SELECTIVE SIDE-CHAIN OXIDATION OF PERALKYLATED PYRROMETHENE-BF2 COMPLEXES

Treatment with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) oxidize d 2,6-diethyl-1,3,5,7,8-pen-tamethylpyrromethene-BF2 complex 1, 13,14- tri-methyl-2, 3, 4, 5,9,10,11,12-octahydroindomethene-BF2 complex 5, a nd 1,3,5,7,8-pentamethyl-1,2,3, 5,6,7-hexahydropyrromethene-BF2 comple x 8 to the weakly fluorescent 3-formyl, 5-oxo, and 8-formyl derivative s 4, 6, and 9, respectively. The dye 1 was oxidized by lead tetraaceta te to l-2,6-di-ethyl-3,5-diacetoxymethylpyrromethene-BF2 complex 12 [l ambda(f) (ethanol) 538 nm, PHI 0.62, lambda(las) (ethanol) 555-570 nm] . Catalytic reduction (Pd/C) converted the aldehyde 4 to hydroxymethyl -1,5,7,8-te-tramethylpyrromethene-BF2 COMPlex 10 [lambda(f) (ethanol) 537 nm, PHI 0.70, lambda(las) (ethanol) 547-575 nm].