Diisopropylethylamine → N-Methyl-L-valinamide

Participants

Reaction Steps

1200 mg (2.33 mmol) N-(tert-butoxycarbonyl)-N-methyl-L-valyl-N-[(2R,3S,4S)-1-carboxy-2-methoxy-4-methyl-hexan-3-yl]-N-methyl-L-valinamide (intermediate 5) was combined with 910.8 mg (2.33 mmol) benzyl-(2R,3R)-3-methoxy-2-methyl-3-[(2S)-pyrrolidin-2-yl]propanoate trifluoroacetic acid salt (intermediate 6), 1327 mg (3.49 mmol) O-(7-azabenzotriazol-1-yl)-N,N,N′,N′-tetramethyluronium hexafluorophosphate and 2027 μL N,N-diisopropylethylamine in 50 mL DMF and stirred for 5 min at RT. Next the solvent was removed in vacuo. The remaining residue was dissolved in ethyl acetate and then extracted with 5% aqueous citric acid solution and saturated sodium bicarbonate solution in succession. The organic phase was separated and concentrated. The residue was purified by preparative HPLC. The product fractions were combined, concentrated and the residue was dried in a high vacuum, yielding 1000 mg (55% of the theoretical) of the benzyl ester intermediate N-(tert-butoxycarbonyl)-N-methyl-L-valyl-N-[(3R,4S,5S)-1-{(2S)-2-[(1R,2R)-3-benzyloxy)-1-methoxy-2-methyl-3-oxopropyl]pyrrolidin-1-yl}-3-methoxy-5-methyl-1-oxoheptan-4-yl]-N-methyl-L-valinamide as a resin.

Provenance & Evidence