1
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Tzeli D, Gerontitis IE, Petsalakis ID, Tsoungas PG, Varvounis G. Self Cycloaddition of o-Naphthoquinone Nitrosomethide to (±) Spiro{naphthalene(naphthopyranofurazan)}-one Oxide: An Insight into its Formation. Chempluschem 2022; 87:e202200313. [PMID: 36479609 DOI: 10.1002/cplu.202200313] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Revised: 11/22/2022] [Indexed: 11/25/2022]
Abstract
2-Hydroxy-1-naphthaldehyde oxime was oxidized by AgO (or Ag2 O), in presence of N-methyl morpholine N-oxide (NMMO), to the title spiro adduct-dimer (±)-Spiro{naphthalene-1(2H),4'-(naphtho[2',1':2,3]pyrano[4,5-c]furazan)}-2-one-11'-oxide by a Diels-Alder(D-A) type self-cycloaddition, through the agency of an o-naphthoquinone nitrosomethide (o-NQM). Moreover, 2-hydroxy-8-methoxy-1-naphthaldehyde oxime was prepared and subjected to the same oxidation conditions. Its sterically guided result, 9-methoxynaphtho[1,2-d]isoxazole, was isolated, instead of the expected spiro adduct. The peri intramolecular H bonding in the oxime is considered to have a key contribution to the outcome. Geometry and energy features of the oxidant- and stereo-guided selectivity of both oxidation outcomes have been explored by DFT, perturbation theory and coupled cluster calculations. The reaction free energy of the D-A intermolecular cycloaddition is calculated at -82.0 kcal/mol, indicating its predominance over the intramolecular cyclization of ca. -37.6 kcal/mol. The cycloaddition is facilitated by NMMO through dipolar interactions and hydrogen bonding with both metal complexes and o-NQM. The 8(peri)-OMe substitution of the reactant oxime sterically impedes formation of the spiro adduct, instead it undergoes a more facile cyclodehydration to the isoxazole structure by ca. 4.9 kcal/mol.
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Affiliation(s)
- Demeter Tzeli
- Laboratory of Physical Chemistry, Department of Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis Zografou Athens, 157 84, Athens, Greece
- Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, 48 Vassileos Constantinou Ave., Athens, 116 35, Greece
| | - Ioannis E Gerontitis
- Section of Organic Chemistry and Biochemistry, Department of Chemistry, University of Ioannina, 451 10, Ioannina, Greece
| | - Ioannis D Petsalakis
- Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, 48 Vassileos Constantinou Ave., Athens, 116 35, Greece
| | - Petros G Tsoungas
- Department of Biochemistry, Hellenic Pasteur Institute, 127 Vas. Sofias Ave., 115 21, Athens, Greece
| | - George Varvounis
- Section of Organic Chemistry and Biochemistry, Department of Chemistry, University of Ioannina, 451 10, Ioannina, Greece
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2
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Photodehydration mechanisms of quinone methide formation from 2-naphthol derivatives. J Photochem Photobiol A Chem 2022. [DOI: 10.1016/j.jphotochem.2022.114171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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3
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Forjan M, Zgrablić G, Vdović S, Šekutor M, Basarić N, Kabacinski P, Nazari Haghighi Pashaki M, Frey HM, Cannizzo A, Cerullo G. Photogeneration of quinone methide from adamantylphenol in an ultrafast non-adiabatic dehydration reaction. Phys Chem Chem Phys 2022; 24:4384-4393. [PMID: 35112685 PMCID: PMC8849006 DOI: 10.1039/d1cp05690e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The ultrafast photochemical reaction of quinone methide (QM) formation from adamantylphenol was monitored in real time using femtosecond transient absorption spectroscopy and fluorescence upconversion in solution at room temperature. Experiments were complemented by theoretical studies simulating the reaction pathway and elucidating its mechanism. Excitation with sub-20 fs UV pulses and broadband probing revealed ultrafast formation of the long-lived QM intermediate directly in the ground state, occurring with a time constant of around 100 fs. UV-vis transient absorption data covering temporal dynamics from femtoseconds to hundreds of milliseconds revealed persistence of the absorption band assigned to QM and partially overlapped with other contributions tentatively assigned to triplet excited states of the adamantyl derivative and the phenoxyl radical that are clearly distinguished by their evolution on different time scales. Our data, together with the computations, provide evidence of a non-adiabatic photodehydration reaction, which leads to the formation of QM in the ground state via a conical intersection, circumventing the generation of a transient QM excited state. Photochemical formation of quinone methide from adamantylphenol was investigated computationally and experimentally, showing evidence of ultrafast non-adiabatic dehydration via a conical intersection.![]()
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Affiliation(s)
- Mateo Forjan
- Institute of Physics, Bijenička cesta 46, 10 000 Zagreb, Croatia.
| | - Goran Zgrablić
- Institute of Physics, Bijenička cesta 46, 10 000 Zagreb, Croatia.
| | - Silvije Vdović
- Institute of Physics, Bijenička cesta 46, 10 000 Zagreb, Croatia.
