Reaction Steps
To a solution of 11 (2.2 g, 4.80 mmol) in THF (50.0 mL) at 0° C. was added triphenyl phosphine (5.0 g, 19.2 mmol), diethylazodicarboxylate (3.3 g, 19.2 mmol), Diphenylphosphoryl azide (2.5 g, 9.6 mmol) sequentially. The reaction mixture was stirred at room temperature for 24 h after which it was concentrated under vacuum and purified on silica gel to get the desired azide (1.6 g, 70% yield). Rf=0.35 (10% ethyl acetate/hexanes). [α]23D=+16.3 (c 1.6, CHCl3). 1H NMR (400 MHz, Chloroform-d) δ 7.56-7.39 (m, 6H), 7.38-7.13 (m, 10H), 5.48 (dt, J=17.3 Hz, 10.1 Hz, 1H), 4.96 (dd, J=10.3 Hz, 1.9 Hz, 1H), 4.84 (dd, J=17.3 Hz, 1.8 Hz, 1H), 4.30 (dt, J=11.9 Hz, 2.4 Hz, 1H), 3.98 (td, J=12.1 Hz, 2.7 Hz, 1H), 3.88-3.71 (m, 1H), 3.69-3.64 (m, 1H), 3.38 (dd, J=10.1 Hz, 2.6 Hz, 1H), 3.07 (dd, J=10.0 Hz, 7.9 Hz, 1H), 1.98 (td, J=10.2 Hz, 2.2 Hz, 1H), 1.81-1.59 (m, 1H), 1.49 (s, 3H), 1.35 (s, 3H), 1.20-1.03 (m, 1H). 13C NMR (100 MHz, CDCl3) δ 143.8, 133.6, 128.6, 127.8, 127.0, 119.6, 98.4, 87.0, 67.2, 65.4, 62.3, 59.9, 50.5, 29.7, 28.4, 18.9.
