Enzymic hydrolysis of alkyl 3,4-epoxybutyrates. A new route to (R)-(-)-carnitine chloride

Synthesis of γ‐Aminobutyric Acid Analogs

“…Enantiomerically pure (R)-g-amino-b-benzyl-b-methylbutyric acid (R)- (197) has been efficiently synthesized using an Oppolzer chiral auxiliary derivative (193) (Scheme 14.55). Diastereoselective benzylation of the chiral enolate gives the product (194) in excellent yield and good diastereomeric excess.…”

“…The effect of ester length and enzyme on the hydrolysis of a series of alkyl 3,4-epoxybutanoates has also been investigated, with good results being obtained with steapsin 700 hydrolysis of isopropyl and n-octyl esters (30 and 40% yield, respectively, and 95% e.e.) [193].…”

Synthesis of l-carnitine by microorganisms and isolated enzymes

“…Thus, (R, S)-isobutyryl-3,4-epoxy butyric acid was enantioselectively hydrolyzed by a lipase (steapsin from porcine pancreas (Sigma Chemical Co.)) to give the optically active unreacted ester of (R) absolute configuration with an enantiomeric excess greater than 95 % [52,53]. After purification (R)-isobutyryl-3,4-epoxy butyric acid was obtained with a yield of 22% (related to the original racemate).…”

“…After heating with trimethylamine and treatment with hydrochloric acid, L-carnitine was obtained. No racemization was observed during the second hydrolysis or the following reactions [52,53].…”

An Efficient Synthesis of Enantiomeric (S)-Phosphocarnitine

“…The crude product was chromatographed on silica gel with chloroform/ methanol (100:1, v/v) to give (R)-10 (1 18. g, 79%) as a colourless oil which solidified at low temperatures, but melted before reaching 20°C.…”