Synthesis of Porphyrinoids, BODIPYs, and (Dipyrrinato)ruthenium(II) Complexes from Prefunctionalized Dipyrromethanes

Abstract

The introduction of functional groups into the meso‐position of dipyrromethanes, boron‐dipyrromethenes (BODIPYs) and porphyrinoids, is of fundamental importance in designing such dye systems for material sciences or photomedicine. One route that has proven to be particularly useful in this respect is the nucleophilic aromatic substitution (SNAr) on porphyrinoids and their precursors carrying electron‐withdrawing substituents. To further expand this methodology, the potential of the 4‐fluoro‐3‐nitrophenyl and the 3,4,5‐trifluorophenyl moieties for the synthesis of functionalized dipyrromethanes, BODIPYs, and porphyrinoids has been evaluated. The 3,4,5‐trifluorophenyl moiety proved not to be applicable in the SNAr with nucleophiles. The introduction of the 4‐fluoro‐3‐nitrophenyl group, however, allowed fast and efficient SNAr with various amine nucleophiles. The synthesized 4‐amino‐3‐nitrophenyl‐substituted dipyrromethanes were successfully applied in the synthesis BODIPYs and were tested in the synthesis of “trans”‐A2B2 porphyrins and A2B corroles. Furthermore, the dipyrromethanes – after oxidation to the dipyrromethenes – were found to be suitable ligands for metal ions giving access to functionalized ruthenium(II) metal complexes.

Dipyrrinato‐Iridium(III) Complexes for Application in Photodynamic Therapy and Antimicrobial Photodynamic Inactivation

“…Syntheses of heteroleptic metal complexes employing dipyrrinato ligands based on late transition metals, e.g., ruthenium(II), rhodium(III) and iridium(III), are known in the literature [21a, 23a,b, 26a, 29] . The synthesis of the dipyrrinato complexes typically involves reaction of the dipyrrins under basic conditions with a commercially available (dichlorido‐bridged) metal‐arene precursor [2a,b, 23b, 26a, 27a, 28d, 29a,b, 30] …”

“…In preparation for the following experiments, the meso ‐substituted dipyrromethanes 1 – 15 were synthesized according to known procedures published by us and others [28a,b,d,e, 33] . Dipyrromethanes can then be transformed into the dipyrrins via oxidation with a suitable oxidation agent [22b, 27a, 28d, 33, 34] . Here, dipyrromethanes ( 1 – 15 ) served as starting materials for the required dipyrrins (Scheme 1).…”

“… Synthesis of meso ‐substituted dipyrrins via oxidation of dipyrromethanes (dipyrromethanes were synthesized according to the literature) [28a,b,d,e, 33] …”

“…Similarly, the meso ‐(4‐amino‐3‐nitrophenyl)‐substituted dipyrrins 24 , 25 , 27 , 29 , and 30 were prepared from the corresponding dipyrromethanes by oxidation with p ‐chloranil as already described in the literature [28d] . Based on this procedure, the dipyrrins 26 and 28 were prepared with the same oxidation reagent.…”

Current Advances in the Synthesis of Valuable Dipyrromethane Scaffolds: Classic and New Methods

“…Regarding the three latter molecular targets, meta -SF 5 -phenyl-substituted dipyrromethanes 37a – c , prepared in high yields (62%–80%) under standard TFA-catalyzed reaction conditions using appropriate pentafluorosulfanyl-bearing aryl aldehydes and surplus pyrrole, were the strategic intermediates (Figure 2). More recently, the same authors reported the efficient preparation, under similar standard conditions, of useful meso -aryldipyrromethane scaffolds 37d [49] and 37e [50] (in 92% and 87% yields, correspondingly), which were further functionalized and/or used as building blocks for the formation of other interesting BODIPY or porphyrinoid molecular species.…”