Visible light-promoted reductive transformations of various organic substances by using hydroxyaryl-substituted benzimidazolines and bases

Hasegawa, Eietsu; Izumiya, Norihiro; Fukuda, Takuya; Nemoto, Keiichi; Iwamoto, Hajime; Takizawa, Shin‐ya; Murata, Shigeru

doi:10.1016/j.tet.2016.05.078

Cited by 23 publications

(8 citation statements)

References 124 publications

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“…In this context, we developed a desulfonylation reaction of N -sulfonylindoles, which utilizes substituted pyrenes as organic photocatalysts and Ar-BIHs as reductants . In recent investigations, we designed Ar-BIH analogues, which contain arene or hydroxyarene chromophores connected to the BIH framework to extend their light absorption profile into the visible light region . Thus, investigations of PET promoted desulfonylation reactions of N -tosylbenzamides independently conducted by Yu and Xiao (Figure ) particularly motivated us to apply the protocol utilizing a visible light absorbing HOAr-BIH to the desulfonyltaion reactions of their substrates and others.…”

Section: Introductionmentioning

confidence: 99%

Visible Light and Hydroxynaphthylbenzimidazoline Promoted Transition-Metal-Catalyst-Free Desulfonylation of N-Sulfonylamides and N-Sulfonylamines

et al. 2018

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A visible light promoted process for desulfonylation of N-sulfonylamides and -amines has been developed, in which 1,3-dimethyl-2-hydroxynaphthylbenzimidazoline (HONap-BIH) serves as a light absorbing, electron and hydrogen atom donor, and a household white light-emitting diode serves as a light source. The process transforms various N-sulfonylamide and -amine substrates to desulfonylated products in moderate to excellent yields. The observation that the fluorescence of 1-methyl-2-naphthoxy anion is efficiently quenched by the substrates suggests that the mechanism for the photoinduced desulfonylation reaction begins with photoexcitation of the naphthoxide chromophore in HONap-BIH, which generates an excited species via intramolecular proton transfer between the HONap and BIH moieties. This process triggers single electron transfer to the substrate, which promotes loss of the sulfonyl group to form the free amide or amine. The results of studies employing radical probe substrates as well as DFT calculations suggest that selective nitrogen-sulfur bond cleavage of the substrate radical anion generates either a pair of an amide or amine anion and a sulfonyl radical or that of an amidyl or aminyl radical and sulfinate anion, depending on the nature of the N-substituent on the substrate. An intermolecular version of this protocol, in which 1-methyl-2-naphthol and 1,3-dimethyl-2-phenylbenzimidazoline are used concomitantly, was also examined.

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Section: Introductionmentioning

confidence: 99%

Visible Light and Hydroxynaphthylbenzimidazoline Promoted Transition-Metal-Catalyst-Free Desulfonylation of N-Sulfonylamides and N-Sulfonylamines

et al. 2018

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“…In recent years, Pd, Ir, Cu, Pt complex, and Ni supported on carbon nitride have been used to undergo reductions of aryl halides under visible light irradiation. Particularly, dehalogenation and aryl radical generation could also be achieved using many visible light organic photoreductants − or photocatalyts. − To further explore our visible-light-promoted method, reduction reaction of aryl or heteroaryl halides in the presence of HE anion was studied. As shown in Table , aryl chloride, bromide, and iodide derivatives are dehalogenated (entries 1–10) in good to excellent yields under visible light irradiation using HE anion as electron and hydrogen atom donor.…”

Section: Resultsmentioning

confidence: 99%

Transition-Metal-Free and Visible-Light-Mediated Desulfonylation and Dehalogenation Reactions: Hantzsch Ester Anion as Electron and Hydrogen Atom Donor

et al. 2020

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Novel approaches for N-and O-desulfonylation under room temperature (rt) and transition-metal-free conditions have been developed. The first methodology involves the transformation of a variety of N-sulfonyl heterocycles and phenyl benzenesulfonates to the corresponding desulfonylated products in good to excellent yields using only KO t Bu in dimethyl sulfoxide (DMSO) at rt. Alternately, a visible light method has been used for deprotection of N-methyl-N-arylsulfonamides with Hantzsch ester (HE) anion serving as the visible-light-absorbing reagent and electron and hydrogen atom donor to promote the desulfonylation reaction. The HE anion can be easily prepared in situ by reaction of the corresponding HE with KO t Bu in DMSO at rt. Both protocols were further explored in terms of synthetic scope as well as mechanistic aspects to rationalize key features of desulfonylation processes. Furthermore, the HE anion induces reductive dehalogenation reaction of aryl halides under visible light irradiation.

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“…The two-pot route is widely used for various synthesis of epoxy chalcone derivatives namely naphthofurans [73], 2-arylbenzo-furan [25], hydroxy ketone [74][75][76], hydrazinopyrimidine [77], pyridazine esters [24], azaisoflavones [78], bis-hydrazinecarboximidamide [79], difluoroboron ketoiminate […”

Section: Two-pot Routementioning

confidence: 99%

One Pot and Two Pot Synthetic Strategies and Biological Applications of Epoxy-Chalcones

Farooq

Ngaini

2020

Chemistry Africa

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Epoxy chalcone is a heterocyclic molecule and an important precursor for the synthesis of biologically active compounds. This mini-review is elucidating the synthetic strategies of chalcone epoxide via one pot and two pot routes including nature of reactants, nature of catalyst and variety of catalyst to improve yield of desired product, biological applications and advantages and drawbacks of these synthetic strategies. One pot route has wide variety of reactants and efficient one is the condensation of aldehyde and ketone. However, two pot route is consisted of chalcone synthesis preceding to epoxy chalcone. The synthetic routes for the preparation of epoxy chalcone and the usage as a precursor for the synthesis of various organic molecules with biological application is comprehensively discussed. This review is outstanding in organic chemistry and pharmaceutical industries to produce new molecules with various applications. Graphic AbstractO O

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Visible light-promoted reductive transformations of various organic substances by using hydroxyaryl-substituted benzimidazolines and bases

Cited by 23 publications

References 124 publications

Visible Light and Hydroxynaphthylbenzimidazoline Promoted Transition-Metal-Catalyst-Free Desulfonylation of N-Sulfonylamides and N-Sulfonylamines

Visible Light and Hydroxynaphthylbenzimidazoline Promoted Transition-Metal-Catalyst-Free Desulfonylation of N-Sulfonylamides and N-Sulfonylamines

Transition-Metal-Free and Visible-Light-Mediated Desulfonylation and Dehalogenation Reactions: Hantzsch Ester Anion as Electron and Hydrogen Atom Donor

One Pot and Two Pot Synthetic Strategies and Biological Applications of Epoxy-Chalcones

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