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Title:
IMPROVED METHOD FOR THE SYNTHESIS OF PYRROLO[3,2-B]PYRROLES
Document Type and Number:
WIPO Patent Application WO/2020/185105
Kind Code:
A1
Abstract:
An improved method for the synthesis of pyrrolo[3,2-b] pyrroles using iron (III) salts as a catalyst is disclosed.

Inventors:
GRYKO DANIEL (PL)
TASIOR MARIUSZ (PL)
KOSZARNA BEATA (PL)
YOUNG DAVID C (PL)
Application Number:
PL2020/050022
Publication Date:
September 17, 2020
Filing Date:
March 14, 2020
Export Citation:
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Assignee:
INST CHEMII ORGANICZNEJ PAN (PL)
International Classes:
C07D487/04; C07B37/10
Other References:
KRZESZEWSKI, M. ET AL.: "Tetraaryl-, Pentaaryl-, and Hexaaryl-1,4- dihydropyrrolo[3,2-b]pyrroles: Synthesis and Optical Properties", THE JOURNAL OF ORGANIC CHEMISTRY, vol. 79, no. 7, March 2014 (2014-03-01), pages 3119 - 3128, XP055739199, DOI: 10.1021/jo5002643
BANASIEWICZ M. ET AL.: "Electronic Communication in Pyrrolo[3,2-b] pyrroles Possessing Sterically Hindered Aromatic Substituents", EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, vol. 2019, no. 31-32, January 2019 (2019-01-01), pages 5247 - 5253, XP055739207, DOI: 10.1002/ejoc.20181809
MARTINS, LM. ET AL.: "Improved synthesis of tetraaryl-1,4-dihydro- pyrrolo[3,2-b]pyrroles a promising dye for organic electronic devices: An experimental and theoretical approach", DYES AND PIGMENTS, vol. 148, January 2018 (2018-01-01), pages 81 - 90, XP085236001, DOI: 10.1016/j.dyepig.2017.08.056
MAITI S . ET AL.: "Iron(III)-Catalyzed Four-Component Coupling Reaction of 1,3-Dicarbonyl Compounds, Amines, Aldehydes, and Nitroalkanes: A Simple and Direct Synthesis of Functionalized Pyrroles", THE JOURNAL OF ORGANIC CHEMISTRY, vol. 75, no. 5, February 2010 (2010-02-01), pages 1674 - 1683, XP055739211, DOI: 10.1021/jo902661y
PILTAN, M.: "One-pot synthesis of pyrrolo[1,2-a]quinoxaline and pyrrolo[1,2-a]pyrazine derivatives via the three-component reaction of 1,2-diamines, ethyl pyruvate and a-bromo ketones", CHINESE CHEMICAL LETTERS, vol. 25, no. 11, November 2014 (2014-11-01), pages 1507 - 1510, XP029092563, DOI: 10.1016/j.cclet.2014.06.013
Attorney, Agent or Firm:
WITEK, Rafał (PL)
Download PDF:
Claims:
Claims

1. A method for the preparation of compounds of formula I:

wherein R1 and R2 are, each independently, an aryl or heteroaryl, optionally substituted with one or more substituents selected, each independently, from: alkyl, alkoxy, aryl, heteroaryl, CN, NO2 and halogen,

characterized in that the reaction of aromatic aldehyde Ar1CHO, aromatic amine Ar2NH2 and butane-2, 3-dione, in a mixture of organic solvents, at a temperature of 0-150 °C, in an open reaction vessel, in the presence of an iron (III) salt catalyst is carried out.

2. The method according to Claim 1, characterized in that one of the solvents being part of said organic solvent mixture is organic acid and the other solvent being part of said organic solvent mixture is preferably selected from toluene, xylene, tetrahydrofuran and dioxane.

3. The method according to Claim 1 or 2, characterized in that one of the solvents being part of said organic solvent mixture is acetic acid and the other solvent being part of said organic solvent mixture is toluene.

4. The method according to Claims 1-3, characterized in that said organic solvents are used in a 1: 1 (v/v) ratio.

5. The method according to Claim 1, characterized in that the reaction is carried out at 0-150 °C, preferably at 90 °C.

6. The method according to Claim 1, characterized in that the reaction is carried out in the presence of an iron (III) salt catalyst, preferably selected from iron (III) chloride, iron (III) triflate or iron (III) perchlorate hydrate.

