反应详情

A solution of the bis-pivaloylate 109 (1 g, 2.54 mmol) in CH2Cl2 was treated with acetyl chloride (0.22 g, 2.8 mmol) was treated with AlCl3 (0.36 g, 2.8 mmol) and stirred at rt overnight. The reaction was worked up by adding EtOAc, washing with 2 N HCl aq, saturated NaHCO3 aq and drying over MgSO4. After filtering and concentrating, the residue was chromatographed on silica gel (EtOAc/hexanes 1:4 to EtOAc/hexanes 1:1) to yield the product which was promptly dissolved in MeOH/THF/2 N NaOH aq and warmed until TLC analysis indicated that the hydrolysis of the pivalate esters was completed. The reaction was concentrated to remove the organic solvents and the residue aqueous was acidified with 2 N HCl aq and extracted with EtOAc. The EtOAc extract was washed with saturated NaHCO3 solution, brine and dried over MgSO4. After filtration and concentration, the residue was chromatographed on silica gel (EtOAc/hexanes 1:4 to EtOAc/hexanes 1:1) to yield 90 mg of the desired pdt: Mp=243–251° C.; 1H NMR (DMSO-d6) δ 10.08 (br s, 1 H), 9.40 (br s, 1 H), 7.63 (d, 2 H, J=8.8 Hz), 7.43 (d, 1 H, d=9.3 Hz), 7.41 (d, 1 H, J=2.4 Hz), 6.92 (d, 2 H, J=8.8 Hz), 6.80 (dd, 1 H, J=8.8 Hz, 2.4 Hz), 2.26 (s, 3 H).

1. washwashing with 2 N HCl aq, saturated NaHCO3 aq
2. dry with materialdrying over MgSO4
3. filtrationAfter filtering
4. concentrationconcentrating
5. customthe residue was chromatographed on silica gel (EtOAc/hexanes 1:4 to EtOAc/hexanes 1:1)
6. customto yield the product which
7. temperaturewarmed until TLC analysis
8. concentrationThe reaction was concentrated
9. customto remove the organic solvents
10. extractionextracted with EtOAc
11. extractionThe EtOAc extract
12. washwas washed with saturated NaHCO3 solution, brine
13. dry with materialdried over MgSO4
14. filtrationAfter filtration and concentration
15. customthe residue was chromatographed on silica gel (EtOAc/hexanes 1:4 to EtOAc/hexanes 1:1)
16. customto yield 90 mg of the desired pdt