Electronic effects of heterocyclic substituents. Spectroscopical and theoretical (AM1) study in a series of heterocyclic carboxaldehydes

Cativiela, C.; Garcı́a, José I.

doi:10.1139/v90-226

Cited by 22 publications

(11 citation statements)

References 13 publications

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“…Research on spectroscopic properties using this method have also been reported. 34 Certain drawbacks of AM1 are known however. The study of the water dimer has shown that AM1 predicts peculiar geometries for the equilibrium structure.…”

Section: Introductionmentioning

confidence: 99%

Analysis of the gas‐phase addition of water to formaldehyde: A semiempirical and ab initio study of bifunctional catalysis by H₂O

et al. 1992

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Semiempirical AM1, MNDO-PM3, and MNDO/M, as well as ab initio Hartree-Fock and Moller-Plesset calculations using the 4-31G, 6-31G(d,p), and 6-31 +G(d,p) basis sets have been done on the water-assisted addition of water to formaldehyde. Ab initio methods predict a reduction of 30% of the bimolecular AGO,* (from 48 to 33 kcalimol) when an ancillary water molecule is used as catalyst. AM1 and MNDO-PM3 predict anticatalysis instead; AGO,* for the termolecular addition is larger than the one for the bimolecular reaction. MNDOiM predicts a modest decrease, from 42 to 39 kcalimol. We conclude that, as predicted by the ab initio calculations, there is a bifunctional catalysis caused by the ancillary water. Two of the semiempirical methods are qualitatively (and all of them quantitatively) in disagreement with this conclusion. 0 1992 by

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Section: Introductionmentioning

confidence: 99%

Analysis of the gas‐phase addition of water to formaldehyde: A semiempirical and ab initio study of bifunctional catalysis by H₂O

et al. 1992

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“…3-Pyridyl substituents on the contrary are sterically much more accessible to be conjugated to platinum(II) complexes in this porphyrin system while displaying the same benefits in terms of rotational freedom, leading to a smaller tendency of forming aggregates and therefore not lowering the effectivity of the PS. Additionally, 3-pyridyl substituents do not show an electron-withdrawing effect in comparison to 2-pyridyl and 4-pyridyl substituents due to a lack of resonance between the site of attachment to the remaining photochemical system and the nitrogen, which is expected to have an influence on the potency of the PS . Porphyrins containing four 3-pyridyl substituents conjugated to metal complexes have been reported to be more photosensitizing than their 4-pyridyl analogues at an equivalent degree of substitution while being more soluble and forming less aggregates in aqueous media .…”

Section: Resultsmentioning

confidence: 99%

Potent PBS/Polysorbate-Soluble Transplatin-Derived Porphyrin-Based Photosensitizers for Photodynamic Therapy

et al. 2021

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In this study, we addressed an important drawback of our previously reported tetraplatinated (metallo)porphyrin-based photosensitizers (PSs) for photodynamic therapy (PDT), namely, the poor solubility in aqueous media. We aimed to create tetraplatinated porphyrin-based PSs that are soluble in aqueous media modified with polysorbate (Tween) and do not need to be pre-dissolved in organic solvents. A structural optimization of the previously reported PSs resulted in the synthesis of an extremely potent novel porphyrin-based PS. The novel PS displays effective phototoxicity upon light irradiation against multicellular tumor spheroids and has a phototoxic index (PI) of 6030 in HeLa cells. This PI value is, to the best of our knowledge, the highest value reported for any porphyrin so far.

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“…81,82 Moreover, a similar competition between the intermolecular Nicholas reaction and intramolecular BF 3promoted O-cyclization has been reported. 83 In the case of indole, its higher donor ability compared to benzothiophene 84 promoted the cyclization of Co-complex 16 within the BF 3activated C 3 -triple bond instead of the Nicholas reaction. All attempts to synthesize a double Co-complex of enediyne 14 with both complexed triple bonds failed, even when fivefold excess of Co 2 (CO) 8 per one alkyne moiety was used: only the formation of monocomplexes 15 and 16 was detected.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Intramolecular Nicholas Reactions in the Synthesis of Heteroenediynes Fused to Indole, Triazole, and Isocoumarin

et al. 2020

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The applicability of an intramolecular Nicholas reaction for the preparation of 10-membered O- and N-enediynes fused to indole, 1,2,3-triazole, and isocoumarin was investigated. The general approach to acyclic enediyne precursors fused to heterocycles includes inter- and intramolecular buta-1,3-diyne cyclizations with the formation of iodoethynylheterocycles, followed by Sonogashira coupling. The nature of both a heterocycle and a nucleophilic group affects the possibility of a 10-membered ring closure by the Nicholas reaction. Among oxacycles, an isocoumarin-fused enediyne was obtained. In the case of O-enediyne annulated with indole, instead of the formation of a 10-membered cycle, BF3-promoted addition of an OH-group to the proximal triple bond at the C3 position afforded dihydrofuryl-substituted indole. For 1,2,3-triazole-fused analogues, using NH-Ts as a nucleophilic functional group allowed obtaining 10-membered azaenediyne, while the substrate with a hydroxyl group gave only traces of the desired 10-membered oxacycle. An improved method for the deprotection of Co-complexes of cyclic enediynes using tetrabutylammonium fluoride in an acetone/water mixture and the investigation of the 10-membered enediynes’ reactivity in the Bergman cyclization are also reported. In the solid state, all synthesized iodoethynylheterocycles were found to be involved in halogen bond (XB) formation with either O or N atoms as XB acceptors.

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Electronic effects of heterocyclic substituents. Spectroscopical and theoretical (AM1) study in a series of heterocyclic carboxaldehydes

Cited by 22 publications

References 13 publications

Analysis of the gas‐phase addition of water to formaldehyde: A semiempirical and ab initio study of bifunctional catalysis by H₂O

Analysis of the gas‐phase addition of water to formaldehyde: A semiempirical and ab initio study of bifunctional catalysis by H₂O

Potent PBS/Polysorbate-Soluble Transplatin-Derived Porphyrin-Based Photosensitizers for Photodynamic Therapy

Intramolecular Nicholas Reactions in the Synthesis of Heteroenediynes Fused to Indole, Triazole, and Isocoumarin

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Electronic effects of heterocyclic substituents. Spectroscopical and theoretical (AM1) study in a series of heterocyclic carboxaldehydes

Cited by 22 publications

References 13 publications

Analysis of the gas‐phase addition of water to formaldehyde: A semiempirical and ab initio study of bifunctional catalysis by H2O

Analysis of the gas‐phase addition of water to formaldehyde: A semiempirical and ab initio study of bifunctional catalysis by H2O

Potent PBS/Polysorbate-Soluble Transplatin-Derived Porphyrin-Based Photosensitizers for Photodynamic Therapy

Intramolecular Nicholas Reactions in the Synthesis of Heteroenediynes Fused to Indole, Triazole, and Isocoumarin

Contact Info

Product

Resources

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Analysis of the gas‐phase addition of water to formaldehyde: A semiempirical and ab initio study of bifunctional catalysis by H₂O

Analysis of the gas‐phase addition of water to formaldehyde: A semiempirical and ab initio study of bifunctional catalysis by H₂O