55809-36-4

Amination of aryl bromides catalyzed by Pd(dba)3 (Aldrich Catalog No. 328774) and Xantphos (Aldrich Catalog No. 526460).1

Example 1: Gaseous hydrogen chloride (26.3 g) was added to 4,4-dimethyl-3-oxopentanenitrile (75.102 g) suspended in a mixture of anhydrous toluene (150 ml) and anhydrous methanol (26.7 ml) at 5° C. to 10° C. with continuous stirring. Subsequently, the reaction mixture was allowed to stand at 10° to 12°C for 23 hours. Under cooling and stirring conditions, anhydrous methanol (750 ml) followed by triethylamine (185.178 g) was added slowly and dropwise to the reaction mixture until a complete solution was formed. Next, hydroxylamine sulfate (51.704 g) was added and the reaction mixture was stirred at 50°C for 2 hours. After completion of the reaction, the mixture was concentrated. Hydrochloric acid (112.629 g) was added dropwise to the concentrated mixture and stirring was continued at 50 °C for 1 hour. After removal of the solvent by evaporation under reduced pressure, the residue was adjusted to alkaline with 48% aqueous sodium hydroxide solution under cooling conditions, followed by extraction of the aqueous solution with toluene. After the organic layer was washed with water, the solvent was removed by azeotropic distillation at atmospheric pressure and finally dried to give 3-amino-5-tert-butylisoxazole (79.480 g) with a melting point of 106° to 109°C and a yield of 94.5%.

[1] Patent: US4200757, 1980, A
[2] Patent: WO2013/100632, 2013, A1. Location in patent: Page/Page column 42; 43
[3] Patent: US2014/371219, 2014, A1. Location in patent: Paragraph 0288; 0289; 0290
[4] Molecules, 2014, vol. 19, # 2, p. 2004 - 2028
[5] Heterocycles, 1991, vol. 32, # 6, p. 1153 - 1158