RESUMO
An enantiopure helical ferrocene ( Rp)-5 with five ortho-condensed aromatic rings was synthesized using a PtCl2-catalyzed cycloisomerization of planar-chiral 2-ethynyl-1-(4-phenanthrenyl)ferrocene ( Rp)-6f, prepared in 3 steps from known enantiopure sulfinyl ferrocenyl boronic acid ( SS, Sp)-7, as the source of planar chirality. This pentacyclic helical ferrocene showed a very high optical rotation value and strong circular dichroism (CD) signals.
RESUMO
Progress reaction profiles are affected by both catalyst activation and deactivation processes occurring alongside the main reaction. These processes complicate the kinetic analysis of reactions, often directing researchers toward incorrect conclusions. We report the application of two kinetic treatments, based on variable time normalization analysis, to reactions involving catalyst activation and deactivation processes. The first kinetic treatment allows the removal of induction periods or the effect of rate perturbations associated with catalyst deactivation from kinetic profiles when the quantity of active catalyst can be measured. The second treatment allows the estimation of the activation or deactivation profile of the catalyst when the order of the reactants for the main reaction is known. Both treatments facilitate kinetic analysis of reactions suffering catalyst activation or deactivation processes.
RESUMO
An efficient approach to (Rp) planar-chiral tri- and tetracyclic ortho-condensed aromatic ferrocenes was developed through the enantioselective cationic Au(i)-catalyzed cycloisomerization, in the presence of bidentate phosphine ligand (R)-DTBM-Segphos, from readily available ortho-alkynylaryl ferrocenes under very mild conditions (11 examples, up to 92% yield and 93% ee).
