Lipase‐Catalyzed Enantiomer Separation of 3‐Hydroxy‐4‐(tosyloxy)butanenitrile: Synthesis of (R)‐GABOB (=(3R)‐4‐Amino‐3‐hydroxybutanoic Acid) and (R)‐Carnitine Hydrochloride (=(2R)‐3‐Carboxy‐2‐hydroxy‐N,N,N‐trimethylpropan‐1‐aminium Chloride)

Abstract

AbstractEnzymatic resolution of racemic 3‐hydroxy‐4‐(tosyloxy)butanenitrile ((±)‐5) by using various lipases in different solvents were studied. The obtained optically pure (3R)‐3‐(acetyloxy)‐4‐(tosyloxy)butanenitrile ((R)‐6), upon treatment with aqueous ammonia followed by conc. HCl solution, provided (R)‐GABOB (=(3R)‐4‐amino‐3‐hydroxybutanoic acid; (R)‐1). Similarly, reaction of (R)‐6 with aqueous trimethylamine solution followed by conc. HCl solution provided (R)‐carnitine hydrochloride (=(2R)‐3‐carboxy‐2‐hydroxy‐N,N,N‐trimethylpropan‐1‐aminium chloride; (R)‐2⋅HCl) in an expeditious manner.