... Laboratory of Natural Products & Organic Synthesis, Department of Chemistry, Visva-Bharati (a Central University), Santiniketan 731 235, West Bengal, India. ... 1249, 1171, 1070, 878, 731 cm –1 . 1 H NMR (400 MHz, CDCl 3 ): δ 8.97 (1H, s, C 4 —H), 7.83–7.78 (2H, m, Ar—H ...