合成路线1

Protection of 2-amino-4-methoxycarbonylphenyl triflate (I) with benzyl chloroformate provided carbamate (II). Stille coupling of aryl triflate (II) with 1-pentynyl (tributyl)stannane (III) furnished adduct (IV), which was further cyclized to the indole derivative (V) upon treatment with gold(III)sodium chloride. The N-benzyloxycarbonyl group of (V) was then removed by catalytic hydrogenolysis, yielding indole (VI). Friedel-Crafts acylation of (VI) with isobutyryl chloride (VII) produced the 3-isobutyryl indole (VIII). Subsequent alkylation of the indole N of (VIII) with 2-chlorobenzyl bromide (IX) in the presence of NaH gave the N-benzyl derivative (X). The methyl ester group of (X) was then hydrolyzed to the carboxylic acid (XI) under basic conditions. Finally, conversion of acid (XI) to the title amide was carried out via activation with EDC/HOBt, followed by quenching with ammonium hydroxide.