| | - Marina Šekutor
- Department of Organic Chemistry and Biochemistry, Ruđer Bošković Institute, Bijenička cesta 54, 10 000 Zagreb, Croatia
| | - Nikola Basarić
- Department of Organic Chemistry and Biochemistry, Ruđer Bošković Institute, Bijenička cesta 54, 10 000 Zagreb, Croatia
| | - Piotr Kabacinski
- IFN-CNR, Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133 Milano, Italy
| | | | - Hans-Martin Frey
- Institute of Applied Physics, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
| | - Andrea Cannizzo
- Institute of Applied Physics, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland
| | - Giulio Cerullo
- IFN-CNR, Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, I-20133 Milano, Italy
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4
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Foscolos AS, Papanastasiou I, Tsotinis A, Taylor MC, Kelly JM. Synthesis and Evaluation of Nifurtimox-Adamantane Adducts with Trypanocidal Activity. ChemMedChem 2019; 14:1227-1231. [PMID: 31066972 DOI: 10.1002/cmdc.201900165] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Revised: 04/11/2019] [Indexed: 11/08/2022]
Abstract
The synthesis and pharmacological evaluation of C1-substituted adamantane hydrazones, their C2-substituted isomers, and C1-substituted adamantane furanoic carboxamides is described. These new adamantane derivatives exhibited an interesting pharmacological profile in terms of trypanocidal activity and selectivity. The most active adduct with the best selectivity in this study was found to be the phenylacetoxy hydrazone 1 b (2-[4-(tricyclo[3.3.1.13,7 ]dec-1-yl)phenyl]-N'-[(5-nitrofuran-2-yl)methylene]acetohydrazide; EC50 =11±0.9 nm, SITb =770).
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Affiliation(s)
- Angeliki-Sofia Foscolos
- School of Health Sciences, Department of Pharmacy, Division of Pharmaceutical Chemistry, National and Kapodistrian University of Athens, Panepistimioupoli-Zografou, 157 84, Athens, Greece
| | - Ioannis Papanastasiou
- School of Health Sciences, Department of Pharmacy, Division of Pharmaceutical Chemistry, National and Kapodistrian University of Athens, Panepistimioupoli-Zografou, 157 84, Athens, Greece
| | - Andrew Tsotinis
- School of Health Sciences, Department of Pharmacy, Division of Pharmaceutical Chemistry, National and Kapodistrian University of Athens, Panepistimioupoli-Zografou, 157 84, Athens, Greece
| | - Martin C Taylor
- Department of Pathogen Molecular Biology, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1 E7HT, UK
| | - John M Kelly
- Department of Pathogen Molecular Biology, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1 E7HT, UK
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5
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Wu F, Zhu S. A Strategy To Obtain o-Naphthoquinone Methides: Ag(I)-Catalyzed Cyclization of Enynones for the Synthesis of Benzo[ h]chromanes and Naphthopyryliums. Org Lett 2019; 21:1488-1492. [PMID: 30789279 DOI: 10.1021/acs.orglett.9b00281] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A new strategy to obtain o-NQM intermediates through a ring-formation strategy by Ag(I)-catalyzed cyclization of 2-alkenylphenyl alkynyl ketones and its [4 + 2] annulations with styrenes has been developed. This reaction features high efficiency, mild reaction conditions, as well as flexible substitutions and atom economy. The obtained benzo[ h]chromane products were further oxidized to naphthopyryliums, which displayed tunable photophysical properties.
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Affiliation(s)
- Feng Wu
- Key Laboratory of Functional Molecular Engineering of Guangdong Province, School of Chemistry and Chemical Engineering , South China University of Technology , Guangzhou 510640 , P.R. China
| | - Shifa Zhu
- Key Laboratory of Functional Molecular Engineering of Guangdong Province, School of Chemistry and Chemical Engineering , South China University of Technology , Guangzhou 510640 , P.R. China.,State Key Laboratory of Elemento-Organic Chemistry , Nankai University , Tianjin 300071 , P.R. China
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6
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Yan Z, Du L, Lan X, Li Y, Wang W, Phillips DL. Time-Resolved Spectroscopic and Density Functional Theory Investigation of the Photogeneration of a Bifunctional Quinone Methide in Neutral and Basic Aqueous Solutions. Molecules 2018; 23:E3102. [PMID: 30486443 PMCID: PMC6321171 DOI: 10.3390/molecules23123102] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Revised: 11/20/2018] [Accepted: 11/23/2018] [Indexed: 01/01/2023] Open
Abstract
Binol quinone methides (BQMs) can be generated from 1,1'-(2,2'-dihydroxy-1,1'-binaphthyl-6,6'-diyl)bis(N,N,N-trimethylmethanamiuium) bromide (BQMP-b) in a 1:1 MeCN:H₂O mixed solution via a ground state intramolecular proton transfer (GSIPT), as mentioned in our previously reported studies. Here, the photoreaction of BQMP-b in neutral and basic aqueous solution (pH = 7, 10, 12) was investigated to explore the possible mechanisms and the key intermediates produced in the process of the photoreaction and to examine whether they are different from those in a neutral mild-mixed MeCN:H₂O solution. The studies were conducted using femtosecond transient absorption (fs-TA), nanosecond transient absorption (ns-TA), and nanosecond time-resolved resonance Raman spectroscopy (ns-TR³) in conjunction with results from density functional theory (DFT) computations. The results showed that BQMP-b was deprotonated initially and produced BQMs species more effectively through an E1bc elimination reaction in a strong basic aqueous condition (pH = 12), which differed from the reaction pathway that took place in the solution with pH = 7 or 10. A related single naphthol ring molecule 1-(6-hydroxynaphthalen-2-yl)-N,N,N-trimethylmethanaminium bromide (QMP-b) that did not contain a second naphthol ring was also investigated. The related reaction mechanisms are elucidated in this work, and it is briefly discussed how the mechanisms vary as a function of aqueous solution pH conditions.
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Affiliation(s)
- Zhiping Yan
- Department of Chemistry, The University of Hong Kong, Hong Kong, China.
| | - Lili Du
- Department of Chemistry, The University of Hong Kong, Hong Kong, China.
| | - Xin Lan
- Department of Chemistry, The University of Hong Kong, Hong Kong, China.
| | - Yuanchun Li
- Department of Chemistry, The University of Hong Kong, Hong Kong, China.
| | - Wenchao Wang
- Department of Chemistry, The University of Hong Kong, Hong Kong, China.
