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, 12.2 mmol) in CH2Cl2 (150 mL) and t-butyl acetate (105 mL) at rt was added perchloric acid (3.15 mL, 36.7 mmol). The reaction flask was sealed. After stirring for 3 h, the reaction mixture was diluted with CH2Cl2 (100 mL), carefully quenched with sat. aq. NaHCO3 (50 mL). The organic layer was separated and washed with brine (100 mL), dried (Na2SO4), filtered and concentrated in vacuo to give a yellow liquid. This crude product was purified by flash column chromatography on a 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. In addition, 700 mg of starting material was 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. customThe reaction flask was sealed
2. customcarefully quenched with sat. aq. NaHCO3 (50 mL)
3. customThe organic layer was separated
4. washwashed with brine (100 mL)
5. dry with materialdried (Na2SO4)
6. filtrationfiltered
7. concentrationconcentrated in vacuo
8. customto give a yellow liquid
9. customThis crude product was purified by flash column chromatography on a silica gel column