There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

Ru-, Rh-, and Pd-Catalyzed C-C Bond Formation Involving C-H Activation and Addition on Unsaturated Substrates: Reactions and Mechanistic Aspects

Catalytic C–H activation has emerged as a powerful tool for sustainable syntheses. In the recent years, notable success was achieved with the development of cobalt-catalyzed C–H functionalizations with either in situ generated or single-component cobalt-complexes under mild reaction conditions. Herein, recent progress in the field of organometallic cobalt-catalyzed C–H activation is reviewed until November 2015.

Cobalt-Catalyzed C―H Activation

The development of new methods for the direct functionalization of unactivated C–H bonds is ushering in a paradigm shift in the field of retrosynthetic analysis. In particular, the catalytic enantioselective functionalization of C–H bonds represents a highly atom- and step-economic approach toward the generation of structural complexity. However, as a result of their ubiquity and low reactivity, controlling both the chemo- and stereoselectivity of such processes constitutes a significant challenge. Herein we comprehensively review all asymmetric transition-metal-catalyzed methodologies that are believed to proceed via an inner-sphere-type mechanism, with an emphasis on the nature of stereochemistry generation. Our analysis serves to document the considerable and rapid progress within in the field, while also highlighting limitations of current methods.

/pdf/catalytic-enantioselective-transformations-involving-c-h-4dm3wav9qj.pdf

Catalytic Enantioselective Transformations Involving C-H Bond Cleavage by Transition-Metal Complexes.

1.

A new C-C bond on homolytic addition of dimethyl esters of succinic, glutaric, and adipic acids to the dimethyl or diethyl ester of citraconic, itaconic, and acetylenedicarboxylic acids is formed between theα-C atom of the acyl part of the ester of the alkanedicarboxylic acid and the least substituted C atom of the C=C bond of the ester of the unsaturated acid.




2.

As an acceptor of radicals generated from esters of alkanedicarboxylic acids, the ester of citraconic acid is substantially less effective than the esters of maleic, itaconic, and acetylenedicarboxylic acids. The latter are close to one another in capability of forming addition products with esters of succinic, glutaric, and adipic acids.




3.

The principal products of homolytic reaction of dimethyl esters of glutaric and adipic acids with the dimethyl ester of acetylenedicarboxylic acid are respectively the tetramethyl esters of 2-pentene-1,2,3,5-tetracarboxylic acid and 2-hexene-1,2,3,6-tetracarboxylic acid.

Free-radical addition of esters to esters of citraconic, itaconic, and acetylenedicarboxylic acids

1.

By the action of the K3Fe(CN)6-NaOH system, primary alkylamines RCH2NH2 are oxidized into alkanoic acid nitriles RCN. The action of the K3Fe(CN)6-NaOH system on heptylamine also leads to its N-cyanation with the formation of N-heptylurea, which is readily hydrolyzed under the reaction conditions.




2.

By the action of the K3Fe(CN)6-NaOH system, primary sec-alkylamines R,R'CHNH2 convert into alkylhydrazones of alkanones RR'C=N-NHCHRR' as the result of oxidative dimerization.

Oxidation of primary amines by potassium ferricyanide

1.

Tert-Butyl hydroperoxide can be used as an initiator of the chain radical reaction for the addition of alcohols to the methyl esters of acrylic and maleic acids.




2.

The decomposition of tert-butyl hydroperoxide in butanol and cyclohexanol at 115° obeys the first-order reaction.




3.

tert-Butyl hydroperoxide in butanol at 115° undergoes mainly induced decomposition, with a small proportion of the decomposition going through the stage of forming the complex with the alcohol.

Initiation of free-radical addition reactions of alcohols by tertiary butyl hydroperoxide

1.

The possibility of using tert-butyl hydroperoxide to initiate the reaction of homolytic alkylation of cycloalkanones with 1-alkenes at temperatures of 100–140° was studied.




2.

Tert-butyl hydroperoxide is analogous to ditert-butyl peroxide in the indicated ability.

Homolytic alkylation of cycloalkanones by 1-alkenes initiated by tertiary-butyl hydroperoxide

1.

Fe(III) aqua ions catalyze the homolytic decomposition of 2-methyltetrahydro-2-furyl hydroperoxide; the catalytic activity of the Fe(III) complexes is determined by the nature of the coordinated ligand and the pH of the medium. The homolytic nature of the reaction is confirmed by the conversion of tetranitromethane by free radicals to the intensely colored nitroform anion.




2.

Based on the potentiometric measurement data, the Fe(III) peroxo complexes have an ionic nature in aqueous medium.

G. I. Nikishin

Papers

Free-radical addition of esters to esters of citraconic, itaconic, and acetylenedicarboxylic acids

Oxidation of primary amines by potassium ferricyanide

Initiation of free-radical addition reactions of alcohols by tertiary butyl hydroperoxide

Homolytic alkylation of cycloalkanones by 1-alkenes initiated by tertiary-butyl hydroperoxide

Effect of nature of ligands on catalytic decomposition of 2-methyltetrahydro-2-furyl hydroperoxide by iron salts