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7
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Škalamera Đ, Antol I, Mlinarić-Majerski K, Vančik H, Phillips DL, Ma J, Basarić N. Ultrafast Adiabatic Photodehydration of 2-Hydroxymethylphenol and the Formation of Quinone Methide. Chemistry 2018; 24:9426-9435. [PMID: 29677402 DOI: 10.1002/chem.201801543] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Indexed: 12/13/2022]
Abstract
The photochemical reactivity of 2-hydroxymethylphenol (1) was investigated experimentally by photochemistry under cryogenic conditions, by detecting reactive intermediates by IR spectroscopy, and by using nanosecond and femtosecond transient absorption spectroscopic methods in solution at room temperature. In addition, theoretical studies were performed to facilitate the interpretation of the experimental results and also to simulate the reaction pathway to obtain a better understanding of the reaction mechanism. The main finding of this work is that photodehydration of 1 takes place in an ultrafast adiabatic photochemical reaction without any clear intermediate, delivering quinone methide (QM) in the excited state. Upon photoexcitation to a higher vibrational level of the singlet excited state, 1 undergoes vibrational relaxation leading to two photochemical pathways, one by which synchronous elimination of H2 O gives QM 2 in its S1 state and the other by which homolytic cleavage of the phenolic O-H bond produces a phenoxyl radical (S0 ). Both are ultrafast processes that occur within a picosecond. The excited state of QM 2 (S1 ) probably deactivates to S0 through a conical intersection to give QM 2 (S0 ), which subsequently delivers benzoxete 4. Elucidation of the reaction mechanisms for the photodehydration of phenols by which QMs are formed is important to tune the reactivity of QMs with DNA and proteins for the potential application of QMs in medicine as therapeutic agents.
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Affiliation(s)
- Đani Škalamera
- Department of Organic Chemistry and Biochemistry, Ruđer Bošković Institute, Bijenička cesta 54, 10000, Zagreb, Croatia.,Department of Organic Chemistry, Faculty of Science, University of Zagreb, Horvatovac 102a, 10000, Zagreb, Croatia
| | - Ivana Antol
- Department of Organic Chemistry and Biochemistry, Ruđer Bošković Institute, Bijenička cesta 54, 10000, Zagreb, Croatia
| | - Kata Mlinarić-Majerski
- Department of Organic Chemistry and Biochemistry, Ruđer Bošković Institute, Bijenička cesta 54, 10000, Zagreb, Croatia
| | - Hrvoj Vančik
- Department of Organic Chemistry, Faculty of Science, University of Zagreb, Horvatovac 102a, 10000, Zagreb, Croatia
| | - David Lee Phillips
- Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong S.A.R., P.R. China
| | - Jiani Ma
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of, Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi'an, P.R. China
| | - Nikola Basarić
- Department of Organic Chemistry and Biochemistry, Ruđer Bošković Institute, Bijenička cesta 54, 10000, Zagreb, Croatia
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8
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Husak A, Noichl BP, Šumanovac Ramljak T, Sohora M, Škalamera Đ, Budiša N, Basarić N. Photochemical formation of quinone methides from peptides containing modified tyrosine. Org Biomol Chem 2018; 14:10894-10905. [PMID: 27812591 DOI: 10.1039/c6ob02191c] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
We have demonstrated that quinone methide (QM) precursors can be introduced in the peptide structure and used as photoswitchable units for peptide modifications. QM precursor 1 was prepared from protected tyrosine in the Mannich reaction, and further used as a building block in peptide synthesis. Moreover, peptides containing tyrosine can be transformed into a photoactivable QM precursor by the Mannich reaction which can afford monosubstituted derivatives 2 or bis-substituted derivatives 3. Photochemical reactivity of modified tyrosine 1 and dipeptides 2 and 3 was studied by preparative irradiation in CH3OH where photodeamination and photomethanolysis occur. QM precursors incorporated in peptides undergo photomethanolysis with quantum efficiency ΦR = 0.1-0.2, wherein the peptide backbone does not affect their photochemical reactivity. QMs formed from dipeptides were detected by laser flash photolysis (λmax ≈ 400 nm, τ = 100 μs-20 ms) and their reactivity with nucleophiles was studied. Consequently, QM precursors derived from tyrosine can be a part of the peptide backbone which can be transformed into QMs upon electronic excitation, leading to the reactions of peptides with different reagents. This proof of principle showing the ability to photochemically trigger peptide modifications and interactions with other molecules can have numerous applications in organic synthesis, materials science, biology and medicine.
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Affiliation(s)
- Antonija Husak
- Department of Organic Chemistry and Biochemistry, Ruđer Bošković Institute, Bijenička cesta 54, 10 000 Zagreb, Croatia.
| | - Benjamin P Noichl
- Institute for Chemistry, Technical University Berlin, Müller-Breslau-Str. 10, 10623 Berlin, Germany
| | - Tatjana Šumanovac Ramljak
- Department of Organic Chemistry and Biochemistry, Ruđer Bošković Institute, Bijenička cesta 54, 10 000 Zagreb, Croatia.
| | - Margareta Sohora
- Department of Organic Chemistry and Biochemistry, Ruđer Bošković Institute, Bijenička cesta 54, 10 000 Zagreb, Croatia.
| | - Đani Škalamera
- Department of Organic Chemistry and Biochemistry, Ruđer Bošković Institute, Bijenička cesta 54, 10 000 Zagreb, Croatia.
| | - Nediljko Budiša
- Institute for Chemistry, Technical University Berlin, Müller-Breslau-Str. 10, 10623 Berlin, Germany
| | - Nikola Basarić
- Department of Organic Chemistry and Biochemistry, Ruđer Bošković Institute, Bijenička cesta 54, 10 000 Zagreb, Croatia.
