Triphenylphosphine → 4-methoxybenzyl N-[4-bromo-1-(tert-butoxycarbonyl)-1H-pyrazol-3-yl]-N-[(2,2,2-trichloroethoxy)carbonyl]leucinate

Participants

Reaction Steps

To tert-butyl 4-bromo-3-{[(2,2,2-trichloroethoxy)carbonyl]amino}-1H-pyrazole-1-carboxylate (2.32 g, 5.3 mmol), 4-methoxybenzyl 2-hydroxy-4-methylpentanoate (2.02 g, 8.0 mmol, prepared as described in Example 16) and triphenyl phosphine (2.1 g, 8.0 mmol) in dry DMF (50 mL) at 0° C. under dry nitrogen was added diisopropyl azodicarboxylate (1.6 mL, 8.0 mmol) dropwise and the reaction was stirred overnight. The reaction was poured into water and the product extracted with Et2O (2×), dried over Na2SO4, concentrated in vacuo and purified by flash chromatography over silica gel (EtOAc/Hex, 2/8) to afford 4-methoxybenzyl N-[4-bromo-1-(tert-butoxycarbonyl)-1H-pyrazol-3-yl]—N-[(2,2,2-trichloroethoxy)carbonyl]leucinate.

Provenance & Evidence