Studies in the Chlorophyll Series. Iv. The Degradation of Chlorophyll and Allomerized Chlorophyll to Simple Chlorins

Conant, James Β.; Hyde, J.; Moyer, William W.; Dietz, Emma M.

doi:10.1021/ja01352a054

Cited by 24 publications

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“…266 Among dye chemists, purpurin refers to the madder dye 1,2,4trihydroxy-9,10-anthraquinone. 267 The first report of purpurins of relevance here from the tetrapyrrole field concerns "purplishbrown" compounds ("phaeopurpurins") identified by Conant and Moyer 268 upon examination of the degradation of methyl pheophorbide a, itself derived from chlorophyll a. Over time, the term purpurins came to be used to denote chlorins that bear an electron-withdrawing group at the meso-position.…”

Section: Annulation By Side-chain Cyclizationmentioning

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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Section: Annulation By Side-chain Cyclizationmentioning

confidence: 99%

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

2016

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“…Chlorin-imides (previously often termed purpurinimides) have traditionally been prepared by ring expansion of naturally occurring or naturally derived chlorophylls. 65,68 Such modifications represent one of the earliest and most common methods for semisynthesis with chlorophylls, dating to the work of Conant 388 and of Fischer. 12,389 The imide unit spans positions 13 and 15 on the chlorin macrocycle.…”

Section: Acidic Brominationmentioning

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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“…Still milder conditions of oxidative hydrolysis (4) result in a stable chlorin, which is a monomethyl ester. Hydrolysis of this ester yields the unstable chlorin, hence the former is monomethyl chlorin g (IX), while diazomethane further esterifies it directly to dimethyl pheopurpurin 7. Hot saponification of either pheopurpurin 7 or its ester (8,5) gives rise acetic acid, and subsequent re-oxidation in air, results in the formation of the dibasic acid, rhodoporphyrin (Va). Since the latter contains no side chain on the -bridge carbon atom, neither does chlorin /.…”

Section: Investigations Of Conantmentioning

confidence: 99%

Recent Progress in Determining the Chemical Structure of Chlorophyll.

Steele¹

1937

Chem. Rev.

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Studies in the Chlorophyll Series. Iv. The Degradation of Chlorophyll and Allomerized Chlorophyll to Simple Chlorins

Cited by 24 publications

References 0 publications

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

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

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

Recent Progress in Determining the Chemical Structure of Chlorophyll.

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