New Heck-Type Coupling Reactions of Natural Tetrapyrroles − Synthesis of Porphyrinoligomers Bridged by Divinyl- and Trivinylbenzene

Facile preparation of novel β-substituted metalloporphyrins via Suzuki cross-coupling reaction

“…ZnBrDPDME (1) and ZnBr2DPDME (2) were obtained from heme as published previously. 10,11 All solvents were dried and distilled according to standard procedures and stored under argon. Chromatographic separation was performed on silica gel (Merck, 0.04-0.063 mm).…”

“…Porphyrins linked by aryl spacers are the subject of many reports. 11,12 In this connection 4g,h,j represent important key intermediates in the preparation of dimeric or oligomeric porphyrins by cross-coupling reactions. Upon reaction of 1 with 2-allyl-4,4,5,5-tetramethyl-1,3,2-dioxaborolane 3a (entry 1, Table 1) a polar by-product was obtained, the porphyrin dimer 8 (Figure 1) as revealed by FAB mass spectrometry (C 67 The unexpected formation of 8 can be explained by a Heck reaction of the Suzuki cross-coupling product 4a with boronic ester 3a.…”

Transition Metal Catalysis in Porphyrin Modifications

“…The same is true for Sonogashira reaction which was first applied for the porphyrin modifications also in 1994, [5] and halogen-substituted porphyrins [6] as well as porphyrins with acetylene moieties [7] participate in the coupling. Heck and so-called "click" reactions were also among those which were successfully applied to the creation of new C-C bonds in porphyrins, the first one applied to porphyrin modifications dates back to 1998 [8] while the second one began to be widely employed a decade later [9] and is especially useful for the conjugation of porphyrins with various pharmacophores, sugars, oligonucleotides, fullerene, and moieties used for immobilization.…”

Synthesis and Light-Harvesting Properties of Niphaphyrins

“…Such snowflake-shaped porphyrin hexamers, for which we suggest the trivial name niphaphyrins, [3] belong semantically to the group of stellular (star-like) porphyrins, different types of which have been synthesized in our laboratory [4,5] and elsewhere. [6][7][8][9][10][11][12][13] Compounds 4a,c are, however, the first examples of D 6h -symmetric porphyrin hexamers in which rotation of the individual porphyrin chromophores is strongly restricted by intramolecular intercore through rigid ethynyl linkers. A very efficient singlet excited-state energy transfer has been observed from the Zn chelates to the free-base porphyrin (Fb) chromophores in a niphaphyrin in which three zinc porphyrin chelates alternate with three porphyrin free bases.…”