1-acetyl-3-[((2r)-1-methylpyrrolidin-2-yl)methyl]-5-[(e)-2-(phenylsulfonyl)vinyl]indole

N-Acetyl-dehydro-Eletriptan (1-acetyl-3-[((2r)-1-methylpyrrolidin-2-yl)methyl]-5-[(e)-2-(phenylsulfonyl)vinyl]indole), is the impurity of Eletriptan (E505000), which is A serotonin 5-HTIB/ID receptor agonist, used for the treatment of migraine headaches.

1-acetyl-3-[((2r)-1-methylpyrrolidin-2-yl)methyl]-5-[(e)-2-(phenylsulfonyl)vinyl]indole has acute toxicity, causes skin irritation and severe eye irritation.

1-acetyl-3-[((2r)-1-methylpyrrolidin-2-yl)methyl]-5-[(e)-2-(phenylsulfonyl)vinyl]indole can be synthesized as follows: Charge a sealable reaction tube equipped with a stirring bar with Pd (OAc)2 (4.5 mg, 0.02 mmol, 2 mol %), Dicyclohexyl[2′,4′,6′-tris(1-methylethyl)[1,1′:3′,1′′-terphenyl]-2-yl]phosphine (22.4 mg, 0.04 mmol, 4 mol %) and NaHCO3 (202 mg, 2.4 mmol). Add the phenyl vinyl sulfone (109 mg, 0.65 mmol), 1-[5-Bromo-3-[[(2R)-1-methyl-2-pyrrolidinyl]methyl]-1H-indol-1-yl]ethanone (168 mg, 0.5 mmol) and 2 mL of DMF to the reaction. Seal the tube with a Teflon-lined septum and heat to 16 h with vigorous stirring. Cool the suspension to room temperature, dilute with EtOAc and filter througha pad of Celite. Concentrate the filtrate in vacuo to dryness. Wash the residue with 1.0 M NaOH and extract with EtOAc. Consolidate the organic layer, dry with Na2SO4, filter and concentrate.

[1] DANIEL WEILIANG TAY*. Palladium-meta-Terarylphosphine Catalyst for the Mizoroki–Heck Reaction of (Hetero)Aryl Bromides and Functional Olefins[J]. Journal of Organic Chemistry, 2015, 80 8: 4054-4063. DOI:10.1021/acs.joc.5b00386.