Patent ID: 6566552
Filing Date: 2003-05-20
Classification: C07C

Abstract:
A process for the synthesis of L-carnitine comprising the following steps:(a) enantioselectively reducing an alkyl 4-chloro-3-oxobutyrate or 4-chloro-3-oxobutyramide according to the following diagram: where: Y is OR1, NHâ€”R1, or N(R1R2) in which R1 and R2, which may be the same or different, are alkyl C1-C10 alkylaryl, and where the reduction reaction catalyst consists of a ruthenium complex corresponding to one of the two formulas (III) or (IV) where: A is S in formula (III) and A is NR3 in formula (IV), R3 is C1-C10 alkyl, Q is C1-C4 alkyl, R, Râ€², which may be the same or different, are optionally alkyl-substituted phenyl, C1-C6 alkyl, C3-C8 cycloalkyl or R and Râ€² together form a 4-6 atom phosphorocyclic system, X and L, are the same or different, in which X is halogen, alkylsulphonate, or arylsulphonate, and L is halogen, aryl, &pgr; aryl, an olefin system, or carboxylate; provided at least one of X or L is halogen; wherein said reduction is performed at a hydrogen pressure ranging from 2 to 7 bar, a temperature ranging from 90 to 150Â° C. and at a substrate: catalyst molar ratio ranging from 10,000:1 to 30,000:1; (b) reacting the formula (II) derivative obtained in step (a) with trimethylamine to form L-carnitine.