Synlett 2011(14): 2001-2004  
DOI: 10.1055/s-0030-1260977
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

A One-Pot Rearrangement of 2-(N-Alkyl-N-aryl)aminochromone-3-carbaldehyde to N-Alkyl-3-salicyloyl-2-quinolone - An Antileishmanial Agent

Sourav Maitia, Suvadip Mallickb, Suman Kalyan Panjaa, Chiranjib Palb, Chandrakanta Bandyopadhyay*a
a Department of Chemistry, R. K. Mission Vivekananda Centenary College, Rahara, Kolkata 700 118, West Bengal, India
e-Mail: kantachandra@rediffmail.com;
b Cellular Immunology and Experimental Therapeutics Laboratory, Department of Zoology, West Bengal State University, Barasat, West Bengal, India
Further Information

Publication History

Received 1 April 2011
Publication Date:
03 August 2011 (online)

Abstract

2-(N-Aryl)aminochromone-3-carbaldehyde does not show any change on heating in acetic acid, but under the same reaction conditions 2-(N-alkyl-N-aryl)aminochromone-3-carbaldehyde rearranges to 3-salicyloyl-2-quinolones, which exhibits antileishmanial activity.

25

Typical Experimental Procedure for the Rearrangement of 2-( N -Methyl- N -phenyl)aminochromone-3-carbox-aldehyde (4a) Compound 4a (0.14 g, 0.5 mmol) was heated under reflux in AcOH (3 mL) containing 4 drops of H2O for 2 h when the absence of 4a was observed by TLC. The reaction mixture was cooled to r.t. and poured into ice-cold water. The resultant acidic mixture was neutralized with NaHCO3 when a solid began to precipitate. The precipitated solid was filtered, dried in air, and crystallized from benzene-light PE (2:1) to give pale yellow crystalline solid 6a.
N -Methyl-3-salicyloyl-2-quinolone (6a) Yield 0.12 g (86%); mp 182-184 ˚C. IR (KBr): 3036, 1645, 1626, 1589 cm. ¹H NMR (300 MHz, CDCl3): δ = 3.78 (s, 3 H, NCH3), 6.81-6.87 (m, 1 H, 5′-H), 7.04 (br d, J = 8.1 Hz, 1 H, 3′-H), 7.28-7.34 (m, 1 H, ArH), 7.42-7.47 (m, 1 H, ArH), 7.49-7.54 (m, 2 H, ArH), 7.63-7.71 (m, 2 H, ArH), 7.86 (s, 1 H, 4-H), 11.96 (s, exchangeable, 1 H, OH). ¹³C NMR (75 MHz, CDCl3): δ = 29.6, 114.3, 118.2, 118.9, 119.2, 119.4, 122.7, 129.8, 130.6, 132.3, 132.9, 136.9, 139.1, 140.5, 159.4, 162.9, 199.0. MS: m/z = 280 [M + H+], 302 [M + Na+]. Anal. Calcd for C17H13NO3: C, 73.11; H, 4.69; N, 5.02. Found: C, 72.92; H, 4.60; N, 4.97.