TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Process: The (2S)-N-((1R)-1-((4R,5R)-4,5-dicyclohexyl-1,3,2-dioxaborolan-2-yl)-3-methylbutyl)-3-phenyl-2-(pyrazin-2-ylformamido)propanamide is prepared by reacting (2S)-3-phenyl-2-((pyrazin-2-ylcarbonyl)amino)propanoic acid and (1S)-1-((4R,5R)-4,5-dicyclohexyl-1,3,2-dioxaborolan-2-yl)-3-methylbutan-1-amine in presence of base and condensing agent. Alternatively, the(2S)-N-((1R)-1-((4R,5R)-4,5-dicyclohexyl-1,3,2-dioxaborolan-2-yl)-3-methylbutyl)-3-phenyl-2-(pyrazin-2-ylformamido)propanamide is prepared by reacting 3-phenylpropanoic acid of formula (IV) and (1S)-1-((4R,5R)-4,5-dicyclohexyl-1,3,2-dioxaborolan-2-yl)-3-methylbutan-1-amine, obtaining dioxaborolane derivative of formula (VII), and reacting the obtained dioxaborolane derivative with pyrazine-2-carboxylic acid. Alternatively, the(2S)-N-((1R)-1-((4R,5R)-4,5-dicyclohexyl-1,3,2-dioxaborolan-2-yl)-3-methylbutyl)-3-phenyl-2-(pyrazin-2-ylformamido)propanamide is prepared by reacting (2S)-2-((tert-butoxycarbonyl)amino)-3-phenylpropanoic acid and (1S)-1-((4R,5R)-4,5-dicyclohexyl-1,3,2-dioxaborolan-2-yl)-3-methylbutan-1-amine in presence of solvent, obtaining tert-butyl N-((1S)-1-(((1R)-1-((4R,5R)-4,5-dicyclohexyl-1,3,2-dioxaborolan-2-yl)-3-methylbutyl)carbamoyl)-2-phenylethyl)carbamate, reacting the obtained tert-butyl N-((1S)-1-(((1R)-1-((4R,5R)-4,5-dicyclohexyl-1,3,2-dioxaborolan-2-yl)-3-methylbutyl)carbamoyl)-2-phenylethyl)carbamate with hydrochloric acid, obtaining (2S)-2-amino-N-((1R)-1-((4R,5R)-4,5-dicyclohexyl-1,3,2-dioxaborolan-2-yl)-3-methylbutyl)-3-phenylpropanamide hydrochloride, and reacting the obtained(2S)-2-amino-N-((1R)-1-((4R,5R)-4,5-dicyclohexyl-1,3,2-dioxaborolan-2-yl)-3-methylbutyl)-3-phenylpropanamide hydrochloride with pyrazine-2-carboxylic acid in presence of condensing agent and base. The (1S)-1-((4R,5R)-4,5-dicyclohexyl-1,3,2-dioxaborolan-2-yl)-3-methylbutan-1-amine is prepared by reacting (4R,5R)-2-((1S)-1-chloro-3-methylbutyl)-4,5-dicyclohexyl-1,3,2-dioxaborolane with lithium hexamethyldisilazide in presence of tetrahydrofuran at 80-60 degrees C. The (4R,5R)-2-((1S)-1-chloro-3-methylbutyl)-4,5-dicyclohexyl-1,3,2-dioxaborolane is prepared by performing Matteson rearrangement reaction of (4R,5R)-4,5-dicyclohexyl-2-(2-methylpropyl)-1,3,2-dioxaborolane with methylene chloride in presence of lithium diisopropylamide using anhydrous zinc chloride as Matteson rearrangement catalyst.R=H, 1-5C alkyl or 1-5C alkoxycarbonyl.Preferred Composition: The condensing agent is N,N-diisopropylethylamine(1-(bis(dimethylamino)methylene)-1H-1,2,3-triazolo(4,5-b)pyridinium 3-oxid hexafluorophosphate) or 2-(1H-benzotriazole-1-yl)-1,1,3,3-tetramethyluronium tetrafluoroborate. The base is N,N-diisopropylethylamine. The solvent is dichloromethane. The dioxaborolane derivative (A) is chosen from(4R,5R)-2-((1S)-1-chloro-3-methylbutyl)-4,5-dicyclohexyl-1,3,2-dioxaborolane, (1S)-1-((4R,5R)-4,5-dicyclohexyl-1,3,2-dioxaborolan-2-yl)-3-methylbutan-1-amine, tert-butyl N-((1S)-1-(((1R)-1-((4R,5R)-4,5-dicyclohexyl-1,3,2-dioxaborolan-2-yl)-3-methylbutyl)carbamoyl)-2-phenylethyl)carbamate, (2S)-N-((1R)-1-((4R,5R)-4,5-dicyclohexyl-1,3,2-dioxaborolan-2-yl)-3-methylbutyl)-3-phenyl-2-(pyrazin-2-ylformamido)propanamide and (2S)-2-amino-N-((1R)-1-((4R,5R)-4,5-dicyclohexyl-1,3,2-dioxaborolan-2-yl)-3-methylbutyl)-3-phenylpropanamide.