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9
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Yang B, Gao S. Recent advances in the application of Diels–Alder reactions involving o-quinodimethanes, aza-o-quinone methides and o-quinone methides in natural product total synthesis. Chem Soc Rev 2018; 47:7926-7953. [DOI: 10.1039/c8cs00274f] [Citation(s) in RCA: 240] [Impact Index Per Article: 40.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
This review summarizes recent advances in Diels–Alder reactions involving o-QDMs, o-QMs and aza-o-QMs. The power and potential of this strategy in organic synthesis and natural product total synthesis is highlighted.
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Affiliation(s)
- Baochao Yang
- Shanghai Key Laboratory of Green Chemistry and Chemical Processes
- School of Chemistry and Molecular Engineering
- East China Normal University
- Shanghai 200062
- China
| | - Shuanhu Gao
- Shanghai Key Laboratory of Green Chemistry and Chemical Processes
- School of Chemistry and Molecular Engineering
- East China Normal University
- Shanghai 200062
- China
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10
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Škalamera Đ, Veljković J, Ptiček L, Sambol M, Mlinarić-Majerski K, Basarić N. Synthesis of asymmetrically disubstituted anthracenes. Tetrahedron 2017. [DOI: 10.1016/j.tet.2017.08.038] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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11
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Škalamera Đ, Mlinarić-Majerski K, Martin Kleiner I, Kralj M, Oake J, Wan P, Bohne C, Basarić N. Photochemical Formation of Anthracene Quinone Methide Derivatives. J Org Chem 2017; 82:6006-6021. [PMID: 28534631 DOI: 10.1021/acs.joc.6b02735] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Anthrols 2-7 were synthesized and their photochemical reactivity investigated by irradiations in aq CH3OH. Upon excitation with visible light (λ > 400 nm) in methanolic solutions, they undergo photodehydration or photodeamination and deliver methyl ethers, most probably via quinone methides (QMs), with methanolysis quantum efficiencies ΦR = 0.02-0.3. Photophysical properties of 2-7 were determined by steady-state fluorescence and time-correlated single photon counting. Generally, anthrols 2-7 are highly fluorescent in aprotic solvents (ΦF = 0.5-0.9), whereas in aqueous solutions the fluorescence is quenched due to excited-state proton transfer (ESPT) to solvent. The exception is amine 4 that undergoes excited-state intramolecular proton transfer (ESIPT) in neat CH3CN where photodeamination is probably coupled to ESIPT. Photodehydration may take place via ESIPT (or ESPT) that is coupled to dehydration or via a hitherto undisclosed pathway that involves photoionization and deprotonation of radical cation, followed by homolytic cleavage of the alcohol OH group from the phenoxyl radical. QMs were detected by laser flash photolysis and their reactivity with nucleophiles investigated. Biological investigation of 2-5 on human cancer cell lines showed enhancement of antiproliferative effect upon exposure of cells to irradiation by visible light, probably due to formation of electrophilic species such as QMs.
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Affiliation(s)
| | | | | | | | - Jessy Oake
- Department of Chemistry, University of Victoria , Box 1700 STN CSC, Victoria BC V8W 2Y2, Canada
| | - Peter Wan
- Department of Chemistry, University of Victoria , Box 1700 STN CSC, Victoria BC V8W 2Y2, Canada
| | - Cornelia Bohne
- Department of Chemistry, University of Victoria , Box 1700 STN CSC, Victoria BC V8W 2Y2, Canada
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12
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Du L, Zhang X, Xue J, Tang W, Li MD, Lan X, Zhu J, Zhu R, Weng Y, Li YL, Phillips DL. Influence of Water in the Photogeneration and Properties of a Bifunctional Quinone Methide. J Phys Chem B 2016; 120:11132-11141. [PMID: 27723330 DOI: 10.1021/acs.jpcb.6b08705] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Quinone methides (QM) are crucial reactive species in molecular biology and organic chemistry, with little known regarding the mechanism(s) for the generation of short-lived reactive QM intermediates from relevant precursors in aqueous solutions. In this study, several time-resolved spectroscopy methods were used to directly examine the photophysics and photochemical pathways of 1,1'-(2,2'-dihydroxy-1,1'-binaphthyl-6,6'-diyl)bis(N,N,N-trimethylmethanaminium) bromide (BQMP-b) from initial photoexcitation to the generation of the key reactive binol QM intermediate (BQM) in aqueous solution. The fluorescence of BQMP-b is effectively quenched with a small amount of water, which suggests an excited state intramolecular proton transfer (ESIPT) occurs. The kinetics isotope effects observed in femtosecond and nanosecond time-resolved transient absorption experiments provide evidence for the participation of water molecules in the BQMP-b singlet excited state ESIPT process and in the subsequent -HNMe3+ group release and ground state intramolecular proton transfer that give rise to production of the reactive BQM intermediate. Nanosecond time-resolved resonance Raman (ns-TR3) measurements were also employed to investigate the structure and properties of several intermediates, including the key reactive BQM in aqueous solution. The ns-TR3 and density functional theory (DFT) computational results were compared, and this indicates the binol moiety and water molecules both have important roles in the characteristics and structure of the key reactive BQM intermediate produced from BQMP-b. The results presented here also provide new benchmark characterization of bifunctional quinone methide intermediates that can be utilized to guide direct time-resolved spectroscopic study of the alkylation and interstrand cross-linking reactions of quinone methides with DNA in the future.
