Solid-Phase Synthesis of a Double 4-Pyridinyl Terminated Leu-Ala-Leu Tripeptide and Macrocyclization by Palladium(II) Coordination

A Leu-Ala-Leu tripeptide, which bears pyridinyl units at the N- as well as C-terminus, is prepared by combination of solid- and solution-phase synthesis. With the Pd(en)2+ fragment it forms a mixture of 1:1 and 2:2 complexes, with the mononuclear complex probably being the dominating species.