| abstract |
A novel intermediate for synthesizing 1β-alkyl-1-carbapenem, i.e., 4β-(1β-alkyl-2-carboxyprop-2-enyl)-azetidin-2-one ( II ), is prepared stereoselectively by treating 4-(leaving group substituted)azetidin-2-one ( I ) with trans-2-(leaving group substituted)methyl-3-alkylacrylic acid ( III ) and a reducing metal.n n wherein, R 1 is hydrogen, alkyl, or substituted alkyl; R 2 is optionally substituted alkyl; R 3 is hydrogen or a carboxy-protecting group; and R 4 and R 5 each is a leaving group. |