S), two.ten (6H, s), two.53 (4H, q, J = 7.three Hz), 2.61 (4H, t, J = 7.2 Hz), two.90 (4H, t, J = 7.two Hz), three.67 (6H, s), five.88 (2H, s), 7.75 (2H, s), ten.5 (2N-H, bs) ppm; 13C NMR in Table three; UV-Vis information in Table 5; FAB-HRMS: exact mass calculated for C36H44N4O6 626.3104, found 626.3084. Inside a separate experiment, 40 mg homorubin dimethyl ester 1e (0.063 mmol) was dissolved in 30 cm3 THF beneath an N2 atmosphere. To it was added 28 mg DDQ (0.122 mmol) in 5 cm3 THF, plus the reaction mixture was stirred for two h at room temperature. Then it was poured into 100 cm3 ice-cold water containing 100 mg ascorbic acid and extracted with CH2Cl2 (three ?75 cm3). After the combined organic extracts had been washed with sat. aq. NaHCO3, the item was dried over anhydrous Na2SO4. The solvent was evaporated (rotovap) to provide a violet-colored mixture of 3e and 5e, which was separated by radialMonatsh Chem. Author manuscript; offered in PMC 2015 June 01.Pfeiffer et al.Pagechromatography making use of CH2Cl2:CH3OH (99:1 by vol) as eluent. The doubly oxidized solution (5e) was much less polar and moved faster within the chromatography as a violet band; whereas, the much more polar singly oxidized solution (3e) followed as a red-violet band. Yield of 5e: 17 mg (42 ); m.p.: 260 . (4Z,15Z)-9,9 -(1,2-Ethanediylidene)bis[3-ethyl-1,9-dihydro-2,7-dimethyl-1-oxodipyrrin-8butanoic acid methyl ester] (6eC38H46N4O6) Homorubin dimethyl ester 2e (40 mg, 0.061 mmol) was oxidized as inside the conversion of 1e to 5e to provide crude 6e, which was purified by radial chromatography employing CH2Cl2:CH3OH (99:1 by vol). Yield: 13 mg (28 ); m.p.: 271 ; 1H NMR: = 1.ten (6H, t, J = 7.two Hz), 1.80 (4H, quint), 1.99 (6H, s), two.10 (6H, s), two.40 (4H, t, J = 7.2 Hz), 2.50 (4H, q, J = 7.two Hz), two.70 (4H, t, J = 7.two Hz), 3.60 (6H, s), 5.80 (2H, s), 7.80 (2H, s), 10.50 (2H, brs) ppm; 13C NMR in Table three; UV-Vis data in Table 5. Ethyl 5-(ethoxycarbonyl)-2-formyl-4-methyl-1H-pyrrole-3-propanoate (9C14H19NO) Ethyl two,4-dimethyl-5-(ethoxycarbonyl)-1H-pyrrole-3-propanoate (726.7 g, 0.ten mol), 15 cm3 THF, 150 cm3 glacial acetic acid, and 100 cm3 H2O have been added to a 1000 cm3 round bottom flask and stirred magnetically to dissolve the pyrrole.1019111-84-2 In stock The option was cooled to -5 applying an ice-salt bath, and 219.1310680-47-7 Chemscene three g ceric ammonium nitrate (CAN, 0.PMID:23537004 40 mol) was added in portions. Just after the final addition, the reaction mixture was allowed to stir for 2 h. Then the reaction mixture was added to a 2000 cm3 separatory funnel containing 1000 cm3 water and extracted with 300 cm3 CH2Cl2. The organic extract was washed with 10 aq. NaHCO3 (4 ?one hundred cm3) to eliminate excess acetic acid, separated, and dried more than anhydrous Na2SO4. The solvent was removed in vacuo to provide a crude solution, which was purified by column chromatography on silica gel utilizing CH2Cl2:CH3OH (99:1 by vol) to offer pure 9. Yield: 24.7 g (88 ); m.p.: 60?1 (Ref. [26, 42] 61?two ); 1H NMR (300 MHz): = 1.25 (3H, t, J = 7.1 Hz), 1.38 (3H, t, J = 7.1 Hz), two.30 (3H, s), two.55 (2H, t, J = 7.1 Hz), 3.06 (2H, t, J = 7.1 Hz), four.10 (2H, q, J = 7.1 Hz), four.35 (2H, q, J = 7.1 Hz), 9.46 (1H, brs), 9.81 (1H, s) ppm; 13C NMR (75 MHz): = 9.8, 14.1, 14.3, 18.eight, 35.3, 60.6, 60.9, 124.5, 126.6, 129.9, 132.1, 160.8, 172.1, 179.5 ppm. Ethyl 5-(ethoxycarbonyl)-2-formyl-4-methyl-1H-pyrrole-3-butanoate (10C15H21NO5) Ethyl 5-(ethoxycarbonyl)-2,4-dimethyl-1H-pyrrole-3-butanoate (828.1 g, 0.ten mol) was dissolved in 250 cm3 acetic acid within a 2000 cm3 round bottom flask. To it 150 cm3 THF and 200 cm3 H2O have been added, plus the option w.