865-16-7Relevant academic research and scientific papers
Pinacol-Pinacolone Rearrangements in vic-Dihydroxychlorins and Bacteriochlorins: Effect of Substituents at the Peripheral Positions
Pandey, Ravindra K.,Isaac, Meden,MacDonald, Ian,Medforth, Craig J.,Senge, Mathias O.,Dougherty, Thomas J.,Smith, Kevin M.
, p. 1463 - 1472 (2007/10/03)
Upon reaction with osmium tetraoxide a series of porphyrins and chlorins were converted into the corresponding vic-dihydroxychlorins and bacteriochlorins. The presence of an electron-withdrawing substituent at a peripheral position on the porphyrins or chlorins deactivated that particular pyrrole unit toward oxidation, and also directed the oxidation regioselectively to the pyrrole ring opposite to the one bearing the electronegative group. The vic-dihydroxychlorins and bacteriochlorins were converted into the corresponding oxochlorins and dioxobacteriochlorins under pinacol-pinacolone reaction conditions. The migratory behavior of the various substituents were found to be quite complex, since distant conjugated peripheral substituents were able to affect the stability of the carbocation intermediates during the process; the ability to rearrange was affected not only by the intrinsic nature of the migratory group but also by steric and electronic factors operative elsewhere on the porphyrin and chlorin macrocycles. Preferential migration of the propionic ester over the methyl substituent in dioxobacteriochlorins obtained from 2,3,12,13-tetrahydroxycoproporphyrin II tetramethyl ester (IUPAC nomenclature) under pinacol-pinacolone conditions was confirmed by a single crystal X-ray study. The dioxobacteriochlorins obtained from mesoporphyrin III dimethyl ester and coproporphyrin II tetramethyl ester were converted into the corresponding dithio-analogues using Lawesson's reagent; this caused a red shift of 62 nm (compared with the dioxo compounds) affording long wavelength absorption at λmax 746 nm.
A novel approach to the synthesis of symmetrical and unsymmetrical porphyrin dimers
Pandey,Forsyth,Gerzevske,Lin,Smith
, p. 5315 - 5318 (2007/10/02)
Methodology for synthesis of symmetrical or unsymmetrical porphyrin dimers linked at the meso positions with phenyl or stilbene functionalities is reported; 5-porphyrinyl-dipyrromethanes are key intermediates in this approach.
The Chemistry of Pyrrolic Compounds. LII. The Preferred Pathway of Electron Delocalization in Metalloporphyrins
Chakraborty, Swapna,Clezy, Peter S.,Sternhell, Sever,Thuc, Le van
, p. 2315 - 2323 (2007/10/02)
Measurement of the proton coupling constant in the allylic unit, CH3-C=C-H, of the zinc(II), nickel(II) and magnesium(II) chelates of the deuteroporphyrin isomer (3a) points in each case to the double bond of this system having a significantly diminished bond order.Similar data have been obtained for the dication derivative of (3a).These findings are in accord with the view that the ?-electron delocalization pathway in porphyrin dications and metalloporphyrins involves the periphery of the molecule as was previously shown for the metal-free porphyrin.New synthetic approaches to the porphyrin (3a) have been studied.
Biosynthesis of Porphyrins and Related Macrocycles. Part 15. Chemical and Enzymic Formation of Uroporphyrinogen Isomers from Unrearranged Aminomethylpyrromethane: Separation of Isomeric Coproporphyrin Esters
Battersby, Alan R.,Buckley, Dennis G.,Johnson, Dawid W.,Mander, Lewis N.,McDonald, Edward,Williams, D. Clive
, p. 2779 - 2785 (2007/10/02)
The unrearranged pyrromethane (1) is transformed chemically mainly into uro'gen-I with a smaller amount of uro'gen-IV but only traces of uro'gen-III are formed.Uro'gen-I is produced via a tetrapyrrolic (bilane) intermediate and when the diaminase-cosynthetase enzyme system from Euglena gracilis is present, this intermediate is converted into uro'gen-III.The rearrangement step for this conversion has the same characteristics found earlier for the natural biosynthetic process from porphobilinogen.Pyrromethane (1) is not a direct biosynthetic precursor of uro'gen-III and reasons are advanced why this is understandable.Methods are developed based on high pressure liquid chromatography for the separation of all four isomeric coproporphyrin esters.
