Trifluoroacetic acid → 3,4-Dichlorobenzyl 4-[4-(2-methyl-6-nitro-2,3-dihydroimidazo[2,1-b]oxazol-2-ylmethoxy)phenyl]piperazine-1-carboxylate

Beteiligte Stoffe

Reaktionsschritte

Tert-butyl 4-[4-(2-methyl-6-nitro-2,3-dihydroimidazo[2,1-b]oxazol-2-ylmethoxy)phenyl]-piperazine-1-carboxylate prepared in Example 131 (118 mg, 0.26 mmol) was dissolved in methylene chloride (5 ml). To the solution, trifluoroacetic acid (5 ml) was added, and the mixture was stirred at room temperature for 3 hours. The reaction mixture was concentrated under reduced pressure and added methylene chloride (2 ml) and triethylamine (2 ml). The solution was stirred at room temperature for 5 minutes and then concentrated under reduced pressure. The residue was dissolved in DMF (15 ml) and the solution was added a solution of 3,4-dichlorobenzyl alcohol (136 mg, 0.77 mmol) and 1,1′-carbonyldiimidazole (125 mg, 0.77 mmol) in DMF (5 ml) stirred at room temperature for 3 hours followed by stirring at room temperature overnight. The reaction mixture was poured into water and extracted with ethyl acetate. The organic phase was washed with a saturated saline solution, dried over magnesium sulfate and then filtered. The resulting filtrate was concentrated under reduced pressure. The residue was purified by silica gel column chromatography (methylene chloride/methanol=200/1) and crystallized from methylene chloride-isopropyl ether to afford 3,4-dichlorobenzyl 4-[4-(2-methyl-6-nitro-2,3-dihydroimidazo[2,1-b]oxazol-2-ylmethoxy)phenyl]piperazine-1-carboxylate (101 mg, yield 70%) as a light yellow powder.

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