HCID 53348343, compound → HCID 25190012, compound

Participants

Reaction Steps

A vessel was charged with an aqueous solution containing (3S)-3-cyano-2-ethoxycarbonyl-5-methyl-hexanoic acid potassium salt (Formula 23, 411 L from Example 2). Raney Nickel (50% aq solution, Sigma-Aldrich) was added to the mixture, and hydrogen gas was introduced into the vessel over a 20 h period to maintain a pressure of 50 psig in the vessel headspace throughout reaction. The hydrogenation reaction was monitored by H2 uptake and HPLC analysis (C18 column, 4.6 mm×150 mm, detection at 200 nm) of the vessel contents. Following reaction, the aqueous mixture was filtered to remove the Raney Ni catalyst. The pH of the concentrated solution was adjusted to 3.0 using 37% HCl (about 14 L). The resulting solution was extracted three times with EtOAc (50% v/v). The combined organic layers were concentrated under vacuum to afford (S)-4-isobutyl-2-oxo-pyrrolidine-3-carboxylic acid (Formula 10). MS m/z [M+H]+186.1130. 13C NMR (75 ppm, CDCl3) δ 175.67, 172.23, 54.09, 47.62, 43.69, 37.22, 26.31, 23.34, 22.54. Yield 40-42%; 97% ee.

Provenance & Evidence