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.

Durch mangan(iii)-acetat initiierte radikalrk. von carbonylverbindungen 3. mitt. darst. beta,gamma- und gamma,delta-ungesaettigter aldehyde aus alkanalen und isoolefinen

1.

Oxidative addition of acetone to butadiene in the presence of the system Mn(OAc)3-Cu(OAc)2 has afforded 5-acetoxy-6-hepten-2-one, three isomeric 1-methyl-3,7-divinyl-2,8-dioxa-cis-bicyclo[3.3.0]octanes with the vinyl groups with the exo,exo, exo,endo, and endo,endo dispositions, and three diastereoisomeric 2,7-divinyl-1,6-dioxaspiro[4.4]nonanes.




2.

Oxidative addition of acetopropyl alcohol and dihydrosylvan to butadiene results in the formation in both cases of identical mixtures of exo- and endo-1-methyl-3-vinyl-2,8-dioxa-cis-bicyclo[3.3.0]octanes and diastereoisomeric 2-vinyl-1,6-dioxaspiro[4.4]nonanes, indicating that the reaction proceeds via the same intermediate, probably a complex of Mn(III) with the ketoalcohol.

Oxidative addition of acetone to butadiene

A study was made of the thermal decomposition of the hydroperoxide and peroxide of 2-methyltetrahydrofuran in solution, the principal products were identified, and it was shown that the decomposition proceeds to a large degree with an opening of the tetrahydrofuran ring A reaction mechanism was proposed

Thermal decomposition reactions of 2-methyltetrahydrofuran hydroperoxide and peroxide

Durch mangan(iii)-acetat initiierte radikalrk. von carbonylverbindungen 1. mitt. einfluss der salzkonzentration auf die richtung der addition von aldehyden an olefine

1.

The oxidative decarboxylation of acids with carboxyl groups at secondary and tertiary C atoms under the action of the S2O82−- Ag+ and S2O82−-Ag+- Cu2+ systems is at least an order of magnitude faster than that of acids with COOH groups at a primary C atom, as a result of which 3- and 4-carboxyalkyl radicals with the general formula R'RĊ(CH2)nCOOH (R is alkyl or phenyl, R′ is H or alkyl, n=2 or 3) are generated with > 90% selectivity from 2-substituted glutaric and adipic acids.




2.

The 3- and 4-carboxyalkyl radicals are completely or partially converted under their generation conditions into lactones. The selectivity of the oxidative lactonization increases from 0.30 to 0.97 along the series of radicals C2H5ĊH(CH2)3COOH, C2H5ĊH(CH2)2COOH, ĊH2(CH2)3COOH, ĊH2(CH2)2COOH, (CH3)2Ċ(CH2)2-COOH, and C2H5ĊH(CH2)2COOH in the case of the S2O82−-Ag+ system and from 0.72 to 1 along this series in the case of the S2O82−- Ag+- Cu2+ system.

G. I. Nikishin

Papers

Durch mangan(iii)-acetat initiierte radikalrk. von carbonylverbindungen 3. mitt. darst. beta,gamma- und gamma,delta-ungesaettigter aldehyde aus alkanalen und isoolefinen

Oxidative addition of acetone to butadiene

Thermal decomposition reactions of 2-methyltetrahydrofuran hydroperoxide and peroxide

Durch mangan(iii)-acetat initiierte radikalrk. von carbonylverbindungen 1. mitt. einfluss der salzkonzentration auf die richtung der addition von aldehyden an olefine

Selectivity of the generation of 3- and 4-carboxyalkyl radicals from substituted glutaric and adipic acids and their oxidative lactonization