Abstract: The present invention relates to novel substituted pyridines/pyrimidines of the formula I where A is CH or N; X is NH, oxygen or S(O)q where q is 0, 1 or 2; Y is a direct bond or CH2; Z is oxygen, NR7 or S(O)m is 0, 1 or 2, and the radicals R1, R2, R3, R4, R5, R6 and R7 are as defined in the description, to processes for their preparation, and to their use as pesticides, fungicides, ovicides or as veterinary medicaments.

Abstract: The present invention provides a process for the substitution of an acylamino .beta.-lactam compound at the carbon atom carrying the acylamino group, which process comprises reacting the .beta.-lactam compound with an halogenating agent and a nucleophilic reagent; characterized in that the acylamino group has an acidic group on the carbon atom adjacent the carbonyl group.In particular the process of this invention comprises reacting a .beta.-lactam of partial structure (I): ##STR1## where X represents an acidic group; with an halogenating agent and a nucleophilic reagent.

Abstract: 6-Halo- and 6,6-dihalo-1,1-dioxopenicillanoyloxymethyl 6-[D-2-(2-alkoxycarbonyl-1-methylvinylamino- and 1-methyl-3-oxo-1-butenylamino)-2-phenylacetamido]penicillanates and analogs; process for their conversion to sultamicillin and analogs; and process for their preparation.