Diisopropylethylamine → (S)-tert-butyl 3-bromo-1-(4-methyl-1-(methylamino)-1-oxopentan-2-ylcarbamoyl)-5,6-dihydroimidazo[1,5-a]pyrazine-7(8H)-carboxylate

Participants

Reaction Steps

To a solution of 3-bromo-7-(tert-butoxycarbonyl)-5,6,7,8-tetrahydroimidazo[1,5-a]pyrazine-1-carboxylic acid (11) (0.53 g, 1.53 mmol), L-leucine-N-methylamide (0.26 g, 1.80 mmol) and DIEA (0.5 mL, 2.9 mmol) in DMF (20 mL) was added TBTU (0.69 g, 2.15 mmol) in two batches over 10 minutes at 0° C. After stirring from 0° C. to room temperature for 2 hours, the reaction was quenched with water and evaporated under vacuum. The residue was extracted between saturated aqueous NaHCO3 and EtOAc. The organic layer was dried over anhydrous Na2SO4 and evaporated to dryness. The crude mixture was purified by column chromatography with 70% to 100% EtOAc/Hexanes to give the desired product 20C as an oil (48% yield). LCMS (+ESI) m/z 474.1, 475.1 [M+H]+.

Provenance & Evidence