Novel 21,23-Ditelluraporphyrins and the First 26,28-Ditellurasapphyrin and 30,33-Ditellurarubyrin

Abstract

21,23-Ditelluraporphyrins 3, 9, and 16 − 18 bearing phenyl, 4-methoxyphenyl, and/or 3,4,5-trimethoxyphenyl meso substituents were prepared by the condensation of 2,5-di[hydroxy(aryl)methyl]tellurophenes 12 with 2,5-di[2-pyrrolo(aryl)methyl]tellurophenes 15 in the presence of BF 3 −etherate followed by oxidation with p -chloranil. Compounds 15 were prepared from tellurophenes 12 with pyrrole and BF 3 −etherate. Tellurophenes 12 were prepared in 44−72% isolated yield by the addition of 1,6-diarylhexa-2,4-diyn-1,6-diols 13 to the reduction product of Te powder and LiBHEt 3 . No additional Lewis acid was necessary in these reactions. Coupling of 1-aryl-2-propyn-1-ols ( 14 ) with CuCl, pyridine, and air in MeOH gave diyndiols 13 . 26,28-Ditellurasapphyrin 10 was isolated in 0.6% yield from the reaction mixture that produced 9 in 12% isolated yield. The X-ray structure of 10 showed a nearly planar sapphyrin core with the Te atoms of both tellurophene rings pointing to the center of the core. 30,33-Ditellurarubyrin 11 was isolated in 32% yield by the reaction of two equivalents of trifluoroacetic acid with tellurophene dipyrrane 15c . 125 Te NMR spectra were recorded for the compounds of this study.