3-(Tert-butyl)isoxazole-5-carboxamide → (3-Tert-butyl-1,2-oxazol-5-yl)methanamine

Participants

Reaction Conditions

Reaction Steps

To a solution of 220 mg (1.27 mmol) of 3-tert-butyl-isoxazole-5-carboxylic acid amide in anhydrous THF (10 mL) are added 2.54 mL (5.08 mmol, 2M solution in THF) of borane-methylsulfide complex at room temperature under nitrogen atmosphere. The reaction is heated to reflux for 3 h. A further portion of borane-methylsulfide complex (1.3 mL) is added and the reaction is heated for 4 h. The reaction mixture is quenched by addition of methanol and allowed to stand at room temperature for 16 h. The mixture is concentrated under reduced pressure and 1M aqueous HCl solution (8 mL) is added. The mixture is heated to reflux for 1 h, then cooled to 0° C., neutralized by addition of 6M aqueous NaOH solution and solid K2CO3. The mixture is extracted with diethyl ether (5×10 mL) and the combined organic extracts are dried (MgSO4), filtered and the filtrate is concentrated under reduced pressure. The residue is purified twice by column chromatography 9silica, eluent DCM, 0-10% methanol) to afford 84 mg of (3-tert-butyl-1,2-oxazol-5-yl)methanamine. Yield: 34%; ES-MS: m/z 155 [M+H]; 1H NMR (250 MHz, CHLOROFORM-d) δ ppm 1.33 (9 H, s), 1.84 (2 H+H2O, br. s.), 3.96 (2 H, s), 6.07 (1 H, s)

Provenance & Evidence