Conjugates of methyl 6-aminopenicillanate with biscatechol-hydroxamate chelators: synthesis and siderophoric activity

A synthesis of biscatechol-hydroxamate and triscatechol chelators and of conjugates of the former with methyl 6-aminopenicillanate is described. It is based on the multiple use of the ylide Ph₃PCCO as a C₂ building block in one-pot coupling reactions between aldehydes and alcohols or amines. These conjugates were actively internalized into siderophore-deficient Escherichia coli mutant H5596.