Applications of triphenylpyrylium salt-sensitized electron-transfer photo-oxygenation reactions to the synthesis of benzo-fused 1,4-diaryl-2,3-dioxabicyclo[2.2.2]octanes as new antimalarial cyclic peroxides

Kamata, Masaki; Hagiwara, Jun; Hokari, Tomoko; Suzuki, Chiharu; Fujino, Ryohta; Kobayashi, Sayaka; Kim, Hye Sook; Wataya, Yusuke

doi:10.1007/s11164-012-0637-3

Cited by 8 publications

(2 citation statements)

References 46 publications

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“…Indeed, during the course of this work, the Yoon research group disclosed a similar strategy employing Ru(bpz) 3 2+ as the photooxidant to effect a 5- exo cyclization/endoperoxidation cascade of bis(styrene) substrates ( Scheme 1 , reaction 2) [ 15 ]. More recently, Kamata and Kim have employed this reaction manifold to forge endoperoxides from 1,2-divinylarene precursors [ 16 ].…”

Section: Introductionmentioning

confidence: 99%

Cyclization–endoperoxidation cascade reactions of dienes mediated by a pyrylium photoredox catalyst

Gesmundo¹,

Nicewicz²

2014

Beilstein J. Org. Chem.

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SummaryTriarylpyrylium salts were employed as single electron photooxidants to catalyze a cyclization–endoperoxidation cascade of dienes. The transformation is presumed to proceed via the intermediacy of diene cation radicals. The nature of the diene component was investigated in this context to determine the structural requirements necessary for successful reactivity. Several unique endoperoxide structures were synthesized in yields up to 79%.

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Section: Introductionmentioning

confidence: 99%

Cyclization–endoperoxidation cascade reactions of dienes mediated by a pyrylium photoredox catalyst

Gesmundo¹,

Nicewicz²

2014

Beilstein J. Org. Chem.

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“…Pyrylium salts are a type of six-membered cationic heterocycles with one positively charged oxygen atom. Compounds with pyrylium salts exhibit excellent absorption, fluorescence, and electron transfer properties, and thus have been widely applied as light emitters 1 , photocatalysts 2 , and sensitizers [3][4][5][6] . The first pyrylium salt with perchlorate as the counterion was reported in 1911 by Baeyer 7 , however, since the discovery of pyrylium salts, such salts have been underappreciated for about a half century.…”

Section: Introductionmentioning

confidence: 99%

Over one century after discovery: pyrylium salt chemistry emerging as a powerful approach for the construction of complex macrocycles and metallo-supramolecules

Wang

2020

Chem. Sci.

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Electron‐Transfer Reactions Triggered by Uncharged or Cationic Photosensitizer: Methodology for Generation of o‐Quinodimethane and Analysis of Back Electron‐Transfer Process

et al. 2017

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Photoinduced electron transfer (PET) followed by back electron transfer (BET) reactions of 1,2-bis(a-styryl)benzenes 1,g enerates o-quinodimethane derivative 2 via the corresponding radical cation 2 · + .T his process serves as af acile methodt of orm o-quinodimethane intermediates. The intermediacy of 2 · + and 2 werec onfirmed by using various spectroscopicm ethods and trapping reactions with 3 O 2 and dienophiles. Kinetic analysisu sing nanosecond time-re-solved absorption showed that 2 · + was transformed to 2 via aB ET process, in which the decay of 2 · + and rise of 2 have almostt he same rate constants of k DECAY = 5.6 10 5 s À1 and k RISE = 5.9 10 5 s À1 ,r espectively.T he net BET rate constant evaluated by using Marcus theory is much faster than these experimental values, owing to the reduction based on diffusion.[a] Prof.form (M · + + +A · )a nd thes econdE Ti n( D + +M · + )f orms (D · + + +M). Ther esulting long distance betweenD · + andA · effectivelyp reventsf ormationo f[ D · + //A · ], thereforet he lifetime of D · + is substantially extended.I nt erms of analyzingt he BETp rocess, the most importanti nt hise fforti sB ET between( D · + + +A · ), whichi s formed in theP ET reactionss hown in Scheme 1b and1 c. As showni nS cheme1d, ther atec onstant (k BET )i sd efined fort he BETreactioni nt he encounterc omplex [D · + //A · ] EC that relatest o theassociation anddissociationof(D · + + A · ).Uncharged organic sensitizers, such as 9,10-dicyanoanthracene (DCA, Figure 1) and 1,4-dicyanonaphthalene (DCN), are conventional. Typical cationic sensitizers such as N-methylquinoliniumt etrafluoroborate (NMQ + BF 4 À ), [6] 2,4,6-triphenylpyrylium tetrafluoroborate( TPP + BF 4 À ), and N-methyl-9-mesitylacridinium perchlorate (Mes-Acr + ClO 4 À ,F ukuzumip hotocatalyst 7 ) can promote reactions of free D · + .R ecently,o rganometallic complexes,s uch as Ru(bpy) 3 2 + (Cl À ) 2 and fac-Ir(ppy) 3 ,h ave also been used in organic synthesis. [8] Upon excitation by visible light, these complexes undergo intersystem crossing to form long-lived triplet excited states.T he long lifetime induces ah igh possibility of collision with D, while the triplet state at alow energy level results in relatively low oxidation ability. g-Irradiationi naspecific solvent can also induce ET without any sensitizer and is often used forspectroscopic measurements.Kinetic analysiss uch as Stern-Volmer analysis is ap owerful tool to examine the synthetics tudy on aP ET reaction. When using an on-fluorescents ensitizer,l aser flash photolysis (LFP) provides informationa bout the formation and decay of D · + (Figure 2a). However, information on the recovery of Db yB ET,

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Applications of triphenylpyrylium salt-sensitized electron-transfer photo-oxygenation reactions to the synthesis of benzo-fused 1,4-diaryl-2,3-dioxabicyclo[2.2.2]octanes as new antimalarial cyclic peroxides

Cited by 8 publications

References 46 publications

Cyclization–endoperoxidation cascade reactions of dienes mediated by a pyrylium photoredox catalyst

Cyclization–endoperoxidation cascade reactions of dienes mediated by a pyrylium photoredox catalyst

Over one century after discovery: pyrylium salt chemistry emerging as a powerful approach for the construction of complex macrocycles and metallo-supramolecules

Electron‐Transfer Reactions Triggered by Uncharged or Cationic Photosensitizer: Methodology for Generation of o‐Quinodimethane and Analysis of Back Electron‐Transfer Process

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