Synthesis of novel potassium selective valinomycins

The synthesis is described of three aryl substituted valinomycins, in which the aryl groups are placed around the poles of the cyclodepsipeptide. In one synthesis a valinomycin is prepared carrying a pendant hydroxyphenyl residue. In this synthesis the use of the acetate functionality to protect the phenolic site in tyrosine is developed. The spectroscopic and electrochemical evidence indicating the potential importance of such modified valinomycins in the design of improved ion selective electrodes is discussed.