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M. J. Plater, T. Jackson / Tetrahedron 59 (2003) 4673–4685
dimethoxytetrahydrofuran (6.00 g, 45.9 mmol) were heated
to reflux at 1168C for 2 h. The mixture was cooled, poured
into H2O (100 mL) and extracted with CH2Cl2. Polar
impurities were removed by filtering through silica and the
solvent was removed under reduced pressure. Recrystalliza-
tion from dichloromethane/hexane yielded the title com-
pound (7.95 g, 65%) as a yellow/orange crystalline solid.
Sublimation of a small quantity gave a white crystalline
solid, mp 128–1298C. (lit. 131–1338C) (Found:C, 44.8; H,
3.0; N, 5.2. C10H8NI requires C, 44.6; H, 3.0; N, 5.2%); nmax
(KBr)/cm21 3148w, 3128m, 3101w, 3064w, 1885w, 1586s,
1496s, 1407m, 1330s, 1247m, 1188m, 1120m, 1078m,
999m, 918m, 815s, 725s, and 608m; dH (250 MHz; CDCl3)
6.35 (2H, t, J¼2.3 Hz, Ar), 7.05 (2H, t, J¼2.14 Hz, Ar),
7.15 (2H, d, J¼8.7 Hz, Ar) and 7.72 (2H, d, J¼8.6 Hz, Ar);
dC (62.9 MHz; CDCl3) 89.4, 111.0, 119.1, 122.2, 128.6 and
140.4; m/z 269.1 (Mþ, 10%).
4.2.22. N-Phenylpyrrole-2-carboxaldehyde 40. To DMF
(3.06 g, 41.9 mmol) cooled in an salt–ice bath was added
dropwise phosphorus oxychloride (6.42 g, 41.9 mmol). A
solution of N-phenylpyrrole (5.0 g, 34.9 mmol) in 1,2-
dichloroethane (100 mL) was added and the mixture
warmed to room temperature and then heated with stirring
at 1008C for 3 h. The mixture was washed with concentrated
aqueous Na2(CO3)2 solution and then distilled H2O (£2).
The organic extract dried over MgSO4 and the solvents
removed under reduced pressure. Column chromatography,
eluting with dichloromethane, yielded a brown/yellow non-
viscous oil which crystallised on standing in the cool to give
the title compound (5.1 g, 84%) as a white crystalline solid,
mp 26–278C. (lit. 27–308C)14 (Found: C, 77.6; H, 5.3; N,
8.1. C11H9NO requires C, 77.2; H, 5.3; N, 8.2%); nmax
(KBr)/cm21 3113w, 3055m, 2985w, 2842w, 2800m,
2782w, 1673s, 1597s, 1525s, 1499s, 1452s, 1415s, 1391s,
1367s, 1329s, 1201w, 1167w, 1063m, 1039s, 888w, 181s,
741s, 699s, 671m and 602m. dH (250 MHz, CDCl3) 6.40–
6.42 (1H, dd, J¼2.5, 6.4 Hz), 7.06–7.08 (1H, t, J¼2.4 Hz),
7.15–7.17 (1H, dd, J¼1.5, 5.5 Hz), 7.31–7.50 (5H, m, Ar)
and 9.57 (1H, s, CHO). dC (62.9 MHz, CDCl3) 110.9, 122.0,
126.1, 128.3, 129.1, 131.1, 132.6, 138.8 and 179.1; m/z 171
(Mþ, 10%).
4.2.20. N-[4-(N0,N0-Diphenylamino)]phenylpyrrole 38.
N-(4-Iodophenyl)pyrrole 37 (1.00 g, 3.72 mmol), N,N-
diphenylamine (0.63 g, 3.72 mmol), copper powder
(0.23 g, 3.72 mmol), K2CO3 (1.03 g, 7.40 mmol), 18-
crown-6 (0.20 g) and o-dichlorobenzene (100 mL) were
heated to 1808C for 90 h. The mixture was allowed to cool
and slurried with CH2Cl2 and filtered. The filtrate was
washed with distilled H2O (£2) and dried over MgSO4.
Solvents were removed under reduced pressure to leave a
yellow/brown solid. Column chromatography, eluting with
dichloromethane/light petroleum (10:90), yielded an off
white solid. Recrystallisation from dichloromethane/light
petroleum gave the title compound (253 mg, 22%), as a
colourless solid, mp 116–1178C (from hexane) (Found: C,
85.0; H, 5.8; N, 9.0. C22H18N2 requires C, 85.1; H, 5.8; N,
9.0%); lmax (CH2Cl2)/nm 308 (log 1 5.13); nmax (KBr)/
cm21 3123m, 3099m, 3055m, 3035m, 1934w, 1910w,
1590s, 1483s, 1449m, 1385w, 1327s, 1314s, 1278s, 1245m,
1172m, 1114m, 1070s, 1020m, 922m, 844m, 824m,
754s, 733s, 696s and 612m; dH (250 MHz; CDCl3)
6.32–6.33 (2H, t, J¼2.14 Hz, Ar), 6.99–7.05 (4H, m, Ar),
7.08–7.15 (6H, m, J¼8.5 Hz, Ar) and 7.22–7.29 (6H, m,
Ar); dC (62.9 MHz; CDCl3) 110.1, 119.4, 121.6, 122.9,
124.2, 124.9, 129.4, 135.8, 145.7 and 147.7; m/z 310 (Mþ,
100%).
