The templating effect of potassium ions on the ionophore antibiotic X-206 (1) ensured that most of the hydroxy, hemiacetal, and ether groups were involved in encapsulation of the metal atom, which allowed a selective derivatization at the unbound C (22) position. The mechanism of acylation at C (22) was investigated and the aquired knowledge used to achieve selective reactions on the benzyl ester 8 using a similar metal template protection.
