反应详情

To 4-methoxybenzyl N-[4-bromo-1-(tert-butoxycarbonyl)-1H-pyrazol-3-yl]-N-[(2,2,2-trichloroethoxy)carbonyl]leucinate (2.38 g, 3.54 mmol) in THF (40 mL) was added activated zinc powder (2.3 g, 35.4 mmol) and an aqueous solution of KH2PO4 (1.0 M, 14.2 mL, 14.2 mmol) dropwise. After 1 hour additional aliquots of activated zinc powder (2.3 g, 35.4 mmol) and aqueous KH2PO4 solution were added (1.0 M, 14.2 mL, 14.2 mmol) and the reaction mixture was stirred for 1 hour. The zinc powder was filtered off, rinsed with Et2O and water and the product extracted with ether (2×), dried over Na2SO4, concentrated in vacuo, and purified by flash chromatography over silica gel (EtOAc/Hex, 3/7) to afford 4-methoxybenzyl N-[4-bromo-1-(tert-butoxycarbonyl)-1H-pyrazol-3-yl]leucinate.

1. filtrationThe zinc powder was filtered off
2. washrinsed with Et2O and water
3. extractionthe product extracted with ether (2×)
4. dry with materialdried over Na2SO4
5. concentrationconcentrated in vacuo
6. custompurified by flash chromatography over silica gel (EtOAc/Hex, 3/7)