From Azides to Nitrogen‐Centered Radicals: Applications of Azide Radical Chemistry to Organic Synthesis

Minozzi, Matteo; Nanni, Daniele; Spagnolo, Piero

doi:10.1002/chem.200802710

Cited by 185 publications

(77 citation statements)

References 75 publications

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“…In literature, gamma irradiation of cysteine has been reported to generate hydrogen sulfide; [160][161][162][163] and H 2 S, as a reducing agent, can spontaneously reduce AZT to its amino counterpart, which was also confirmed experimentally. 80,82,164 Under the described condition, I did not find evidence of the interaction between alkyl thiyl radicals and alkyl azide. It is also worth to mention that reactions of γ-irradiation of 2-mercaptoethanol and AZT was studied.…”

Section: Gamma Irradiation Of Cysteine In the Presence Of Aztmentioning

confidence: 71%

“…79,80 However, azides have contributed greatly as substrates and/or intermediates to organic synthesis in such processes as cycloadditions, synthesis of aniline N-alkyl-substituted-anilines, and nitrenes. [80][81][82][83][84] In the last century, organic azides have also contributed to industrial uses as well as to medicine. For example, azides were employed in the synthesis of heterocycles such as triazoles and tetrazoles, and azidonucleosides for treatment of AIDS, as well as for use as detonators in explosive technology.…”

Section: Chemistry Of Alkyl Azidesmentioning

confidence: 99%

“…82,[87][88][89][90][91][92] Aliphatic, aromatic, and sulfonyl azides serve as good acceptors of carbon-and heteroatom-centered radicals. 82,92,93 Reported studies have suggested that homolytic addition to an azide can occur at either position N α or N χ of 48a, generating 3,3-triazenyl (51) or 1,3-triazenyl radical (52), respectively. 94,95 It is unclear at which position the addition would occur preferentially because the aminyl radicals can be formed from both triazenyl radicals by the release of dinitrogen.…”

Section: Reduction Of Alkyl Azides By Radicalsmentioning

confidence: 99%

“…As for sulfonyl azides, homolytic addition is more likely to take place at the terminal nitrogen N χ , generating the 1,3-trianenyl radical intermediate. 82 Under the radical conditions, the aminyl radicals are further reduced to amines. However, carbon radicals including alkyl, vinyl, aryl, and acyl radicals, can undergo intramolecular additions onto aliphatic and aromatic azides affording six-and/or five-membered cyclic aminyl radicals that can be further converted into various Nheterocycles.…”

Section: Reduction Of Alkyl Azides By Radicalsmentioning

confidence: 99%

“…However, carbon radicals including alkyl, vinyl, aryl, and acyl radicals, can undergo intramolecular additions onto aliphatic and aromatic azides affording six-and/or five-membered cyclic aminyl radicals that can be further converted into various Nheterocycles. 82,93,96 One of the very first evidence of the reaction between the carbon radical and an azide group was the intramolecular addition of 2'-azido-2-biphenylyl radical 53, onto an aromatic azide yielding the cyclic carbazolyl radical 54. However, despite such discovery, studies involving aryl radical cyclization with aryl azides have not gained much interest ( Figure 18).…”

Section: Reduction Of Alkyl Azides By Radicalsmentioning

confidence: 99%

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Biomimetic Modeling of the Nitrogen-centered Radical Postulated to occur during the Inhibition of Ribonucleotide Reductases by 2'-Azido-2'-deoxynucleotides.

Dang¹

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This dissertation, written by Thao P. Dang, and entitled Biomimetic Modeling of the Nitrogen-centered radical Postulated to occur during the Inhibition of Ribonucleotide Reductases by 2'-Azido-2'-deoxynucleotides, having been approved in respect to style and intellectual content, is referred to you for judgment.We have read this dissertation and recommend that it be approved. _______________________________________

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Section: Gamma Irradiation Of Cysteine In the Presence Of Aztmentioning

confidence: 71%

Section: Chemistry Of Alkyl Azidesmentioning

confidence: 99%

Section: Reduction Of Alkyl Azides By Radicalsmentioning

confidence: 99%

Section: Reduction Of Alkyl Azides By Radicalsmentioning

confidence: 99%

Section: Reduction Of Alkyl Azides By Radicalsmentioning

confidence: 99%

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Biomimetic Modeling of the Nitrogen-centered Radical Postulated to occur during the Inhibition of Ribonucleotide Reductases by 2'-Azido-2'-deoxynucleotides.

