ChemInform Abstract: Migratory Aptitudes in Pinacol Rearrangement of vic‐Dihydroxychlorins.

CHANG, C. K.; Sotiriou, C.

doi:10.1002/chin.198632104

Cited by 5 publications

(5 citation statements)

References 1 publication

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“…89,90 The use of OsO 4 in the presence of pyridine to form the vicinal diol followed by acid-mediated pinacol rearrangement was implemented by Inhoffen 87,91 and by Chang. 92,93 …”

Section: Early Landmarks In Chlorin Chemistrymentioning

confidence: 99%

De NovoSynthesis of Gem-Dialkyl Chlorophyll Analogues for Probing and Emulating Our Green World

2015

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Woodward reported his infamous synthesis of chlorin e 6 trimethyl ester, a known synthetic precursor to chlorophyll a. [59][60][61][62][63][64]124 The work was posited on a half-century of intensive studies by many investigators in tetrapyrrole chemistry and began a decade after the close of Fischer's lifetime of research 125−128 (which included an uncompleted synthetic program directed toward chlorophylls 15 ). Indeed, "he read all the umpteen papers on the chlorophylls written by Willstaẗter and Fischer, including the experimental parts." 129 The Woodward synthesis of chlorin e 6 trimethyl ester required 46 steps, of which 24 were spent on converting the sole precursor, Knorr's pyrrole, to the four pyrroles destined to form rings A−D; 7 additional steps accrued to obtain the dipyrromethanes that constitute the Eastern and Western halves (Scheme 13, the step numbers are identical to those shown in ref 64.). The first step formed the Knorr pyrrole (in several kg quantities), the next 24 steps were divided into four parallel paths, whereas the remaining 21 steps proceeded in linear fashion. Remarkable features of the synthesis include the directed intramolecular joining (via an imine) of the Eastern and Western halves (step 33), construction of the acrylate Scheme 10. Hydrogenation of a Porphyrin to Form a Chlorin Scheme 11. Representative meso-Tetraarylchlorins Scheme 12. Methyl Pyropheophorbide a

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“…89,90 The use of OsO 4 in the presence of pyridine to form the vicinal diol followed by acid-mediated pinacol rearrangement was implemented by Inhoffen 87,91 and by Chang. 92,93 …”

Section: Early Landmarks In Chlorin Chemistrymentioning

confidence: 99%

De NovoSynthesis of Gem-Dialkyl Chlorophyll Analogues for Probing and Emulating Our Green World

2015

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“…The β-substituted cis -dihydroxychlorins undergo pinacol-pinacolone rearrangement in perchloric acid or fuming sulfuric acid to give β-oxochlorins (for example 119 from 118 ). The regioselectively of the osmylation reaction and the migratory aptitudes of different peripheral substituents in the pinacol-pinacolone rearrangement have been investigated [278-282]. Metal-free oxochlorins such as 119 react further with osmium tetroxide regioselectively at the opposite pyrrole ring, whereas metal derivatives react preferentially at the adjacent β-β’ double bond producing the corresponding vic -dihydroxy- and oxo-bacteriochlorins and isobacteriochlorins [283-287].…”

Section: Porphyrin Functionalizationmentioning

confidence: 99%

Syntheses and Functionalizations of Porphyrin Macrocycles

Vicente¹,

Smith²

2014

COS

108

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Porphyrin macrocycles have been the subject of intense study in the last century because they are widely distributed in nature, usually as metal complexes of either iron or magnesium. As such, they serve as the prosthetic groups in a wide variety of primary metabolites, such as hemoglobins, myoglobins, cytochromes, catalases, peroxidases, chlorophylls, and bacteriochlorophylls; these compounds have multiple applications in materials science, biology and medicine. This article describes current methodology for preparation of simple, symmetrical model porphyrins, as well as more complex protocols for preparation of unsymmetrically substituted porphyrin macrocycles similar to those found in nature. The basic chemical reactivity of porphyrins and metalloporphyrin is also described, including electrophilic and nucleophilic reactions, oxidations, reductions, and metal-mediated cross-coupling reactions. Using the synthetic approaches and reactivity profiles presented, eventually almost any substituted porphyrin system can be prepared for applications in a variety of areas, including in catalysis, electron transport, model biological systems and therapeutics.

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“…The absorbance of the Br-Fe III /L complex at 577 nm completely disappeared and was replaced by the characteristic bands for Fe II porphyrin complexes at around 466 and 500 nm. 49,50 The ATRP activation of Fe II /L with the alkyl halide initiator HEMA-Br yielded the green-line spectrum, which is almost identical to the one recorded for the initial Br-Fe III /L species. The immediate oxidation suggests that Fe II /L is a very active ATRP complex, which will be more closely examined further below.…”

Section: T H Imentioning

confidence: 53%

Kinetics of Fe–Mesohemin–(MPEG₅₀₀)₂-Mediated RDRP in Aqueous Solution

et al. 2016

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A speciation analysis for Fe–mesohemin–(MPEG500)2-mediated reversible-deactivation radical polymerization (RDRP) in aqueous solution was carried out by a combination of visible (vis) and 57Fe Mössbauer spectroscopy. The results were used within kinetic studies of ATRP and OMRP reactions via highly time-resolved EPR spectroscopy. ATRP control was effective with the rate coefficient for deactivation clearly exceeding the one for formation of organometallic species. Deactivation rate coefficients increase by more than 1 order of magnitude in passing from polymerization in 30 to 90 wt % H2O. Media with water contents of and above 70 wt % are well suited for controlled ATRP. The Fe–mesohemin catalyst provides an exceptionally high ATRP equilibrium constant even at ambient temperature, which approaches the one of highly active Cu catalysts.

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ChemInform Abstract: Migratory Aptitudes in Pinacol Rearrangement of vic‐Dihydroxychlorins.

Cited by 5 publications

References 1 publication

De NovoSynthesis of Gem-Dialkyl Chlorophyll Analogues for Probing and Emulating Our Green World

De NovoSynthesis of Gem-Dialkyl Chlorophyll Analogues for Probing and Emulating Our Green World

Syntheses and Functionalizations of Porphyrin Macrocycles

Kinetics of Fe–Mesohemin–(MPEG₅₀₀)₂-Mediated RDRP in Aqueous Solution

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ChemInform Abstract: Migratory Aptitudes in Pinacol Rearrangement of vic‐Dihydroxychlorins.

Cited by 5 publications

References 1 publication

De NovoSynthesis of Gem-Dialkyl Chlorophyll Analogues for Probing and Emulating Our Green World

De NovoSynthesis of Gem-Dialkyl Chlorophyll Analogues for Probing and Emulating Our Green World

Syntheses and Functionalizations of Porphyrin Macrocycles

Kinetics of Fe–Mesohemin–(MPEG500)2-Mediated RDRP in Aqueous Solution

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Product

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Kinetics of Fe–Mesohemin–(MPEG₅₀₀)₂-Mediated RDRP in Aqueous Solution