Description:
Improved method for the synthesis of pyrrolo[3,2-b]pyrroles

The present invention relates to an improved method for the synthesis of pyrrolo[3,2-b pyrroles .

Many methods of preparation of pyrrolo[3,2-b pyrroles are known in the art.

Tsutomu Kamagai et al. (Tetrahedron Letters, 25 (49), 1984, pp. 5669-5672) described 1,4- dihydropyrrolo[3,2-b pyrroles and the method of their preparation.

Japanese patent applications JP 62207276 Al and JP 2010238889 Al describe N-alkyl dihydropyrrolo-pyrroles and the method of their preparation, and their use in the production of polymers with semiconducting properties.

Polish patent PL 227162 and publication in Asian Journal of Organic Chemistry, 2 (5), 2013, pp. 411-415 describes the method for preparation of pyrrolo[3,2-b pyrroles and their optical properties.

Polish patent application PL 226856 and publication in the Journal of Organic Chemistry, 79 (7), 2014, pp. 3119-3128 describe the method for preparation of pyrrolo[3,2-b pyrroles as well as their optical properties and oxidation potentials.

Pyrroles [3,2 -b] pyrroles having aryl rings exhibit interesting spectroscopic properties, such as high Stokes shift (i.e. difference in the position of absorption and fluorescence bands), as well as high absorption coefficient and high fluorescence quantum efficiency. In addition, they have very low oxidation potential. Pyrrolo[3,2-b pyrroles derivatives proved to be excellent model systems for studying symmetry breaking in excited state (DH Friese et al., Chemistry - A European Journal, 21 (50), 2015, pp. 18364-18374), direct solvent probing via H-bonding interactions (B. Dereka and E. Vauthey, Chemical Science, 8, 2017, pp. 5057-5066), resistive memory devices (RKC Balasubramanyam et al., Journal of Physical Chemistry C, 120 (21), 2016, pp. 11313- 11323), aggregation-induced emission (B. Sadowski et al., Organic Letters, 20 (11), 2018, pp. 3183-3186) and photochromic analysis of halocarbons (J.-Y Wu et al., Analitical Chemistry, 88 (2), 2016, pp. 1195- 1201).

Due to the growing interest in pyrrolo[3,2-b pyrroles , there has been a need for improved methods for the synthesis of these compounds. This demand results, among others on the development of fluorimetric techniques and increasing the universality of their use in modem biomedical techniques and diagnostics (e.g. optical imaging). In addition, compounds emitting blue light and having very narrow emission bands are particularly desirable from the point of view of their use in the production of organic light-emitting diodes (OLEDs).

Unfortunately, methods for making pyrrolo[3,2-b]pyrroles known in the art are far from perfect, providing synthesis yields not exceeding 50% and showing a narrow range of applicability. The above problem found a solution in the present invention.

The present invention relates to a process for the preparation of compounds of formula I

wherein R 1 and R 2 are each independently an aryl or heteroaryl, optionally substituted with one or more substituents selected, each independently, from: alkyl, alkoxy, aryl, heteroaryl, CN, NO 2 and halogen, characterized in that the reaction of aromatic aldehyde Ar 1 CHO, aromatic amine Ar 2 NH 2 and butane-2, 3-dione, in a mixture of organic solvents, at a temperature of 0-150 °C, in an open reaction vessel, in the presence of an iron (III) salt catalyst is carried out, preferably according to the Scheme 1 shown in Example 1.

Preferably, the aryl is selected from phenyl, naphthyl and anthracenyl group.

Preferably, the heteroaryl is selected from quinoxalin-2-yl, thiazol-2-yl, benzothiazol-2-yl, fur- 2-yl, thien-2-yl, benzothien-2-yl and acridin-9-yl group.

Preferably, the alkyl group is any straight or branched chain alkyl, preferably selected fromCH 3 , t-C 4 H 9 and C 8 H 17 .

Preferably, the alkoxy group is OCH 3 .

Preferably, halogen is fluorine, chlorine, bromine, iodine.

Preferably, one of the solvents being a component of said organic solvent mixture is organic acid, preferably acetic acid, and the other solvent being a component of said organic solvent mixture is preferably selected from toluene, xylene, tetrahydrofuran and dioxane. More preferably, the second organic solvent is toluene.

Preferably, said organic solvents are used in a 1 : 1 (v/v) ratio.

