p-Toluenesulfonic acid → Dibenzyl 5,5'-[(3,4-diethyl-1H-pyrrole-2,5-diyl)bis(methylene)]bis[4-(3-methoxy-3-oxopropyl)-3-methyl-1H-pyrrole-2-carboxylate]

Participants

Reaction Conditions

Reaction Steps

7C, FIG. 7. In a 500 mL round bottom flask was placed 250 mL of ethanol from an unopened bottle and this was then purged with dry nitrogen for ten minutes. 3,4-Diethylpyrrole 7B (1.29 g, 0.01 mol) and 2-acetoxymethyl-5-benzyloxycarbonyl-4-methyl-3-methoxycarbonylethylpyrrole 7A (7.83 g, 0.02 mol) were added and the mixture heated until all of the pyrroles dissolved. p-Toluenesulfonic acid (65 mg) was added and the reaction temperature maintained at 60° C. The reaction slowly changed color from a clear yellow to a dark red with the product precipitating out of the solution as the reaction progressed. After ten hours the reaction was cooled to room temperature, the volume reduced to one-half on a rotary evaporator, and then placed in the freezer for several hours. The product was collected by filtration, washed with a small amount of cold ethanol to afford 4.61 g of an off white fine powder (61%): 1H NMR (CDCl3, 250 MHz): δ 1.14 (6H, t, CH2CH3), 2.23 (6H, s, pyrrole-CH3), 2.31 (4H, t, CH2CH2CO2CH3), 2.50 (4H, q, CH2CH3), 2.64 (4H, t, CH2CH2CO2CH3), 3.60 (10H, br s, CH3CO2 - and (pyrrole)2 -CH2), 4.44 (4H, br s, C6H5CH2), 6.99-7.02 (4H, m, aromatic), 7.22-7.26 (6H, m, aromatic), 8.72 (1H, s, NH), 10.88 (2H, br s, NH); 13C NMR (CDCl3, 250 MHz) 10.97, 16.78, 17.71, 19.40, 22.07, 35.09, 51.46, 65.32, 117.37, 119.34, 122.14, 126.58, 126.79, 127.36, 128.19, 133.55, 136.62, 162.35, 173.49; CI MS (M+H)+ 750; HRMS 749.3676 (calc. for C44H51N3O8 : 749.3676).

Provenance & Evidence