1H NMR (400 MHz, CDCl3) δ 7.42 (d, J = 6.9 Hz, 4H), 7.39 – 7.28 (m, 6H), 1.69 (s, 9H). 13C{1H} NMR (101 MHz, CDCl3) δ 171.8, 136.0, 130.0, 129.5, 128.8, 128.4, 57.8, 29.0.