Synthesis of non-aromatic stable di-para-benzihomoporphyrins

Sengupta, Rima; Ravikanth, Mangalampalli

doi:10.1016/j.tet.2021.132126

Cited by 9 publications

(15 citation statements)

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“…The homopentaphyrin(2.1.1.1.1)s 1 – 4 were synthesized as outlined in Scheme . The desired precursors such as 2,5-bis(2-pyrrolyl(phenyl)methyl)tellurophene ( 5 , 16-telluratripyrrane) and diols such as ((1,2-di- p -tolylethene-1,2-diyl)bis(1 H -pyrrole-5,2-diyl))bis( p -tolylmethanol) ( 6a # ), (but-2-ene-2,3-diyldifuran-2,5-diyl)bis(p-tolylmethanol) ( 7 ), butane-2,3-diyl-bisthiophene-2,5-diyl-bis( p -methoxyphenylmethanol) ( 8 ), and (but-2-ene-2,3-diylbis(4,1-phenylene))bis( p -tolylmethanol) ( 9 ) were synthesized over sequence of steps by adopting the reported procedures. ,− To synthesize pentaphyrin 1a , we reduced bis-acyl dipyrroethene 6 in situ by treating it with NaBH 4 in THF/CH 3 OH to afford dipyrroethene-dicabinol 6a # which was then condensed with 16-telluratripyrrane 5 in the presence of 1 equiv of TFA in CH 2 Cl 2 at room temperature under inert atmosphere for 45 min followed by oxidation with DDQ in open air for additional 1.5 h. The crude compound was purified by basic alumina column chromatography to afford pure pentaphyrin 1a in 11% yield. We varied the conditions by changing various acid catalysts and their equivalents, but the best yield of pentaphyrin 1a was obtained when we used 1 equiv of TFA.…”

Section: Resultsmentioning

confidence: 99%

Tellurophene-Containing Core-Modified Pentaphyrin(2.1.1.1.1)s

et al. 2022

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Various core-modified tellurophene-containing pentaphyrin(2.1.1.1.1)s were synthesized via (3 + 2) condensation of 16-telluratripyrrane with different heterodiols under mild acid catalyzed conditions in 5–12% yields. The formation of pentaphyrin (2.1.1.1.1) with a N2O2Te core was not successful due to its inherent instability. The new pentaphyrins were characterized and studied by HR-MS, 1D and 2D NMR, X-ray crystallography for one of the pentaphyrins, absorption and DFT/TD-DFT techniques. The NMR studies indicated their nonaromatic nature. The X-ray structure obtained for pentaphyrin(2.1.1.1.1) with N4Te core revealed that the macrocycle exists in a highly distorted nonplanar structure. The DFT studies showed that the macrocycles are nonaromatic and exists in highly distorted nonplanar geometry. Furthermore, as the core heterocyclic groups at ethene moiety were changed from pyrrole to furan to thiophene to benzene, the macrocycles tended toward more planar structures. The absorption spectra of pentaphyrins showed one strong sharp band in the region of 450–540 nm along with a broad band in the region of 700–800 nm. The pentaphyrin(2.1.1.1.1) with N4Te core upon protonation showed distinct color change in solution and large bathochromic shifts in absorption bands with an absorption in the NIR region.

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confidence: 99%

Tellurophene-Containing Core-Modified Pentaphyrin(2.1.1.1.1)s

et al. 2022

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“…The synthesis of N-fused homoporphyrins is outlined in Scheme 1. The required precursors, dithienyl diol 21 8 , p -phenylene ethene diol 24,25 9a / 9b and N-confused dipyrromethane 27,28 10a / 10b were synthesized over a sequence of reaction steps by following the reported procedures. The diol 8 was synthesized starting from commercially available 2-acetylthiophene in two steps.…”

