Triphenylphosphine → phosphoric acid dibenzyl ester 4-{[3-(1-methyl-1H-indol-3-yl)-4-(1-methyl-6-nitro-1H-indol-3-yl)-2,5-dioxo-2,5-dihydro-pyrrole-1-carbonyl]-amino}butyl ester

Participants

Reaction Conditions

Reaction Steps

Triphenylphosphine (0.86 g, 3.29 mmol) and Dibenzyl phosphate (0.91 g, 3.29 mmol) were added to a solution of 3-(1-methyl-1H-indol-3-yl)-4-(1-methyl-6-nitro-1H-indol-3-yl)-2,5-dioxo-2,5-dihydro-pyrrole-1-carboxylic acid (4-hydroxybutyl)-amide (prepared as in example 23, 1.41 g, 2.74 mmol) in THF (50 mL). The mixture was cooled to −78° C. Diethyl azodicarboxylate (0.52 mL, 3.29 mmol) was added dropwise over 5 min. The cooling bath was removed and after 2 h, the mixture was evaporated. Chromatography of the residue over silica gel using 2:1 EtOAc/hexane then EtOAc gave phosphoric acid dibenzyl ester 4-{[3-(1-methyl-1H-indol-3-yl)-4-(1-methyl-6-nitro-1H-indol-3-yl)-2,5-dioxo-2,5-dihydro-pyrrole-1-carbonyl]-amino}butyl ester (1.76 g, 83%).

Provenance & Evidence