Bromide ion → 5-(2-Methyl-[1,3]dioxolan-2-yl)-2-(3-nitro-pyrazol-1-ylmethyl)-oxazole

Beteiligte Stoffe

Reaktionsschritte

In a flame dried round-bottomed flask equipped with a magnetic stir bar and under inert atmosphere (N2), a solution of [5-(2-methyl-[1,3]dioxolan-2-yl)-oxazol-2-yl]-methanol (35 mg, 0.19 mmol) in dry CH2Cl2 (1.0 mL) was treated at 0° C. with Et3N (0.03 mL, 0.25 mmol) followed by DMAP (2.3 mg, 0.02 mmol) and Ms-Cl (0.02 mL, 0.23 mmol). After stirring at rt for 30 min, the reaction mixture was quenched with water (10 mL), extracted with CH2Cl2 (10 mL) and the combined org. extracts were dried over Na2SO4, filtered, and the solvents were removed under reduced pressure to give crude 2-chloromethyl-5-(2-methyl-[1,3]dioxolan-2-yl)-oxazole as a yellow oil. A solution of this crude 2-chloromethyl-5-(2-methyl-[1,3]dioxolan-2-yl)-oxazole (38 mg, 0.19 mmol) in acetone (1.0 mL) was treated with 5-nitro-1H-pyrazole (21 mg, 0.19 mmol) and TBA bromide (12 mg, 0.04 mmol) followed by K2CO3 (77 mg, 0.56 mmol). The reaction mixture was stirred at rt until completion. The solvent was removed under reduced pressure and water (10 mL) followed by EA (10 mL) were added. The aq. layer was extracted with EA (10 mL) and the combined org. extracts were dried over MgSO4, filtered, and the solvents were removed under reduced pressure. Purification of the residue by FC (4:6 hept-EA) gave the title compound as a colorless oil. TLC: rf (4:6 hept-EA)=0.15. LC-MS-conditions 02: tR=0.83 min; [M+H]+=281.05.

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