Phosphorus pentachloride → 9-Benzenesulfonyl-3,5-dichloro-9H-dipyrido[2,3-b;4',3'-d]pyrrole-6-carbonitrile

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Reaction Steps

A solution of 9-benzenesulfonyl-3-chloro-5-hydroxy-9H-dipyrido[2,3-b;4′,3′-d]pyrrole-6-carbonitrile (1.9 g, 4.94 mmol) and phosphorus pentachloride (3.1 g, 14.8 mmol) in phosphorus oxychloride (8 mL) was heated at 105° C. for 2 hours. The reaction mixture was cooled to ambient temperature and then the solvent removed in-vacuo to afford a residue. The resultant residue was dissolved in dichloromethane (300 mL) and then the solution was diluted with ice/water (300 mL). The layers were separated and the aqueous layer further extracted with dichloromethane. The combined organic layer was washed with brine, dried (Na2SO4), filtered and evaporated. The resultant residue was triturated with diethyl ether and dried to afford the title compound as a tan solid (1.17 g, 59%). 1H NMR (400 MHz, CDCl3): 9.81 (s, 1H), 8.77 (d, J=2.4 Hz, 1H), 8.75 (d, J=2.4 Hz, 1H), 8.26-8.22 (m, 2H), 7.66-7.66 (m, 1H), 7.53-7.53 (m, 2H).

Provenance & Evidence