Condensation Of Dipyrromethane Research Articles

Stable core-modified calixsmaragdyrins: synthesis, structure and specific sensing of the hydrogen sulfate ion

Stable calixoxa- and calixthiasmaragdyrins containing three methine bridges and two direct bonds connecting the five pyrrole/heterocycle rings were synthesized by [3 + 2] condensation of dipyrromethane with 16-oxatripyrrane and 16-thiatripyrrane respectively under mild acid-catalyzed conditions. The compounds were characterized by HR-MS, 1D & 2D NMR, absorption and electrochemical techniques and the structure of calixoxasmaragdyrin was solved by X-ray crystallography. The crystal structure analysis indicated that the calixoxasmaragdyrin macrocycle was highly distorted due to the flexibility introduced by one sp(3)meso-carbon. The compounds show ill-defined absorption bands and irreversible oxidation and reduction waves which were attributed to the disruption of conjugation of the macrocycle by incorporation of one sp(3)meso-carbon. The anion binding studies indicated that the calixoxasmaragdyrin exhibited specific sensing ability for the HSO4(-) ion over other anions whereas calixthiasmaragdyrins did not even show an ability to bind anions.

Synthesis of meso-tetraphenyl porphyrins via condensation of dipyrromethanes with N-tosyl imines

A new synthetic route for the synthesis of 5,10,15,20-tetraphenyl porphyrins has been developed based on the reaction of 5-substituted dipyrromethanes with N-tosyl imines in the presence of a metal triflate catalyst. meso-Substituted tetraphenyl porphyrins were synthesized in a two-step process. The first step of the method is the metal triflate-catalyzed condensation of 5-substituted dipyrromethanes with N-tosyl imines to form a porphyrinogen intermediate and the second step is the oxidation of the porphyrinogen to porphyrin. The method was applied to the synthesis of trans-A 2B 2-tetraarylporphyrins and the products were obtained with only a trace amount of one scrambling product. The synthesis of two important building blocks for porphyrin synthesis, mono and di-sulfonamide alkylated 5-substituted dipyrromethanes, was achieved by the addition of 5-substituted dipyrromethane to N-tosyl imine. The application of mono and di-sulfonamide alkylated 5-substituted dipyrromethanes in ‘2+2’ porphyrin formation reactions is presented.

Synthesis of tetraphenylsubstituted porphyrins by interaction of 5-aryldipyrromethanes with 4-substituted benzaldehydes

Synthesis of tetraphenyl-substituted porphyrins with tret-butyl and methoxycarbonyl groups in meso-aryl radicals is described. It is shown that, during the condensation of dipyrromethanes with substituted benzaldehydes, a rearrangement occurs with the formation of a mixture of isomeric porphyrins. The character of these rearrangements depends on the position of substituents in the starting compounds.

Synthesis of 5,15-diaryltetrabenzoporphyrins.

A general method of synthesis of 5,15-diaryltetrabenzoporphyrins (Ar 2TBPs) has been developed, based on 2 + 2 condensation of dipyrromethanes followed by oxidative aromatization. Two pathways to Ar 2TBPs were investigated: the tetrahydroisoindole pathway and the dihydroisoindole pathway. In the tetrahydroisoindole pathway, precursor 5,15-diaryltetracyclohexenoporphyrins (5,15-Ar 2TCHPs) were assembled from cyclohexeno-fused meso-unsubstituted dipyrromethanes and aromatic aldehydes or, alternatively, by way of the classical MacDonald synthesis. In the first case, scrambling was observed. Aromatization by tetracyclone was more effective than aromatization by DDQ but failed in the cases of porphyrins with electron-withdrawing substituents in the meso-aryl rings. The dihydroisoindole pathway was found to be much superior to the tetrahydroisoindole pathway, and it was developed into a general preparative method, consisting of (1) the synthesis of 4,7-dihydroisoindole and its transformation into meso-unsubstituted dipyrromethanes, (2) the synthesis of 5,15-diaryloctahydrotetrabenzoporphyrins (5,15-Ar 2OHTBPs), and (3) their subsequent aromatization by DDQ. Ar 2TBP free bases exhibit optical absorption spectra similar to those of meso-unsubstituted tetrabenzoporphyrins and fluoresce with high quantum yields. Pd complex of Ph 2TBP was found to be highly phosphorescent at room temperature.

