Serendipitous synthetic entrée to tetradehydro analogues of cobalamins

Deans, Richard M.; Mass, Olga A.; Diers, James R.; Bocian, David F.; Lindsey, Jonathan S.

doi:10.1039/c3nj00574g

Cited by 6 publications

(10 citation statements)

References 38 publications

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“…Reconnaissance. After several years of study (for an earlier attempt, see ref 16), two precedents proved enlightening for developing a directed synthesis of unsymmetrically substituted bacteriochlorins. The first precedent was Woodward's pioneering synthesis of chlorin e 6 trimethyl ester, a precursor of chlorophyll, which relies on directed joining of an AD half and a BC half to form an unsymmetric porphyrin (Scheme 3).…”

Section: ■ Resultsmentioning

confidence: 99%

“…( 3) Yb(OTf) 3 and Sc(OTf) 3 were especially efficient in catalyzing pyrrole−acetal condensations, although tetradehydrocorrintype macrocycles were obtained rather than bacteriochlorins. 16,28 Six acids were examined for the double ring-closure process of 12-T (Table 1, entries 1−6). The reaction was conducted with 0.2 mM 12-T and 2 mM acid with the indicated solvent or temperature.…”

Section: ■ Resultsmentioning

confidence: 99%

“…(2) Our previous studies on the self-condensation of dihydrodipyrrin–acetals identified Lewis acids suitable for the condensation between pyrrole and acetal units (e.g., BF 3 ·OEt 2 in CH 3 CN, TMSOTf/DTBP (2,6-di- tert -butylpyridine) in CH 2 Cl 2 ). (3) Yb(OTf) 3 and Sc(OTf) 3 were especially efficient in catalyzing pyrrole–acetal condensations, although tetradehydrocorrin-type macrocycles were obtained rather than bacteriochlorins. , …”

Section: Resultsmentioning

confidence: 99%

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Construction of the Bacteriochlorin Macrocycle with Concomitant Nazarov Cyclization To Form the Annulated Isocyclic Ring: Analogues of Bacteriochlorophyll a

Zhang

Lindsey

2017

J. Org. Chem.

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Bacteriochlorophylls contain a bacteriochlorin macrocycle bearing an annulated fifth ring. The fifth ring, termed the isocyclic ring or ring E, is equipped with 13-oxo and 13-carbomethoxy substituents. Herein, a general route to stable, synthetic bacteriochlorophyll analogues is described. Knoevenagel condensation (∼40 mM, rt, CHCl, piperidine/AcOH/molecular sieves) of a dihydrodipyrrin-carboxaldehyde (AD half) and a dihydrodipyrrin substituted with a β-ketoester (BC half) forms a propenone bearing the two halves (a hydrobilin analogue). Subsequent treatment (0.2 mM) with acid (Yb(OTf), CHCN, 80 °C) promotes a double ring-closure process: (i) condensation between the α-position of pyrrole ring A and the α-acetal unit attached to pyrroline ring B forms the bacteriochlorin macrocycle, and (ii) Nazarov cyclization of the β-(propenoyl)-substituted ring C forms the isocyclic ring (E). Five new bacteriochlorins bearing various substituents (alkyl/alkyl, aryl, and alkyl/ester) at positions 2 and 3 (β-pyrrole sites, ring A) and 13 carboalkoxy groups (R = Me or Et) were constructed in 37-61% yield from the hydrobilin analogues. The BC half and AD half are available in five and eight steps, respectively, from the corresponding pyrrole-2-carboxaldehyde and unsaturated ketone. The bacteriochlorins exhibit absorption spectra typical of bacteriopheophytins (free base bacteriochlorophylls), with a strong near-infrared absorption band (707-751 nm).

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Section: ■ Resultsmentioning

confidence: 99%

Section: ■ Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Construction of the Bacteriochlorin Macrocycle with Concomitant Nazarov Cyclization To Form the Annulated Isocyclic Ring: Analogues of Bacteriochlorophyll a

Zhang

Lindsey

2017

J. Org. Chem.

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“… a Adapted from ref with permission from the Centre National de la Recherche Scientifique (CNRS) and the Royal Society of Chemistry. …”

Section: Annulation By Side-chain Cyclization: Benzochlorinsmentioning

confidence: 99%

“…The conversion of an A,B,C,D-octadehydrocorrin to a corrin requires an 8e − , 8H + reduction (Scheme 104). 358 Each of the discrete intermediateshexadehydrocorrin, tetradehydrocorrin, and didehydrocorrinhas multiple isomers depending on the position of saturation/unsaturation and nature of the stereochemistry of substituents. The physicochemical properties of such intermediates along the path of reductive transformation from corroles to corrins have hardly been explored, due chiefly to undeveloped synthetic access.…”

Section: Monoaryl Benzochlorinsmentioning

confidence: 99%

Synthetic Chlorins, Possible Surrogates for Chlorophylls, Prepared by Derivatization of Porphyrins

2016

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Chlorophylls make Earth green, are the central constituents in the engine of photosynthesis, and not surprisingly have garnered immense attention. A chlorin, the core chromophore of a chlorophyll, is a dihydroporphyrin macrocycle that contains one pyrroline ring and three pyrrole rings. The dominant method for the synthesis of chlorins has entailed the derivatization of porphyrins. The present review covers the ostensibly simple conversion of porphyrins, regardless of synthetic or biological origin, to chlorins. The period covered encompasses the entire history since the beginnings of chlorin synthetic chemistry in the early 20th century through 2015. Representative transformations include hydrogenation, cycloaddition, annulation, and diverse "breaking and mending" approaches. Altogether, the synthesis of >1000 chlorins or chlorin-like compounds (containing >50 distinct pyrroline motifs) is described. Such diversity animates the question "what structural features are essential for a chlorin to resemble chlorophyll?" To begin to address the structure-spectrum relationship, > 250 absorption spectra are provided for representative structures. The synthesis and spectral properties of the vast collection of compounds described herein are expected to illuminate the scope to which synthetic chlorins can serve as surrogates for chlorophylls and be exploited in diverse ways.

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B12 and F430 models: Metal- versus ligand-centered redox in cobalt and nickel tetradehydrocorrin derivatives

Ghosh

Conradie

2023

Journal of Inorganic Biochemistry

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Serendipitous synthetic entrée to tetradehydro analogues of cobalamins

Cited by 6 publications

References 38 publications

Construction of the Bacteriochlorin Macrocycle with Concomitant Nazarov Cyclization To Form the Annulated Isocyclic Ring: Analogues of Bacteriochlorophyll a

Construction of the Bacteriochlorin Macrocycle with Concomitant Nazarov Cyclization To Form the Annulated Isocyclic Ring: Analogues of Bacteriochlorophyll a

Synthetic Chlorins, Possible Surrogates for Chlorophylls, Prepared by Derivatization of Porphyrins

B12 and F430 models: Metal- versus ligand-centered redox in cobalt and nickel tetradehydrocorrin derivatives

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