A two-step, one-pot route to swap the pyrroline moiety in meso-tetraaryldihydroxy-chlorins with an O/N-substituted oxazoline (original) (raw)
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The Journal of Organic Chemistry, 2010
The OsO 4 -mediated dihydroxylation of meso-tetraphenylporphyrin N-oxide yields two regioisomeric chlorin N-oxides. These chlorin N-oxides can be manipulated to provide pairs of regioisomers of pyrrole-modified porphyrin N-oxides. The UV-vis absorption and fluorescence emission spectra of the neutral and protonated regioisomers are distinct from each other, and generally different from the parent chromophore. The outcome of diol oxidation reactions of some N-oxide diolchlorins varies from the corresponding reactions of the parent diolchlorins. The crystal structure of a free base porpholactone N-oxide carrying the N-oxide on the oxazolone moiety is reported.
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Tetrahedron Letters, 2012
The reaction of free base or Ni(II) complex secochlorin bisaldehydes 4H 2 and 4Ni regenerates the ultimate starting material of the bisaldehydes, meso-tetraphenylporphyrin 2H 2 and 2Ni, respectively. Depending on the reaction conditions employed (hydrazine hydrate in pyridine at reflux or hydrazine hydrate activated with sulfur in the presence of aqueous NaOH at ambient temperature), either porphyrin 2H 2 is formed together with known dihydroxymorpholinochlorin 9H 2 or known 2-hydroxychlorin 8H 2 . Two different reaction pathways for the hydrazine reaction can be derived, either involving the formation of a meso-tetraphenyl-1,4,5-triazepinoporphyrin that loses spontaneously N 2 or a Wolff-Kishner-type pathway that also involves an intramolecular aldol-type reaction. Neither reaction is synthetically useful but both highlight in an impressive fashion the high thermodynamic stability of porphyrins. They also bring the 'breaking and mending of porphyrin' strategy to its ultimate conclusion by regenerating the starting porphyrin.
Porphyrin Macrocycle Modification: Pyrrole Ring-Contracted or -Expanded Porphyrinoids
Molecules, 2016
In recent years, several synthetic strategies aiming at the peripheral functionalization of porphyrins were developed. Particularly interesting are those involving the modification of β-pyrrolic positions leading to pyrrole-modified porphyrins containing four-, five-, six-or seven-membered heterocycles. Azeteoporphyrins, porpholactones and morpholinoporphyrins are representative examples of such porphyrinoids. These porphyrin derivatives have recently gained an increasing interest due to their potential application in PDT, as multimodal imaging contrast agents, NIR-absorbing dyes, optical sensors for oxygen, cyanide, hypochlorite and pH, and in catalysis.
The Journal of Organic Chemistry, 2006
N-(Porphyrin-2-ylmethyl)glycine was synthesized and used as precursor of azomethine ylide, which was trapped with several dipolarophiles. The reaction of that azomethine ylide with dimethyl fumarate afforded the expected adduct. However, with 1,4-benzo-and 1,4-naphthoquinones only dehydrogenated adducts were isolated. Also, the reaction of that ylide with meso-tetrakis(pentafluorophenyl)porphyrin and tetraazaporphine allowed access to novel porphyrin-chlorin and porphyrin-tetraazachlorin dyads.
The Journal of Organic Chemistry, 2009
The methyltrioxorhenium (MTO)/pyrazole-mediated H 2 O 2 oxidation of octaethylporphyrin and a number of meso-tetraarylporphyrins offers simple and good yielding access to the corresponding N-oxides, only few of which were prepared before. The crystal structure of a free base tetraarylporphyrin N-oxide demonstrates the degree to which the oxygenated pyrrole moiety is slanted with respect to the rest of the otherwise nearly planar macrocycle. The method is also suitable to the preparation of hitherto unknown chlorin N-oxides. Oxidation of meso-tetraphenyldithiaporphyrin and meso-tetraphenyldithiachlorin furnishes the corresponding novel S-oxides. The optical properties of the novel chromophores are described and rationalized.
Aromatic core-modified expanded porphyrinoids with meso-aryl substitutents
Pure and Applied Chemistry, 2002
Porphyrins are the most widespread of all prosthetic groups found in Nature. The ubiquity of their functions in Nature led researchers around the globe to focus their attention on these highly colored macrocycles. The interdisciplinary interest generated by porphyrins resulted in the syntheses of modified porphyrins, which can be put to a variety of uses in medicine and industry. A brief overview of the synthetic methodologies resulting in the formation of aromatic meso-aryl-substituted core-modified aromatic heterocyclic ring-inserted expanded porphyrinoids like sapphyrins, smaragdyrins, rubyrins, hexaphyrins, heptaphyrins, and octaphyrins reported to date are discussed in this article.
Aromatic Core-Modified Expanded Porphyrinoids with meso-Aryl Substituents
ChemInform, 2003
Porphyrins are the most widespread of all prosthetic groups found in Nature. The ubiquity of their functions in Nature led researchers around the globe to focus their attention on these highly colored macrocycles. The interdisciplinary interest generated by porphyrins resulted in the syntheses of modified porphyrins, which can be put to a variety of uses in medicine and industry. A brief overview of the synthetic methodologies resulting in the formation of aromatic meso-aryl-substituted core-modified aromatic heterocyclic ringinserted expanded porphyrinoids like sapphyrins, smaragdyrins, rubyrins, hexaphyrins, heptaphyrins, and octaphyrins reported to date are discussed in this article.