Stereoselective synthesis of .beta.-lactams by oxidative coupling of dianions of acyclic tertiary amides
摘要:
Tertiary amides RCH2CON(R')CH2Z, where Z is an electron-withdrawing group, were converted into dianions by treatment with 2 equiv of n-butyllithium or tert-butyllithium, and the dianions were oxidized with N-iodosuccinimide (NIS) or a Cu(II) carboxylate to form beta-lactams stereoselectively. The stereochemistry of beta-lactam formation depends on the oxidant; NIS is cis-selective, whereas Cu(II) is nonselective or slightly trans-selective. A high degree of asymmetric induction in the formation of beta-lactams was achieved by using (R)-1-phenylethylamine as a chiral auxiliary. This asymmetric ring closure was applied to the preparation of cis-beta-lactam 31, an intermediate for the synthesis of the monobactam antibiotic carumonam.
Regio- and chemoselective epimerization of cis-3-amino-β-lactams to the trans-isomers: a new synthesis of aztreonam
作者:Takeo Kawabata、Kazuhiro Itoh、Tamejiro Hiyama
DOI:10.1016/s0040-4039(01)80522-0
日期:1989.1
The title isomerization reaction was effected with trifluoroacetic acid and shown to be applicable to the synthesis of an optically active monobactamantibiotic, aztreonam.