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.

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

The action of catalytic amounts of copper ions in the presence of MX salts (M=K and Na, X=Cl, Br, I, SCN) leads to the decomposition of the hydroperoxides of C5-C7 cycloalkanones with the formation of ω-chloro-,ω-bromo-, ω-iodo-, and ω-thiocyanoalkanoic acids

Synthesis of ω-haloalkanoic acids by the catalytic decomposition of cycloalkane hydroperoxides by copper ions

Mechanism of the oxidation of aldehydes by oxygen: Communication 1. Demonstration of the structure of the intermediate peroxide by the nuclear magnetic resonance method

The reactions of electrochemical cyclotrimerization of C-H acids, as well as electrochemical cyclocondensation of C-H acids and carbonyl compounds into corresponding, functionally substituted cyclopropanes, are found. The general method of electrochemical cyclization of esters of α,α,ω,ω-alkane tetracarboxylic acids is realized. Under the effect of catalytic amounts of alkoxy anions, tetracyanocyclopropanes are quatitatively transformed into corresponding, bicyclic pyrrolines

The electrochemical synthesis of cyclopropanes

A catalytic procedure has been developed for the synthesis of 15-pentadecanolide (1) from readily available 1-hydroperoxy-16-oxabicyclo[10.4.0]hexadecane (2). The method is based on the reaction of hydroperoxide2 with copper acetate (0.15–5 mol.%). Ring expansion occurred as a result of generation of tertiary bicyclohexadecyloxyl radicals4 from hydroperoxide2 under the action of Cu1 ions, β-scission of the radicals accompanied by regioselective cleavage of the bridge bond to form macrocyclic C-centered radicals5, and their oxidation by Cu11 ions to (E)-11- and (E)-12-pentadecen-15-olides (6). The products obtained were converted into 15-pentadecanolide by subsequent catalytic hydrogenation over a Pd catalyst in a yield of more than 90% with respect to hydroperoxide2.

Ring-expansion reaction of 1-hydroperoxy-16-oxabicyclo[10.4.0]hexadecane catalyzed by copper ions: use in the synthesis of 15-pentadecanolide

1.

A study was made of the sodium peroxydisulfate-initiated reaction of 1-heptene with acetic and propionic acids at 90–105°, as well as the effect of potassium hydroxide on this reaction.




2.

We were the first to discover that an olefin can be oxidized by a peroxydisulfate. The composition and character of the oxidation products are in agreement with the mechanism of a one-electron oxidation of the olefin and the formation of the cation-radical\(R--CH--\mathop {CH_2 }\limits^ + \) as the primary reaction product.




3.

Potassium hydroxide substantially suppresses the oxidation of the olefin by the peroxydisulfate and facilitates the homolytic alkylation of acids by the olefin.

G. I. Nikishin

Papers

Synthesis of ω-haloalkanoic acids by the catalytic decomposition of cycloalkane hydroperoxides by copper ions

Mechanism of the oxidation of aldehydes by oxygen: Communication 1. Demonstration of the structure of the intermediate peroxide by the nuclear magnetic resonance method

The electrochemical synthesis of cyclopropanes

Ring-expansion reaction of 1-hydroperoxy-16-oxabicyclo[10.4.0]hexadecane catalyzed by copper ions: use in the synthesis of 15-pentadecanolide

Peroxydisulfate-initiated reactions of 1-heptene with acetic and propionic acids