1H NMR spectrum, δ, ppm (J, Hz): 6.91 (1H, d, J ~ 4, H thiophene); 6.88 (1H, d, J ~ 4, H thiophene); 6.78 (1H,
d, J ~ 4, H thiophene); 6.75 (1H, s, H pyrrole); 6.72 (1H, d, J ~ 4, H thiophene); 3.88 (2H, t, J ~ 7, NCH2); 2.57
(3H, s, CCH3); 2.52 (3H, s, CCH3); 2.16 (3H, s, CH3CO); 1.60-1.10 (12H, m, 6CH2); 0.88 (3H, t, J ~ 7,
CH2CH3). Found, %: C 71.20; H 7.60; S 15.22. C24H31NOS2. Calculated, %: C 69.69; H 7.55; S 15.50.
B. As in the above method but holding the reaction mixture for 2 h gave the starting 1c (0.014 g, 7%),
the monoacylation product 7b (0.043 g, 19%), and the diacylation product 8b (0.086 g, 35%) as an oil. 1H NMR
spectrum, δ, ppm (J, Hz): 6.92 (2H, d, J ~ 4, H thiophene); 6.78 (2H, d, J ~ 4, H thiophene); 3.76 (2H, t, J ~ 7,
NCH2); 2.55 (6H, s, 2CCH3); 2.16 (6H, s, 2CH3CO); 1.60-1.00 (12H, d, 6CH2); 0.88 (3H, t, J ~ 7, CH2CH3).
Found, %: C 68.40; H 7.58; S 13.52. C26H33NO2S2. Calculated, %: C 68.53; H 7.30; S 14.07.
C. Acetic anhydride (0.05 g, 0.5 mmol) was added to a solution of compound 1c (0.15 g, 0.4 mmol) in
dry benzene (20 ml) at 10ºC followed by dropwise addition of a solution of SnCl4 (0.027 g, 0.45 mmol) in
benzene (1 ml). The dark-violet solution formed was held for 3 h at room temperature and poured into iced
water. When shaken the mixture took on a light-lilac color. The organic layer was separated, washed with dilute
HCl and water, and dried over MgSO4. Evaporation of the solvent gave an oil (0.2 g), column chromatography
of which (PE–EA, 10:1) gave the starting 1c (0.04 g, 27%) and the product 7b (0.08 g, 48%), identical to the
sample prepared as in method A by TLC.
3-Hydroxymethyl-1-methyl-2,5-bis(5-methyl-2-thienyl)-1H-pyrrole (9a). A solution of NaBH4
(0.1 g, 2.66 mmol) in absolute ethanol (1.5 ml) was added at ~ 20ºC to a suspension of aldehyde 2b (0.2 g,
0.66 mmol) in methanol (3.5 ml). After 15 min a solution was formed which was held for 2 h at room
temperature, water (1.5 ml) saturated with potassium carbonate was added, and the product was extracted with
ether. Evaporation of solvent gave ~ 0.2 g of white, crystalline product 9a (quantitative yield) with mp 88-91ºC,
stable upon storage, which was then washed with hexane to give an analytically pure sample with mp 95ºC.
1H NMR spectrum, δ, ppm (J, Hz): 6.88 (1H, J ~ 4, H thiophene); 6.85 (1H, d, J ~ 4, H thiophene); 6.80 (1H,
br. s, H thiophene); 6.73 (1H, br. s, H thiophene); 6.39 (1H, s, H pyrrole); 4.52 (2H, br. s, CH2); 3.60 (3H, s,
NCH3); 2.55 (3H, s, CCH3); 2.53 (3H, s, CCH3); the OH signal was not observed because of exchange with
water present in the CDCl3. Mass spectrum, m/z (Irel, %): 303 [M]+ (100), 286 [M-OH]+ (30). Found, %: C 63.55;
H 5.87; N 4.60. C16H17NOS2. Calculated, %: C 63.32; H 5.65; N 4.63.
2,6-Dimethyl-1,3,5,7-tetrakis(5-methyl-2-thienyl)-4,8-dihydropyrrolo[3,4-e]benzo[b]pyrrole (11a).
Upon keeping a solution of carbinol 9a in chloroform or methylene chloride containing traces of HCl it was
gradually converted to compound 11a with mp 240-250ºC. An analytically pure sample formed after column
1
purification (PE–EA, 10:1) has mp 255ºC. H NMR spectrum, δ, ppm (J, Hz): 6.62 (4H, br. s, H thiophene);
6.48 (4H, d, J ~ 4, H thiophene); 3.68 (4H, s, 2CH2); 3.31 (6H, s, 2NCH3); 2.49 (12H, s, 4CCH3). Mass
spectrum, m/z (Irel, %): 570 [M]+ (100), 303 (72). Found, %: C 67.43; H 5.43; N 4.56. C32H30N2S4. Calculated,
%: C 67.32; H 5.30; N 4.93.
3-Hydroxymethyl-2,5-bis(5-methyl-2-thienyl)-1-octyl-1H-pyrrole (9b) and 1,3,5,7-Tetrakis(5-methyl-
2-thienyl)-2,6-dioctyl-4,8-dihydropyrrolo[3,4-e]benzo[b]pyrrole (11b). A suspension of aldehyde 2c (0.29 g,
0.73 mmol) in a solution of NaBH4 (0.125 g, 3.32 mmol) in MeOH (7 ml) was stirred for 3 h at a temperature
not exceeding 20ºC. A saturated solution of K2CO3 (1.5 ml) was added to the solution formed which was then
extracted with ether. The extract was dried, evaporated, and the residue was column chromatographed (PE–EA,
20:1) to give the products 11b (0.08 g, 27%) and 9b (0.17 g, 51%), both in the form of an oil.
Compound 11b. Mass spectrum, m/z (Irel, %): 653 [M–C8H17]+ (56), 540 [M–C8H17–C8H17]+ (21), 384
[M/2+H]+ (36), 149 (75), 59 (100). Found, %: C 71.35; H 7.85; N 3.31. C46H30N2S4. Calculated, %: C 72.01;
H 7.62; N 3.65.
Compound 9b. 1H NMR spectrum, δ, ppm (J, Hz): 6.86 (1H, d, J ~ 4, H thiophene); 6.85 (1H, d, J ~ 4,
H thiophene); 6.78 (1H, d, J ~ 4, H thiophene); 6.73 (1H, d, J ~ 4, H thiophene); 6.40 (1H, s, H pyrrole); 4.50
(2H, br. s, OCH2); 4.00 (2H, t, J ~ 7, NCH2); 2.55 (3H, s, CCH3); 2.52 (3H, s, CCH3); 1.50-1.10 (12H, m,
6CH2); 0.88 (3H, t, J ~ 7, CH3). The OH signal was not observed due to exchange with water present in CDCl3.
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