Asymmetric radical carboesterification of dienes

The straightforward strategy of building a chiral C-O bond directly on a general carbon radical center is challenging and stereocontrol of the reactions of open-chain hydrocarbon radicals remains a largely unsolved problem. Advance in this elementary step will spur the development of asymmetric radical C-O bond construction. Herein, we report a copper-catalyzed regioselective and enantioselective carboesterification of substituted dienes using alkyl diacyl peroxides as the source of both the carbon and oxygen substituents. The participation of external acids in this reaction substantially extends its applicability and leads to structurally diverse allylic ester products. This work represents the advance in the key elementary reaction of intermolecular enantioselective construction of C-O bond on open-chain hydrocarbon radicals and may lead to the discovery of other asymmetric radical reactions.

Cooperative Hydrogen Atom Transfer: From Theory to Applications

Hydrogen atom transfer (HAT) is one of the fundamental transformations of organic chemistry, allowing for the interconversion of open and closed shell species through the concerted movement of a proton an electron. While the value of this transformation is well-appreciated in isolation, allowing for homolytic C–H activation via abstractive HAT and radical reduction via donative HAT, cooperative HAT (cHAT) reactions, where two hydrogen atoms are removed or donated to vicinal reaction centers in succession proceeding through radical intermediates, are comparatively unknown outside of the mechanism of desaturase enzymes. This tandem reaction scheme has important ramifications in the thermochemistry of each HAT, with the bond dissociation energy of the C–H bond adjacent to the radical center being significantly lowered compared to that of the parent alkane, allowing for each HAT to be performed by different species. Here we discuss the thermodynamic basis of this bond strength differential in cHAT and demonstrate its use as a design principle in organic chemistry for both dehydrogenative (application 1) and hydrogenative (application 2) reactions. Together, we hope that this overview will highlight the exciting reactivity possible with cHAT and inspire further development using this mechanistic approach.

Circles on the Complex Plane

The Euclidean plane and Euclidean space themselves do not contain imaginary elements by definition, but are inextricably linked with them through special cases, and this leads to the need to propagate geometry into the area of imaginary values. Such propagation, that is adding a plane or space, a field of imaginary coordinates to the field of real coordinates leads to various variants of spaces of different dimensions, depending on the given axiomatics. Earlier, in a number of papers, were shown examples for solving some urgent problems of geometry using imaginary geometric images [2, 9, 11, 13, 15]. In this paper are considered constructions of orthogonal and diametrical positions of circles on a complex plane. A generalization has been made of the proposition about a circle on the complex plane orthogonally intersecting three given spheres on the proposition about a sphere in the complex space orthogonally intersecting four given spheres. Studies have shown that the diametrical position of circles on the Euclidean E-plane is an attribute of the orthogonal position of the circles’ imaginary components on the pseudo-Euclidean M-plane. Real, imaginary and degenerated to a point circles have been involved in structures and considered, have been demonstrated these circles’ forms, properties and attributes of their orthogonal position. Has been presented the construction of radical axes and a radical center for circles of the same and different types. A propagation of 2D mutual orthogonal position of circles on 3D spheres has been made. In figures, dashed lines indicate imaginary elements.

Oxidation of the inert sp3 C–H bonds of tetrahydroisoquinolines through C–H activation relay (CHAR): construction of functionalized isoquinolin-1-ones

An unprecedented functionalization of the 3,4-C–H bonds of THIQs was realized by CHAR, accomplishing the shift of radical center from the active position to the inert position.

National “Politics against Policy” in the Eurozone Crisis

Chapter 10 explores the input legitimacy of Eurozone crisis governance as seen through its impact “at the bottom,” on national politics. The chapter first details citizens’ rising Euroskepticism against a background of declining trust in national and EU political institutions, fueled by socioeconomic and sociocultural sources of discontent. But Euroskepticism also stems from a range of other EU-related beliefs and plays out differently as a result of political institutional and geopolitical factors. All such factors help explain the EU’s increasing political polarization and party realignments during the Eurozone crisis, along with the electorate’s crosscutting cleavages of right versus left and open/cosmopolitan versus closed/communitarian. The chapter next charts the fate of mainstream parties during the crisis, first detailing the declining fortunes of center-left and right parties in the periphery, including Ireland, Greece, Spain, and Italy, with the exception of the center left in Portugal. It then considers the fate of such parties in core countries, first in Germany, where the center left has fared worse than Angela Merkel’s center right, and then in France, where center left and right have succumbed to the “critical center” of Emmanuel Macron. The chapter follows by considering the rise of populist parties across Europe, but in particular on the extremes of the right with France’s Marine Le Pen and Italy’s Matteo Salvini, on the extremes of the left with France’s Jean-Luc Mélenchon and Greece’s Alexis Tsipras, and in the “radical center” with Italy’s Beppe Grillo and his successor, Luigi di Maio.

ELECTRON STRUCTURE OF RADICALS OF SULFOXYLIC ACID ESTERS

The density functional theory B3LYP/6-311++G(3df,3pd) has been used to optimize the geometry of homologues of a series of sulfoxylic acid ester radicals and to obtain the electron density distributions of the first nine compounds. The hydrogen bond presented in the initial molecules of the unbranched esters of sulfoxylic acid between the hydrogen of the second carbon atom of the alkyl chain (from the ester bond) and the oxygen of the hydroxyl group of the sulfur-containing fragment (-C(Н)H-CH2-O-S-ОН) and the corresponding cycle are not observed in the radicals. The fragmentation of the structures into topological groups of CH3, CH2, and (-O-S-O)● has been proposed and their electron integral characteristics are presented including charges, unpaired electron density, energy, and volume. The steric effect of the fragment (-O-S-O)● has been established and its inductive effect has been considered based on the groups charge parameters changes triggered by an increase in the hydrocarbon chain. The scale of group electronegativities of the studied homologues has been constructed by comparing the charges of topological groups. The fact that the radical center corresponds to the fragment (-O-S-O)● has been demonstrated by the spin density delocalization results (having the largest fraction on the sulfur atom (0.57), slightly less fraction on the oxygen atom with a free valence (0.32) and an insignificant fraction on oxygen atom using the ether bond (0.10)). The increment value of the total energy contributed by the CH2 group of each subsequent homologue of the series under the study has been estimated. It is 103260 kJ/mol. The evaluation of the “standard” value of the groups’ total electron energy and the use of their relative energy (ΔE(R)) for comparing with ΔE(R) of molecules and radicals of other homologous series have been described. A decrease in the volumes of the two closest to the sulfur-containing fragment CH2 groups caused by an outflow of electron density from them toward the fragment (-O-S-O)● has been noted.

Isomerization versus dissociation of phenylalanylglycyltryptophan radical cations

Four isomers of the radical cation of tripeptide phenylalanylglycyltryptophan, in which the initial location of the radical center is well defined, have been isolated and their collision-induced dissociation (CID) spectra examined.