597569-42-1

1205676-44-3

(3) Intermediate 2 (700 g, 2.8 mol, 1.0 eq.) was added to a saturated ethanol solution of hydrogen chloride (3.0 L). Heat was refluxed and stirred for 3 h. Stirring was stopped when the reaction was complete. The ethanol solvent was removed by rotary evaporator and the resulting residue was recrystallized from petroleum ether to give 580 g of ethyl (1S,3aR,6aS)-octahydrocyclopenta[c]pyrrole-1-carboxylate hydrochloride as a white solid. The yield was 96.4% and the enantiomeric excess (ee) was 99.7%.