text: A 5-step process to synthesise levobupivacaine from N-CBZ (S)-lysine, published in 1996, is depicted in Scheme 1. The key steps in this process include oxidative de-animation and stereospecific ring closure to form the pipecolamide core structure. This method is claimed to be efficient, but showed to be dangerous for mass production due to the high risk of explosion of the diazonium salt intermediates. 
  A more recent patent from 2008, consists of a 3-step process (see Scheme 2) to synthesise levobupivacaine hydrochloride of an optical purity of at least 99%. (S)-2,6-pipecocholxylide (I) is reacted with 1-bromobutane and a base (a), such as potassium carbonate, to obtain a solution of (S)-bupivacaine (II) and its enantiomers. Recrystallisation of this solution with a solvent (b), preferably cyclohexane, can lead to an optical purity of at least 98% levobupivacaine. Lastly, the addition of hydrochloride (c) is possible.