Preferably, the reaction is carried out at 0- 150 °C, more preferably at 90 °C.

Preferably, the reaction is carried out in an open reaction vessel.

Preferably, the reaction is carried out in the presence of an iron (III) salt catalyst, preferably selected from iron (III) chloride, iron (III) triflate or iron (III) perchlorate hydrate. More preferably, the reaction is carried out in the presence of iron (III) perchlorate hydrate.

Preferably, the catalyst is used in an amount of less than 10 mol%, more preferably the catalyst is used in an amount of 3 mol%.

Preferably, the obtained pyrrolo[3,2-b pyrroles precipitate from the reaction mixture and are isolated by filtration, and the product of analytical purity is obtained by recrystallization from an organic solvent, preferably selected from ethyl acetate or acetonitrile. In the event that the product does not precipitate, preferably the organic solvents are removed under reduced pressure, and then the product is obtained by crystallization from an organic solvent, preferably by crystallization from acetonitrile, or using chromatographic techniques or other techniques known to a person skilled in the art.

The advantage of the method according to the invention is a significant increase in the yield of pyrrolo[3,2-b pyrroles synthesis compared to the methods known in the art (Patent applications PL 227162 and PL 226856) with an unchanged, simple method of isolating the pure product from the reaction mixture. Table 1 shows selected compounds and yields obtained by the previously disclosed method (Patent application PL 226856) and the method according to the present invention. In many cases, obtaining pyrrolo[3,2-b pyrroles using the previously disclosed method was simply impossible due to the negligible yields. The method according to the invention allows the synthesis of such pyrrolo[3,2-b pyrroles in satisfactory yield.

In addition, the method according to the present invention makes it possible to obtain pyrrolo[3,2-b pyrroles when carrying out the reaction at room temperature, while the previously disclosed methods (Patent applications PL 227162 and PL 226856) require strong heating of the reaction mixture, otherwise no desired product is formed. The yield of pyrrolo[3,2-b pyrroles synthesis by the method of the present invention when carrying out the reaction at room temperature is slightly lower than that obtained when the reaction mixture was heated, however, it is still satisfactory. This is a great advantage compared to methods for the synthesis of pyrrolo[3,2-b pyrroles known in the art (patent applications PL 227162 and PL 226856) and makes this process applicable to the temperature sensitive starting materials. When the reaction is carried out at room temperature, the reaction is often heterogeneous, which in no case prevents the formation of pyrrolo[3,2-b pyrroles in satisfactory yield. In addition, by using a non-polar solvent, such as toluene or xylene, the method of the present invention allows obtaining pyrrolo[3,2-b pyrroles having large, nonpolar substituents, such as naphthyl or anthracenyl. The synthesis of such pyrrolo[3,2-b pyrroles carried out by methods known in the art (Patent applications PL 227162 and PL 226856) presents some difficulties due to the very limited solubility of the starting aldehydes in acetic acid, i.e. the solvent used in the methods known in the art. The method of the present invention solves the above problem by using a co-solvent.

The following examples and Table 1 illustrate the advantages of the method of the present invention.

EXAMPLES

Example 1. General method for the synthesis of pyrrolo[3,2-b ]pyrroles (I).

2 mmol of aromatic aldehyde and 2 mmol of aromatic amine were dissolved in 1.5 ml of acetic acid and 1.5 ml of toluene in a 50-ml round-bottomed flask,. The resulting mixture was heated in an open flask at 90 °C for 30 minutes and 21 mg (3 mol%) Fe(ClO 4 ) 3 · H 2 0 was added, followed by 88 ml (1 mmol) of butane-2, 3-dione and heating at 90 °C was continued for 3 hours. The reaction mixture was brought to room temperature, the precipitate was filtered off, washed with a small amount of acetic acid and recrystallized from ethyl acetate or acetonitrile to give the desired product. In the event that the product did not precipitate from the reaction mixture, the organic solvents were removed under reduced pressure using a rotary evaporator, the resulting dark oil was heated to boiling with a small amount of acetonitrile (about 5 ml) and allowed to cool, the precipitated crystals were filtered off and washed with cold acetonitrile obtaining the desired product. In some cases, due to crystallization problems, after removal of the solvents from the reaction mixture, it was necessary to carry out silica gel column chromatography and then crystallization to obtain the desired product.

