2-Cyclopropyl-5H-pyrrolo[2,3-b]pyrazine-7-carboxylic acid ((S)-1-cyclohexyl-2-hydroxy-2-methylpropyl)-amide step 1 (S)-aminocyclohexylacetate hydrochloride (1.0 g, 5.16 mmol) was dissolved in 17 mL of 2:1,4-dioxane:water and cooled in an ice bath. Sodium hydroxide solution (10.4 mL of 1M aqueous solution) was slowly added to the reaction solution, followed by solid sodium bicarbonate (0.43 g, 5.16 mmol). Di-tert-butyl carbonate (1.68 g, 7.74 mmol) was added, and the reaction mixture was stirred for 16 h. The reaction mixture was partially evaporated, then absorbed in ethyl acetate and water, and acidified to pH 2 with potassium bisulfate solution. The layers were separated, and the aqueous layer was extracted twice with ethyl acetate. The combined ethyl acetate layer was washed with sodium chloride solution, dried over sodium sulfate, and evaporated to give 1.52 g of Boc-L-cyclohexylglycine.
Figure: Synthetic Route of Boc-L-Cyclohexylglycine
