2768-15-2Relevant articles and documents
Slippage of a porphyrin macrocycle over threads of varying bulkiness: Implications for the mechanism of threading polymers through a macrocyclic ring
Deutman, Alexander B. C.,Varghese, Shaji,Moalin, Mohamed,Elemans, Johannes A. A. W.,Rowan, Alan E.,Nolte, Roeland J. M.
, p. 360 - 370 (2015)
Threading of a polymer through a macrocyclic ring may occur directly, that is, by finding the end of the polymer chain, or by a process in which the polymer chain first folds and then threads through the macrocyclic ring in a hairpin-like conformation. We present kinetic and thermodynamic studies on the threading of a macrocyclic porphyrin receptor (H21) onto molecular threads that are blocked on one side and are open on the other side. The open side is modified by groups that vary in ease of folding and in bulkiness. Additionally, the threads contain a viologen binding site for the macrocyclic receptor, which is located close to the blocking group. The rates of threading of H21 were measured under various conditions, by recording as a function of time the quenching of the fluorescence of the porphyrin, which occurs when receptor H21 reaches the viologen binding site. The kinetic data suggest that threading is impossible if the receptor encounters an open side that is sterically encumbered in a similar way as a folded polymer chain. This indicates that threading of polymers through macrocyclic compounds through a folded chain mechanism is unlikely.
Radical reduction of epoxides using a titanocene(III)/water system: Synthesis of β-deuterated alcohols and their use as internal standards in food analysis
Jimenez, Tania,Campana, Araceli G.,Bazdi, Btissam,Paradas, Miguel,Arraez-Roman, David,Segura-Carretero, Antonio,Fernandez-Gutierrez, Alberto,Oltra, J. Enrique,Robles, Rafael,Justicia, Jose,Cuerva, Juan M.
experimental part, p. 4288 - 4295 (2010/10/21)
We describe a comprehensive study into the Cp2TiCl-mediated reductive epoxide ring opening using either water as a hydrogen source or deuterium oxide as a deuterium source. The remarkable chemical profile of this reaction allows access to alcohols with anti-Markovnikov regiochemistry from different epoxides. The use of D2O as a deuterium source leads to an efficient synthesis of β-deuterated alcohols, including a deuterated sample of tyrosol, a bioactive compound contained in the leaves of the olive, which was successfully applied as an internal standard in food analysis.