Example 2. General method for the synthesis of pyrrolo[3,2-b pyrroles (I) at room temperature. The synthesis was carried out according to the procedure described in Example 1, except that that the reaction was carried out at room temperature (25 °C).

Table 1. Comparison of yields of selected pyrrolo[3,2-b pyrroles obtained using the previously disclosed method (Patent application PL 226856) and using the method according to the present invention (with Fe(ClO 4 ) 3 ELO as a catalyst).

Examples 3-18 provide the results of the synthesis of compounds of formulas 1-16 by the method described in Example 1.

Example 3. 2,5-Bis(4-cyanophenyl)-1,4-bis(4-methylphenyl)-1,4-dihydropy rrolo[3,2- b ] pyrrole (1)

Yellow solid. Yield: 377 mg (77%). M. p. 319-321 °C.

IH NMR (600 MHz, CDCl 3 ) d 7.47 (AA’XX’, 4H), 7.27 (AA’XX’, 4H), 7.21 (AA’XX’, 4H), 7.14 (AA’XX’, 4H), 6.45 (s, 2H), 2.40 (s, 6H) ppm;

13 C NMR (150 MHz, CDCl 3 ) d 137.7, 136.7, 136.5, 135.0, 133.4, 131.9, 130.1, 127.8, 125.2, 119.1, 109.0, 95.8, 21.1 ppm.

HRMS (FD-TOF) calculated for C 34 H 24 N 4 : 488.2001 [M+], found 488.2014.

Elemental analysis calculated (%) for C 34 H 24 N 4 : C, 83.58; H, 4.95; N, 11.47; found: C, 83.53; H, 4.97; N, 11.33.

Example 4. 1,4-Bis(4-bromophenyl)-2,5-bis(4-cyanophenyl)-1,4-dihydropyr rolo[3,2- b] pyrrole (2)

Yellow solid. Yield: 395 mg (64%). M. p. 351-353 °C (decomp.).

1 H NMR (500 MHz, CDCl 3 ) d 7.55 (dd, J = 6.8, 1.9 Hz, 4H), 7.52 (dd, J = 6.8, 1.9 Hz, 4H), 7.27 (dd, J = 6.9, 2.0 Hz, 4H), 7.13 (dd, J = 6.9, 2.0 Hz, 4H), 6.54 (s, 2H) ppm;

1 3 C NMR (125 MHz, CDCl 3 ) d 138.2, 137.1, 135.2, 133.1, 132.8, 132.2, 128.0, 126.8, 120.3, 118.9, 109.8, 96.6 ppm.

HRMS (El) calculated for C 32 H 18 N 4 Br 2 : 615.9898 [M +], found: 615.9924. Elemental analysis calculated (%) for C 32 H 18 N 4 Br 2 : C, 62.16; H, 2.93; Br, 25.85; N, 9.06; found: C, 62.11; H, 3.03; Br, 25.94; N, 9.15.

Example 5. 1,2,4,5-Tetrakis(4-cyanophenyl)-1,4-dihydropyrrolo[3,2-b ]pyrrole (3)

Yellow solid. Yield: 152 mg (30%).

1 H NMR (400 MHz, (CD 3 ) 2 SO) d 7.95 (d, J = 8.56 Hz, 4H), 7.77 (d, J = 8.44 Hz, 4H), 7.48 (d, J = 8.56 Hz, 4H), 7.39 (d, J = 8.40 Hz, 4H), 6.93 (s, 2H) ppm.

13 C NMR (101 MHz, (CD 3 ) 2 SO) d 142.9, 137.1, 135.3, 134.4, 133.0, 132.9, 128.6, 126.0, 109.4, 109.2, 102.5, 99.6 ppm.

HRMS (El): calculated for C 34 H 18 N 6 : 510.1593 [M +], found: 510.1595.

Example 6. 2,5-Bis(4-cyanophenyl)-1,4-bis(naphth-l-yl)-1,4-dihydropyrro lo[3,2- b] pyrrole (4)

Yellow solid. Yield: 180 mg (32%).

