p-Toluenesulfonic acid → Ro4368554

Participants

Reaction Conditions

Reaction Steps

To a solution of 2.3 g of 2-benzenesulfonylmethyl-6-(4-methyl-piperazin-1-yl)-phenylamine in 20 mL trimethyl orthoformate was added p-toluenesulfonic acid (120 mg). The mixture was heated under reflux in a nitrogen atmosphere for 2 hours. The mixture was cooled to 60° C. and one flake of KOH was added. The mixture was reheated to reflux for 1.5 hours. The heating oil bath was turned off and the mixture stirred overnight under nitrogen. The mixture was treated with 50 mL saturated ammonium chloride solution and 100 mL EtOAc. The purple organic layer was separated from the clear aqueous solution, and washed with water (45 mL) and evaporated to a foam. This foam was dissolved in 80 mL 200 proof EtOH. After dissolution, the freebase crystallized. This mixture was heated under reflux to redissolve the solid, and after removal of the heating, 5 mL of a saturated solution of HCl in ethanol was added to this mixture. The mixture was cooled with stirring to room temperature and seeded to ensue immediate crystallization. The mixture was concentrated to ca. 40 mL and filtered. This collected solid was washed with ca. 3 mL EtOH and vacuum oven dried at 50° C. to give 1.9 g 3-benzenesulfonyl-7-(4-methyl-piperazin-1-yl)-1H-indole (501) mp 160-162° C.

Provenance & Evidence