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The catalytic activity of novel two-coordinate palladium N-heterocyclic carbene complexes that differ in their steric and electronic properties is compared in catalytic amination and Suzuki-Miyaura cross-couplings. 相似文献
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Ipsita Devi 《Tetrahedron letters》2004,45(47):8625-8627
Sodium bromide catalysed three-component cyclocondensation of aryl aldehydes, alkyl nitriles and dimedone proceeds under microwave irradiation in solvent free conditions to give highly functionalised tetrahydrobenzo[b]pyrans in excellent yields. 相似文献
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The Diels-Alder reaction of enantiomerically pure (E)-γ-keto-α,β-unsaturated p-tolylsulphoxides 3 with cyclopentadiene give four easily separable diastereomers. The effect of several Lewis acids on the reaction was studied, finding a high endo selectivity with respect to the carbonyl group and moderate π-diastereoselectivity using BF3·Et2O as catalyst. The reactivity of compounds 3 as well as their endo selectivity are both higher than those observed for the corresponding (E)-3-sulfinylacrylates. 相似文献
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S. S. E. H. Elnashaie M. A. El-Rifai G. Ibrahim 《Applied biochemistry and biotechnology》1983,8(4):275-288
The phenomenon of multiplicity is investigated for an isothermal continu ous stirred tank reactor (CSTR) in which an enzyme
reaction producing hydrogen ions is taking place. The activity of the enzyme considered is sensitive to the hydrogen ion concentration
and is inhibited by excess substrate. The enzyme is bound and the washout phenomenon is negligible.
The investigation has uncovered a new type of hysteresis, consisting of a closed curve on the multiplicity diagram, and is
disconnected from the rest of the multiplicity curve. This phenomenon has also been observed and analyzed by Uppal et al.
(1) in their investigation of the non-isothermal, non-adiabatic (CSTR), and they have termed those closed curves “Isolas.” In
the present paper we have elucidated the physical reason for the occurrence of those “Isolas” for the enzymatic reaction under
consideration. We have also investigated the effect of different parameters on the appearance, disappearance, and size of
the “Isolas.” 相似文献
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