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Aza‐Michael addition is known to be one of the most exploited reactions in organic chemistry. Taking into account the fact that each seventh reaction in pharmaceutical industry involves the formation of at least one C−N bond, it is not surprising that this reaction is especially valuable for the synthesis of bioactive compounds and drugs. Traditionally, only push‐pull alkenes are regarded as starting material for this reaction. The participation of pull‐pull alkenes as Michael acceptors is much less studied. The presence of two vicinal electron‐withdrawing groups makes them highly reactive in nucleophilic reactions especially with nitrogen‐centered nucleophiles. This feature allows them to be excellent building blocks in the synthesis of bioactive molecules and polyfunctional materials. The review considers the most important and sometimes unexpected results obtained over the last two decades on the conjugate addition of nitrogen nucleophiles to pull‐pull alkenes bearing various acceptor moieties (alkoxycarbonyl‐, carbonyl‐, formyl‐, cyano‐, trifluoromethyl‐ or nitro group) in various combinations. [ABSTRACT FROM AUTHOR]

Cyclic 8-, 9-, 10-, and 12-membered bis(anisylphosphonothioyl)disulfanes were synthesized. Next, structurally related 7 to 9-membered cis and trans sulfanes were isolated as a result of sulfur atom extrusion from the parent cyclic disulfanes. The results of the desulfurization of the disulfanes using triphenylphosphine were compared to the results obtained for desulfurization of the respective bis(anisylphosphodithioates) with the aid of 2-chloro-N-methylpyridinium iodide. Cyclic disulfanes predominantly provide trans-sulfanes, and the expansion of their ring sizes causes the cis/trans isomer ratio of the cyclic sulfanes to increase. Moreover, bis(anisylphosphodithioates) mainly afford cis-sulfanes, and the cis/trans isomer ratio is greater than 3 : 1. Mechanistic and stereochemical aspects of cyclic disulfane desulfurization have been presented to elucidate the above findings. Although it was suggested by calculations that cis-sulfanes are more thermodynamically stable than their respective trans isomers, the cyclisation is a kinetically controlled reaction, which results in predominance of trans-sulfanes in the case of trans-disulfane desulfurization. Disulfanes exhibit thermal and solvolytic stability (except in wet DMSO). A characteristic persistent deep-blue coloration of methanolic ammonia solutions is an unusual feature of cyclic disulfanes. The mechanism of their ammonolysis has been studied and has been compared to that of the respective reaction performed on acyclic disulfanes. Ammonia solution of an acyclic disulfane is colourless and contains phosphosulfenamide and dithiophosphate, while the respective mixture of cyclic disulfane consists of thiophosphonoamide-phosphonodithioate, O-methyl thiophosphonate–phosphonodithioate and deep blue sulfur-ammonia species. Detailed X-ray structural analysis was performed for all trans-disulfanes and cis- and trans-sulfanes. They were compared to each other and to their acyclic or cyclic known analogs that comprise common subunits. 8-, 9-, 10-, and 12-membered disulfanes exist as trans isomers exclusively both in the solid state and in solution. They are significantly more stable than their hypothetical cis isomers, as shown by DFT calculations. The PSSP torsion angles of cyclic disulfanes lie in the range of 94° to 125° and increase with the size of the ring. These values are greater than the typical torsion angles found for the respective non-cyclic disulfanes. The greater stability of the cis-sulfanes was confirmed by calculations and can be ascribed mainly to the characteristic anisyl–anisyl stacking. Special attention was paid to the importance and the role of weak hydrogen bonds (CH...O/S) in conformational stabilization and intermolecular interactions. The conformations of cyclic disulfanes and cyclic sulfanes found in the crystalline state were also preserved in solution (variable temperature NMR). A Karplus relationship has been established between the dihedral angles and vicinal H–P coupling constants for all disulfanes and sulfanes. The effects of solvent on the 1H NMR chemical shifts (ASIS) were determined and were associated with the dipole moments of the sulfanes. [ABSTRACT FROM AUTHOR]

The first synthesis of benzoxaphospholenes dates back to the 1960s. Since then, the structural variety of reported (benz)oxaphospholenes has steadily increased. Organophosphorus compounds have caught the interest of synthetic chemists for a couple of decades now because of their interesting biological properties. Oxaphospholenes, in particular, could serve as carbohydrate mimetics, and benzoxaphospholenes have been reported to possess bactericidal, insecticidal, herbicidal, and fungistatical properties. Transesterification reactions and addition of phosphorus nucleophiles to carbonyl compounds were reaction types that led to the production of the first (benz)oxaphospholenes. When it was discovered that allenylphosphonates could easily be obtained from propargyl alcohols and dialkyl halophosphites, the electrophile-induced cyclization reaction of these allenylphosphonate precursors resulted in a huge boom in the amount of reports on oxaphospholene synthesis. To this day, this method is still frequently used. Ring-closing metathesis and Horner-Wadsworth-Emmons reactions have also proven their potential for the preparation of oxaphospholenes. In recent years, Pd, Rh and Au-catalysis have made their entry, generating (benz)oxaphospholenes from a wide variety of simple substrates. A couple of miscellaneous methods are summarized at the end of the Review. [ABSTRACT FROM AUTHOR]

Among the alternative host materials for solid polymer electrolytes (SPEs), polycarbonates have recently shown promising functionality in all-solid-state lithium batteries from ambient to elevated temperatures. While the computational and experimental investigations of ion conduction in conventional polyethers have been extensive, the ion transport in polycarbonates has been much less studied. The present work investigates the ionic transport behavior in SPEs based on poly(trimethylene carbonate) (PTMC) and its co-polymer with ε-caprolactone (CL) via both experimental and computational approaches. FTIR spectra indicated a preferential local coordination between Li+ and ester carbonyl oxygen atoms in the P(TMC20CL80) co-polymer SPE. Diffusion NMR revealed that the co-polymer SPE also displays higher ion mobilities than PTMC. For both systems, locally oriented polymer domains, a few hundred nanometers in size and with limited connections between them, were inferred from the NMR spin relaxation and diffusion data. Potentiostatic polarization experiments revealed notably higher cationic transference numbers in the polycarbonate based SPEs as compared to conventional polyether based SPEs. In addition, MD simulations provided atomic-scale insight into the structure–dynamics properties, including confirmation of a preferential Li+–carbonyl oxygen atom coordination, with a preference in coordination to the ester based monomers. A coupling of the Li-ion dynamics to the polymer chain dynamics was indicated by both simulations and experiments. [ABSTRACT FROM AUTHOR]