2-(2´-Hydroxybenzoyl)pyrrole N-Benzoylhydrazone

In continuation of our interest in using o-hydroxyaryl ketone hydrazones as starting materials in organic synthesis [1], we synthesised 2-(2´-hydroxybenzoyl)pyrrole N-benzoylhydrazone.

Benzoic hydrazide is commercially available and it was supplied by Aldrich, whereas 2-(2´-hydroxybenzoyl)pyrrole was prepared in three steps according to the literature method [2]. Benzoic hydrazide (0.68 g, 5 mmol) was added to a solution of 2-(2´-hydroxybenzoyl)pyrrole (1 g, 5 mmol) in propanol-1 (10 mL). The reaction mixture was refluxed for 24 hours. It was then allowed to cool at room temperature. Subsequently, it was stored in the refrigerator overnight. Filtration of the precipitate, which was formed, afforded (1.41 g, 92 %) of the desired 2-(2´-hydroxy benzoyl)pyrrole N-benzoylhydrazone as light yellow crystals. The product was identified by ¹H NMR, ¹³C NMR and MS and it was subjected to elemental analysis without further purification.

M.p. 213-215 °C.

¹H NMR (300 MHz, DMSO-d₆): 6.93-7.19 (m, 2H), 7.33-7.61 (m, 7H), 7.62-7.79 (m, 3H), 9.73 (s, 1H),10.79 (s, 1H), 12.03 (s, 1H).

¹³C NMR (75 MHz, DMSO-d₆): 114.0, 111.8, 117.4, 119.2, 120.2, 123.5, 124.0, 127.1, 127.4, 128.5,130.6, 131.5, 133.6, 133.7, 158.7, 166.4.

MS m/z (ES+): 328 [M+Na]⁺, 306 [M+1]⁺.

Anal. Calc. for C₁₈H₁₅N₃O₂: C 70.81, H 4.95, N 13.76; found: C 70.84, H 5.10, N, 13.81.