Porphyrins incorporating heterocyclic N-oxides: (oxidopyridyl)porphyrins, porphyrin-N-oxides, and a tirapazamine-porphyrin conjugate

摘要

Porphyrins containing one to four 4-pyridyl groupsas meso-substituents were synthesized via a mixed aldehydecondensation, and then "N-oxidized" with m-chloroperbenzoicacid to produce five novel (oxidopyridyl) porphyrins and sevenporphyrin-N-oxides, which were characterized by analysis andspectroscopic methods, especially NMR; an X-ray crystalstructure of 5-(1-oxido-4-pyridyl)-10,15,20-triphenylporphyrinwas also obtained. Crystals of (oxidopyridyl)triphenylporphyrinare tetragonal, a = b = 15.174(1), c = 13.709(1) A, z = 4, spacegroup 12d. The structure was solved by direct methods andrefined by full-matrix least-squares procedures to R = 0.031 (Rw= 0.026) for 685 reflections with I >- 3o(I). Sulfonation of twoof the (oxidopyridyl)porphyrins was achieved readily with noloss of oxygen from the oxidopyridyl groups. Tirapazamine (3-amino-l,2,4-benzotriazine-1,4-di-N-oxide) was treated withtriphosgene to yield the previously reported 2H-[l ,2,4]oxadiazolo[3,2-c][1,2,4]benzotriazin-2-one-5-oxide (1);this reacts like an isocyanate and with 5-(4-aminophenyl)-10,15,20-triphenylporphyrin yields a tirapazamine-porphyrin conjugate (2).