Phenacyl ester (III) was prepared by treatment of the cesium salt of N-Boc-tryptophan (I) with 2-bromoacetophenone (II) in DMF. Cyclization of keto ester (III) with ammonium acetate in refluxing xylene yielded the target imidazole (IV). Acidic Boc group deprotection of (IV) then gave amine (V). Finally, Pictet-Spengler cyclization of (V) with 6-undecanone (VI) provided the desired tetrahydrocarboline.