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Affiliation(s)
- Lili Du
- Department of Chemistry, University of Hong Kong , Pokfulam Road, Hong Kong S.A.R., P. R. China
| | - Xiting Zhang
- Department of Chemistry, University of Hong Kong , Pokfulam Road, Hong Kong S.A.R., P. R. China
| | - Jiadan Xue
- Department of Chemistry, Zhejiang Sci-Tech University , Hangzhou 310018, P. R. China
| | - WenJian Tang
- School of Pharmacy, Anhui Medical University , Meishan Road 81, Hefei 230032, P.R. China
| | - Ming-De Li
- Department of Chemistry, University of Hong Kong , Pokfulam Road, Hong Kong S.A.R., P. R. China
| | - Xin Lan
- Department of Chemistry, University of Hong Kong , Pokfulam Road, Hong Kong S.A.R., P. R. China
| | - Jiangrui Zhu
- Key Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences , Beijing 100190, P. R. China
| | - Ruixue Zhu
- Department of Chemistry, University of Hong Kong , Pokfulam Road, Hong Kong S.A.R., P. R. China
| | - Yuxiang Weng
- Key Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences , Beijing 100190, P. R. China
| | - Yun-Liang Li
- Key Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences , Beijing 100190, P. R. China
| | - David Lee Phillips
- Department of Chemistry, University of Hong Kong , Pokfulam Road, Hong Kong S.A.R., P. R. China
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13
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Cindro N, Antol I, Mlinarić-Majerski K, Halasz I, Wan P, Basarić N. Reactivity of Cations and Zwitterions Formed in Photochemical and Acid-Catalyzed Reactions from m-Hydroxycycloalkyl-Substituted Phenol Derivatives. J Org Chem 2015; 80:12420-30. [PMID: 26595342 DOI: 10.1021/acs.joc.5b02297] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Three m-substituted phenol derivatives, each with a labile benzylic alcohol group and bearing either protoadamantyl 4, homoadamantyl 5, or a cyclohexyl group 6, were synthesized and their thermal acid-catalyzed and photochemical solvolytic reactivity studied, using preparative irradiations, fluorescence measurements, nanosecond laser flash photolysis, and quantum chemical calculations. The choice of m-hydroxy-substitution was driven by the potential for these phenolic systems to generate m-quinone methides on photolysis, which could ultimately drive the excited-state pathway, as opposed to forming simple benzylic carbocations in the corresponding thermal route. Indeed, thermal acid-catalyzed reactions gave the corresponding cations, which undergo rearrangement and elimination from 4, only elimination from 5, and substitution and elimination from 6. On the other hand, upon photoexcitation of 4-6 to S1 in a polar protic solvent, proton dissociation from the phenol, coupled with elimination of the benzylic OH (as hydroxide ion) gave zwitterions (formal m-quinone methides). The zwitterions exhibit reactivity different from the corresponding cations due to a difference in charge distribution, as shown by DFT calculations. Thus, protoadamantyl zwitterion has a less nonclassical character than the corresponding cation, so it does not undergo 1,2-shift of the carbon atom, as observed in the acid-catalyzed reaction.
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Affiliation(s)
| | | | | | | | - Peter Wan
- Department of Chemistry, University of Victoria , Box 3065 STN CSC, Victoria, BC V8W 3V6, Canada
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14
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Škalamera Đ, Mlinarić-Majerski K, Martin-Kleiner I, Kralj M, Wan P, Basarić N. Near-visible light generation of a quinone methide from 3-hydroxymethyl-2-anthrol. J Org Chem 2014; 79:4390-7. [PMID: 24758707 DOI: 10.1021/jo500290y] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Excitation of 2-hydroxy-3-(diphenylhydroxymethyl)anthracene (7) to S1 initiates photodehydration, giving the corresponding quinone methide (QM) that was detected by laser flash photolysis (LFP) in 2,2,2-trifluoroethanol (λ = 580 nm, τ = 690 ± 10 ns). The QM decays by protonation, giving a cation (λ = 520 nm, τ = 84 ± 3 μs), which subsequently reacts with nucleophiles. The rate constants in the reactions with nucleophiles were determined by LFP, whereas the adducts were isolated via preparative photolyses. The photogeneration of QMs in the anthrol series is important for potential use in biological systems since the chromophore absorbs at wavelengths > 400 nm. Antiproliferative investigations conducted with 2-anthrol derivative 7 on three human cancer cell lines showed higher activity for irradiated cells.
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Affiliation(s)
- Đani Škalamera
- Department of Organic Chemistry and Biochemistry, Ruđer Bošković Institute , Bijenička cesta 54, 10 000 Zagreb, Croatia
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15
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Rosenberg M, Dahlstrand C, Kilså K, Ottosson H. Excited State Aromaticity and Antiaromaticity: Opportunities for Photophysical and Photochemical Rationalizations. Chem Rev 2014; 114:5379-425. [DOI: 10.1021/cr300471v] [Citation(s) in RCA: 272] [Impact Index Per Article: 27.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Martin Rosenberg
- Department
of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark
| | - Christian Dahlstrand
- Department
of Chemistry - BMC, Uppsala University, Box 576, 751 23 Uppsala, Sweden
| | - Kristine Kilså
- Department
of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark
| | - Henrik Ottosson
- Department
of Chemistry - BMC, Uppsala University, Box 576, 751 23 Uppsala, Sweden
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16
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Singh MS, Nagaraju A, Anand N, Chowdhury S. ortho-Quinone methide (o-QM): a highly reactive, ephemeral and versatile intermediate in organic synthesis. RSC Adv 2014. [DOI: 10.1039/c4ra11444b] [Citation(s) in RCA: 183] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
In this critical review, we provide a comprehensive view of the chemistry of ortho-quinone methides as versatile reactive intermediates in organic synthesis.
