Hydrochloric Acid → 2-(6-methylpyridin-2-yl)-5,6-dihydro-4H-pyrrolo[1,2-b]pyrazole-3-carboxylic acid

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Reaction Conditions

Reaction Steps

Add sodium ethoxide (90 g, 1.32 mol), toluene (5 L) and 3-[6-methyl-(pyridin-2-yl)]-3-(2-oxo-pyrrolidin-1-ylimino)-propionic acid ethyl ester (Preparation 2-B; 201 g, 0.661 mol) to a 22 L flask equipped with a mechanical stirrer, nitrogen inlet and a reflux condenser. Heat the mixture at 100° C. for 24 h then cool to room temperature. Add water (4 L) and adjust the pH to 4 with concentrated hydrochloric acid. Separate the organic layer and extract the aqueous portion with 10% isopropyl alcohol in chloroform (3×4.5 L). Combine the organic layers, dry (sodium sulfate), filter, and concentrate in vacuo to yield the subtitled product 138 g (86%) as a yellow solid in 78% purity by HPLC analysis. MS ES+ m/e 244 (M+1).

Provenance & Evidence