Water → 3-(4-Pyridinylamino)-1H-indole maleate

Participants

Reaction Steps

A solution of 3-aminoindole (8 g) and 4-chloropyridine hydrochloride (12 g) in 150 mL 1-methyl-2-pyrrolidinone (NMP hereinafter) was stirred at 70-75° C. for one hour, after which additional 4-chloropyridine hydrochloride (4 g) was added. After stirring a total of two hours, the mixture was cooled, stirred with water, basified with sodium carbonate and extracted with ethyl acetate. The organic extract was washed successively with water and a saturated sodium chloride solution and thereafter dried (anhydrous magnesium sulfate), filtered and concentrated to 20 g of a dark oil. This was eluted through silica with 20% methanol in dichloromethane (DCM hereinafter) via HPLC (high performance liquid chromatography) to yield 7 g of a dark oil. This oil was crystallized from acetonitrile to yield 3 g of light brown crystals, m.p. 192-193°. A 2.8 g portion was converted to the maleate salt in 50% methanol/ether to yield 3.5 g of light tan crystals, m.p. 149-151° C. Recrystallization from 50% methanol/ether yielded 3.4 g of light tan crystals, m.p. 149-151° C.

Provenance & Evidence