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Affiliation(s)
- Maya Shankar Singh
- Department of Chemistry
- Faculty of Science
- Banaras Hindu University
- Varanasi 221 005, India
| | - Anugula Nagaraju
- Department of Chemistry
- Faculty of Science
- Banaras Hindu University
- Varanasi 221 005, India
| | - Namrata Anand
- Department of Chemistry
- Faculty of Science
- Banaras Hindu University
- Varanasi 221 005, India
| | - Sushobhan Chowdhury
- Department of Chemistry
- Faculty of Science
- Banaras Hindu University
- Varanasi 221 005, India
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17
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Veljković J, Antol I, Basarić N, Smrečki V, Molčanov K, Müller N, Mlinarić-Majerski K. Atropisomerism in 1-(2-adamantyl)naphthalene Derivatives. J Mol Struct 2013. [DOI: 10.1016/j.molstruc.2013.04.027] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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18
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Chen MW, Cao LL, Ye ZS, Jiang GF, Zhou YG. A mild method for generation of o-quinone methides under basic conditions. The facile synthesis of trans-2,3-dihydrobenzofurans. Chem Commun (Camb) 2013; 49:1660-2. [PMID: 23340596 DOI: 10.1039/c3cc37800d] [Citation(s) in RCA: 102] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A novel and efficient method for the generation of o-quinone methide intermediates was developed from the readily available 2-tosylalkylphenols under the mild basic conditions, and their reactions with sulfur ylides were investigated for the stereoselective synthesis of trans-2,3-dihydrobenzofurans.
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Affiliation(s)
- Mu-Wang Chen
- State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, China
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19
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Škalamera Đ, Mlinarić-Majerski K, Uzelac L, Kralj M, Wan P, Basarić N. Photosolvolysis of bulky (4-hydroxyphenyl)naphthalene derivatives. Photochem Photobiol Sci 2013; 12:2043-56. [DOI: 10.1039/c3pp50190f] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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20
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Wang YH, Wan P. Solvent-dependent excited state intramolecular proton transfer (ESIPT) pathways from phenol to carbon in 2,5-dihydroxyphenyl arenes. Photochem Photobiol Sci 2013; 12:1571-88. [DOI: 10.1039/c3pp50091h] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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21
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Abstract
In this chapter, most of the reported work deals with the photochemistry of carbonyl compounds; however, the photoreactions of other functions, such as the photo-Claisen rearrangement or the photocleavage of cyclic ethers, are also included. In the present volume, time coverage is 2010–2011, and only original research articles are quoted. In general, reviews or purely theoretical calculations are not systematically included. As usually, the material is organized according to established types of reactions (e.g., Norrish I/II, hydrogen abstraction, Paternò-Büchi, photoelimination, photo-Fries/photo-Claisen, etc.). After presenting the basic photochemical aspects, more specific findings are reported. They include synthetic applications, stereoselectivity, and biological or technological implications. Next, the attention is focused on photochemical reactions in anisotropic media, including (micro)heterogeneous or supramolecular systems, solid matrixes or fully organized crystals. Finally, mechanistic studies based on direct experimental evidence are highlighted, especially when transient absorption spectroscopy or related ultrafast detection are employed.
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Affiliation(s)
- M. Consuelo Jiménez
- Departamento de Química, Instituto de Tecnología Química UPV-CSIC Universidad Politécnica de Valencia camino de Vera s/n, E-46022 Valencia Spain
| | - Miguel A. Miranda
- Departamento de Química, Instituto de Tecnología Química UPV-CSIC Universidad Politécnica de Valencia camino de Vera s/n, E-46022 Valencia Spain
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22
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Veljković J, Uzelac L, Molčanov K, Mlinarić-Majerski K, Kralj M, Wan P, Basarić N. Sterically congested adamantylnaphthalene quinone methides. J Org Chem 2012; 77:4596-610. [PMID: 22533612 DOI: 10.1021/jo3002479] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Five new (2-adamantyl)naphthol derivatives (5-9, quinone methide precursors, QMP) were synthesized and their photochemical reactivity was investigated by preparative photolyses, fluorescence spectroscopy, and laser flash photolysis (LFP). Excitation of QMP 5 to S(1) leads to efficient excited state intramolecular proton transfer (ESIPT) coupled with dehydration, giving quinone methide QM5 which was characterized by LFP (in CH(3)CN-H(2)O, λ(max) = 370 nm, τ = 0.19 ms). On irradiation of QMP 5 in CH(3)OH-H(2)O (4:1), the quantum yield of methanolysis is Φ = 0.70. Excitation of naphthols QMP 6-8 to S(1) in CH(3)CN leads to photoionization and formation of naphthoxyl radicals. In a protic solvent, QMP 6-8 undergo solvent-assisted PT giving QM6 or zwitterion QM8 that react with nucleophiles delivering adducts, but with a significantly lower quantum efficiency. QMP 9 in a protic solvent undergoes two competitive processes, photosolvolysis via QM9 and solvent-assisted PT to carbon atom of the naphthalene giving zwitterion. QM9 has been characterized by LFP (in CH(3)CN-H(2)O, λ(max) > 600 nm, τ = 0.9 ms). In addition to photogenerated QMs, two stable naphthalene QMs, QM10 and QM11 were synthesized thermally and characterized by X-ray crystallography. QM10 and QM11 do not react with H(2)O but undergo acid-catalyzed fragmentation or rearrangement. Antiproliferative activity of 5-9 was investigated on three human cancer cell lines. Exposure of MCF-7 cells treated with 5 to 300 nm irradiation leads to an enhanced antiproliferative effect, in accordance with the activity being due to the formation of QM5.
