1) The diazotation of 4-amino-N-methylbenzenemethanesulfonamide (I) with NaNO2-HCl followed by reduction with SnCl2 gives the 4-hydrazino compound (II), which is condensed with (phenylthio)acetaldehyde (III) in ethanol yielding the ethylideneamino compound (IV). The cyclization of (IV) with HCl in ethanol affords N-methyl-3-(phenylthio)-1H-indole-5-methansulfonamide (V), which is desulfurized with RaNi in refluxing ethanol-water to give N-methyl-1H-indole-5-methanesulfonamide (VI). The reaction of (VI) with oxalyl chloride and dimethylamine yields the oxalyl derivative (VII), which is finally reduced with LiAlH4 in refluxing THF.
2) The condensation of hydrazine (II) with 4,4-dimethoxy-N,N-dimethylbutylamine (VIII) by means of HCl in water gives the butylidenehydrazino compound (IX), which is cyclized with polyphosphate ester (PPE) in CHCl3.
3) The condensation of indole (VI) with N,N-diethylchloroacetamide (X) by means of POCl3 gives 3-chloroacetyl-N-methyl-1H-indole-5-methanesulfonamide (XI), which is treated with dimethylamine (XII) in refluxing ethanol to afford the dimethylaminoacetyl derivative (XIII), which is finally reduced with NaBH4 in refluxing propanol.
4) The condensation of hydrazine (II) with 3-nitropropanal (XIV) in water gives the nitrobutylidenehydrazino derivative (XV), which is cyclized with PPE as before yielding N-methyl-3-(2-nitroethyl)-1H-indole-5-methansulfonamide (XVI), which is reduced with H2 over Pd/C in ethyl acetate to afford the 2-aminoethyl compound (XVII). Finally, this compound is methylated with ICH3 and NaHCO3 or with formaldehyde and NaBH4
5) The condensation of hydrazino compound (II) with 4,4-dimethoxybutyronitrile (XVIII) gives the cyanobutylideneamino derivative (XIX), which is cyclized with PPE as before yielding 3-(cyanomethyl)-N-methyl-1H-indole-5-methanesulfonamide (XX). Finally, this compound is reduced with H2 over Rh/Al2O3 to afford the 2-aminoethyl derivative (XVII), already obtained.