Linearly ‐π‐ extended porphyrins: Synthesis of novel tetrabenzoylporphyrins

The π‐extended porphyrins 11a – c with a λ_max = 644, 643 and 639 nm were synthesized by an acid catalysed reaction of the dipyrrolylmethane 10 with different aldehydes followed by oxidation with 2,3‐dichloro‐5,6‐dicyano‐1,4‐quinone (DDQ). In a second approach, 10 was decarboxylated to yield 12, which was treated with DMF and benzoylchloride to give the diformyl compound 13. Acid catalysed reaction of 12 and 13 led to the porphyrin 11a after oxidation.