| 摘要 |
A syn compound of the formula: …<CHEM>… wherein… R<1> is an aliphatic hydrocarbon group which may have suitable substituent(s),… R<2> is carboxy or protected carboxy,… R<3> is hydrogen or hydroxy,… X<1> and X<2> are each halogen, and… the dotted line represents cepham or cephem nucleus, or a salt thereof, and processes for their preparation.… The invention also relates to intermediates of the formula …<CHEM>… and their preparation and to processes for preparing known cephamen-compounds and their intermediates. |