1 H NMR (500 MHz, CDCl 3 ) d 8.06 (d, J = 8.2 Hz, 1H), 8.03 (d, J = 7.9 Hz, 1H), 8.00 (d, J = 8.1 Hz, 1H), 7.92 - 7.97 (m, 2H), 7.87 (d, J = 8.4 Hz, 1H), 7.55 - 7.66 (m, 3H), 7.51 (t, J = 7.83 Hz, 2H), 7.46 (t, J = 7.74 Hz, 1H), 7.39 (d, J = 7.3, 1H), 7.26 - 7.31 (m, 4H), 7.21 (d, J = 7.3 Hz, 1H), 7.06 - 7.15 (m, 4H), 6.29 (s, 1H), 6.28 (s, 1H) ppm

1 3 C NMR (126 MHz, CDCl 3 ) d 137.4, 137.3, 137.2, 137.2, 136.1, 135.9, 135.1, 135.0, 134.7, 134.6, 131.9 (2), 131.9, 130.0, 129.9, 128.6, 128.5, 128.4, 128.3, 127.3, 127.2, 127.0, 126.9, 126.8, 125.8, 125.7, 125.6 (2), 123.5, 123.4, 119.0, 108.9, 108.8, 96.2, 95.7 ppm.

HRMS (El): calculated for C 40 H 24 N 4 : 560.2001 [M +], found: 560.1998.

Example 7. 2,5-Bis(4-cyanophenyl)-1,4-bis[3,5-bis(trifluoromethyl)pheny l]-1,4- dihydropyrrolo[3,2-b ]pyrrole (5)

Yellow solid. Yield: 352 mg (48%).

1 H NMR (500 MHz, CDCl 3 ) d 7.83 (s, 1H), 7.66 (s, 2H), 7.60 (d, J = 8.5 Hz, AA’BB’, 2H), 7.29 (d, J = 8.5 Hz, AA’BB’, 2H), 6.55 (s, 2H) ppm.

1 3 C NMR (126 MHz, CDCl 3 d 140.4, 136.0, 135.5, 133.5, 133.2, 132.5 (2), 128.4, 124.8, 120.1, 118.4, 110.9, 97.7 ppm.

HRMS (El): calculated for C 36 H 16 F 12 N 4 : 732.1183 [M +], found: 732.1185.

Example 8. 1,2,4,5-Tetrakis(4-methylphenyl)-1,4-dihydropyrrolo[3,2-b ]pyrrole (6)

Beige solid. Yield: 192 mg (41%). M. p. 261-262 °C.

1 H NMR (500 MHz, CDCl 3 ) d 7.17 (AA’XX’, 4H), 7.15 (AA’XX’, 4H), 7.11 (AA’XX’, 4H), 7.02 (AA’XX’, 4H), 6.33 (s, 2H), 2.36 (s, 6H), 2.30 (s, 6H) ppm.

1 3 C NMR (126 MHz, CDCl 3 ) d 137.7, 135.7, 135.6, 135.1, 131.3, 131.0, 129.6, 128.8, 128.0, 125.0, 94.1, 21.1, 21.0 ppm.

HRMS (El) calculated for C 34 H 30 N 2 : 466.2409 [M +], found: 466.2406.

Elemental analysis calculated (%) for C 34 H 30 N 2 ; C, 87.52; H, 6.48; N, 6.00; found: C, 87.47; H, 6.43; N, 5.94.

Example 9. 2,5-Bis(4-methylphenyl)-1,4-bis(4-nitrophenyl)-1,4-dihydropy rrolo[3,2- b] pyrrole (7)

Red solid. Yield: 138 mg (26%). M. p. 317-319 °C.

1 H NMR (500 MHz, (CD 3 ) 2 SO) d 8.28 (AA’XX’, 4H), 7.50 (AA’XX’, 4H), 7.13-7.17 (m, 8H), 6.69 (s, 2H), 2.30 (s, 6H) ppm.

HRMS (El) calculated for C 32 H 24 N 4 O 4 : 528.1790 [M +], found: 528.1798.

Elemental analysis calculated (%) for C 32 H 24 N 4 O 4 : C, 72.72; H, 4.58; N, 10.60; found: C, 72.63; H, 4.44; N, 10.57. Example 10. 2,5-Bis(2-bromophenyl)-1,4-bis(4-methylphenyl)-1,4-dihydropy rrolo[3,2- b] pyrrole (8)

Off-yellow solid. Yield: 303 mg (51%). M. p. 239-241 °C.

