A Practical Route to Pyrazines and Quinoxalines, and an Unusual Synthesis of Benzimidazoles

Mougin, Catherine; Sançon, Julien; Zard, Samir Z.

doi:10.3987/com-07-s(w)55

Cited by 13 publications

(2 citation statements)

References 6 publications

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“…The new bonds formed are colored in red. In this manner numerous functional groups could be introduced, a phthalimido‐protected methylamino unit as in 127 ; [27] a phosphonylketone as in 128 ; [28] a selectively protected ketoaldehyde as in 129 ; [29] a dithiane mono‐oxide as in 130 ; [30] a difluoromethylsulfide as in 131 ; [31] chlorodifluoromethyl motif as in 132a , from which the xanthate can be reduced off using (Me3Si)3SiH and the chlorine eliminated from 132b by treatment with DBU to give finally difluorovinyl derivative 133 ; [32] a sulfoxide ester 134 , which can be directly thermolyzed in refluxing toluene to give unsaturated methyl ester 135 [33] . In this Scheme, and in the rest of this article, the diastereoisomeric ratio is approximately 1 : 1, unless indicated otherwise.…”

Section: Introductionmentioning

confidence: 99%

Radicals and Carbohydrates: A Grand Alliance

Quiclet‐Sire,

Zard

2024

Helvetica Chimica Acta

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This review describes applications of radical reactions developed in the authors’ laboratory for the modification of carbohydrates. It focuses on tin‐free variation on the Barton‐McCombie deoxygenation; on reductive de‐iodination; on intermolecular radical additions of xanthates; on allylations and vinylations of xanthates and iodides, with emphasis on allylations using allylic alcohols activated as fluoropyridyl ethers; and, finally, on the synthesis of mercaptosugars. @font‐face {font‐family:"MS Mincho"; panose‐1:2 2 6 9 4 2 5 8 3 4; mso‐font‐alt:"ＭＳ明朝"; mso‐font‐charset:128; mso‐generic‐font‐family:modern; mso‐font‐pitch:fixed; mso‐font‐signature:‐536870145 1791491579 134217746 0 131231 0;}@font‐face {font‐family:"Cambria Math"; panose‐1:2 4 5 3 5 4 6 3 2 4; mso‐font‐charset:0; mso‐generic‐font‐family:roman; mso‐font‐pitch:variable; mso‐font‐signature:‐536870145 1107305727 0 0 415 0;}@font‐face {font‐family:"Myriad Pro"; panose‐1:2 11 6 4 2 2 2 2 2 4; mso‐font‐alt:Corbel; mso‐font‐charset:0; mso‐generic‐font‐family:swiss; mso‐font‐pitch:variable; mso‐font‐signature:‐1610612049 1342185547 0 0 415 0;}@font‐face {font‐family:"\@MS Mincho"; panose‐1:2 2 6 9 4 2 5 8 3 4; mso‐font‐charset:128; mso‐generic‐font‐family:modern; mso‐font‐pitch:fixed; mso‐font‐signature:‐536870145 1791491579 134217746 0 131231 0;}p.MsoNormal, li.MsoNormal, div.MsoNormal {mso‐style‐unhide:no; mso‐style‐parent:""; margin:0cm; line‐height:150%; mso‐pagination:widow‐orphan; font‐size:8.0pt; mso‐bidi‐font‐size:12.0pt; font‐family:"Myriad Pro",sans‐serif; mso‐fareast‐font‐family:"MS Mincho"; mso‐bidi‐font‐family:"Times New Roman"; mso‐ansi‐language:DE; mso‐fareast‐language:JA;}p.Helv‐Abstract, li.Helv‐Abstract, div.Helv‐Abstract {mso‐style‐name:Helv‐Abstract; mso‐style‐unhide:no; mso‐style‐qformat:yes; margin‐top:6.0pt; margin‐right:0cm; margin‐bottom:6.0pt; margin‐left:0cm; text‐align:justify; text‐justify:inter‐ideograph; line‐height:150%; mso‐pagination:widow‐orphan; font‐size:8.0pt; mso‐bidi‐font‐size:10.0pt; font‐family:"Myriad Pro",sans‐serif; mso‐fareast‐font‐family:"MS Mincho"; mso‐bidi‐font‐family:"Times New Roman"; mso‐ansi‐language:EN‐US; mso‐fareast‐language:JA;}.MsoChpDefault {mso‐style‐type:export‐only; mso‐default‐props:yes; font‐size:10.0pt; mso‐ansi‐font‐size:10.0pt; mso‐bidi‐font‐size:10.0pt; mso‐fareast‐font‐family:"MS Mincho";}div.WordSection1 {page:WordSection1;}

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Section: Introductionmentioning

confidence: 99%

Radicals and Carbohydrates: A Grand Alliance

Quiclet‐Sire,

Zard

2024

Helvetica Chimica Acta

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“…Synthesis of aliphatic and alicyclic α-(acyloxy)alkyl xanthates by radical addition to vinyl esters. Xa = -SC(=S)OEt; Piv = pivalate; Bz = benzoate; PhthN = phthalimido[13,[15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31]. Scheme 4.…”

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confidence: 99%

Some Aspects of a-(Acyloxy)alkyl Radicals in Organic Synthesis

Zard,

Quiclet-Sire

2023

Preprint

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The preparation and use of -(acyloxy)alkyl xanthates to generate and capture -(acyloxy)alkyl radicals is briefly reviewed. Their inter- and intramolecular additions to both activated and unactivated, electronically unbiased, alkenes, and to (hetero)aromatic rings, as well as their radical allylation and vinylation reactions are described. Application to the total synthesis of two 4-hydroxytetralone natural products is also presented.

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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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A Practical Route to Pyrazines and Quinoxalines, and an Unusual Synthesis of Benzimidazoles

Cited by 13 publications

References 6 publications

Radicals and Carbohydrates: A Grand Alliance

Radicals and Carbohydrates: A Grand Alliance

Some Aspects of a-(Acyloxy)alkyl Radicals in Organic Synthesis

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

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