Synthesis of Levetiracetam

The first-generation synthesis of levetiracetam (3), as shown in Scheme 14.9 [29], starts with benzoyl protection and oxidation of (S)-aminobutanol (32), which gives rise to the corresponding N-benzoyl protected (S)-aminobutyric acid (33). After N-benzoyl amidation and deprotection, (S)-aminobutyramide (34) is obtained. Chemoselective butyrolactam ring formation using the intermediate 34 and 4-chlorobutyryl chloride finally affords levetiracetam (3). 

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