Catalytic enantioselective synthesis of optically active α-hydroxyl-β,γ-unsaturated acid esters as novel side chains of cerebrosides

Six optically active α-hydroxyl-β,γ-unsaturated acid esters 1a to 1f were synthesised, and they are significant moieties of the cerebrosides. The chiral intermediate alkynol 4 prepared by catalytic asymmetric addition had 99% ee, and which was converted into the target compounds 1a to 1f with high enantiomeric purity.

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(R,E)-Methyl 2-acetoxytetradec-3-enoateC17H30O4[α]D20=+30.0 (c 0.5, CH2Cl2)Source of chirality: asymmetric catalysisAbsolute configuration: (2R)

(R,E)-Methyl 2-acetoxypentadec-3-enoateC18H32O4[α]D20=+33.6 (c 0.5, CH2Cl2)Source of chirality: asymmetric catalysisAbsolute configuration: (2R)

(R,E)-Methyl 2-acetoxyhexadec-3-enoateC19H34O4[α]D25=+64.6 (c 0.5, CH2Cl2)Source of chirality: asymmetric catalysisAbsolute configuration: (2R)

(R,E)-Methyl 2-acetoxyheptadec-3-enoateC20H36O4[α]D20=+37 (c 0.5, CH2Cl2)Source of chirality: asymmetric catalysisAbsolute configuration: (2R)

(R,E)-Methyl 2-acetoxyoctadec-3-enoateC21H38O4[α]D20=+64.5 (c 0.5, CH2Cl2)Source of chirality: asymmetric catalysisAbsolute configuration: (2R)

(R,E)-Methyl 2-acetoxynonadec-3-enoateC22H40O4[α]D20=+88.2 (c 0.5, CH2Cl2)Source of chirality: asymmetric catalysisAbsolute configuration: (2R)