IH NMR (500 MHz, CDCl 3 ) d 7.57 (dd, J = 8.1, 1.1 Hz, 2H), 7.28 (dd, J = 7.6, 1.7 Hz,

2H), 7.20 (dt, J = 7.5, 1.1 Hz, 2H), 7.10 (m, 10H), 6.45 (s, 2H), 2.31 (s, 6H) ppm. 13 C NMR (125 MHz, CDCl 3 ) d 137.4, 135.1, 134.7, 133.4, 133.1, 133.0, 129.8, 129.5, 128.6, 126.9, 124.4, 124.0, 96.3 ppm.

HRMS (El) calculated for C 32 H 24 N 2 Br 2 : 594.0306 [M +], found: 594.0305.

Elemental analysis calculated (%) for C 32 H 24 N 2 Br 2 : C, 64.45; H, 4.06; Br, 26.80; N, 4.70; found: C, 64.51; H, 4.24; Br, 26.78; N, 4.52.

Example 11. 2,5-Bis(2-nitrophenyl)-1,4-bis(4-octylphenyl)-1,4-dihydropyr rolo[3,2- b] pyrrole (9)

Red solid. Yield: 235 mg (32%). M. p. 174-175 °C.

1 H NMR (500 MHz, CDCl 3 ): d 7.72 (dd, 7=8.1, 0.9 Hz, 2H), 7.48 (ddd, J = 7.7, 7.7, 1.2 Hz, 2H), 7.42 (dd, J = 7.7, 1.2 Hz, 2H), 7.35 (ddd, J = 8.1, 8.1, 1.4 Hz, 2H), 7.09 (s, 8H), 6.35 (s, 2H), 2.57 (t, J = 7.7 Hz, 4H), 1.62-1.57 (m, 4H), 1.34-1.25 (m, 20H), 0.88 (t, J = 6.9 Hz, 6H) ppm.

lsC NMR (125 MHz, CDCl 3 ): d 149.0, 140.7, 136.3, 133.0, 132.0, 131.5, 130.4, 129.1, 128.3, 127.7, 124.5, 124.1, 95.3, 35.4, 31.9, 31.3, 29.4, 29.3, 29.2, 22.7, 14.1 ppm.

HRMS (El) calculated for C 46 H 52 N 4 O 4 : 724.3989 [M +]; found: 724.3961.

Elemental analysis calculated (%) for C 46 H 52 N 4 O 4 : C 76.21, H 7.23, N 7.73; found: C 76.18, H 7.24, N 7.70.

Example 12. 2,5-Bis(3-cyanophenyl)-1,4-bis(4-methylphenyl)-1,4-dihydropy rrolo[3,2- b] pyrrole (10)

Yellow solid. Yield: 230 mg (47%). M. p. 314-316 °C

1 H NMR (500 MHz, CDCl 3 ) d 7.53-7.50 (m, 2H), 7.44-7.40 (m, 2H), 7.38 (dd, J = 5.7, 4.0 Hz, 2H), 7.32-7.27 (m, 2H), 7.20 (AA’XX’, 4H), 7.13 (AA’XX’, 4H), 6.41 (s, 2H), 2.40 (s, 6H). 13 C NMR (126 MHz, CDCl 3 ) d 136.6, 136.4, 134.7, 134.0, 132.5, 132.0, 131.0, 130.1,

129.4, 128.9, 125.1, 118.7, 112.4, 95.3, 21.1.

HRMS (El) calculated for C 34 H 24 N 4 : 488.2001 [M +], found: 488.1999.

Elemental analysis calculated (%) for C 34 H 24 N 4 : C, 83.58; H, 4.95; N, 11.47; found: C, 83.73;

H, 4.86; N, 11.45.

Example 13. 1,4-Bis(4-methylphenyl)-2,5-bis(thiazol-2-yl)-1,4-dihydropyr rolo[3,2- b] pyrrole (11)

Yellow solid. Yield: 139 mg (31%).

1 H NMR (500 MHz, CDCl 3 ) d 7.67 (d, J = 3.3 Hz, 2H), 7.31 (AA’XX’, 4H), 7.27 (AA’XX’, 4H), 7.08 (d, J = 3.3 Hz, 2H), 6.77 (s, 2H), 2.44 (s, 6H).

1 3 C NMR (125 MHz, CDCl 3 ) d 160.0, 142.6, 137.8, 136.2, 133.8, 130.1, 127.0, 117.6, 95.8,

21.4.

