反应详情

A solution of 3.43 g (14.9 mmol) of 7-2, 1.15 mL (14.9 mmol) of TFA and 2.104 mL (14.9 mmol) of trifluoroacetic anhydride in 60 mL of acetic acid was heated to 80° C. under a slow stream of Ar for 7 h. After HPLC analysis of the reaction progress, an additional 766 μL (9.9 mmol) of TFA and 1.4 mL (9.9 mmol) of trifluoroacetic anhydride were added and the reaction mixture was heated for an additional 24 h. After standing at rt for several hours, the solvents were removed at reduced pressure, and the residue digested in 7 mL of acetic acid at 60° C. for 10 min, then 35 mL of isopropyl acetate (iPAc) was added dropwise to the warm mixture. After the addition, the slurry was allowed to cool to rt, filtered, and washed with 1:5 HOAc-iPAc. The solid was air dried to give 7-3 as an almost colorless solid: 1H NMR (CDCl3) δ 10.92 (br s, 1H), 6.185 (s, 1H), 4.66 (s, 2H), 4.25 (q, 2H, 7.1 Hz), 2.08 (s, 3H), 1.30 (t, 3H, 7.1 H

1. temperaturethe reaction mixture was heated for an additional 24 h
2. waitAfter standing at rt for several hours
3. customthe solvents were removed at reduced pressure
4. addition35 mL of isopropyl acetate (iPAc) was added dropwise to the warm mixture
5. additionAfter the addition
6. filtrationfiltered
7. washwashed with 1:5 HOAc-iPAc
8. customdried
9. customto give 7-3 as an almost colorless solid