Step b: Synthesis of 2-tert-butyl-1H-imidazole
Ethyl pivaloimidate hydrochloride (4.2 g, 25.2 mmol) and aminoacetaldehyde dimethyl acetal (3.2 g, 30.45 mmol) were dissolved in methanol (8.0 mL) and the reaction was stirred at room temperature overnight. After the reaction was completed, the reaction mixture was concentrated under reduced pressure and concentrated hydrochloric acid (5.0 mL) was added. After concentrating again, it was diluted by adding water (10.0 mL). The pH of the mixture was adjusted to 11 with potassium carbonate solution, followed by the addition of ethanol (10.0 mL). The resulting suspension was filtered and the filtrate was concentrated under reduced pressure. The residue was purified by fast column chromatography on silica gel with an eluent ratio of dichloromethane/methanol (100:1 to 50:1) to give 2.3 g of 2-tert-butylimidazole as a white solid in 73% yield.
