Condensation of 3,4,5-trimethoxybenzaldehyde (I) with nitromethane in the presence of KOH produced the nitro alcohol (II), which was subsequently hydrogenated over Pd/C to afford amino alcohol (III). Acylation of (III) with 5-indolecarboxylic acid (IV) gave the corresponding amide (V). Oxazoline (VI) was then obtained by cyclization of (V) in the presence of Burgess reagent. Finally, N-methylation of the indole ring with MeI and KOH furnished the title compound.
In a closely related procedure, amino alcohol (III) was coupled with 1-methyl-5-indolecarboxylic acid (VII) to afford amide (VIII). This was then cyclized to the target oxazoline by using the Burgess reagent.