4 (C-6), 171.8 (C-2); HRMS (ESI+) calcd for C17H16N2O2Na: click here 303.1109 (M+Na)+ found 303.1115. (3 S ,5 S )-3e: white powder; mp 126–129 °C; TLC (PE/AcOEt 3:1): R f = 0.17; [α]D =+5.5 (c 0.887, CHCl3); IR (KBr): 700, 744, 1240, 1454, 1695, 2855, 2922, 3070, 3204, 3312; 1H NMR (CDCl3, 500 MHz): δ 2.48 (bs, 1H, NH), 4.76 (s, 2H, H-3, H-5), 7.36–7.44 (m, 10H, H–Ar), 8.22 (bs, 1H, Selleckchem Fosbretabulin CONHCO); 13C NMR (CDCl3, 125 MHz): δ 59.5 (C-3, C-5), 127.7

(C-2′, C-6′, C-2″, C-6″), 128.8 (C-4′, C-4″), 129.1 (C-3′, C-5′, C-3″, C-5″), 135.2 (C-1′, C-1″), 171.5 (C-2, C-6); HRMS (ESI−) calcd for C16H13N2O2 265.0977 (M−H)− found 265.0982. (3 S ,5 R )-3e: white powder; mp 172–174 °C; TLC (PE/AcOEt 3:1): R f = 0.10; [α]D = 0 (c 0.733, CHCl3); IR (KBr): 698, 737, 1219, 1263, 1454, 1709, 3034, 3065, 3103, 3223, 3317; 1H NMR (CDCl3, 500 MHz): δ 2.22 (bs, 1H, NH), 4.75 (s, 2H, H-3, H-5), 7.35–7.44 (m, 6H, H–Ar), 7.45–7.49 (m, 4H, H–Ar), 8.08 (bs, 1H, CONHCO); 13C NMR (CDCl3, 125 MHz): δ 65.1 (C-3, C-5), 128.7 (C-2′, C-6′, C-2″, C-6″), 128.8 (C-3′, C-5′, C-3″, C-5″), 129.0 (C-4′, C-4″), 135.9 (C-1′, C-1″), 171.2 (C-2, C-6); HRMS (ESI−) calcd for C16H13N2O2 265.0977 (M−H)− found 265.0976. (+/−)-4-Benzyl-3-phenylpiperazine-2,6-dione rac -3f From rac -2f (0.32 g, 1.03 mmol) and NaOH (0.04 g, 1 equiv.); FC (gradient: PE/EtOAc Bacterial neuraminidase 3:1–1:1): yield 0.28 g (98 %): white powder; mp 156–169 °C; TLC 5-Fluoracil concentration (PE/AcOEt 3:1): R f = 0.22; IR (KBr): 698, 744, 1246, 1454, 1699, 2814, 2852, 2924, 3030, 3209; 1H NMR (CDCl3, 500 MHz): δ 3.30 (d, 2 J = 17.5, 1H, PhCH 2), 3.57 (d, 2 J = 17.5, 1H, Ph\( \rm CH_2^’ \)), 3.63 (d, 2 J = 13.5, 1H, H-3), 3.83 (d, 2 J = 13.5, 1H, H′-3), 4.50 (s, 1H, H-5), 7.23–7.39 (m, 6H, H–Ar), 7.41 (m, 4H, H–Ar), 8.24 (bs, 1H, CONHCO); 13C NMR (CDCl3, 125 MHz): δ 51.3 (PhCH2), 58.7 (C-3),

67.1 (C-5), 128.1, 128.8 (C-4′, C-4″), 128.1, 128.8 (C-2′, C-6′, C-2″, C-6″), 128.9, 129.0 (C-3′, C-5′, C-3″, C-5″), 134.0, 136.2 (C-1′, C-1″), 170.1 (C-6), 171.0 (C-2); HRMS (ESI−) calcd for C17H15N2O2 279.1133 (M−H)− found 279.1126. Pharmacological evaluation The compounds obtained have been submitted for in vivo evaluation in the ASP of NINDS, Bethesda, USA (White et al., 2002). The experiments were performed in male albino Carworth Farms No. 1 mice (weighing 18–25 g). The animals had free access to feed and water except during the actual testing period. Housing, handling, and feeding were all in accordance with recommendations contained in the “Guide for the Care and Use of Laboratory Animals.” The test compounds were dissolved or suspended in 0.5 % (v/v) aqueous solution of methylcellulose.