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

Participants

Reaction Conditions

Reaction Steps

Add sodium ethoxide (145 g, 2.03 mol), followed by toluene (7 L) and 3-(2-oxo-pyrrolidin-1-ylimino)-3-pyridin-2-yl-propionic acid ethyl ester (Preparation 3-B; 280 g, 1.02 mol) to a 22 L flask equipped with mechanical stirrer, nitrogen inlet and a reflux condenser. Heat the mixture to 100° C. for 21 h. Cool to room temperature, add water (6 L), and adjust to pH 5 with concentrated hydrochloric acid. Separate the organic layer and extract the aqueous layer with 10% isopropyl alcohol in chloroform (2×9 L). Combine the organic layers, dry (sodium sulfate), filter, and concentrate in vacuo to yield 218 g (93%) of the title compound as a yellow solid MS ES+ m/e 230 (M+1).

Provenance & Evidence