Trifluoroacetic acid → 1-Benzyl-4-(4-chloro-3-fluoro-phenyl)-2,5-dihydro-1H-pyrrole-3-carboxylic acid

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Reaction Conditions

Reaction Steps

At r.t., a solution of N-(methoxymethyl)-N-(phenylmethyl)-N-(trimethylsilyl)methyl amine (61.3 g, 0.26 mol) in CH2Cl2 (120 ml) was added dropwise over 90 minutes to a stirred solution of (4-chloro-3-fluoro-phenyl)-propynoic acid ethyl ester (39.0 g, 0.17 mol) and trifluoroacetic acid (1.30 ml, 0.02 mol) in CH2Cl2 (170 ml). The reaction mixture was stirred at 25° C. for 72 h and afterward evaporated to dryness. The residue was dissolved in dioxane (390 ml). An aqueous solution of NaOH (45.0 ml, 0.48 mol, 2.8 eq.) was added, and the resulting emulsion was stirred at r.t. for 18 h. The low boiling organic solvent was removed under vacuum. Water (100 ml) was added, the aqueous layer was separated and washed with TBME (2 times 100 ml). The aqueous layer was then acidified to a pH value of 2.5 by addition of 25% HCl. The resulting suspension was stirred overnight and the white precipitate was filtered off, washed with water and ethanol and dried under high vacuum to yield 42.0 g (75%) of IId as a white solid.

Provenance & Evidence