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.

Together with the main products, namely cyclohexen-2-ol and cyclohexen-2-one, the oxidation of cyclo-hexene with cerium ammonium nitrate or cerium ammonium sulfate gives cyclohexanol and cyclohexanone, which are probably formed by the cation-radical mechanism.

https://link.springer.com/content/pdf/10.1007/BF00928553.pdf

Oxidation of cyclohexene with Ce (IV) salts

Rhodium(I) complex with η4-coordinated methyl vinyl ketone

Oxoalkyl radicals are generated by the reaction of 1-alkylcycloalkanols (ring size C5-C7) with the Pb(OAc)4-KSCN system, which are oxidized by the ligand transfer mechanism to give oxoalkyl thiocyanates.

Oxidative cleavage of tertiary cyclic alcohols by Pb(OAc) 4 -KSCN system

1.

In the free-radical addition of primary tetrahydrofuranalkanols to unsaturated compounds mainly 2,2-derivative s of tetrahydrofuran are formed.




2.

Previously unknown 2,2-disubstituted tetrahydrofurans were prepared which contained 5- or 6-membered lactone rings, one or two hydroxy groups, and a hydroxy and a keto or a hydroxy and an ester group.

G. I. Nikishin

Papers

Oxidation of cyclohexene with Ce (IV) salts

Rhodium(I) complex with η4-coordinated methyl vinyl ketone

Oxidative cleavage of tertiary cyclic alcohols by Pb(OAc) 4 -KSCN system

Free-radical addition of tetrahydrofuranalkanols to unsaturated compounds

Homolytic Oxoalkylation of Protonated N-Heteroaromatic Compounds.