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

6C, FIG. 6A. In a 500 mL round bottom flask was placed 250 mL of ethanol from an unopened bottle which is purged with dry nitrogen for ten minutes. 3,4-Diethylpyrrole 6B (1.29 g, 0.01 mol) and 2-acetoxymethyl-5-benzyloxycarbonyl-4-methyl-3-methoxycarbonylethylpyrrole 6A (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): δ 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