Solution-phase study procedure

The resin-bound trienes 83 (Scheme 11) were prepared in a similar fashion to the solution-phase studies (Sect. 2.2.2) and underwent tandem RCM resin-cleavage to liberate four macrolactones 84a,b and 85a,b in a combined yield of 52%. Although, as expected, a large amount of initiator 3 was required to effect this transformation, the procedure constituted a novel and efficient route to the epothilones which paved the way for the generation of a library of epothilone analogs. The library synthesis was achieved using the recently developed SMAR-I9 microreactors (SMART=single or multiple addressable radiofrequency tag) [25] (Scheme 12). 

For the development of an appropriate strategy for cleavage from the novel syringaldehyde resin, the authors adapted a previously elaborated solution-phase model study on intramolecular Diels-Alder reactions for the solid-phase procedure (Scheme 7.60). The resulting pyridines could be easily separated from the polymer-bound by-products by employing a simple filtration step and subsequent evaporation of the solvent. The remaining resins were each washed and dried. After drying,... 

The Claisen rearrangement of allyl vinyl ether in aqueous solution was studied by Gao et al. [157] by using the gas-phase ab initio MEP determined previously by the Jorgensen s group [60], In this case, 69 of the 143 frames were employed along the perturbation procedure in the isothermal-isobaric ensemble at 25 °C and 1 atm. The... 

Electrodeposition is by its nature a condensed phase process, whereas most studies of ALE have been performed using gas phase or vacuum methodologies, CVD or MBE. A solution phase deposition methodology related to ALE has been developed in France by Nicolau et al. [27-32] (Fig. 2), in which adsorbed layers of elements are formed by rinsing a substrate in aqueous solutions containing ionic precursor for the desired elements, sequentially, in a cycle. After exposure to each precursor, the substrate is copiously rinsed and then transferred to a solution containing the precursor for the next element. The method is referred to as successive ionic layer adsorption and reaction (SILAR). Reactivity in SILAR appears to be controlled by the rinsing procedure, solution composition, pH, and specifically... 

In this study, a factorial experiment was set up to evaluate the effects of four variables at two levels on extraction efficiencies by using bonded-phase isolation techniques and a 27-component synthetic test mixture. The compounds studied and the respective mass ions used for quantitation are given in the box. The compounds in the mix vary greatly in water solubility and volatility and, in general, represent a wide class of organic compounds typical of those present in environmental samples. To maximize solute recoveries, the procedure was... 

Several model reactions were studied by Sordo et al. at the MP2/6-31G //RHF/ 6-31G, B3LYP/6-31G, and RHF/6-31G //RHF/3-21G levels of theory, both in the gas phase and in anisole (e = 4.33) and (V,(V-dimethylformamide (e = 37.0) solution, using SCRF procedures. Under these conditions, both concerted [n2s + n2a] and stepwise mechanisms were found, although only the latter were obtained in solution (Scheme 20). 

Drugs placed on the surface of hair must have some mechanism for entry into the hair matrix. If a solid is placed on the hair surface, most of it can be readily removed. However, after the deposition of the solid drugs onto the hair surface, hair may be bathed at some point in an aqueous media, be that sweat, sebum, normal hygienic solutions, or during the hair analysis procedure. Alternatively, an individual might come in contact with a solution of a drug by transfer of sweat from another individual. It is for these reasons that we and others studied solution phase transfer as the vector for admission and incorporation of drugs into hair. 

Another approach to the assessment of ion speciation in the resin and solution phases with equal ility for the determination of formation constants of complexes in these two environments is provided by NMR spectroscopy. The method can provide sharp, well-separated signals for each successive complex species formed, the peak area being proportional to the atomic concentration of the element being measured, irrespective of its complex form. For a completely labile system, a well-defined chemical shift change is often observed with successive complex formation. These features make this analytical procedure well suited for study of metal ion complexation by the ion-exchanger phase. 

The synthesis of rubyrin 7.25 involves an acid-catalyzed 4 + 2 MacDonald-type condensation between the diformyl bipyrrole 7.21 and the diacid tetrapyrrane 7.23 (Scheme 7.2.1). After oxidation and purification, a roughly 20% yield of a blue crystalline solid is obtained, which, on the basis of solution-phase spectroscopic and solid-state structural studies vide infra), was assigned the hexapyrrolic structure 7.25. Using a similar procedure, rubyrins 7.26 and 7.27 were also prepared. While the first of these (like 7.25) proved stable, rubyrin 7.27 was found to decompose during chromatographic purification. It was thus characterized only by UV-vis spectroscopy and mass spectrometry. ... 

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