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Affiliation(s)
- Jelena Veljković
- Department of Organic Chemistry and Biochemistry, Ruđer Bošković Institute, Bijenička cesta 54, 10 000 Zagreb, Croatia
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23
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Doria F, Percivalle C, Freccero M. Vinylidene-quinone methides, photochemical generation and β-silicon effect on reactivity. J Org Chem 2012; 77:3615-9. [PMID: 22397717 DOI: 10.1021/jo300115f] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Irradiation of 2-alkynylphenols resulted in the generation of vinylidene-quinone methides (QMs), which were detected by laser flash photolysis in organic solvents and aqueous acetonitrile. QMs' spectroscopic properties and electrophilicity were both significantly affected by β-silicon effect. The hydration of the alkynyl moiety (22 and 900 M(-1) s(-1)for QM-1 and QM-2, in aqueous acetonitrile) was an acid- and base-catalyzed process. The addition of amines was fast (9.2 × 10(3) M(-1) s(-1) < k(2) < 1.3 × 10(8) M(-1) s(-1)), yielding ketimines, with primary amines.
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Affiliation(s)
- Filippo Doria
- Dipartimento di Chimica, Università di Pavia, V.le Taramelli 10, 27100 Pavia, Italy
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24
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Shaikh AK, Cobb AJA, Varvounis G. Mild and rapid method for the generation of ortho-(naphtho)quinone methide intermediates. Org Lett 2012; 14:584-7. [PMID: 22233235 DOI: 10.1021/ol203196n] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
A new mild method has been devised for generating o-(naphtho)quinone methides via fluoride-induced desilylation of silyl derivatives of o-hydroxybenzyl(or 1-naphthylmethyl) nitrate. The reactive o-(naphtho)quinone methide intermediates were trapped by C, O, N, and S nucleophiles and underwent "inverse electron-demand" hetero-Diels-Alder reaction with dienophiles to give stable adducts. The method has useful potential application in natural product synthesis and drug research.
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Affiliation(s)
- Abdul kadar Shaikh
- Department of Chemistry, University of Ioannina, Section of Organic Chemistry and Biochemistry, 451 10 Ioannina, Greece
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25
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Basarić N, Cindro N, Bobinac D, Uzelac L, Mlinarić-Majerski K, Kralj M, Wan P. Zwitterionic biphenyl quinone methides in photodehydration reactions of 3-hydroxybiphenyl derivatives: laser flash photolysis and antiproliferation study. Photochem Photobiol Sci 2012; 11:381-96. [PMID: 22212815 DOI: 10.1039/c1pp05338h] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In aqueous media, photochemical excitation to S(1) of 3-phenylphenols 4-8 leads to deprotonation of the phenol OH, coupled with protonation of the benzyl alcohol and overall dehydration that delivers zwitterions 17-21. The zwitterions react with nucleophiles (CH(3)OH, CF(3)CH(2)OH and ethanolamine) converting them in high quantum yields to the corresponding adducts and photosolvolysis products (for photomethanolysis Φ~0.1-0.5). Zwitterions 20 and 21 were characterized by laser flash photolysis in CH(3)CN-H(2)O (τ~7.5 and 25 μs, respectively) and the associated quenching rate constants with nucleophiles azide and ethanolamine determined. In vitro studies of antiproliferative activity of the photochemicaly generated QMs and zwitterions formed from 2-, 3- and 4-phenylphenols were carried out on three human cancer cell lines HCT 116 (colon), MCF-7 (breast), and H 460 (lung). Irradiation of cells incubated with 3, 6, and 26 showed enhanced antiproliferative activity compared to the cells that were not irradiated.
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Affiliation(s)
- Nikola Basarić
- Department of Organic Chemistry and Biochemistry, Ruđer Bošković Institute, Bijenička cesta 54, 10 000, Zagreb, Croatia.
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26
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Basarić N, Cindro N, Bobinac D, Mlinarić-Majerski K, Uzelac L, Kralj M, Wan P. Sterically congested quinone methides in photodehydration reactions of 4-hydroxybiphenyl derivatives and investigation of their antiproliferative activity. Photochem Photobiol Sci 2011; 10:1910-25. [PMID: 22008723 DOI: 10.1039/c1pp05182b] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In aqueous media, photochemical excitation (S(1)) of hydroxyadamantyl, diphenylhydroxymethyl, and hydroxypropyl derivatives of 4-phenylphenol 5-9 leads to solvent-assisted deprotonation of the phenol OH, and protonation of the benzyl alcohol coupled with dehydration, that delivers quinone methides (QMs) 14-18. The QMs react with CH(3)OH converting them in high quantum yields to the photosolvolysis products (overall Φ∼ 0.1-0.5). QMs were characterized by laser flash photolysis in CH(3)CN-H(2)O and TFE. In TFE, the zwitterionic QM 15 has a lifetime of 250 ns, whereas para QMs 16 and 17 have lifetimes of 500 μs and 1.1 s, respectively. Introduction of the steric hindrance to the parent QM structure (with the adamantyl moiety), or additional stabilization by two phenyl rings, results in an increase of QM lifetimes and selectivity in the reactions with nucleophiles. In vitro studies of the antiproliferative activity of photochemically generated QMs 15-17 were carried out on one human cancer cell line. Irradiation of cells incubated with 7 showed enhanced antiproliferative activity compared to cells that were not irradiated, in accordance with the activity being due to the formation of QM 16.
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Affiliation(s)
- Nikola Basarić
- Department of Organic Chemistry and Biochemistry, Ruđer Bošković Institute, Zagreb, Croatia.
