L-Threonine was transformed, stereospecifically, to a versatile β-lactam (5a) in 3 steps. This β-lactam was further converted to a key intermediate (25) for the synthesis of thienamycin and its biologically active analogues. Furthermore, the compound 5a was changed to iodides (18 and 23), cyanides (19 and 24), chloromethylketone (26) and aldehydes (30 and 31) which appear to have a latent potential
Stereospecific and stereoselective syntheses of cis-12, and stereoselective synthesis of (±)-trans-12 from D-allo threonine and trans-crotonic acid, respectively, are described. The key steps in the syntheses are the formation of the β-lactam ring (4) by cyclization of the amide (3) via a complete Sn2 mechanism and stereocontrolled conversion of the azetidinone (4) to 12, 13 and 14, which are intermediates
立体特异性和立体选择性合成顺- 12,和(±)立体选择性合成-反式- 12从d-异体苏氨酸和反式-巴豆酸,分别进行说明。合成的关键步骤是通过酰胺(3)的S n 2完全作用机理将酰胺(3)环化,以及将氮杂环丁酮(4)立体转化为12、13和14,从而形成β-内酰胺环(4)。是青霉菌和碳青霉烯的中间体。