Carbonium ions from alkyl radicals by electron transfer

Kochi, Jay K.; Bemis, A.

doi:10.1021/ja01017a022

Cited by 65 publications

(19 citation statements)

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“…However, detailed kinetic studies for R = methyl (37)(38)(39) have shown that it proceeds via the formation of a directly observable transient organocopper(III) intermediate. Similar studies (2,(40)(41)(42)(43) have established H 0 'CHg + Cuf* CuCHgZ* Cu"*" + CHgOH + H"*" (24) the generality of this oxidative pathway. A similar example of the ambiguity regarding the products and stoichiometry of radical reactions can be found in the formation of alkyl chlorides from alkyl radicals and…”

Section: Part I the Reactions Of The 2-hydr0xy-2-pr0pyl A-ethoxyethsupporting

confidence: 59%

Kinetics and mechanisms of the reactions of aliphatic free radicals with organocobaloximes and fluoropentaamminecobalt(III) ion, and of iron(III) with methylrhodoxime

Mchatton

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Cobaloxlmes Organochromlurn reagents 19 Miscellaneous reagents Methods Analyses and characterizations 23 % Co analysis Product analyses Rate determinations DESIGN OF COMPETITION EXPERIMENTS •CH(CH^)0C2H^ Radical-CfCHgigOH Radical RESULTS 41 Reactions of the-CHfCHgïOCgHg Radical with Organocobaloximes 41 Benzyl(aquo)cobaloxime, PhCHgCofdmgHjgOHg 4l Other alkylcobaloxlmes, RCo(dmgH)_OH_ (R = CH,, CH"CH_, and Reactions of the "CfCH^jgOH Radical with Organocobaloximes 55 Benzyl(aquo)cobaloxime, PhCHgCofdmgHjgOHg 55 Other alkylcobaloxlmes, RCo(dmgH)_0H_ (R = CH,, CH«CH_, and 63 î i I Products of the Coupling Reactions Between Selected Free Radicals and Benzy1(aquo)cobaloxime 72 Preparation of a Large Sample of 2-Methyl-1-phenyl-2-propano1 79 Protonation Constant for Benzyl coba loxi me 80 DISCUSSION 84 Mechanistic Alternatives 86 Electron transfer mechanisms 88 Bimolecular homolytic substitution 89 Addition-elimination mechanisms 91 Fate of the 0-radicals from 2-propanol and ethanol 97 Conclusions 99 PART II. REDUCTION OF FLUORGPENTAAMMINECOBALT(III), CoCNHgigF^*, BY 2-HYDR0XY-2-PR0PYL AND a-ETHOXYETHYL RADICALS 100

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Section: Part I the Reactions Of The 2-hydr0xy-2-pr0pyl A-ethoxyethsupporting

confidence: 59%

Kinetics and mechanisms of the reactions of aliphatic free radicals with organocobaloximes and fluoropentaamminecobalt(III) ion, and of iron(III) with methylrhodoxime

Mchatton

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confidence: 67%

“…[3] Recently the research group of Ellman reported the first use of metalated enamines 3 derived from chiral N-sulfinylimines in addition reactions to aldehydes. [4] Since in this case primary sulfinamide-derived Nsulfinylimines were employed, the products were b-hydroxy-N-sulfinylketimines which could be reduced stereoselectively to afford either the syn-or anti-1,3-amino alcohols.Although high diastereoselectivity was observed in many of the above cases, stoichiometric amounts of the chiral component (as well as stoichiometric amounts of a strong base to prepare the metalloenamines) were necessary. Recently we reported the development of highly diastereoand enantioselective addition reactions of enecarbamates to ethyl glyoxylate.…”

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confidence: 99%

Enesulfonamides as Nucleophiles in Catalytic Asymmetric Reactions

et al. 2007

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Enamines and metalated enamines are useful as nucleophiles in synthesis because of the resonance-donating property of the nitrogen atom, which is greater than that of oxygen atoms, thus they are more reactive than the enols and enolates. [1] Asymmetric reactions of enamines and metalated enamines have been reported. Yamada et al. first reported the chiral nonracemic enamines 1 which were derived from ketones and secondary amines [2] and subsequently several chiral enamines such as 2, based on this concept, have been developed and successfully employed. [3] Recently the research group of Ellman reported the first use of metalated enamines 3 derived from chiral N-sulfinylimines in addition reactions to aldehydes.[4] Since in this case primary sulfinamide-derived Nsulfinylimines were employed, the products were b-hydroxy-N-sulfinylketimines which could be reduced stereoselectively to afford either the syn-or anti-1,3-amino alcohols.Although high diastereoselectivity was observed in many of the above cases, stoichiometric amounts of the chiral component (as well as stoichiometric amounts of a strong base to prepare the metalloenamines) were necessary. Recently we reported the development of highly diastereoand enantioselective addition reactions of enecarbamates to ethyl glyoxylate.[5] These reactions proceeded smoothly with high selectivity in the presence of a catalytic amount of a chiral Lewis acid, and was marked by a stereospecific conversion of a-substituted ketone-derived enecarbamates into 1,3-imino alcohols. Despite the importance of enecarbamates, direct methods of synthesizing enecarbamates from the corresponding ketones have not been developed to the same extent as other types of enamines or imines.[6] Herein we report the first asymmetric nucleophilic addition reactions of a wide range of readily prepared enesulfonamides.[7] The enesulfonamides could be rapidly and efficiently synthesized from the corresponding ketones and underwent smooth reactions with a range of electrophiles such as ethyl glyoxylate, azodicarboxylate, and phenylglyoxal in stereoselective fashion. The product sulfonylimines could be readily reduced to the corresponding sulfonamides, which are important functional groups in medicinal chemistry. [8] Enesulfonamides were synthesized from the corresponding ketones via the N-sulfonylimine intermediates (Scheme 1).[9] Separation of the geometric isomers was achieved by column chromatography on silica gel or recrystallization. [10] In contrast to the enecarbamates, which were synthesized from the corresponding nitriles or a,b-unsaturated carboxylic acids, [6] a wide range of enesulfonamides could be synthesized directly from the corresponding ketones and sulfonamides by modification of a previously reported method. [9] The reaction of enesulfonamides with ethyl glyoxylate, which was freshly distilled from a commercially available solution of the polymer in toluene, was performed in the presence of the complex formed between Cu I and diimine ligand 5. Our investigation began with a survey of...

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“…80 Free radicals generated using various methods also may be oxidized to the carbenium ion, and then converted into the Ritter product (equation 36). 81 Some of these methods give low yields or mixtures, but the series of aryl bromides represented by equation 35 is synthetically significant. 79 Nair has reported the novel radical formation-oxidation sequence, using sodium azide and cerium(IV) ammonium nitrate (CAN), shown in equation 38.…”

Section: Cleavage Of Single Bondsmentioning

confidence: 99%

6.07 Ritter-Type Reactions

Bishop

2014

Comprehensive Organic Synthesis II

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Carbonium ions from alkyl radicals by electron transfer

Cited by 65 publications

References 1 publication

Kinetics and mechanisms of the reactions of aliphatic free radicals with organocobaloximes and fluoropentaamminecobalt(III) ion, and of iron(III) with methylrhodoxime

Kinetics and mechanisms of the reactions of aliphatic free radicals with organocobaloximes and fluoropentaamminecobalt(III) ion, and of iron(III) with methylrhodoxime

Enesulfonamides as Nucleophiles in Catalytic Asymmetric Reactions

6.07 Ritter-Type Reactions

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