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.

The reaction of primary alcohols with formalin or paraformaldehyde initiated by t-butyl peroxide in a glass apparatus under atmospheric pressure leads to the formation of alkane-1,2-diols.

On the free-radical reaction of primary alcohols with formaldehyde

Oxidative coupling of oxime and β-dicarbonyl compounds dominates in a β-dicarbonyl compound/oxime/Cu(II)/t-BuOOH system; in the absence of oxime, oxidative coupling of t-BuOOH and a β-dicarbonyl compound (Kharasch peroxidation) takes place The proposed conditions for oxidative coupling of oximes with dicarbonyl compounds require only catalytic amounts of copper salt and t-BuOOH serves as a terminal oxidant The C–O coupling reaction proceeds via the formation of tert-butoxyl, tert-butylperoxyl and iminoxyl radicals Apparently, tert-butylperoxyl radicals oxidize oxime into iminoxyl radical faster than they react with β-dicarbonyl compounds forming the Kharasch peroxidation product Iminoxyl radicals are responsible for the formation of the target C–O coupling products; the yields are up to 77%

/pdf/iminoxyl-radicals-vs-tert-butylperoxyl-radical-in-5dxt943uaq.pdf

Iminoxyl radicals vs. tert-butylperoxyl radical in competitive oxidative C–O coupling with β-dicarbonyl compounds. Oxime ether formation prevails over Kharasch peroxidation

Electrolysis of aromatic aldehydes and malononitrile in alcohols in an undivided cell in the presence of a NaBr-NaOAc mediatory system stereoselectively gave bicyclic compounds containing the cyclopropane and pyrroline fragments in 60 to 70% yields. In the bicyclic products, the benzene and pyrroline rings are on different sides of the cyclopropane ring.

Stereoselective electrocatalytic transformations of malononitrile and aromatic aldehydes into (1R,5S,6R)*-4,4-dialkoxy-2-amino-6-aryl-1,5-dicyano-3-azabicyclo[3.1.0]hex-2-enes

1-Aryl-1-hydroperoxy-2-imidooxyethanes are selectively formed at room temperature from styrenes, N-hydroxyphthalimide, and atmospheric oxygen with the participation of tert-butyl hydroperoxide as a radical initiator.

Addition of N -hydroxyphthalimide and atmospheric oxygen to styrenes using tert -butyl hydroperoxide as a radical initiator

http://jes.ecsdl.org/content/160/7/G3053.full.pdf

G. I. Nikishin

Papers

On the free-radical reaction of primary alcohols with formaldehyde

Iminoxyl radicals vs. tert-butylperoxyl radical in competitive oxidative C–O coupling with β-dicarbonyl compounds. Oxime ether formation prevails over Kharasch peroxidation

Stereoselective electrocatalytic transformations of malononitrile and aromatic aldehydes into (1R,5S,6R)*-4,4-dialkoxy-2-amino-6-aryl-1,5-dicyano-3-azabicyclo[3.1.0]hex-2-enes

Addition of N -hydroxyphthalimide and atmospheric oxygen to styrenes using tert -butyl hydroperoxide as a radical initiator

Electrocatalytic Fast and Efficient Multicomponent Approach to Medicinally Relevant Pyrano[3,2-c]quinolone Scaffold