反应详情

Treatment of 3,5-dibromo-4-nitro-1H-pyrazole 1 with 2-bromoethanol and NaH in DMF affords 2-(3,5-dibromo-4-nitro-1H-pyrazol-1-yl)ethanol 2. Reaction of the compound 2 with lithium bis(trimethylsilyl)amide in the presence of bis(dibenzylidene)palladium (0) and P(t-Bu)3 in toluene affords the bis-silylamine 3, which is readily converted to 2-(5-amino-3-bromo-4-nitro-1H-pyrazol-1-yl)ethanol 4 by addition of aqueous HCl and neutralization (Org. Lett. 2001, 3, 2729). Reduction of the compound 4 with Fe in acetic acid provides 2-(4,5-diamino-3-bromo-1H-pyrazol-1-yl)ethanol 5.