Section: Resultsmentioning

confidence: 99%

“…All the required precursors 8 , 9a / 9b and 10a / 10b were characterized by HR-MS and NMR spectroscopy and the characterization data matched with those of the reported compounds. 21,24–27…”

Section: Resultsmentioning

confidence: 99%

“…17–19 However, due to the synthetic advancements over the years, it is now possible to synthesize the stable azahomoporphyrin 20 III and its core-modified analogues 21,22 IV . Recently, Srinivasan et al , 23 Senge et al , 24 and our group 25 reported the synthesis of dibenzi homoporphyrins ( V ) by condensing m -/ p -phenylene based tetrapyrrane with an aryl aldehyde under acid catalysed conditions. The core-modified homoporphyrins 21,22 IV and the dibenzi homoporphyrins 23–25 V were non-aromatic although azahomoporphyrin 20 III was demonstrated to be Mobius aromatic in nature.…”

Section: Introductionmentioning

confidence: 99%

“…Recently, Srinivasan et al , 23 Senge et al , 24 and our group 25 reported the synthesis of dibenzi homoporphyrins ( V ) by condensing m -/ p -phenylene based tetrapyrrane with an aryl aldehyde under acid catalysed conditions. The core-modified homoporphyrins 21,22 IV and the dibenzi homoporphyrins 23–25 V were non-aromatic although azahomoporphyrin 20 III was demonstrated to be Mobius aromatic in nature. Gao and co-workers recently reported the thiophene-embedded N-confused homoporphyrin VI consisting of a 5,5,5-tricyclic fused ring, which is non-aromatic in nature.…”

Section: Introductionmentioning

confidence: 99%

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Synthesis of N-fused dithia and dibenzi homoporphyrins

2022

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Dibenzi Heteroheptaphyrin(2.0.1.1.1.1.0)s: Synthesis, Spectral, Redox and Theoretical Studies

Tiwari,

Ravikanth

2023

Chemistry An Asian Journal

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Three examples of dibenzi heteroheptaphyrin(2.0.1.1.1.1.0)s were synthesized by condensing bis(phenylene ethene) based hexapyrrane with appropriate diol, 2,5‐bis(α‐hydroxy‐α‐arylmethyl) thiophene or selenophene in CH2Cl2 under BF3·OEt2 catalyzed inert atmosphere conditions followed by DDQ oxidation in open air. HR‐MS analyses confirmed the identities of dibenzi heteroheptaphyrins. The DFT optimized structures revealed that dibenzi heteroheptaphyrins were highly distorted nonplanar macrocycles with two thiophene rings preferred to be in an inverted conformation. 1D & 2D NMR helped in deducing the molecular structures of dibenzi heteroheptaphyrins and supported their nonaromatic nature. The theoretical NMR calculations were carried which matched closely with the experimental NMR data. NMR studies also revealed that the π‐delocaliztion was significantly altered in dibenzi heteroheptaphyrins compared to previously reported dibenzi hexaphyrins. The dibenzi heptaphyrins showed one sharp absorption band in 400‐500 nm region and a broad band in the region of 600‐800 nm which were bathochromically shifted in their diprotonated derivatives. The theoretical absorption calculations corroborate the slight hypsochromic shift of the broad absorption band in the lower energy region of dibenzi heptaphyrins compared to dibenzi hexaphyrins. The electrochemical studies revealed that the dibenzi heptaphyrins were easier to reduce but difficult to oxidize compared to dibenzi hexaphyrins.

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Synthesis of non-aromatic stable di-para-benzihomoporphyrins

Cited by 9 publications

References 35 publications

Tellurophene-Containing Core-Modified Pentaphyrin(2.1.1.1.1)s

Tellurophene-Containing Core-Modified Pentaphyrin(2.1.1.1.1)s

Synthesis of N-fused dithia and dibenzi homoporphyrins

Dibenzi Heteroheptaphyrin(2.0.1.1.1.1.0)s: Synthesis, Spectral, Redox and Theoretical Studies

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