Hydrochloric Acid → 4-fluoro-1,3-dihydro-isoindole-2-carboxylic acid (3R,5S)-1-((S)-2-tert-butoxycarbonylamino-non-8-enoyl)-5-((1R,2S)-1-ethoxycarbonyl-2-vinyl-cyclopropyl-carbamoyl)-pyrrolidin-3-yl ester

Participants

Reaction Conditions

Reaction Steps

A solution of 1.15 g (2.55 mmol) (S)-2-tert-butoxycarbonylamino-non-8-enoic acid dicyclohexylammonium salt (commercially available from Synthetech Oregon, USA) and 469 mg (4.64 mmol) NMM in 9.0 mL of THF was added dropwise to a solution of 302 mg (2.53 mmol) pivaloyl chloride in 1.5 mL of THF while maintaining the temperature at 20-25° C. The suspension was stirred for 45 min, then cooled to 0° C. A solution of 1.00 g (2.32 mmol) of 4-fluoro-1,3-dihydro-isoindole-2-carboxylic acid (3R,5S)-5-((1R,2S)-1-ethoxycarbonyl-2-vinyl-cyclopropylcarbamoyl)-pyrrolidin-3-yl ester in 13 mL of THF was added to the mixed anhydride at 0° C. within 25 min. The mixture was first stirred for 2.5 h at 2° C., then for 19 h at 26° C. after which 9.5 mL water and 14.8 mL aqueous HCl (0.5 N) were added. The phases were separated and the aqueous layer was extracted with toluene (3×3 mL). The combined organic layers were washed with 2 mL of water, 5 mL of aqueous Na2CO3 (5 wt %) and dried (Na2SO4). The solvent was removed at 50° C. under reduced pressure using a rotary evaporator. The resulting oil was finally dried under oil pump vacuum yielding 1.75 g (88.3%) of 4-fluoro-1,3-dihydro-isoindole-2-carboxylic acid (3R,5S)-1-((S)-2-tert-butoxycarbonylamino-non-8-enoyl)-5-((1R,2S)-1-ethoxycarbonyl-2-vinyl-cyclopropylcarbamoyl)-pyrrolidin-3-yl ester as a brown resin with an assay of 80.5 wt %.

Provenance & Evidence