@article{RyppaSengeHatscheretal.2005, author = {Ryppa, C. and Senge, Mathias O. and Hatscher, S. S. and Kleinpeter, Erich and Wacker, Philipp and Schilde, Uwe and Wiehe, A.}, title = {Synthesis of mono- and disubstituted porphyrins : A- and 5,10-A(2)-type systems}, issn = {0947-6539}, year = {2005}, abstract = {General syntheses have been developed for meso-substituted porphyrins with one or two substituents in the 5,10- positions and no beta substituents. 5-Substituted porphyrins with only one meso substituent are easily prepared by an acid-catalyzed condensation of dipyrromethane, pyrrole-2-carbaldehyde. and an appropriate aldehyde using a "[2+1+1]" approach. Similarly, 5,10-disubstituted porphyrins are accessible by simple condensation of unsubstituted tripyrrane with pyrrole and various aldehydes using a "[3+1]" approach. The yields for these reactions are low to moderate and additional formation of either di- or mono-substituted porphyrins due to scrambling of the intermediates is observed. However, the reactions can be performed quite easily and the desired target compounds are easily removed due to large differences in solubility. A complementary and more selective synthesis involves the use of organolithium reagents for SNAr reactions. Reaction of in situ generated porphyrin (porphine) with 1.1-8 equivalents of RLi gave the monosubstituted porphyrins, while reaction with 3-6 equivalents of RLi gave the 5,10-disubstituted porphyrins in yields ranging from 43 to 90\%. These hitherto almost inaccessible compounds complete the series of different homologues of A-, 5,15-A(2)-, 5,10-A(2)-, A(3)-, and A(4)-type porphyrin's and allow an investigation of the gradual influence of type, number, and regiochemical arrangement of substituents on the properties of meso-substituted porphyrins. They also present important starting materials for the synthesis of ABCD porphyrins and are potential synthons for supramolecular materials requiring specific substituent orientations}, language = {en} } @article{RyppaSenge2004, author = {Ryppa, C. and Senge, Mathias O.}, title = {Dodecasubstituted porphyrins : an easily accessible type of dendritic porphyrins with tunable properties}, issn = {0385-5414}, year = {2004}, abstract = {Dodecasubstituted dendritic porphyrins with nonplanar macrocycles were synthesized by a convergent approach via Lindsey condensation reactions in good yields}, language = {en} }