C(O)C.[CH:4]1([CH2:10][C@@H:11]2[NH:15][C:14](=[O:16])[C:13](C(OCC)=O)=[C:12]2[OH:22])[CH2:9][CH2:8][CH2:7][CH2:6][CH2:5]1.C(=O)=O>O>[CH:4]1([CH2:10][C@@H:11]2[NH:15][C:14](=[O:16])[CH2:13][C:12]2=[O:22])[CH2:5][CH2:6][CH2:7][CH2:8][CH2:9]1A solution of 1 L of 50% ethanol in water is brought to the boiling point in a large beaker and 68.2 g (0.255 mol) of (S)-5-(cyclohexylmethyl)-2,5-dihydro-4-hydroxy-2-oxo-1H-pyrrole-3-carboxylic acid, ethyl ester is added over about 5 minutes (pot temperature is 82°-84° C.). The solid goes into solution as carbon dioxide evolves. The ethanol is allowed to boil-off over a period of one-half hour (pot temperature is 87° C.). The volume is about 750 ml, a slight turbidity develops and crystals separate on cooling to afford 48.5 g of (S)-5-(cyclohexylmethyl)-2,4-pyrrolidinedione after recrystallization from ethyl acetate; mp 165°-167° C.; [α]D23 =-75° (c=1.1% chloroform).
Wird geladen…
