4 (C, C-1′), 154.7 (C, C-4′),

162.8 (C, C-7), 165.0 (C, C-8a), 165.7 (C, C-5), 191.9 (C, C-4); HRMS (EI) calcd for C18H19O5 315.1154, found 315.1224. NaBH4 (0.3 g, 9.5 mmol) was added portion wise to a solution of 5,7-dimethoxy-3-(4-hydroxybenzyl)-4-chromanone (1.0 g, 3.1 mmol) in anhydrous MeOH (15 ml) at a temperature of 0 °C under nitrogen atmosphere. The mixture was then allowed to reach room temperature and stirred for 1 h. The reaction mixture was quenched with water and extracted with ethyl selleck acetate (3 × 30). The organic layer was washed with brine, dried over magnesium sulphate, and concentrated under reduced pressure to produce a viscous oil mixture of (R,R)-6 and (R,S)-6. The residue obtained after evaporation of the solvent was chromatographed over Selleckchem Duvelisib a silicagel column using mixture of ethyl acetate/hexane (30:70) as eluent to produce an oily syrup at an overall yield of 88%. Compound (R,R)-6; Rf = 0.48 (30:70 ethyl acetate/hexane); oily syrup; 1H NMR (400 MHz, CDCl3) δ: 2.08–2.15 (1H, m, H-3), 2.58 (1H, dd, J = 2.6, 7.2 Hz, H-9a), 2.85 (1H, dd, J = 2.6, 7.2 Hz, H-9b), 3.78 (3H, s, Ar–OCH3-5), 3.83 (3H, s, Ar-OCH3-7), 3.99 (2H, d, J = 8.2 Hz, H-2a & 2b), 4.66 (1H, d, J = 2.5 Hz, H-4), 5.99

(1H, d, J = 7.1 Hz, H-8), 6.01 (1H, d, J = 7.1 Hz, H-6), 6.76 (2H, d, J = 8.2 Hz, H-3′,5′), 7.12 (2H, d, J = 8.0 Hz, H-2′,6′); 13C NMR (100 MHz, CDCl3) 31.9 (CH2, C-9), 40.1 (CH, C-3), 55.3 (OCH3, C-7), 55.4 (OCH3, C-5), 59.6 (CH, C-4), 65.2 (CH2, C-2), 91.3 (CH, C-6), 93.0 (CH, C-8), 106.6 (C, C-4a), 115.2 (CH, C-3′,5′), 130.2 (C, C-1′), 131.6 (CH, C-2′,6′), 153.8 (C, C-4′), 155.9 (C, C-5), Sitaxentan 159.2 (C, C-8a), 161.1 (C, C-7); mass m/z = 317 (M + 1)+. Compound (R,S)-6; Rf = 0.45 (30:70 ethyl acetate/hexane); oily syrup; 1H NMR (400 MHz, CDCl3) δ: 2.12-2.18 (1H, m, H-3), 2.40 (1H, dd,

J = 2.9, 7.9 Hz, H-9a), 2.55 (1H, dd, J = 2.9, 7.9 Hz, H-9b), 3.76 (3H, s, Ar–OCH3-5), 3.81 (3H, s, Ar–OCH3-7), 3.90 (1H, dd, J = 1.8, 1.8 Hz, H-2a), 4.07 (1H, dd, J = 1.9, 2.0 Hz, H-2b), 4.62 (1H, s, H-4), 6.06 (1H, d, J = 3.9 Hz, H-6), 6.07 (1H, d, J = 3.9 Hz, H-8), 6.74 (2H, d, J = 8.3 Hz, H-3′,5′), 7.04 (2H, d, J = 8.3 Hz, H-2′,6′); 13C NMR (100 MHz, CDCl3) 33.6 (CH2, C-9), 40.5 (CH, C-3), 55.3 (OCH3, C-7), 55.5 (OCH3, C-5), 62.9 (CH, C-4), 64.3 (CH2, C-2), 91.8 (CH, C-6), 93.2 (CH, C-8), 104.9 (C, C-4a), 115.3 (CH, C-3′,5′), 130.2 (C, C-1′), 131.2 (CH, C-2′,6′), 154.2 (C, C-4′), 155.8 (C, C-5), 159.8 (C, C-8a), 161.0 (C, C-7); mass m/z = 317 (M + 1)+. To a mixture of either (R,R)-6 or (R,S)-6 respectively (0.1 g, 1.0 mmol) in acetic acid (4 ml) was added CrO3 (0.16 g, 5.0 mmol). The reaction mixture was stirred at room temperature and allowed to stand for 0.5 h. The solvent was evaporated and extracted with ethyl acetate (2 × 15 ml). The organic layer was washed with brine (2 × 15 ml) and dried over magnesium sulphate.