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

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Reaction Steps

A solution of 9-benzenesulfonyl-3-bromo-5-hydroxy-9H-dipyrido[2,3-b;4′,3′-d]pyrrole-6-carbonitrile (2.0 g, 4.66 mmol) and phosphorus pentachloride (2.9 g, 14.0 mmol) in chlorobenzene (6 mL) was heated at 105° C. for 1 hour. The reaction mixture was cooled to ambient temperature and the solvent removed in vacuo to afford a residue. The resultant residue was dissolved in dichloromethane (300 mL) and the solution was treated with ice/water (300 mL). The layers were separated and the aqueous layer further extracted with dichloromethane (300 mL). The combined organic layer was washed with brine, dried (Na2SO4), filtered and evaporated. The resultant residue was triturated with methanol and dried to afford the title compound as a tan solid (1.1 g, 53%). 1H NMR (300 MHz, DMSO-d6): 9.70 (s, 1H), 9.06 (d, J=2.2 Hz, 1H), 8.98 (d, J=2.2 Hz, 1H), 8.27-8.22 (m, 2H), 7.77-7.76 (m, 1H), 7.67-7.60 (m, 2H).

Provenance & Evidence