HRMS (El) calculated for C 26 H 20 N 4 S 2 : 452.1139 [M +], found: 452.1129.

Example 14. 2,5-Bis(benzothiazol-2-yl)-l,4-bis(3,5-di-/<?r/-butylphen yl)-1,4- dihydropyrrolo[3,2-b ]pyrrole (12)

Yellow solid. Yield: 113 mg (15%).

1 H NMR (500 MHz, CDCl 3 ) d 7.90 (d, J = 8.2 Hz, 2H), 7.69 (d, J = 7.9 Hz, 2H), 7.53 (t, J =

1.8 Hz, 2H), 7.39 (t, J = 7.6 Hz, 2H), 7.35 (d, J = 1.8 Hz, 4H), 7.20 - 7.25 (m, 2H), 7.04 (br s, 2H), 1.35 (s, 36H) ppm. HRMS (ESI) calculated for C48H53N4S2: 749.3712 [M+H + ], found: 749.3694.

Example 15. 1,4-Bis(4-methylphenyl)-2,5-bis(tien-2-yl)-1,4-dihydropyrrol o[3,2-6]pyrrole

(13)

Beige solid. Yield 54 mg (12%).

IH NMR (500 MHz, CDCl 3 ) d 7.21, 7.27 (AA’BB’, J = 8.2 Hz, 8H), 7.09 (d, J = 4.9 Hz, 2H), 6.85 (dd, J2 = 5.1 Hz, Ji = 3.1 Hz, 2H), 6.62 (d, J = 3.1 Hz, 2H), 6.32 (s, 2H), 2.41 (s, 6H) ppm. 13 C NMR (125 MHz, CDCl 3 ) d 136.9, 136.4, 135.9, 131.7, 129.7, 129.6, 127.1, 126.1, 124.7,

123.8, 93.9, 21.1 ppm.

HRMS (El) calculated for C 28 H 22 N 2 S 2 : 450.1224 [M +], found: 450.1222.

Example 16. 1,4-Bis(4-methylphenyl)-2,5-bis(5-nitrofur-2-yl)-1,4-dihydro pyrrolo[3,2- 6] pyrrole (14)

Violet solid. Yield: 66 mg (13%).

1 H NMR (500 MHz, THF-d8) d 7.40 (s, 8H), 7.28 (d, J = 4.0 Hz, 2H), 6.70 (s, 2H), 5.81 (d, / = 4.0 Hz, 2H), 2.47 (s, 7H) ppm.

1 3 C NMR (126 MHz, THF) d 154.4, 151.1, 139.5, 136.9, 135.7, 131.2, 128.6, 127.4, 114.4,

108.8, 95.4, 21.2 ppm.

HRMS (El) calculated for C 28 H 20 N 2 O 6 : 508.1383 [M +], found: 508.1361.

Example 17. 2,5-Bis(2-chlorobenzo[h]quinolin-3-yl)-1,4-bis(4-methylpheny l)-1,4- dihydropyrrolo[3,2-6]pyrrole (15)

Beige solid. Yield 139 mg (68%).

1 H NMR (500 MHz, THF-d8) d 9.09 - 9.17 (m, 2H), 8.33 (s, 2H), 7.93 - 8.03 (m, 2H), 7.89 (d, J = 8.8 Hz, 2H), 7.62 - 7.79 (m, 6H), 7.13, 7.24 (dd, J = 8.1 Hz, AA’BB’, 8H), 6.65 (s, 2H), 2.29 (s, 6H) ppm.

Example 18. 2,5-Bis[4-(acridin-9-yl)phenyl]-1,4-bis(4-methylphenyl)-1,4- dihydropyrrolo[3,2-6]pyrrole (16)

Yellow solid. Yield: 254 mg (32%).

1 H NMR (500 MHz, CDCl 3 ) d 8.28 (d, J = 9.2 Hz, 4H), 7.78 (d, J = 8.5 Hz, 8H), 7.50 (d, J = 7.9 Hz, 4H), 7.46 (t, J = 7.7 Hz, 4H), 7.37 (d, J = 8.2 Hz, 4H), 7.33 (d, J = 7.8 Hz, 4H), 7.28 (d, J = 8.1 Hz, 4H), 6.61 (s, 2H), 2.43 (s, 6H) ppm.

HRMS (ESI) calculated for C 58 H 41 N 4 : 793.3331 [M+H+], found: 793.3345.