A novel and highly effective catalytic system for alkoxycarbonylation of (S)-propylene oxide

Methyl (S)-β-hydroxybutyrate, the important chiral building block for organic synthesis was produced in high yield from the methoxycarbonylation of (S)-propylene oxide ((S)-PO) using a catalytic system consisting of dicobalt octacarbonyl [Co2(CO)8] and pyrazole. The effects of different additives, temperature and CO pressure were investigated. The reaction was greatly influenced by the variation of temperature, both the conversion of (S)-PO and the selectivity of methyl (S)-β-hydroxybutyrate decreased with increasing temperature (above 80 °C). Nevertheless, the enantiomeric excess (ee) of methyl (S)-β-hydroxybutyrate is independent of the parameter of reaction temperature, no racemization reaction takes place even the reaction temperature reaches 150 °C. A possible process for the formation of ethers and diethers was presented. The reaction has a bright future in an industrial scale.

Graphical abstractMethyl (S)-β-hydroxybutyrate was produced in high yield from the methoxycarbonylation of (S)-propylene oxide ((S)-PO) using a catalytic system consisting of dicobalt octacarbonyl [Co2(CO)8] and pyrazole in methanol. The effects of different additives, temperature and CO pressure were investigated. The reaction was greatly influenced by the variation of temperature, both the conversion of (S)-PO and the selectivity of methyl (S)-β-hydroxybutyrate decreased with increasing temperature (above 80 °C). Nevertheless, the enantiomeric excess (ee) of methyl (S)-β-hydroxybutyrate is independent of the parameters of reaction temperature, no racemization reaction takes place even the reaction temperature reaches 150 °C. The reaction can be extended to synthesize different β-hydroxybutyrates. The reaction will have a bright future in an industrial scale. Figure optionsDownload full-size imageDownload as PowerPoint slide