Solid phase reaction resin

Despite the relative infancy in the development of solid phase reactions, a wide range of functionalised resins are commercially available. The main uses of these functionalised resins can be roughly classified as follows ... 

For general solid-phase reactions in a dedicated multimode instrument, an adaptable filtration unit is available from Anton Paar (see Fig. 3.18). This tool is connected to the appropriate reaction vessel by a simple screw cap and after turning over the vessel, the resin is filtered by applying a slight pressure of up to 5 bar. The resin can then be used for further reaction sequences or cleavage steps in the same reaction vessel without any material loss. However, at the time of writing, no applications of this system for solid-phase synthesis had been reported. 

To 11.Og (12.3 mmol) of Wang resin (Note 1) in an oven-dried, solid-phase reaction flask (Note 2) equipped with an overhead stirrer and a nitrogen line attached to a bubbler was added 100 mL dichloromethane. The resultant slurry was allowed to stir for... 

Another traditional method used for polymer support characterization is elemental analysis. Its use as an accurate quantitative technique for monitoring solid-phase reactions has also been demonstrated [146]. Microanalysis can be extremely valuable if a solid-phase reaction results in the loss or introduction of a heteroatom (usually N, S, P or halogen). In addition, this method can be used for determination of the loading level of a functional group (e. g. usually calculated directly from the observed microanalytical data). For example, in many cases, the displacement of chloride from Merrifield resin has been used as a guide to determine the yield of the solid-phase reaction. 

To determine if a solid-phase reaction is complete, on-resin analytical methods are preferable [6]. First, the quantitative or qualitative information obtained from on-resin analysis is more relevant to solid-phase reactions. Secondly, this kind of analysis is fast, direct, and without any alteration to the sample. On the other hand, analysis after cleavage would depend on the cleavage efficiency (to be discussed later) and the stability of analyte to cleavage conditions such as TFA. The... 

Non-chemical Factors Affecting the Completion of Solid-phase Reactions 509 Tab. 12.2 Rate constants (xlOOO L/s) for reactions carried out on resin beads with different sizes... 

The rate of a chemical reaction depends on temperature. A rule of thumb for many organic reactions in solution is that a 10 °C change in temperature causes a two- to three-fold change in rate of reaction [25]. To study the temperature dependence of solid-phase reactions, the cleavage reaction of resin (35) with n-butyla-mine at 20, 40 and 60 °C were carried out. The cleavage time courses and pseudo-first-order rate fits at these three temperatures are shown in Fig. 12.20. The rate constants from single bead FTIR analysis are Hsted in Tab. 12.4. Compared with the reaction at 20 °C, the solid-phase cleavage reaction of resin 3b was two times faster at 40 °C and four times faster at 60 °C. 

The resin-bound perfluoroalkylsulfonyl linker is compatible with many common solid-phase reactions, such as tin dichloride-mediated aromatic nitro group reduction, trifluoroacetic acid-mediated tBoc deprotection, reductive amination reactions, acylation, and sulfonation. It is possible to perform several sequential synthetic reactions on the nonflate resin so that multistep syntheses can be carried out. The solid-phase approach provides an operationally simple, inexpensive, and general protocol for the cleavage... 

Rahman SS, Busby DJ, Lee DC, Infrared and Raman spectra of a single resin bead for analysis of solid-phase reactions and use in encoding combinatorial libraries, J. Org. Chem., 63 6196-6199, 1998. 

Modification of porous inorganic materials by carbon makes it possible to obtain porous carboniferous composites with high thermal and chemical stability and strength. To introduce carbon into pores, both gas phase pyrolysis and carbonization through thermochemical solid-phase reactions are employed. The formation of carbon structures depends on carbonization conditions process rate, precursor concentration, presence of catalyst, etc. [1-3]. Phenolic resins, polyimides, carbohydrates, condensed aromatic compounds are most widely used as polymeric and organic precursors[4-6]. 

CjCqmHBFJ Pd(PPh3)4 Na2C03 110 °C. Solid-phase reaction coupling of 4-iodophenol immobilised on a polystyrene-Wang resin with arylboronic acids DMF as co-solvent acceleration in the presence of the ionic liquid catalyst recycling not practical. [102]... 

Crotonates bearing an atropisomeric 1-naphthamide moiety can be reacted in a Sml2-mediated reductive coupling with a variety of aldehydes to yield enantiomerically enriched 7-butyrolactones. The crotonate derived from 2-hydroxy-8-methoxy-Tnaphthamide reacted with pentanal to afford the highest ee of >99% in a combined yield of 90% with a cisltrans-mt o of 90 10. The chiral crotonate can also be linked to a Rink amide resin with the C-8 oxygen, and in the solid-phase reaction the same level of axial-to-central chirality transfer was obtained (Equation 103) <2006JOC2445>. 

The dried resin from the previous reaction (100 mg, 0.63 mmol/g loading, 63 pmol) is transferred to a solid-phase reaction vessel, washed, and swelled in dry DMF under an inert atmosphere for at least 1 h. The resin is then washed several times with dry THF and left as a slurry. The first protected amino acid (0.25 mmol) is dissolved in dry THF, HOBt is added, and the solution cooled... 

The good swelling properties of a peptide resin not only determines its diffusion properties, and therefore the kinetics of a solid-phase reaction,P 9 but also are a requirement for ensuring a uniform distribution of the growing peptide chains throughout the polymeric support. This uniform distribution can actually be achieved, at least in favorable cases, as was shown by an elegant experiment performed by Sarin et al.t where Boc-PH]valine was incorporated into a peptide synthesis and autoradiographs of cross sections of peptide resin beads showed a completely uniform pattern. 

When FTIR spectroscopy is carried out under defined conditions, it provides both quahtative and quantitative information on the performed solid-phase reaction.t Using difference measurements of the sohd support before and after the reaction, absorption bands can be detected which otherwise would be seen only as weak shoulders. The absorption band of H—C—Q stretching vibrations (1250 cm ), for example, can serve as the basis for the quantification of the couphng of carboxyhc acids to a chloromethylated PSty-DVB resin.t 1... 

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