Synthesis of nitrogen heterocycles <i>via</i> α-aminoalkyl radicals generated from α-silyl secondary amines under visible light irradiation

Nakajima, Kazunari; Kitagawa, Masatoshi; Ashida, Yuzuru; Miyake, Yoshihiro; Nishibayashi, Yoshiaki

doi:10.1039/c4cc03000a

Cited by 66 publications

(21 citation statements)

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“…A number of other Ag N -DNA studies have employed DNA oligomers with partial or complete WC pairing in the native DNA [ 10 , 21 , 36 , 44 , 45 ]. However, depending on the relative stabilities of WC pairing and silver-mediated interactions between the bases, the native base pairing may be disrupted by the introduction of silver cations and subsequent reduction.…”

Section: Resultsmentioning

confidence: 99%

“…A fascinating aspect of Ag N -DNA is the equilibrium between fluorescent and dark cluster forms with the same total silver content, N, that has been established for certain choices of DNA template [ 41 , 62 ]. This equilibrium can be manipulated by varying solution conditions, with potential for exploitation in diverse sensing applications, and may be the mechanistic underpinning for changes in fluorescence reported in some of the previously developed sensing schemes [ 10 ].…”

Section: Resultsmentioning

confidence: 99%

“…Such DNA-stabilized Ag clusters (Ag N -DNA), first reported by Petty [ 1 ], are now emerging in applications that range from biological imaging [ 2 ], to molecular logic schemes [ 3 ] and strand-exchange on-off switches [ 4 ], to sensors for single base mutations [ 5 , 6 , 7 ], microRNAs [ 8 ], and DNA target strands [ 9 ]. These applications, recently reviewed in [ 10 ], all rely on the special sensitivity of fluorescence color and intensity to the specific nucleic acid environment of the silver cluster. Here we will focus on what our group has learned about the underlying composition and structure of pure Ag N -DNA that lead to these fascinating properties ( Figure 1 a,b) and the prospects for realizing metal cluster nanophotonics on DNA scaffolds that self-assemble by Watson-Crick pairing of synthetic DNA strands, such as DNA origami [ 11 ], tile-based assemblies [ 12 ], and nanoscale three-dimensional shapes [ 13 ].…”

Section: Introductionmentioning

confidence: 99%

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DNA-Protected Silver Clusters for Nanophotonics

et al. 2015

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DNA-protected silver clusters (AgN-DNA) possess unique fluorescence properties that depend on the specific DNA template that stabilizes the cluster. They exhibit peak emission wavelengths that range across the visible and near-IR spectrum. This wide color palette, combined with low toxicity, high fluorescence quantum yields of some clusters, low synthesis costs, small cluster sizes and compatibility with DNA are enabling many applications that employ AgN-DNA. Here we review what is known about the underlying composition and structure of AgN-DNA, and how these relate to the optical properties of these fascinating, hybrid biomolecule-metal cluster nanomaterials. We place AgN-DNA in the general context of ligand-stabilized metal clusters and compare their properties to those of other noble metal clusters stabilized by small molecule ligands. The methods used to isolate pure AgN-DNA for analysis of composition and for studies of solution and single-emitter optical properties are discussed. We give a brief overview of structurally sensitive chiroptical studies, both theoretical and experimental, and review experiments on bringing silver clusters of distinct size and color into nanoscale DNA assemblies. Progress towards using DNA scaffolds to assemble multi-cluster arrays is also reviewed.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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DNA-Protected Silver Clusters for Nanophotonics

et al. 2015

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“… 22 They also studied in the same way the production of aminomethyl radicals from the corresponding trifluoroborates 23 in order to offer an attractive alternative to the previously known methods to form aminoalkyl radicals via photoredox processes. 24 As indicated in Scheme 6 , a wide range of α-heteroatom methylations of electron-deficient alkenes could be quite successfully accomplished under the conditions previously reported for the photoredox C–C bond formations. They are in agreement with the postulated redox-neutral mechanism presented in Scheme 4 .…”

Section: Visible-light-mediated Photogeneration Of Carbon-centred Radmentioning

confidence: 91%

Boron chemistry in a new light

et al. 2015

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“…Miyake and Nishibayashi utilized α-aminoalkyl radicals to effect an intermolecular cyclization to generate pyrrolidinones or pyrroles. 10 Beginning with an α-silyl secondary amine, a benzylidenemalonate, and a catalytic amount of an Ir(I) photocatalyst, irradiation with 14 W white light generated the α-aminoalkyl radical which coupled with the reactive malonate. Subsequent treatment with t-BuOK gave the pyrrolidinone (Scheme 12).…”

Section: Figure 2 Acridinium Catalystmentioning

confidence: 99%

Photochemical Synthesis of Azaheterocycles

Tanoury

2016

Synthesis

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Synthetic organic photochemistry is a field that continues to offer unique routes to organic structures not typically accessed from thermal reactions. In this review, the photochemical synthesis of five-, six-, seven-, and eight-membered-ring azaheterocycles, as well as some aza-macrocycles, is discussed. The discussion will focus on methods where heterocycle formation occurs during or as a result of a photochemical event. Reaction mechanisms will be discussed also, as these provide a rationale for understanding the synthetic results. 1 Introduction 2 Five-Membered Rings 2.1 Cyclization Reactions 2.2 Cycloadditions 2.3 From Aromatic and Vinyl Azides 2.4 earrangements 2.5 Other Individual Methods 3 Six-Membered Rings 3.1 Cyclization Reactions 3.2 Isocyanide Insertions 3.3 Cycloadditions 4 Seven-Membered Rings and Larger 5 Conclusion Key words azaheterocycles, photocycloaddition, photocyclization, photorearrangement, photocatalyst Dr. Tanoury began his career in the pharmaceutical industry in 1992 as a Medicinal Chemist at the Burroughs-Wellcome Company in North Carolina. In 1996, he moved to Sepracor, Inc. in Massachusetts to start a career as a process development chemist. He moved to Vertex Pharmaceuticals in 2001 where he is currently a Senior Scientific Fellow in the Process Chemistry Department. Prior to starting his industrial career, Dr. Tanoury was a graduate student under the direction of Professor Barry M. Trost, earning his Ph.D. from Stanford University in 1989. This was followed by a National Institutes of Health postdoctoral fellowship at Harvard University from 1989-1992 in the labs of Professor E. J. Corey. In addition to synthetic organic chemistry and developing chemical processes for the manufacture of API, Dr. Tanoury's interests include understanding and probing chemical reactions using state-ofthe-art technology, and studying reaction mechanisms and chemical properties (ground and excited state) using theoretical/computational methods.

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Synthesis of nitrogen heterocycles via α-aminoalkyl radicals generated from α-silyl secondary amines under visible light irradiation

Abstract: We have succeeded in the visible light-mediated synthetic use of α-aminoalkyl radicals derived from α-silyl secondary amines toward addition to α,β-unsaturated carbonyl compounds. The resulting γ-aminocarbonyl compounds are converted into γ-lactams and pyrroles in a one-pot process.

Cited by 66 publications

References 39 publications

DNA-Protected Silver Clusters for Nanophotonics

DNA-Protected Silver Clusters for Nanophotonics

Boron chemistry in a new light

Photochemical Synthesis of Azaheterocycles

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