Substrate studies coupling reactions

In the second series of experiments, O. Nuyken et al. investigated the Heck reaction of iodobenzene with styrene as a model for the numerous palladium-catalyzed coupling reactions (Scheme 6.6) [54]. In the literature only a few Heck coupling reactions of hydrophobic substrates in aqueous solution are known. The most detailed study has been performed by Jeffery et al. on the model reaction of iodobenzene with methylacrylate in the presence of tetrabutylammonia salts. Product yield was at least 95% after 2 h reaction time at 50 °C in pure aqueous solution [55], however more... 

Reetz and Sommer then studied the intramolecular hydroarylation of alkynes when they were looking for carbon triple bond coupling reactions. Depending on the substrate, the choice of gold(I) or gold(III) species was crucial [127]. 

A full consideration of the mechanism of the sodium pump requires an account of the role of the lipid, the binding sites for Na+, K+, Mg2+ and ATP, the mechanism of hydrolysis of ATP and the way in which this is coupled to the transport of the cation. In addition it should be noted that the enzyme also functions as a K+-dependent phosphatase, a reaction usually studied with p-nitrophenyl phosphate as substrate. Studies with inhibitors have been informative, notably with ouabain and with vanadate. Ouabain binds at one site per pump and so has been of value in quantitatively defining the enzyme in various preparations. 

In one of the recent studies on the chemical coupling reaction, Axen (1) succeeded in bonding an enzyme covalently onto an insoluble polymer by employing the isothiocyanate as the chemical coupler. The enzyme retained all its catalytic activities. The method used by us to attach heparin onto a polymer substrate made use of a pendant isocyanate... 

Coupled assays have been used to monitor a variety of different enzymatic reactions and can be split into two types chemically coupled and enzymatically coupled assays. In the former type, the product of the enzymatic reaction under study is detected by reaction with a reactive chemical to allow easy detection of the analyte of interest.23 In enzymatically coupled reactions, the products or substrates of the reaction of interest are acted upon by a second enzyme, creating a tangible readout. One advantage of using such a standardised assay format is that the development of such a method allows the activity of a family of enzymes to be monitored by a single detection method.24,25 The... 

The coupling of alkenyltrialkyltins is a general and a synthetically useful reaction. Most studies are on easily available 1,2-disubstituted substrates which couple efficiently with good stereospecificity except for some of Z substrates. 

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