No abstract

Efficient light-and thermal-activated metathesis reactions of tetra-substituted olefins were obtained by the Schelated ruthenium precatalyst Tol-SCF 3 . Its reactivity in a series of benchmark olefin metathesis reactions was compared to previously reported Mes-SCF 3 and a novel sterically congested S-chelated complex, Dipp-SCF 3 . Tol-SCF 3 is thus the first latent catalyst proven to be capable of promoting olefin metathesis of demanding substrates upon light stimulation at room temperature.

Dendrimers with boronic ester end-groups and an iron porphyrin core were synthesized and characterized. The dendrimer termini were reversibly exchanged by the addition of appropriate diol molecules. According to molecular dynamics (MD) simulations, the exchange of termini may lead to changes in the conformational behavior of the dendrimer, specifically regarding the average position of the end groups relative to the core. The spatial steric disposition attained with different termini was shown to significantly affect epoxidation reaction activity and selectivity with various alkenes, thus allowing for an original way to control and adjust catalytic behavior under alternating environments.

A protocol for the selective photoremoval of alcohol protecting groups modulated by the presence of auxiliary light absorbing molecules is presented. Thus, by this method, a single light source was used to selectively remove a specific protecting group in the presence of another chromophore with a lower molar absorption coefficient. The use of a molecular sunscreen, either internal or external, was found to be crucial to achieve high selectivities.

Beta substituted thiols and various derivatives containing the HX-C-C-SH motif oligomerise in water, preferably in the presence of a carbonate salt. The reaction yields oligomers consisting of one thiol end group, a thiaethylene backbone and an additional terminal group corresponding to the starting material used.Mechanistic studies, as well as the scope of substrates and products of these new promising condensation processes, are presented. In addition, strong nucleophiles were also reacted with mercaptoethanol under simple reaction conditions, leading to the selective formation of more complex molecules.