, 3.4 Hz); 13C NMR (100 MHz; CDCl3) d 14.3 (C-2¢,
q), 23.1 (C-1, q), 31.1 (C-¢2, t), 37.2 (C-1¢, t), 88.6 (C-2, s), 102.0
(C-4, -7, d), 116.9 (C-5, -6, d), 140.2 (C-3a, 7a, s); MS m/z (EI)
406 (M+, 12), 201 (12) 189 (100), 160 (20), 145 (28), 133 (25), 119
(6), 92 (10); HRMS found 406.3089, C26H38N4 requires 406.3096;
IR (ATR) nmax/cm-1 2980 (C–H), 1330 (tertamine), 1165, 1112, 929
(1,2-disubstituted benzene).
1,2,3-Trimethyl-2-[2-(1,2,3-trimethyl-2,3-dihydro-1H-2-peri-
midinyl)ethyl]-2,3-dihydro-1H-perimidine 8. Dimer 8 was pre-
pared from a solution of N,N¢-dimethyl-1,8-naphthalenediamine
(0.34 g, 1.81 mmol), acetonylacetone (0.10 g, 0.90 mmol) and
p-toluenesulphonic acid (17.2 mg, 0.09 mmol) in toluene (5 mL).
The solution was refluxed under nitrogen for 20 h using a flask
provided with a condenser and a Dean–Stark trap. The toluene was
removed under reduced pressure and dichloromethane (20 mL)
was added. The solution was washed with NaHCO3 (saturated
solution, 2 ¥ 15 mL), water (2 ¥ 15 mL), dried over MgSO4,
filtered and concentrated under reduced pressure to give a brown
solid. This brown solid was purified by column chromatography
(neutral alumina, hexane–dichloromethane, 70 : 30) to afford a
white powder. Further purification involved crystallisation from
hot ethanol or dissolving in a minimum amount of toluene
and crystallisation by slow diffusion of pentane, precipitating
colourless crystals (1.76 g, 89%). M.p. 147–150 ◦C.
2-(2-[1,3-Dimethyl-2-[2-(1,2,3-trimethyl-2,3-dihydro-1H-2-peri-
midinyl)ethyl]-2, 3-dihydro-1H -2-perimidinylethyl)]-1, 2, 3-tri-
methyl-2,3-dihydro-1H-perimidine 9. Trimer 9 was prepared
from a solution of N,N¢-dimethyl-1,8-naphthalenediamine (0.62 g,
3.34 mmol), 2,5,8-nonanetrione (0.14 g, 0.83 mmol) and
p-toluenesulphonic acid (16.0 mg, 0.08 mmol) in toluene (5 mL).
The solution was refluxed under nitrogen for 20 h using a flask
provided with a condenser and a Dean–Stark trap. The toluene was
removed under reduced pressure and dichloromethane (20 mL)
was added. The solution was washed with NaHCO3 (saturated
N,N¢-Dimethyl-1,8-naphthalenediamine. Nitrogen was bub-
bled through a solution of potassium hydroxide (145.6 g, 2.60 mol)
in ethanol (800 mL) for 5 min. 1,2-Dimethylperimidinyl methio-
dide (58.45 g, 0.17 mol) was added in one portion to the alkaline
ethanolic solution and the resultant solution was refluxed under
nitrogen. After 3 h, the reaction mixture was cooled and diluted
with water to yield a final volume of 2.5 L. The resulting solution
2712 | Org. Biomol. Chem., 2009, 7, 2704–2715
This journal is
The Royal Society of Chemistry 2009
©