Triethylamine → Br-Boc-C2-azido

2-Azidoethanol (17.40 g, 0.2 mol), freshly distilled methylene chloride (150 mL), and Et3N (21.21 g, 0.21 mol) were added into a three-neck round-bottom flask equipped with a condenser and a dropping funnel. Under nitrogen atmosphere and magnetic stirring, freshly distilled anhydrous methylene chloride (150 mL), DMAP (1.7 g, 14 mmol), and freshly distilled anhydrous Et3N (46.5 g, 0.46 mol) were sequentially added. After the flask was immersed into an ice-water bath, 2-bromoisobutyryl bromide (48.28 g, 0.21 mol) was added dropwise into the previous solution. Twenty-four hours later, the reaction mixture was washed successively with 1 M HCl (3×200 mL) solution and deionized water (1×200 mL). The organic phase was dried over anhydrous MgSO4 overnight. After filter and removal of methylene chloride on a rotary evaporator, the obtained residues were distilled under reduced pressure to give a colorless viscous liquid. The yield was: 33.4 g, 70%. 1H NMR (CDCl3, δ, ppm): 4.24 (t, 2H, N3CH2CH2), 3.52 (t, 2H, N3CH2), 1.96 (s, 6H, (CH3)2Br).