Synthetic methods : Part (i) Free-radical reactions

Rowlands, Gareth J.

doi:10.1039/b614415m

Cited by 11 publications

(4 citation statements)

References 51 publications

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“…In 2006, Narasaka and co-workers developed a AgNO 3 -catalyzed addition of β-keto radicals into silyl enol ethers ( 352 ), allowing for the formation of 1,5-diketones ( 353 ) in good yields (Scheme ). , They found that disubstituted silyl enol ethers were effective in this chemistry; however, trisubstituted silyl enol ethers proved to be less effective, as they were sluggish to react with the β-keto radical. In this case, the product corresponding to β-keto radical addition into pyridine ( 356 ) was observed, showing that Minisci-type chemistry is viable under these conditions.…”

Section: C–c Bond Cleavage To Generate β-Keto Radicalsmentioning

confidence: 99%

Selective Carbon–Carbon Bond Cleavage of Cyclopropanols

et al. 2020

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The carbon–carbon (C–C) bond cleavage of cyclopropanols is a wide area of research with much current activity. This review highlights new developments in this area over the past two decades. A summary is made of the three main reactivity modes, namely, homoenolate chemistry, β-keto radical chemistry, and acid-catalyzed ring-opening, as well as all other methods for the C–C bond cleavage and functionalization of cyclopropanols, including base-mediated ring-opening, metal-catalyzed C–C insertions and eliminations, oxidative fragmentation using hypervalent iodine reagents, reactions of donor–acceptor cyclopropanols, and pericylic reactions. Emphasis is placed on the synthetic utility of cyclopropanols and related derivatives, which have emerged as unique three-carbon synthons.

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Section: C–c Bond Cleavage To Generate β-Keto Radicalsmentioning

confidence: 99%

Selective Carbon–Carbon Bond Cleavage of Cyclopropanols

et al. 2020

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“…A key consideration in the development and application of many radical reactions concerns the nature of the hydrogen atom donor that is employed for trapping carbon-based radicals . Very recently there have been efforts to replace the traditional stoichiometric organotin reagents with transition-metal hydrides. − In principal, transition-metal hydrides can be generated in situ from H 2 and a metal complex, thereby permitting the use of hydrogen gas as the ultimate atom-economical hydrogen atom donor.…”

mentioning

confidence: 99%

Transition-Metal Hydrides as Hydrogen Atom Donors: Stronger Metal−Hydrogen Bonds Can Be Advantageous

O’Connor

Friese

2008

Organometallics

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The tungsten hydride complex (η5-C5H5)W(CO)3H (1-W) functions as a hydrogen atom donor in the [(η5-C5Me5)Ru(NCMe)3]PF6-mediated Bergman cycloaromatization reaction of (Z)-dodeca-4,8-diyn-6-ene. The strong M−H bond in 1-W does not react with the enediyne substrate but does react with the diradical arising from cyclization, thereby demonstrating the advantages of strong metal−hydrogen bonds in the hydrogen atom transfer reactions of metal hydrides with substrates involving alkenes and alkynes.

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“…In last year's review the use of tris(trimethylsilyl)methane was highlighted as a promising new radical reducing reagent; it appears that this statement was premature. 3,27 Re-investigation has now shown it to be an ineffectual reagent and it is presumed that a contaminant facilitated the previous reactions. 28 Sulfur compounds have long been known to be useful alternatives especially for the generation of alkenyl radicals, and this year has seen their use in the synthesis of a number of heterocycles.…”

Section: Alternatives To Tributyltin Hydridementioning

confidence: 99%

“…8 Additionally, Miyabe's and Takemoto's studies on enantioselective radical cyclisations have been summarised in an informative 'concepts' article, 9 as well as being discussed in last year's Annual Report. 3 The highlights this year include new methodology for direct C-C bond formation without pre-functionalisation of substrates, 10-13 the use of enaminebased enantioselective catalysis in radical reactions by Sibi 14 and MacMillan 15 and the application of a radical cyclisation in a key step in the synthesis of azadirachtin. 16…”

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confidence: 99%

Synthetic methods : Part (i) Free-radical reactions

Rowlands

2008

Annu. Rep. Prog. Chem., Sect. B: Org. Chem.

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This year has seen significant developments in the use of radicals in crosscoupling chemistry; a variety of direct C-H activation strategies have been reported that permit the synthesis of highly functionalised indoles, pyrroles, and dicarbonyl compounds from simple precursors. In addition, transition metal-catalysed radical couplings are gaining increasing acceptance. The combination of radical chemistry with enamine catalysis has opened an exciting new chapter in catalytic enantioselective radical reactions. HighlightsThis report is intended to give a brief pre´cis of recent advances in free-radical reactions in organic synthesis. The author has emphasised reactions that are of interest to the practising synthetic chemist. The article is organised in keeping with previous reviews by the author. 1-3 A number of insightful reviews have been published this year, including overviews of stereoselective additions to CQN bonds, 4 the formation of five-and six-membered heterocycles, 5 nitrogen-directed radical rearrangements, 6 aromatic homolytic substitution 7 and the functionalisation of organic compounds catalysed by N-hydroxyphthalimide. 8 Additionally, Miyabe's and Takemoto's studies on enantioselective radical cyclisations have been summarised in an informative 'concepts' article, 9 as well as being discussed in last year's Annual Report. 3 The highlights this year include new methodology for direct C-C bond formation without pre-functionalisation of substrates, 10-13 the use of enaminebased enantioselective catalysis in radical reactions by Sibi 14 and MacMillan 15 and the application of a radical cyclisation in a key step in the synthesis of azadirachtin. 16

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Synthetic methods : Part (i) Free-radical reactions

Cited by 11 publications

References 51 publications

Selective Carbon–Carbon Bond Cleavage of Cyclopropanols

Selective Carbon–Carbon Bond Cleavage of Cyclopropanols

Transition-Metal Hydrides as Hydrogen Atom Donors: Stronger Metal−Hydrogen Bonds Can Be Advantageous

Synthetic methods : Part (i) Free-radical reactions

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