Atmosphere-controlled Dual Reactivity of Triarylphosphine in the Photoexcited State: P–C Bond Cleavage vs. Electron Transfer

<div><p>Here we report a catalytic, light-driven method for the redox-neutral depolymerization of native lignin biomass at ambient temperature. This transformation proceeds via a proton-coupled electron-transfer (PCET) activation of an alcohol O–H bond to generate a key alkoxy radical intermediate, which then drives the <i>β</i>-scission of a vicinal C–C bond. Notably, this depolymerization is driven solely by visible light irradiation, requiring no stoichiometric chemical reagents and producing no stoichiometric waste. This method exhibits good efficiency and excellent selectivity for the activation and fragmentation of <i>β</i>-O-4 linkages in the polymer backbone, even in the presence of numerous other PCET-active functional groups. DFT analysis suggests that the key C–C bond cleavage reactions produce non-equilibrium product distributions, driven by excited-state redox events. These results provide further evidence that visible-light photocatalysis can serve as a viable method for the direct conversion of lignin biomass into valuable arene feedstocks.</p></div>

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Orientation selective bond cleavage reactions of biphenyl-fused 1,2-diphenylcyclobutanes initiated by electron transfer

Tetrahedron Letters ◽

10.1016/s0040-4039(00)89195-9 ◽

1985 ◽

Vol 26 (30) ◽

pp. 3579-3582 ◽

Cited By ~ 5

Author(s):

Yoshiro Yamashita ◽

Hisao Yaegashi ◽

Toshio Mukai

Keyword(s):

Electron Transfer ◽

Bond Cleavage ◽

Cleavage Reactions

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Selective C-N σ Bond Cleavage in Azetidinyl Amides under Transition Metal-Free Conditions

Molecules ◽

10.3390/molecules24030459 ◽

2019 ◽

Vol 24 (3) ◽

pp. 459 ◽

Cited By ~ 3

Author(s):

Hengzhao Li ◽

Zemin Lai ◽

Adila Adijiang ◽

Hongye Zhao ◽

Jie An

Keyword(s):

Electron Transfer ◽

Transition Metal ◽

Transfer Reaction ◽

Bond Cleavage ◽

Electron Transfer Reaction ◽

Amide Bond ◽

Single Electron Transfer ◽

Reaction Conditions ◽

Metal Free ◽

Single Electron Transfer Reaction

Functionalization of amide bond via the cleavage of a non-carbonyl, C-N σ bond remains under-investigated. In this work, a transition-metal-free single-electron transfer reaction has been developed for the C-N σ bond cleavage of N-acylazetidines using the electride derived from sodium dispersions and 15-crown-5. Of note, less strained cyclic amides and acyclic amides are stable under the reaction conditions, which features the excellent chemoselectivity of the reaction. This method is amenable to a range of unhindered and sterically encumbered azetidinyl amides.

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Photoinduced electron-transfer chemistry of the bielectrophoric N-phthaloyl derivatives of the amino acids tyrosine, histidine and tryptophan

Beilstein Journal of Organic Chemistry ◽

10.3762/bjoc.7.60 ◽

2011 ◽

Vol 7 ◽

pp. 518-524 ◽

Cited By ~ 21

Author(s):

Axel G Griesbeck ◽

Jörg Neudörfl ◽

Alan de Kiff

Keyword(s):

Amino Acids ◽

Electron Transfer ◽

Photoinduced Electron Transfer ◽

Bond Cleavage ◽

Derivatives Of

The photochemistry of phthalimide derivatives of the electron-rich amino acids tyrosine, histidine and tryptophan 8–10 was studied with respect to photoinduced electron-transfer (PET) induced decarboxylation and Norrish II bond cleavage. Whereas exclusive photodecarboxylation of the tyrosine substrate 8 was observed, the histidine compound 9 resulted in a mixture of histamine and preferential Norrish cleavage. The tryptophan derivative 10 is photochemically inert and shows preferential decarboxylation only when induced by intermolecular PET.

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