Dang¹

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Cyclization Reactions of Nitrogen‐Centered Radicals

McCombie¹,

Quiclet‐Sire²,

Zard³

2021

Organic Reactions

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The cyclization of nitrogen‐centered radicals constitutes a powerful approach for the synthesis of a broad variety of nitrogen heterocycles. As with carbon‐centered radicals, the most common ring‐closure mode is the 5‐ exo cyclization onto an internal unsaturation, and the stereoselectivity is similar. Numerous methods for the generation of almost every type of nitrogen‐centered radical have been described. They involve the direct or indirect rupture of N–Y bonds, with Y = halogen (except fluorine), oxygen, nitrogen, sulfur, and hydrogen. Indirect methods, such as the addition of carbon radicals to imines, azides, and nitriles, have also been devised. The extended choice of methods and precursors, and the general mildness of the experimental conditions and tolerance for numerous functional groups, represent valuable synthetic advantages. Furthermore, the cyclization step can be part of a radical cascade leading to multiple bond formations and the rapid construction of complex molecular frameworks. This chapter describes the types, structures, and reactivity of nitrogen‐centered radicals, and details the mechanistic basis of the methods used to generate them. The methods include stannane‐based processes, oxidations and reductions by single‐electron transfer, thermolysis, electrolysis, photolysis, and photoredox catalysis. The factors that influence the stereoselectivity of the ring‐closures are discussed briefly. Applications to the total synthesis of natural products, as well as functional‐group compatibilities, reaction variants, and comparison to other methods for the synthesis of nitrogen heterocycles by ionic, organometallic, and uncatalyzed ring‐closures onto alkenes are also presented. The tabular surveys are organized according to the type of nitrogen‐centered radical involved in the cyclization step: aminyls, amidyls, carbamyls, iminyls, amidinyls, and other types of nitrogen‐centered radicals.

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Radical Chemistry with Azides

Jimeno

Renaud

2009

Organic Azides

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Organic azides represent a very interesting class of compounds since they are precursor of a wide range of nitrogen containing organic molecules. 1 Moreover, they possess a unique reactivity pattern orthogonal to many other organic functional groups. This assessment is also true in the fi eld of radical chemistry. For instance, azides can be considered as protected amino groups that are perfectly tolerated in C -C bond forming reactions. This is illustrated by the synthesis of ( − ) -batzelladine D recently disclosed by P.A. Evans. 2 In this synthesis, a pyrrolo[1,2f]pyrimidine is built via a 5exo trig radical cyclization. The two azido substituents present in the molecule are not reduced under the reaction conditions used to run the cyclization (tributyltin hydride and triethylborane in the presence of air at room temperature) (Scheme 8.1 ).The stability of azides in radical reactions is further illustrated by the radical fragmentation of carbohydrate anomeric alkoxyl radicals bearing an azido substituent at position 3 reported by Suarez (Scheme 8.2 ). 3,4 After fragmentation, the 2 -azido -substituted radical is iodinated and no β -fragmentation of the azide is observed.However, under suitable conditions, azides react with a variety of radicals and this is the basis of several useful synthetic procedures for the formation of carbon -nitrogen bonds. For instance, synthesis of azides by radical addition of an azidyl radical to alkenes (Scheme 8.3 a) and by reaction of an alkyl radical with an azidating reagent (Scheme 8.3 b) will be presented. The reduction of azides leading to aminyl radicals (Scheme 8.3 c) and the addition of alkyl radicals to alkyl azides (Scheme 8.3 d) will also be discussed.

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From Azides to Nitrogen‐Centered Radicals: Applications of Azide Radical Chemistry to Organic Synthesis

Cited by 185 publications

References 75 publications

Biomimetic Modeling of the Nitrogen-centered Radical Postulated to occur during the Inhibition of Ribonucleotide Reductases by 2'-Azido-2'-deoxynucleotides.

Biomimetic Modeling of the Nitrogen-centered Radical Postulated to occur during the Inhibition of Ribonucleotide Reductases by 2'-Azido-2'-deoxynucleotides.

Cyclization Reactions of Nitrogen‐Centered Radicals

Radical Chemistry with Azides

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