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 was developed for synthesizing aliphatic ketones by radical addition of aldehydes to olefins without the addition of peroxide and consisting of bubbling of air through a mixture of aldehyde, olefin, and acetic anhydride at 70–85°

Addition of aldehydes to alpha-olefins, induced by oxygen in the presence of acetic anhydride

A selective method has been developed for the synthesis of α-methylene-1,5-diketones by dimerization of vinyl ketones catalyzed by RhCl(PMe3)3. Aromatic vinyl ketones dimerize more readily than aliphatic vinyl ketones.

Selective dimerization of vinyl ketones to 1,5-diketones, catalyzed by RhCl(PMe3)3

1.

The synthesis of a series of secondary alcohols has been carried out by the addition of C5–C10 primary alcohols to C6 – C13 α-olefins. The reaction initiator was t-butyl peroxide.




2.

The optimum conditions for this reaction are: temperature, 140– 160°; time, 3–6 hours; molar ratio alcohol: olefin: peroxide=20 ∶ 1 ∶ 0.3.

Free-radical addition of primary alcohols toα-olefins

1.

Conditions for the free-radical addition of N-acetyl amines to unsaturated compounds were worked out. This reaction can provide a preparative method for the synthesis of amines, including amines containing various functional groups.




2.

The effect of reaction conditions and the structure of the reactants on the ability of the latter to form 1∶1 adducts was studied, and it was shown, in particular, that this ability is the greater, the more highly electrophilic the double bond.

G. I. Nikishin

Papers

Addition of aldehydes to alpha-olefins, induced by oxygen in the presence of acetic anhydride

Selective dimerization of vinyl ketones to 1,5-diketones, catalyzed by RhCl(PMe3)3

Free-radical addition of primary alcohols toα-olefins

Free-radical addition of N-acetyl amines to unsaturated compounds

Electrochemical Cleavage of Double Bonds in Conjugated Cycloalkenyl- and 1,2-Alkenobenzenes.