“…6a: mp 50.0−52.0°C. 1 H NMR (400 MHz, CDCl 3 , TMS): δ 7.69 (2H, dd, J = 1.6, 7.2 Hz), 7.54 (2H, dd, J = 1 6,. 7.2 Hz), 7.47 (2H, dt, J = 1.6, 7.2 Hz), 7.43 (2H, dt, J = 1.6, 7.2 Hz), 7.25 (4H, d, J = 8.4 Hz), 7.08 (4H, d, J = 8.4 Hz), 3.68 (4H, t, J = 7.6 Hz), 1.53− 1.46 (4H, m), 1.30 (4H, sext, J = 7.2 Hz), 0.89 (6H, t, J = 7.2 Hz) 13.…”