Diisopropylethylamine → (S)-tert-butyl 3-bromo-1-(4-methyl-1-(methylamino)-1-oxopentan-2-ylcarbamoyl)-6,7-dihydro-5H-imidazo[1,5-a][1,4]diazepine-8(9H)-carboxylate

Participants

Reaction Steps

To a solution of 3-bromo-8-(tert-butoxycarbonyl)-6,7,8,9-tetrahydro-5H-imidazo[1,5-a][1,4]diazepine-1-carboxylic acid (33E) (1.08 g, 3.0 mmol), H-Leu-NHMe (20B) (0.62 g, 4.30 mmol) and DIEA (0.52 mL, 3.0 mmol) in DMF (25 mL) was added TBTU (1.46 g, 4.55 mmol) in two batches over 10 min at 0° C. After stirring from 0° C. to room temperature overnight, 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 60% to 100% EtOAc/Hex to give an oily product 55A at 51% yield. LCMS (+ESI) m/z 486.1, 489.1 [M+H]+.

Provenance & Evidence