Synthesis of Phosphorus- and Selenium-Containing Macrocycles and Their Complexation with Pd(II)Cl2.

A one-pot reaction was developed to synthesize phosphorus- and selenium-containing macrocycles starting from selenium via reduction with KBH4, treatment with bis[o-(bromomethyl)phenyl]phenylphosphine oxide 1 and reduction with KBH4 followed by the addition of an appropriate dibromide. Thus, ten- to seventeen-membered macrocycles 3 having one phosphorus and two selenium atoms were synthesized. In this synthesis an eight-membered heterocycle 4 was also obtained. In addition, the condensation of compound 1 with selenium-containing diols 7 and 8 in the presence of sodium tert-butoxide gave macrocyclic ligands 9 and 10, respectively. Reaction of these macrocycles with palladium(II) chloride gave 1 ∶ 1 complexes, except 9 which gave a 2 ∶ 1 complex. The molecular structures of the macrocycles 3c, 3f and 10 as well as the 2 ∶ 1 palladium(II) complex 21 of related 2-(p-methylphenoxy)-2-oxo-1,3,6,2-dioxaselenaphosphocane 20 have been established by X-ray diffraction.