反应详情

To a stirred solution of (S)-ethyl 6-(2-ethoxy-1-hydroxy-2-oxoethyl)-7-iodo-5-methylpyrazolo[1,5-a]pyrimidine-2-carboxylate (5.3 g, 12.23 mmol) in CH2Cl2 (150 mL) and t-butyl acetate (105 mL) was added perchloric acid (3.15 mL, 36.7 mmol) at rt and sealed the reaction flask. After 3 h, the reaction mixture was diluted with CH2Cl2 (100 mL), carefully quenched with sat. NaHCO3 (50 mL), organic layer separated and washed with brine (100 mL), dried (Na2SO4), filtered and concentrated to give yellow liquid. This was purified by flash column chromatography on silica gel column using (10-50% EtOAc/Hex as eluant) to afford the desired (S)-ethyl 6-(1-(tert-butoxy)-2-ethoxy-2-oxoethyl)-7-iodo-5-methylpyrazolo[1,5-a]pyrimidine-2-carboxylate (4.5 g, 8.28 mmol, 67.7% yield) as viscous oil. 700 mg of starting material was also recovered. 1H NMR (500 MHz, CDCl3) δ: 7.31 (s, 1H), 5.56 (s, 1H), 4.51 (q, J=7.1 Hz, 2H), 4.26-4.16 (m, 2H), 2.71 (s, 3H), 1.48 (t, J=7.2 Hz, 3H), 1.30 (s, 9H), 1.23 (t, J=7.0 Hz, 3H). LCMS (M+H)=490.0.

1. customsealed the reaction flask
2. customcarefully quenched with sat. NaHCO3 (50 mL), organic layer
3. customseparated
4. washwashed with brine (100 mL)
5. dry with materialdried (Na2SO4)
6. filtrationfiltered
7. concentrationconcentrated
8. customto give yellow liquid
9. customThis was purified by flash column chromatography on silica gel column