反应详情

A mixture of (S)-methyl 2-(2-(3-bromophenyl)-7-chloro-5-methylpyrazolo[1,5-a]pyrimidin-6-yl)-2-hydroxyacetate (7.81 g, 19.02 mmol), t-butylacetate (160 mL) in DCM (330 mL) was added perchloric acid (3.43 mL, 57.1 mmol) and the mixture was stirred at rt for 3 h. It was then quenched with sat.aq.NaHCO3 (adjusted to pH=7-8 by the addition of solid NaHCO3). This mixture was diluted with EtOAc and the organic phase was washed with water. The organic phase was dried (MgSO4), filtered, and concentrated in vacuo to obtain ˜7 g of crude product as an oil. Filtration through 70 g of silica gel eluting with CH2Cl2 gave (S)-methyl 2-(2-(3-bromophenyl)-7-chloro-5-methylpyrazolo[1,5-a]pyrimidin-6-yl)-2-(tert-butoxy)acetate (5.71 g, 12.23 mmol, 64.3% yield). 1H NMR (400 MHz, CDCl3) δ 8.20 (t, J=1.6 Hz, 1H), 7.95 (dt, J=7.8, 1.1 Hz, 1H), 7.63-7.53 (m, 1H), 7.37 (t, J=7.9 Hz, 1H), 6.94 (s, 1H), 5.69 (s, 1H), 3.76 (s, 3H), 2.70 (s, 3H), 1.30 (s, 9H). LCMS (M+H)=466 and 468.

1. customIt was then quenched with sat.aq
2. additionNaHCO3 (adjusted to pH=7-8 by the addition of solid NaHCO3)
3. additionThis mixture was diluted with EtOAc
4. washthe organic phase was washed with water
5. dry with materialThe organic phase was dried (MgSO4)
6. filtrationfiltered
7. concentrationconcentrated in vacuo
8. customto obtain ˜7 g of crude product as an oil
9. filtrationFiltration through 70 g of silica gel eluting with CH2Cl2