Substd 7-amino ceph-3-em 4-carboxylic acids - by elimination from the 3-hydroxy or 3-acyloxy cepham analogues

摘要

Title cpds are of formula (I): (where R1 degree = H or a N-protecting gp; R2 = H, Ar (X)n CHRCO or opt. protected 5-amino 5-carboxy or R1 + R2 try = a bivalent N-protecting gp; Ar = Ph opt. substd. by OH, Only, or Cl, 2-thienyl, cyclohexa-1,4-dienyl, or 4-isothiazolyl; X = O or S; n = 0 or 1; R = H or (if n = 0), opt. subst. NH2, opt. protected CO2H, opt. protected SO3H, opt., protected OH, HCO2; O-alkylphosphono or O, O-dialkylphosphono) are prepd. from II, where R4 = OH an ester residue by elimination of H2O, pref. under acid conditions, or by acid or base catalysed elimination of R4OH (R4 is not = H).