| 摘要 |
NEW MATERIAL:2-Azetidinones of formula I (R<1> is H, carboxyl-protecting group, salt-forming cation; R<2> is H, amino-protecting group). EXAMPLE:(4S)-1-Benzyl-4-methoxycarbonylmethyl-2-azetidinone. USE:Synthetic intermediate of carbapenems and azetidinone derivatives or optically active carbapanems and azetidinone derivatives used as medicines. PREPARATION:The ring closing reaction of a 3-(substituted)amino-4-(substituted) carboxybutanoic acid is effected in a solvent or without a solvent in the presence of an active halogenating agent such as thionyl chloride, phosphorus trichloride or the like and of a base such as triethylamine to give the compound of formula I. L- Aspartic acid is chemically derived to optically active (4S)-2-azetidinones of formula III. |
