| 摘要 |
<p>A stereo-controlled process is described for preparing a compound of the formula: <CHEM> wherein R<1> is, e.g,. C1-C4 alkyl, R<2> and R<9> are independently selected from hydrogen, C1-C4 linear, branched or cyclic alkyl, unsubstituted or substituted with fluoro,, hydroxy, or protected hydroxy, with the proviso that both R<2> and R<9> are not unsubstituted alkyl, and R<3> is H or easily removable protecting group, comprising the steps of (a) reacting the compound: <CHEM> wherein L is a leaving group, with the chiral compound: <CHEM> wherein X<1> and X<2> are independently O or S, R<8> is an easily removable enol protecting group, R<4> and R<5> and R<6> are independently selected from H, C1-C4 alkyl, C7-C10 aralkyl, C6-C10 alkaryl, which can be substituted with -OH, -OR<1><0>, -SH, -SR<1><0>, where R<1><0> is C1-C4 alkyl, with proviso that R<4> and R<5> are not identical, in the presence of an organic base and a Lewis acid catalyst to afford the compound: <CHEM> and then (b) contacting said compound in a solvent therefor, under basic hydrolysis conditions. This compound can be transformed into a carbapenem antibiotic.</p> |