New Approach towards meso-Substituted trans-A2B-Corroles from Alkyl Oxalyl Chlorides and Dipyrromethanes

A one-pot synthesis of TRANS-A 2 B-corroles via the condensation of dipyrromethanes with alkyl oxalyl chlorides followed by the macrocyclization mediated by DDQ has been developed. After thorough examination of different substrates, only reactive acid chlorides have been found to be suitable for this transformation. It was proved that these conditions work well for dipyrromethanes possessing various electron-withdrawing or sterically hindered substituents. No porphyrins are formed under these conditions. The whole sequence implies the formation of a ketone followed by its reaction with the second molecule of dipyrromethane and oxidation of a bilene to the respective corrole. Under the present reaction conditions, the use of typical dipyrromethanes and aromatic/aliphatic acid chlorides did not lead to the formation of corroles.

Facial discrimination in monoarylporphyrins: Synthesis and stereochemical behaviour of bis(ligated) monospirobifluorenylporphyrin ruthenium complexes

Condensation of dipyrromethane, pyrrole-2-carbaldehyde with either 9,9′-spirobifluorene or fluorene aldehyde yields new meso-monosubstituted, β-unsubstituted porphyrins. The large size of spirobifluorene hinders the rotation around the C meso –C aryl bond to give, for bis-ligated complexes, two different topological faces.

Isolation of Phlorin‐Dipyrrin Conjugates from the Acid‐Catalyzed Condensation of Dipyrromethanes and Aldehydes

AbstractThe product distribution of the acid‐mediated condensation of dipyrromethanes and aldehydes was studied and a novel type of macrocycle phlorin‐dipyrrin conjugate was isolated and identified by X‐ray analysis. The generality of its formation from sterically hindered dipyrromethanes and pentafluorophenyldipyrromethane was demonstrated. The influence of the meso‐aryl groups on the stability of the phlorin was studied. The reported two‐step synthesis of a phlorin derivative is one of the simplest routes leading to this type of molecules. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

A practical synthesis of meso-monosubstituted, beta-unsubstituted porphyrins.

[formula: see text] A simple straightforward synthesis for meso-monosubstituted, beta-unsubstituted porphyrins is reported. Porphyrins of this type are easily prepared by condensation of dipyrromethane, pyrrole-2-carbaldehyde, and the desired aromatic or aliphatic aldehyde. The method can be used for a variety of functional groups with yields between 2 and 12%. In most cases, the 5, 15-disubstituted porphyrin is obtained as a second product but can be removed easily.

Customized, core-modified corroles from [2+2] condensation of dipyrromethanes

Corroles and core-modified corroles were synthesized by acid-catalyzed condensation under low-scrambling conditions. The synthesis utilized [2+2] condensation of two different dipyrromethanes. The condensation afforded different corroles bearing heteroatoms in a predesignated location depending on the starting dipyrromethanes. Selective α–α′ linkage was achieved by positioning a linking carbon unit at a different site of dipyrromethanes.

Synthesis of meso-tetraaryl-21-oxa-22-thiaporphyrin from 2+2 condensation

The first synthesis of porphyrin containing oxygen and sulfur adjacent to each other is described. The synthesis utilizes the 2+2 condensation of dipyrromethane and ( meso-aryl)furylthienylmethane.

Improved synthesis of meso substituted 21-Oxa and 21-Thia tetra phenyl porphyrins

An efficient method for the exclusive formation of 21-Oxa and 21-Thia tetra phenyl porphyrins in high yields by condensation of dipyrromethane and furan or thiophene diols is described.

Synthesis of corrins. Part I. Nickel and cobalt 1,19-dimethylcorrin and 1,19-dimethyl-4,5-dihydrocorrin perchlorates

Condensation of dipyrromethane with 2-formyl-5-methylpyrrole yields, 1,19-dimethyl-1,19-dideoxybiladiene-ac dihydrobromide, which can be cyclised in the presence of nickel or cobalt ions to give the corresponding metal 1,19-dimethyltetradehydrocorrin salts. Hydrogenation of these salts under a wide variety of experimental conditions gives a mixture of the metal 1,19-dimethyl-corrin and -4,5-dihydrocorrin salts, which have been separated and isolated as the perchlorates. The corrin has also been isolated as the neutral dicyanocobalt(III) complex.