Despite recent advances, a general method for the synthesis of α-carbonyl-α'-(hetero)aryl sulfoxonium ylides is needed to benefit more greatly from the potential safety advantages offered by these compounds over the parent diazo compounds. Herein, we report the palladium-catalyzed cross-coupling of aryl bromides and triflates with α-carbonyl sulfoxonium ylides. We also report the use of this method for the modification of an active pharmaceutical ingredient and to the synthesis of a key precursor of antagonists of the neurokinin-1 receptor. In 2 addition, the mechanism of the reaction was inferred from several observations. Thus, the oxidative addition complex [(XPhos)PhPdBr] and its dimer were observed by 31 P{ 1 H} NMR and these complexes were shown to be catalytically and kinetically competent. Moreover, a complex resulting from the transmetallation of [(XPhos)ArPdBr] (Ar = p-CF3-C6H4) with a model sulfoxonium ylide was observed by mass spectrometry. Finally, the partial rate law suggests that the transmetallation of and the subsequent deprotonation are rate-determining in the catalytic cycle.
Six biphasic systems containing heptane, ethanol, and either hydrogen bond donor compounds (HBD), glycerol, ethylene glycol, levulinic acid, or the corresponding choline chloride-based DES were studied as potential extracting systems for five natural compounds, namely, quercetin, apigenin, coumarin, β-ionone, and α-tocopherol. Phase diagrams for all biphasic systems are reported. It appears that the polarity of the HBD is the most relevant property driving the phase separation and that choline chloride has only a minor influence on the phase diagram. Measurements of the partition coefficients for the five natural compounds mentioned above reveal that the influence of choline chloride on the partition coefficient of a natural compound is only significant when the latter is present in both phases. Finally, binodal curves and partition coefficients were calculated using a conductor-like screening model for real solvents (COSMO-RS). Calculated and experimental results are in good agreement, confirming that COSMO-RS is a useful and promising tool for screening such complex biphasic systems to find the most adequate system for purifying specific natural compounds.
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