| 摘要 |
alpha -[3(R)-Substituted amino-4(R)-substituted alkoxy-2-oxo-azetidin-1-yl]- alpha -isopropenylacetate (Ia) and alpha -[3(R)-substituted amino-4(R)-substituted alkoxy-2-oxo-azetidin-1-yl]- alpha -isopropylideneacetate (Ib) prepared from (1R,5S)- alpha -(3-substituted-7-oxo-4-oxa-2,6-diazabicyclo[3.2.0]hept-2-en-6-yl)- alpha -isopropenylacetate or (1R,5S)- alpha -(3-substituted-7-oxo-4-oxa-2,6-diazabicyclo-[3.2.0]hept-2-en-6-yl)- alpha -isopropylideneacetate with a primary alcohol in the presence of an acid. The products are useful intermediates for preparing oxadethiacephalosporins. |
