反应详情

To a round-bottomed flask equipped with magnetic stir bar was charged 1a (3.0 g, 20 mmol), pyridine (4.7 g, 59 mmol, 3 equiv) and CH2Cl2 (25 mL). The mixture was cooled in a dry ice-acetone bath and Tf2O (6.6 mL, 11.1 g, 39 mmol, 2 equiv) was added dropwise over 30 min Afterwards, the mixture was stirred at room temperature for 2 h. The reaction mixture was washed with H2O (2×25 mL) followed by brine (25 mL). The organic phase was separated, dried over anhydrous MgSO4 and evaporated under reduced pressure leaving a brownish oil (5.12 g, 90%). The crude product could be further purified by short-path distillation at reduced pressure (0.1 ton) to give the product as colorless oil. However, the compound appears to be heat sensitive as there was a significant decomposition residue in the distillation pot. 1H NMR (CDCl3): δ 9.98 (s, 1H), 7.56 (d, J=1.7 Hz, 1H), 7.51 (dd, J=8.2 and 1.8 Hz, 1H), 7.40 (d, J=8.0 Hz, 1H), 3.99 (s, 3H); 13C NMR (CDCl3): δ 190.53, 152.49, 142.97, 137.06, 124.27, 123.45, 121.06, 118.92 (q, 1JCF=321.5 Hz), 112.06, 56.75; 19F {13C} NMR (CDCl3): δ −74.2. The product was used in the synthesis of compound 3a without further purification.

1. customTo a round-bottomed flask equipped with magnetic stir bar
2. temperatureThe mixture was cooled in a dry ice-acetone bath
3. washThe reaction mixture was washed with H2O (2×25 mL)
4. customThe organic phase was separated
5. dry with materialdried over anhydrous MgSO4
6. customevaporated under reduced pressure