B.[Na].S(=O)(=O)(O)O.Cl.[OH-].[Na+].[CH2:11]([N:18]1[C:22](=O)[CH2:21][C@H:20]([OH:24])[C:19]1=O)[C:12]1[CH:17]=[CH:16][CH:15]=[CH:14][CH:13]=1>COCCOC.O.C1(C)C=CC=CC=1.CO>[CH2:11]([N:18]1[CH2:22][CH2:21][C@H:20]([OH:24])[CH2:19]1)[C:12]1[CH:13]=[CH:14][CH:15]=[CH:16][CH:17]=1158 g (approximately 0.745 mole) crude (S)-1-benzyl-3-hydroxy-2,5-pyrrolidinedione (IIa) were obtained. It was dissolved in 800 ml DME to which 85.1 g (2.25 moles) sodium boron hydride were then added. A solution of 60.3 ml (1.125 moles) sulfuric acid in 200 ml DME was added dropwise to the thick suspension produced at 20°-32° C. within 2.5 h and subsequently agitated 3 h at 70° C. After cooling off, 200 ml methanol were added dropwise and the batch was subsequently rotated in to dryness. The residue was taken up in 700 ml water, compounded under ice cooling with 180 ml conc. hydrochloric acid and agitated 1 h until the end of the development of gas. Then, 270 ml sodium hydroxide solution and 1 1 toluene were added. After the mixture was heated to 70° C. the toluene phase was separated and the aqueous phase subsequently extracted with 300 ml toluene. After the rotating in of the organic phase the residue began to gas, so that it was taken up in 600 ml water and 600 ml toluene and agitated overnight at room temperature with 90 ml conc. hydrochloric acid. The mixture was then made basic again and extracted and rotated in as above, yielding 131.3 g (99.4%) crude (S)-1-benzyl-3-hydroxypyrrolidine (IIIa).
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