Phenylhydrazine hydrochloride → 6-(2,3-dimethyl-3H-indol-3-yl)hexanoic acid

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Reaction Steps

To a stirred solution of phenylhydrazine hydrochloride (Aldrich, 7.2 g, 0.05 mol) in acetic acid (50 ml) was added 7-acetyloctanoic acid (11 g, 0.06 mol). The reaction mixture was heated under reflux for 4 hrs. The solution was cooled. (No clear precipitate was observed). Acetic acid was removed under reduced pressure. The resulting yellow liquid was chromatographed on a silica gel column using chloroform/methanol mixture as solvent. Pure 6-(2,3-dimethyl-3H-indol-3-yl)hexanoic acid (8.0 g, 61%) was obtained as pale yellow oil which crystallized on standing, m.p. 115-118° C.; IR νcm−1=2927, 2860, 2526, and 1709. 1H NMR, CDCl3, δ, 7.6 (d, 1H, J=7 Hz, 4-H); 7.2-7.4 (m, 3H, aromatic protons); 2.25 (s, 3H, —CH3); 2.1-2.2(t, —CH2COOH); 1.72-1.94 (m 2H, —CH2); 1.4-1.45 (m, 2H, —CH2); 1.23-1.05 (m, singlet merged in m, 5H, —CH2, —CH3); 0.55-0.85 (m, 2H, —CH2). TLC, Rf=0.22 (silica gel, methanol-chloroform, 5:95).

Provenance & Evidence