Unusual radical addition on a heteroaromatic nitrogen. A convenient access to new pyrimidine derivatives

Laot, Yann; Petit, Laurent; Zard, Samir Z.

doi:10.1039/c0cc00533a

Cited by 21 publications

(14 citation statements)

References 12 publications

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“…Zard and co-workers extendedt his unusualr adical addition system for convenienta ccess to pyrimidinone derivatives in 2010. [51] This time, 2-N-alkylamino-4,6-dichloropyrimidine was employed as the substrate to cross-couple with different kinds of xanthates to achieve intermolecular cyclization. Interestingly, the Ac group on the amino nitrogen atom played ak ey role in accessing pyrimidinones.…”

Section: Alkyl Radical Additionmentioning

confidence: 99%

Carbon‐Centered Radical Addition to C=X Bonds for C−X Bond Formation

Liu

Lei

2015

Chemistry An Asian Journal

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Among various kinds of radical reactions, the addition of carbon-centered radicals to unsaturated bonds represents a powerful tool for the construction of different C-C and C-X (X = N, O, S, etc.) bonds, in which typically applied unsaturated bonds include alkenes, alkynes, imines, carbonyls, and even thiocarbonyls. When C=X bonds are utilized as the radical acceptors, reactions usually occur at the carbon position to generate a heteroatom radical, during which C-C coupling products are formed. This reaction mode has dominated this field for several decades. However, there is also another unconventional type of radical addition mode, in which carbon-centered radicals attack the heteroatom position of C=X bonds to generate carbon radicals, during which selective C-X bond formation is achieved. This reaction mode demonstrates an effective method for the construction of different C-X bonds, such as C-O, C-N, and C-S bonds. This Focus Review gives an overview of recent advances in this unconventional field.

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Section: Alkyl Radical Additionmentioning

confidence: 99%

Carbon‐Centered Radical Addition to C=X Bonds for C−X Bond Formation

Liu

Lei

2015

Chemistry An Asian Journal

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“…A similar difference in reactivity was observed in the pyrimidine series, even though the product composition was slightly more complex (Scheme 21). [69] Thus, an N-acetyl group in xanthate 82a resulted in the formation of diazaindoline 83a in 54% yield, whereas an N-Boc group in xanthate 82b gave rise to pyrimidone 85 as the major product (43%) along with small amount of isomeric pyrimidinone 84 (9%) and diazaindoline 83b (14%). Both pyrimidinones 84 and 85 derive from a radical attack on the ring nitrogen and differ only in the regiochemistry of the last hydrolysis step (cf.…”

Section: The Carbamate Puzzlementioning

confidence: 99%

Some intriguing mechanistic aspects of the radical chemistry of xanthates

Zard

2012

J of Physical Organic Chem

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International audienceXanthates are exceedingly useful substrates for intermolecular and intramolecular radical additions, even to unactivated alkenes. Various functional groups can be brought together under mild, neutral conditions, thus providing tremendous opportunities for organic synthesis. Because the products of the additiontransfer process are also xanthates, iteration allows the formation of block polymers by a controlled radical polymerisation (the RAFT/MADIX technology). The present overview concentrates on mechanistic and unexpected aspects of this chemistry, which may be of particular interest to physical organic chemists. Copyright (C) 2012 John Wiley & Sons, Ltd

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“…The presenceo ft he chlorine atom in most of the products is beneficial, both in counteracting the nucleophilicity of the pyridine nitrogen and in providing a handle for many subsequent transformations, especially as regards transition metal mediated coupling reactions. [33,34] When two positions for cyclisation are available, am ixture of two regioisomersa re generally observed, with one of the two often dominating. The conversion of adduct 52 f thus furnishes azaindolines 53 f and 53 f' in 18 and 68 %y ield, respectively,i n line with the earlier observations regarding the greater reactivity of the 2-positiont owards radical attack.…”

Section: Radical Cyclizations Onto Aromatic Ringsmentioning

confidence: 99%

“…[35] Compounds 53 jn are examples of diazaindolines derived from radical cyclisations onto ap yrimidine ring. [34] Finally,s everalo ft he azaindolines in Scheme 8w ere prepared directly,w ithouti solation of the intermediate adducts 52.T hisi st he case fora zaindolines 53 h-n.…”

Section: Radical Cyclizations Onto Aromatic Ringsmentioning

confidence: 99%

The Xanthate Route to Indolines, Indoles, and their Aza Congeners

Zard

2020

Chemistry A European J

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Convergentr outes to av ariety of indolines, indoles, oxindoles, and their aza analogues involving radical additions of xanthates are described. Three approaches are summarized. The first is the least general and relies on the generation of aryl or heteroaryl radicals startingf rom diazonium salts. The second involves radical addition to N-allylanilines followed by ring-closure onto the aromatic core. A large varietyo fi ndolines and azaindolines can thus be obtained and, in many cases, converted into the corresponding indoles and azaindoles by variousm ethods. Thes ynthesiso f novel fluoroazaindolines and fluoroazaindoles by ar are homolytic ipso-substitution of fluorine atoms is particularly noteworthy.T he last approachh inges on the direct modification of indoles by radical addition to the pyrrole subunit of the indolen ucleus. Application of this methodology to the total synthesis of melatonin andt he alkaloids mersicarpine, caulerpine, and the pentacyclic skeleton of tronocarpine is briefly discussed. Mosto ft he compounds described herein would be difficult to obtain by more traditional routes.

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Unusual radical addition on a heteroaromatic nitrogen. A convenient access to new pyrimidine derivatives

Abstract: A radical generated on the side-chain of a 2- or 4-N-alkylamino-4,6- or 2,6-dichloropyrimidine can cyclise on the nitrogen or on the carbon of the pyrimidine ring depending on its position and on whether an acetyl or a Boc group is present on the extra-nuclear nitrogen.

Cited by 21 publications

References 12 publications

Carbon‐Centered Radical Addition to C=X Bonds for C−X Bond Formation

Carbon‐Centered Radical Addition to C=X Bonds for C−X Bond Formation

Some intriguing mechanistic aspects of the radical chemistry of xanthates

The Xanthate Route to Indolines, Indoles, and their Aza Congeners

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