Reaction Steps
A solution of (4,4′,5,6-tetramethoxybiphenyl-2,2′-diyl)dimethanol (170 mg, 0.51 mmol) in THF (2 mL), 2M HCl (2 mL) and concentrated hydrochloric acid (1 mL) was stirred under reflux for 3 hours. Water (15 mL) and ethyl acetate (15 mL) were added to the reaction mixture, the layers were separated and the aqueous layer was extracted with ethyl acetate (2×10 mL). The extracts were combined, dried over Na2SO4, filtered and concentrated in vacuo. Flash chromatography of the residue over silica gel (20 g), eluting with hexane-ethyl acetate (4:1), yielded the title compound as a white solid (150 mg, 93%); m.p. 151-153° C.; Elemental Analysis Found: C, 68.5; H, 6.5 (C18H20O5 requires C, 68.34; H, 6.37%); NMR Spectrum δH (300 MHz, CDCl3) 7.63 (1H, d, J 8.4 Hz, 11-H), 6.98 (1H, dd, J 2.6, 8.4 Hz, 10-H), 6.96 (1H, d, J 2.6 Hz, 8-H), 6.75 (1H, s, 4-H), 4.42 (2H, m), 4.08 (2H, m), 3.94 (3H, s, OCH3), 3.91 (3H, s, OCH3), 3.86 (3H, s, OCH3), 3.65 (3H, s, OCH3); NMR Spectrum δC (75 MHz, CDCl3) 55.7, 56.4, 61.2, 61.5, 68.1, 109.1, 114.2, 114.8, 126.7, 129.7, 131.1, 131.4, 136.8, 143.1, 150.9, 153.1, 159.4; νmax/cm−1 (thin film) 2963, 2936, 2858, 2839, 1612, 1491, 1456, 1332, 1243, 1150, 1104, 1052, 1006; m/z (ES) 380 (MNa2H2O+, 100%), 287 (MH+—CH2O, 100); Rf (hexane-ethyl acetate 3:1) 0.39.
