Radical Anions as Intermediates in Substitution Reactions

Kornblum, Nathan; Michel, Robert E.; Kerber, Robert C.

doi:10.1021/ja00975a061

Cited by 108 publications

(25 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Previously reported chain processes via radical anion intermediates nicely complement standard enolate alkylations, as they give good results with tertiary alkyl and aryl halides. [3,4] The nitroalkylation of alkyl iodides via silyl nitronates [5] has also been described, as well as the previously known reduction of tertiary nitro groups with Bu 3 SnH/2,2'-azobisisobutyronitrile (AIBN). [6] Our approach for the radical alkylation of organic nitro compounds is outlined in Scheme 1.…”

mentioning

confidence: 99%

Radical Alkylation of Bis(silyloxy)enamine Derivatives of Organic Nitro Compounds

2006

View full text Add to dashboard Cite

show abstract

mentioning

confidence: 99%

Radical Alkylation of Bis(silyloxy)enamine Derivatives of Organic Nitro Compounds

2006

View full text Add to dashboard Cite

show abstract

“…24 p Nitrobenzyl halides undergo substitution instead of elimination even in the case of tertiary compounds 25 : α,p Dinitrocumene does not react with the azide ion. However, in the presence of the reducing agent (2 nitro propane anion), the substitution product is formed in 97% yield 26 :…”

Section: Methodsmentioning

confidence: 99%

Reductive electrocatalytic dehalogenation of nitrobenzyl halides: nitrophilic or halophilic attack?

et al. 2005

View full text Add to dashboard Cite

Electrochemical reduction of Cp 2 TiCl 2 in the presence of benzylic halides results in their catalytic dehalogenation to form toluene derivatives. Possible schemes for the process were proposed on the basis of the results of electrochemical studies and digital simulation data. The catalytic scheme including the halophilic attack of the Ti III complex to organic halide as a key step occurs for unsubstituted benzylic halides. In the case of nitro substituted substrates, the reaction is strongly accelerated. In this case, an electron transfer from the reduced form of the catalyst to the NO 2 group of organic halide is possibly accompanied by the intramolecular charge transfer to the С-Hal bond, thus facilitating its cleavage. Thus, the nitro group in the starting benzylic halide acts as a "redox antenna," transferring an electron to the C-Hal bond. The proposed scheme is supported by semiempirical calculations of the geometry of molecular complexes with the Ti-Hal or Ti-NO 2 coordination.Reactions of halogen substitution by hydrogen in or ganic compounds are well known and can be effected with various reagents and proceed via different mecha nisms. A possible way is the reductive dehalogenation of benzylic halides (ArCH 2 X) catalyzed by Ti III complexes. 1 This reaction is of interest as a method for the selective dehalogenation in polyfunctional compounds. It can be used, in particular, as a synthesis of glycals from glycosyl halides. 2,3 The Ti III complexes used as catalysts are gen erally synthesized from titanocene dichloride or other available Ti IV complexes by the action of reducing agents, e.g., metals (Zn, Mn, Al) or organometallic compounds (RMgX, RLi). 1,4 However, in recent works, the active form of the catalyst is prepared by electrochemical reduc tion of the Ti IV complex, 5-8 and this form favors the reductive coupling of aldehydes to form pinacones 5 and the selective reduction of the nitro group. 6-8 The recent data 9,10 on the nature of active species produced by the electrochemical reduction of Cp 2 TiCl 2 in solution show that these species undergo the subsequent electrocatalytic reactions with benzaldehyde or benzyl chloride.It is known that electrocatalytic processes have several substantial advantages over common catalysis (high se lectivity and ecological safety, no necessity for chemical oxidative or reducing agents in the reaction mixture, etc.). Therefore, it seems of special interest to develop new electrochemically activated reactions involving different types of transformations.The purpose of the present work is to study the electrocatalytic dehalogenation of compounds of the ArCH 2 X series catalyzed by the reduced form of bis(η 5 cyclopentadienyltitanium) dichloride in solution. ExperimentalInstruments and electrodes. Cyclic voltammograms were re corded on IPC Win and Autolab PGSTAT30 potentiostats (Ecochemie, Netherlands) at stationary platinum electrodes 3.8 and 0.8 mm in diameter in anhydrous organic solvents (THF, MeCN) with Bu n 4 NPF 6 as a supporting electrolyte at 20 °C. A ...

show abstract

“…2and 4-nitrobenzyl and 2,4-dinitrobenzyl effect principally C-alkylation. 427. For example, with 4-nitrobenzyl chloride yields of C-alkylation products are : CH,CH=NO,-(24%) and (CH,),C=NO,-(62%) 397. Evidence for radical anion intermediates has been obtained by esr measurements in the C-alkylation with 4-nitrobenzyl chlo-ride314.424-427.…”

Section: Arnold T Nielsenmentioning

confidence: 99%

Nitronic acids and esters

Nielsen

Breuer

Aurich

1989

PATAI'S Chemistry of Functional Groups

View full text Add to dashboard Cite

Radical Anions as Intermediates in Substitution Reactions

Abstract: Purdtie Uniue rs it y , Lafa yette , Ind.The anion derived from a n aliphatic nitro compound is capable of covalency formation at either carbon o r oxygen; i.e., it i s a n ambident anion.

Cited by 108 publications

References 0 publications

Radical Alkylation of Bis(silyloxy)enamine Derivatives of Organic Nitro Compounds

Radical Alkylation of Bis(silyloxy)enamine Derivatives of Organic Nitro Compounds

Reductive electrocatalytic dehalogenation of nitrobenzyl halides: nitrophilic or halophilic attack?

Nitronic acids and esters

Contact Info

Product

Resources

About