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27
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Basarić N, Cindro N, Hou Y, Žabčić I, Mlinarić-Majerski K, Wan P. Competing photodehydration and excited-state intramolecular proton transfer (ESIPT) in adamantyl derivatives of 2-phenylphenols. CAN J CHEM 2011. [DOI: 10.1139/v10-102] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
2-Phenylphenol derivatives strategically substituted with a hydroxyadamantyl substituent were synthesized and their photochemical reactivity was investigated. Derivatives 9 and 10 undergo competitive excited-state intramolecular proton transfer (ESIPT) from the phenol to the carbon atom of the adjacent phenyl ring and formal ESPT from the phenol to the hydroxyl group coupled with dehydration. These two processes (both via S1) give rise to two classes of quinone methides (QMs) that revert to starting material or react with nucleophiles, respectively. ESIPT to carbon atoms was studied by performing photolyses in the presence of D2O, whereupon deuterium incorporation to the adjacent phenyl ring was observed ([Formula: see text] = 0.1–0.2). The competing formal ESPT and dehydration takes place with quantum yields that are an order of magnitude lower and was studied by isolation of photomethanolysis products. Derivative 8 did not undergo ESIPT to carbon atom. Owing to the presence of an intramolecular H bond, an efficient ESIPT from the phenol to the hydroxyl group coupled with dehydration gives a QM that efficiently undergoes electrocyclization (overall [Formula: see text] = 0.33), to give chroman 16. In addition, spiro[adamantane-2,9′-(4′-hydroxy)fluorene] (12) undergoes ESIPT, unlike the previously reported unreactive parent 2-hydroxyfluorene. The reactive singlet excited states of the prepared biphenyl and fluorene molecules were characterized by fluorescence spectroscopy, whereas laser flash photolysis (LFP) was performed to characterize the longer lived QM intermediates.
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Affiliation(s)
- Nikola Basarić
- Department of Organic Chemistry and Biochemistry, Ruđer Bošković Institute, Bijenička cesta 54, 10 000 Zagreb, Croatia
- Department of Chemistry, Box 3065, University of Victoria, Victoria, BC V8W 3V6, Canada
| | - Nikola Cindro
- Department of Organic Chemistry and Biochemistry, Ruđer Bošković Institute, Bijenička cesta 54, 10 000 Zagreb, Croatia
- Department of Chemistry, Box 3065, University of Victoria, Victoria, BC V8W 3V6, Canada
| | - Yunyan Hou
- Department of Organic Chemistry and Biochemistry, Ruđer Bošković Institute, Bijenička cesta 54, 10 000 Zagreb, Croatia
- Department of Chemistry, Box 3065, University of Victoria, Victoria, BC V8W 3V6, Canada
| | - Ivana Žabčić
- Department of Organic Chemistry and Biochemistry, Ruđer Bošković Institute, Bijenička cesta 54, 10 000 Zagreb, Croatia
- Department of Chemistry, Box 3065, University of Victoria, Victoria, BC V8W 3V6, Canada
| | - Kata Mlinarić-Majerski
- Department of Organic Chemistry and Biochemistry, Ruđer Bošković Institute, Bijenička cesta 54, 10 000 Zagreb, Croatia
- Department of Chemistry, Box 3065, University of Victoria, Victoria, BC V8W 3V6, Canada
| | - Peter Wan
- Department of Organic Chemistry and Biochemistry, Ruđer Bošković Institute, Bijenička cesta 54, 10 000 Zagreb, Croatia
- Department of Chemistry, Box 3065, University of Victoria, Victoria, BC V8W 3V6, Canada
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28
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Verga D, Nadai M, Doria F, Percivalle C, Di Antonio M, Palumbo M, Richter SN, Freccero M. Photogeneration and reactivity of naphthoquinone methides as purine selective DNA alkylating agents. J Am Chem Soc 2011; 132:14625-37. [PMID: 20863115 DOI: 10.1021/ja1063857] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A one-step protecting-group-free synthesis of both 6-hydroxy-naphthalene-2-carbaldehyde and the bifunctional binaphthalenyl derivative afforded 6-hydroxymethylnaphthalen-2-ol, 6-methylaminomethyl-naphthalen-2-ol, [(2-hydroxy-3-naphthyl)methyl]trimethyl ammonium iodide, and a small library of bifunctional binol analogues in good yields. Irradiation of naphthol quaternary ammonium salt and binol-derivatives (X = OH, NHR, NMe(3)(+), OCOCH(3), and L-proline) at 310 and 360 nm resulted in the photogeneration of the 2,6-naphthoquinone-6-methide (NQM) and binol quinone methide analogues (BQMs) by a water-mediated excited-state proton transfer (ESPT). The hydration, the mono- and bis-alkylation reactions of morpholine and 2-ethanethiol, as N and S prototype nucleophiles, by the transient NQM (λ(max) 310, 330 nm) and BQMs (λ(max) 360 nm) were investigated in water by product distribution analysis and laser flash photolysis (LFP). Both the photogeneration and the reactivity of NQM and BQMs exhibited striking differences. BQMs were at least 2 orders of magnitude more reactive than NQM, and they were generated much more efficiently from a greater variety of photoprecursors including the hydroxymethyl, quaternary ammonium salt and several binol-amino acids. On the contrary, the only efficient precursor of NQM was the quaternary ammonium salt. All water-soluble BQM precursors were further investigated for their ability to alkylate and cross-link plasmid DNA and oligonucleotides by gel electrophoresis: the BQMs were more efficient than the isomeric o-BQM (binol quinone methide analogue of 2,3-naphthoquinone-3-methide). Sequence analysis by gel electrophoresis, HPLC, and MS showed that the alkylation occurred at purines, with a preference for guanine. In particular, a BQM was able to alkylate N7 of guanines resulting in depurination at the oligonucleotide level, and ribose loss at the nucleotide level. The photoreactivity of BQM precursors translated into photocytotoxic and cytotoxic effects on two human cancer cell lines: in particular, one compound showed promising selectivity index on both cell lines.
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Affiliation(s)
- Daniela Verga
- Dipartimento di Chimica Organica, Università di Pavia, V. le Taramelli 10, 27100 Pavia, Italy
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