4.2.23. N-Phenyl-2-[N-(2,4-dimethyl)phenyl-N-phenyl-4-
(ethenyl)phenylamine]pyrrole 41. In a dry flask a slurry of
4-(N-(2,4-dimethylphenyl)-N-phenylamino)benzyltriphenyl-
phosphonium bromide 19 (2.50 g, 3.97 mmol) and NaH
(0.10 g, 3.97 mmol) in dry THF (40 mL) was stirred under
nitrogen. After 1 h N-phenylpyrrole-2-carboxaldehyde 40
(0.70 g, 3.97 mmol) in dry THF (10 mL) was added
dropwise and the reaction then left to stir at room
temperature for 2 h. The mixture was subsequently
quenched in H2O and extracted with CH2Cl2, dried over
MgSO4 and the solvents removed under reduced pressure to
give a viscous brown oil. Column chromatography, eluting
with dichloromethane/light petroleum mixture (25:75)
yielded two yellow viscous oils. Complete removal of
solvent gave the two isomers of the title compound (0.56 g,
31%) as two yellow solids which proved to be cis, mp 50–
518C, and trans, mp 70–718C, respectively. cis lmax
(CH2Cl2)/nm 300 (log 1 5.52) and 359 (5.67); dH
(250 MHz; CDCl3) 2.01 (3H, s, Me), 2.34 (3H, s, Me),
6.04 (1H, d, J¼12.2 Hz, vinyl), 6.20 (1H, t, J¼2.5 Hz, Ar),
6.25 (1H, d, J¼12.2 Hz, vinyl), 6.42 (1H, dd, J¼1.5, 2.4 Hz,
Ar), 6.82–7.06 (8H, m, Ar) and 7.16–7.44 (10H, m, Ar). dC
(62.9 MHz; CDCl3) 18.5, 21.0, 109.1, 110.2, 118.3, 120.4,
121.4, 121.7, 122.1, 125.8, 126.8, 128.0, 128.1, 128.9,
129.0, 129.4, 129.5, 130.0, 130.3, 132.4, 135.9, 136.3,
139.9, 142.5, 146.4 and 147.3; m/z 440 (Mþ, 100%). trans
(Found: C, 87.3; H, 6.5; N, 6.1. C32H28N2 requires C, 87.2;
H, 6.4; N, 6.4%); lmax (CH2Cl2)/nm 302 (log 1 5.49) and
373 (6.32); nmax (KBr)/cm21 3058w, 3028m, 2916m,
2852w, 1600w, 1591s, 1499s, 1457s, 1414w, 1376w,
1323s, 1289s, 1273s, 1231m, 1175w, 1146w, 1096w,
1036w, 955m, 854w, 813m, 752m, 696s, 672w. 610w; dH
(250 MHz; CDCl3) 1.99 (3H, s, Me), 2.33 (3H, s, Me), 6.31
(1H, t, J¼3.4 Hz, Ar), 6.60 (1H, dd, J¼1.5, 2.1 Hz, Ar),
6.63–6.69 (1H, d, J¼16.2 Hz, vinyl), 6.81 (1H, d,
J¼16.2 Hz, vinyl), 6.85–7.04 (9H, m, Ar), 7.14–7.21
(4H, m, Ar) and 7.33–7.49 (5H, m, Ar). dC (62.9 MHz;
CDCl3) 18.4, 21.0, 106.8, 109.6, 115.9, 121.0, 121.4, 121.5,
4.2.21. N-{4-[N0-(2,4-Dimethylphenyl)]-N0-phenylami-
no}phenylpyrrole 39. General procedure as for 38 N-(4-
iodophenyl)pyrrole 37 (5.00 g, 1.90 mmol), N-(2,4-
dimethylphenyl)-N-phenylamine (3.94 g, 20.0 mmol),
copper powder (1.15 g, 18.0 mmol), K2CO3 (5.15 g,
37.0 mmol), 18-crown-6 (0.50 g) and o-dichlorobenzene
(100 mL) were heated to 1808C for 90 h. Yield 48%;
yellow/orange glass (after sublimation of unreacted starting
materials) (Found:C, 84.9; H, 6.5; N, 7.8. C24H22N2 requires
C, 85.2; H, 6.55; N, 8.2%). lmax (CH2Cl2)/nm 307 (log 1
5.71); nmax (KBr)/cm21 3100w, 3036m, 2917m, 2856w,
1594s, 1513s, 1493s, 1339w, 1326s, 1271s, 1230m, 1116w,
1070s, 1019m, 923m, 821m, 753m, 722s, 693s and 552m;
dH (250 MHz; CDCl3): 2.02 (3H, s, Me), 2.34 (3H, s. Me),
6.30–6.32 (2H, t, J¼2.14 Hz, Ar), 6.88–7.03 (9H, m, Ar),
7.08 (1H, bs, Ar) and 7.17–7.25 (4H, m, Ar); dC (62.9 MHz;
CDCl3) 18.5, 21.1, 109.9, 119.5, 121.3, 121.4, 121.5, 122.0,
128.2, 129.1, 129.4, 132.5, 134.6, 136.0, 136.2, 142.5, 145.6
and 147.4; m/z 338 (Mþ, 100%).