Radiofrequency encoding

Each microreactor consists of a polymer-bound substrate and a radiofrequency encoded microchip enclosed within a small porous vessel. The radiofrequency tag allows the identity of the substrate contained within each microreactor to be established readily. Using this technology, the polymer-bound substrates 86 were individually elaborated, within separate microreactors, by sequential reactions with acids 87 and alcohols 88 in a similar way to the solution-phase processes [25c]. Each of the microreactors was then subjected to the tandem RCM resin-cleavage conditions employing initiator 3. The products from each microreactor were obtained as a mixture of four compounds (89-92). The library of analogs prepared by this technique was then screened for biological activity [25c]. 

Fig. 5. Pulse sequence for MR detection of vibration using a radiofrequency field gradient. A binomial 1331 radiofrequency pulse (pulse length D, interpulse delay r) is applied in-phase with the mechanical wave. Thus the vibration period 7V is equal to 4(D + r). The number of cycles can be increased to ensure a better frequency selectivity. The constant RF field gradient generated by a dedicated RF coil allows space encoding without using conventional static field gradients (from Ref. 16 with permission from Elsevier).

Xiao, X.-Y. Parandoosh, Z. Nova, M. P. Design and Synthesis of aTaxoid Library Using Radiofrequency Encoded Combinatorial Chemistry, J. Org. Chem. 1997, 62, 6029. 

An intermediate level of sophistication was achieved by semiautomated sorting of radiofrequency tagged containers (e.g., MicroKans,8 Lanterns11). A simple instrument that integrates the process of one-dimensional necklace encoding by creating a linear sequences of solid-phase particles is the Encore synthesizer. 

A. Split-Mix Synthesis Using Resin Enclosed in Radiofrequency-Encoded Capsules... 

Moran EJ, Sarshar S, Cargill JF, Shahbaz M, Lio A, Mjalli AMM, Armstrong RW, Radiofrequency tog encoded combinatorial library method for the discovery of tripeptide-substituted cinnamic acid inhibitors of the protein tyrosine phosphatase PTPSB J. Am. Chem. Soc., 117 10787-1788, 1995. 

Nicolaou KC, Xiao X-Y, Parandoosh Z, Senyei A, Nova MP, Radiofrequency encoded combinatorial chemistry, Angew. Chem. Inti. Ed. Engl., 34 2289-2291, 1995. 

Recently two different groups [82, 83] reported the use of radiofrequency tags for the encoding of chemical libraries. While the materials used were different, the coding strategy was rather similar and it is depicted schematically in Figure 9.20. 

Xiao X, Parandoosh Z, Nova MP, Design and synthesis of a taxoid library using radiofrequency encoded combinatorial chemistry, J. Org. Chem. 62 6029-6033, 1997. 

Sofia et al. (41) reported a SP library of disaccharides L7 made by 1300 individuals and inspired by the disaccharide core of moenomycin A, a bacterial cell wall inhibitor (Fig. 4.8). Both the structure of the library and its main features are shown in Fig. 4.8. The four major disaccharide scaffolds (X, Y, and W variations) were either built on resin via glycosylation or attached onto the photolabile linker, and subsequently decorated by introduction of Ri, R2, and R3 radiofrequency encoding (42) was used to obtain a large number of discretes with an affordable number of reactions. The... 

A more complex combinatorial strategy based on a natural scaffold was reported by Nicolaou et al. (56) with the synthesis of an epothilone-based SP library L27 (Fig. 4.18). This biased library was prepared asa3x3x5 = 45-member collection, but the final reaction vessels could, theoretically contain 4 different isomeric desoxyepothi-lones (Fig. 4.18), thus leading to a total number of 45 x 4 = 180 components. The library was prepared using a radiofrequency encoding technique (42), and the final... 

An Example Synthesis of a Tyrphostin Radiofrequence Encoded Library... 

Figure 7.36 Radiofrequency encoding directed sorting for a hypothetical 16-member discrete library.

Figure 7.38 SP synthesis of a radiofrequency encoded, 432-member discrete tyrphostin-inspired library LIO.

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