Pyridine → HCID 178427731, compound

Participants

Reaction Steps

642 mg (1 mmol) 3-methyl-2-((1E,3E)-4-phenylamino-buta-1,3-dienyl)-5-sulfo-1,3-bis-(3-sulfo-propyl)-3H-indolium disodium salt and 483 mg (1 mmol) 3-(3-Carboxypropyl)-2,3-dimethyl-5-sulfonato-1-(3-sulfopropyl)-3H-indolium sodium salt were dissolved in a mixture of 10 ml acetic acid and 10 ml acetic anhydride. Five ml pyridine was added. The solution was stirred under reflux for 15 min. Twenty ml ether was added after cooling to room temperature. The obtained precipitate (mixture of the diastereomers OB-5.5a and OB-5.5b) was extracted by suction, washed with ether, and dried.

Provenance & Evidence