Krystyna Baczko

Thermoregulated aqueous biphasic catalysis of Heck reactions using an amphiphilic dipyridyl-based ligand

A neat water-based thermoregulated system for Pd-catalyzed Heck reactions is described. It uses a thermo-responsive ligand L that enables (1) the transfer of the catalyst in the organic phase upon heating thus allowing the reaction to take place in one phase, and (2) the separation/recovery of the catalyst in the water phase upon cooling and hence catalyst reuse. The amphiphilic ligand L with an inverse temperature-dependent solubility in water is prepared by covalent attachment of 2,2′-dipyridylamine to the tip of a nonionic polyoxyethylene surfactant (decyloctaethyleneglycol C10E8). Spectroscopic studies reveal that the amphiphilic dipyridyl-based ligand L forms a 1 : 1 Pd complex (PdLCl2) in organic solvent and a 1 : 2 Pd complex in water. Cross-coupling reactions of iodobenzene with ethyl acrylate and styrene are achieved, without any organic solvent, at 100–120 °C with sodium carbonate as a base using 0.1 to 0.5 mol% of Pd catalyst generated in water from L and Na2PdCl4. The reaction products, trans-cinnamic acid and stilbene, are readily isolated at room temperature, and the catalyst is recovered in the aqueous phase, without the need to add any organic solvent. The aqueous phase can be used in three catalytic runs with an almost constant catalytic activity for the coupling of iodobenzene with ethyl acrylate.

Synthesis and surfactant properties of symmetric and unsymmetric sulfosuccinic diesters, Aerosol-OT homologues

The synthesis and surfactant behaviour of two series of sulfosuccinic diesters, AOT-related compounds, are described [Aerosol-OT 1: sodium bis(2-ethylhexyl) sulfosuccinate]. The first family contains unsaturated, racemic or enantiopure, 2-ethylhex(en)yl chains with various positions of the double bond. These compounds are readily prepared from the corresponding unsaturated alcohol by the standard two-step procedure; their critical micelle concentrations are higher than those of normal AOT and depend on the position of the double bond. The second series consists of nonsymmetric homologues with two different substituents: various unsymmetrical sulfosuccinic diesters with two enantiopure saturated or unsaturated chains of opposite configuration, or with two different substituents like methyl and 2-ethylhexyl, hydrogenated and deuterated chains as well as saturated and unsaturated chains are described. These unsymmetrical sulfosuccinic diesters are readily obtained in a three-step synthetic procedure involving the regiospecific sulfonation of maleic monoester in aqueous medium. The structure of the sodium 4-alkyl-2-sulfosuccinic acid key intermediate is unambiguously resolved by NMR comparative analysis of the hydrogenated and deuterated derivatives. The surfactant behaviour of some unsymmetrical compounds is studied.

Sequential Copper-Catalyzed Alkyne-Azide Cycloaddition and Thiol-Maleimide Addition for the Synthesis of Photo- and/or Electroactive Fullerodendrimers and Cysteine-Functionalized Fullerene Derivatives.

In this study, the functionalization of a fullerene building block in a stepwise process by means of the copper-catalyzed alkyne-azide cycloaddition (CuAAC) and thiol-maleimide reactions is reported. Grafting of the fullerene platform with a variety of azido derivatives, including Bodipy, pyrene and ferrocene, was carried out first. These fullerene compounds were then reacted with thiol derivatives to yield sophisticated structures comprising photo- and/or electroactive fullerodendrimers and cysteine-functionalized fullerene assemblies. This strategy, which combines the CuAAC and thiol-maleimide processes, could become more widely adopted in the field of fullerene chemistry.