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.

A method for the synthesis of 1,2,4,5,7,8-hexaoxonanes by the reaction of 1,1′-dihydroperoxydi(cycloalkyl)peroxides with acetals using SnCl4 has been developed. For the first time, it was shown that SnCl4 can serve as an effective reagent for the synthesis of cyclic organic peroxides. The proposed method allows obtaining 9-membered cyclic triperoxides selectively and in the yields of up to 90% based on the isolated product.

Selective synthesis of cyclic triperoxides from 1,1′-dihydroperoxydi(cycloalkyl)peroxides and acetals using SnCl4

Reactions of β-diketones and β-keto esters with tert-butyl hydroperoxide under heterogeneous conditions using SiO2-supported copper(II) perchlorate as a catalyst give rise to α-peroxidation products in 65—82% yields. A possibility to reuse the catalyst was demonstrated.

Peroxidation of β-diketones and β-keto esters with tert-butyl hydroperoxide in the presence of Cu(ClO4)2/SiO2

Electrochemical dehydrotrimerization of dimethyl malonate to the hexamethyl ester of cyclopropanehexacarboxylic acid

The action of lithium butyl acetylenide in THF causes 4,4-diethyl-1,2-dithiolane to undergo ring-opening to form 2,2-diethyl-4-thia-5-decyne-1-thiol, which cyclizes to give 2-butyl-6,6-diethyl-5,6-dihydro-1,4-dithiepin by either a homolytic or a nucleophilic mechanism.

Ring expansion of 4,4-diethyl-1,2-dithiolane in the reaction with butylacetylene. involvement of anion and radical intermediates

1.

The radical addition of aliphatic aldehydes to various unsaturated compounds, initiated by autooxidation, was studied.




2.

The mechanism of initiation by oxygen in the presence of cobalt salts and without the participation of a catalyst was discussed.

G. I. Nikishin

Papers

Selective synthesis of cyclic triperoxides from 1,1′-dihydroperoxydi(cycloalkyl)peroxides and acetals using SnCl4

Peroxidation of β-diketones and β-keto esters with tert-butyl hydroperoxide in the presence of Cu(ClO4)2/SiO2

Electrochemical dehydrotrimerization of dimethyl malonate to the hexamethyl ester of cyclopropanehexacarboxylic acid

Ring expansion of 4,4-diethyl-1,2-dithiolane in the reaction with butylacetylene. involvement of anion and radical intermediates

Addition of aldehydes to unsaturated compounds induced by autooxidation