Part A: N-Propyl-N-(4-pyridinyl)-1H-indol-1-amine maleate:
A solution of N-(4-pyridinyl)-1H-indol-1-amine (6 g) in 25 ml of
dimethylformamide was slowly added to an ice-cooled suspension of NaH (1.3
g of 60% NaH dispersion in mineral oil was washed with hexanes, the liquid
was decanted and the residual solid was dispersed in 5 ml of
dimethylformamide). After anion formation, a solution of 1-bromopropane (4
g) in 5 ml of dimethylformamide was added. After one hour of stirring at
ambient temperature, the reaction mixture was stirred with ice-water and
extracted with dichloromethane. The organic extract was washed with water
and saturated sodium chloride solution, was dried over anhydrous magnesium
sulfate, filtered and concentrated to 8 g of oil. This oil was purified by HPLC
(silica, ethyl acetate) and thereafter by column chromatography (alumina,
ether) to give 6.4 g oil. This oil was converted to the maleate salt and
recrystallized from methanol/ether to give 6.8 g of crystals, m.p. 115-116°C.
Part B: N-Propyl-N-(4-pyridinyl)-1H-indol-1-amine hydrochloride:
N-Propyl-N-(4-pyridinyl)-1H-indol-1-amine maleate was converted to the free
base by action of alcaline agent. Then the free base oil was converted to the
hydrochloride salt which was recrystallized from methanol; m.p. 212-214°C.
