This compound can be obtained by several different ways: 1) The reaction of 2-fluorobenzyl chloride (I) with ethyl acetoacetate (II) by means of sodium ethoxide in refluxing ethanol gives ethyl 2-(2-fluorobenzyl)acetoacetate (III), which is cyclized with 4-chloroaniline (IV) in HCl - water yielding ethyl 5-chloro-3-(2-fluorophenyl)indole-2-carboxylate (V). The hydrolysis of (V) with KOH affords the corresponding free acid (VI), which by treatment with SOCl2 is converted into the acyl chloride (VII). The treatment of (VII) with dry ammonia in ether gives the carboxamide (VIII), which is methylated with dimethyl sulfate to 5-chloro-3-(2-fluorophenyl)-1-methylindole-2-carboxamido (IX). The reduction of (IX) with LiAlH4 in ether affords 2-aminomethyl-3-(2-fluorophenyl)-5-chloroindole (X) (1), which is finally oxidized and cyclized again by treatment with CrO3 in acetic acid - water.
4) The methylation of 3-(2-fluorophenyl)-5-chloroindole-2-carbonitrile (XV) with dimethyl sulfate gives 3-(2-fluorophenyl)-5-chloro-1-methylindole-2-carbonitrile (XVI), which is reduced to yield 2-aminomethyl-3-(2-fluorophenyl)-5-chloroindole (X) (1), which is finally oxidized and cyclized again by treatment with CrO3 in acetic acid - water (X).
2) By cyclization of 2-methylamino-5-chloro-2?fluorodiphenylmethyleneimine (XI) with ethyl glycinate (XII) in refluxing pyridine.
3) By cyclization of 2-methylamino-5-chloro-2?fluorobenzophenone (XIII) with 2,5-oxazolidinedione (XIV) in methylene chloride.